diff --git a/.gitignore b/.gitignore
index a63b224..ed7f03a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -52,4 +52,7 @@ atlassian-ide-plugin.xml
 .idea/sonarlint/
 
 # Editor-based Rest Client
-.idea/httpRequests
\ No newline at end of file
+.idea/httpRequests
+
+# Local Properties
+local.properties
\ No newline at end of file
diff --git a/.idea/libraries/bld.xml b/.idea/libraries/bld.xml
index f713fc9..0f59db6 100644
--- a/.idea/libraries/bld.xml
+++ b/.idea/libraries/bld.xml
@@ -2,11 +2,11 @@
   <library name="bld">
     <CLASSES>
       <root url="file://$PROJECT_DIR$/lib/bld" />
-      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.14.jar!/" />
+      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.16.jar!/" />
     </CLASSES>
     <JAVADOC />
     <SOURCES>
-      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.14-sources.jar!/" />
+      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.16-sources.jar!/" />
     </SOURCES>
     <excluded>
       <root url="jar://$PROJECT_DIR$/lib/bld/bld-wrapper.jar!/" />
diff --git a/.idea/misc.xml b/.idea/misc.xml
index 4747f6b..a9eecbd 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -6,6 +6,9 @@
     <pattern value="rife.bld.extension.propertyFile.Entry" method="key" />
     <pattern value="rife.bld.extension.propertyFile.Entry" method="operation" />
     <pattern value="rife.bld.extension.propertyFile.Entry" method="unit" />
+    <pattern value="rife.bld.extension.propertyfile.Entry" method="delete" />
+    <pattern value="rife.bld.extension.propertyfile.Entry" />
+    <pattern value="rife.bld.extension.propertyfile.Entry" method="setDelete" />
   </component>
   <component name="PDMPlugin">
     <option name="skipTestSources" value="false" />
diff --git a/.vscode/settings.json b/.vscode/settings.json
index bce4c6c..2aea7f2 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -7,7 +7,7 @@
     ],
     "java.configuration.updateBuildConfiguration": "automatic",
     "java.project.referencedLibraries": [
-        "${HOME}/.rife2/dist/rife2-1.5.14.jar",
+        "${HOME}/.rife2/dist/rife2-1.5.16.jar",
         "lib/compile/*.jar",
         "lib/runtime/*.jar",
         "lib/test/*.jar"
diff --git a/README.md b/README.md
index 44d334e..277bf16 100755
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # [Bld](https://github.com/rife2/rife2/wiki/What-Is-Bld) Extension to Create or Modify Properties Files
 
 [![License (3-Clause BSD)](https://img.shields.io/badge/license-BSD%203--Clause-blue.svg?style=flat-square)](http://opensource.org/licenses/BSD-3-Clause)
+[![Java](https://img.shields.io/badge/java-17%2B-blue)](https://www.oracle.com/java/technologies/javase/jdk17-archive-downloads.html)
 [![GitHub CI](https://github.com/rife2/bld-property-file/actions/workflows/bld.yml/badge.svg)](https://github.com/rife2/bld-property-file/actions/workflows/bld.yml)
 
 An extension for creating or modifying [property files](https://docs.oracle.com/javase/tutorial/essential/environment/properties.html) with [bld](https://github.com/rife2/rife2/wiki/What-Is-Bld). It is inspired by the [ant PropertyFile task](https://ant.apache.org/manual/Tasks/propertyfile.html).
@@ -10,13 +11,12 @@ An extension for creating or modifying [property files](https://docs.oracle.com/
 public void updateMajor() throws Exception {
     new PropertyFileOperation(this)
             .file("version.properties")
-            .entry(new Entry("version.major").defaultValue(0).type(Types.INT).operation(Operations.ADD))
-            .entry(new Entry("version.minor").value(0))
-            .entry(new Entry("version.patch").value(0))
-            .entry(new Entry("build.date").value("now").pattern("yyyy-MM-dd").type(Types.DATE))
+            .entry(new Entry("version.major", Types.INT).defaultValue(0).calc(ADD))
+            .entry(new Entry("version.minor").set(0))
+            .entry(new Entry("version.patch").set(0))
+            .entry(new Entry("build.date", Types.DATE).set("now").pattern("yyyy-MM-dd"))
             .execute();
 }
-
 ```
 Invoking the `updateMajor` command, will create the `version.propertees`file:
 
@@ -52,42 +52,41 @@ version.patch=0
 
 The `PropertyFileOperation` class is used to configure the [properties file](https://docs.oracle.com/javase/tutorial/essential/environment/properties.html) location, etc.
 
-| Attribute       | Description                                                      | Required |
-|:----------------|:-----------------------------------------------------------------|:---------|
-| `file`          | The location of the properties files to modify.                  | Yes      |
-| `comment`       | Comment to be inserted at the top of the properties file.        | No       |       
-| `failOnWarning` | If set to `true`, will cause executiion to fail on any warnings. | No       |        
+| Function          | Description                                                     | Required |
+|:------------------|:----------------------------------------------------------------|:---------|
+| `file()`          | The location of the properties files to modify.                 | Yes      |
+| `comment()`       | Comment to be inserted at the top of the properties file.       | No       |       
+| `failOnWarning()` | If set to `true`, will cause execution to fail on any warnings. | No       |
 
 ## Entry
 
 The `Entry` class is used to specify modifications to be made to the [properties file](https://docs.oracle.com/javase/tutorial/essential/environment/properties.html).
 
-| Attribute      | Description                                                                                                                                                                                                                                                                                 |
-|:---------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `key`          | The name of the property name/value pair.                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                   
-| `value`        | The value of the property.                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                  
-| `defaultVlaue` | The initial value to set for the property if not already defined. For `Type.DATE`, the `now` keyword can be used.                                                                                                                                                                           |                                                                                                                                                                           
-| `type`         | Tread the value as `Types.INT`, `Types.DATE`, or `Types.STRING`. If none specified, `Types.STRING` is assumed.                                                                                                                                                                              |                                                                                                                                                                              
-| `operation`    | See [operations](#operations).                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                              
-| `pattern`      | For `Types.INT` and `Types.DATE` only. If present, will parse the value as [DecimalFormat](https://docs.oracle.com/javase/7/docs/api/java/text/DecimalFormat.html) or [SimpleDateFormat](https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html) patterns, respectively. |
-|  `unit`        | The unit value to be applied to `Operations.ADD` and `Operations.SUBTRACT` for `Types.DATE`. See [Units](#units).                                                                                                                                                                           |                                                                                                                                                                          
+| Function         | Description                                                                                                                                                                                                                                                                                 |
+|:-----------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `key()`          | The name of the property name/value pair.                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                   
+| `set()`          | The value to set the property to, regardless of its previous value.                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                  
+| `defaultValue()` | The initial value to set for the property to, if not already defined.                                                                                                                                                                                                                       |                                                                                                                                                                           
+| `type()`         | The value datatype, either `Types.INT`, `Types.DATE`, or `Types.STRING`. If none specified, `Types.STRING` is assumed.                                                                                                                                                                      |                                                                                                                                                                              
+| `pattern()`      | For `Types.INT` and `Types.DATE` only. If present, will parse the value as [DecimalFormat](https://docs.oracle.com/javase/7/docs/api/java/text/DecimalFormat.html) or [SimpleDateFormat](https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html) patterns, respectively. |
+| `unit()`         | The unit value to be used with `Types.DATE` calculations. See [Units](#units).                                                                                                                                                                                                              |                                                                                                                                                                          
 
-`key` is required. `value` or `defaultValue` are required unless the `operation` is `Operations.DELETE`.
+- For convenience the `key` (and optional `type`) is first set in the constructor.
+- `key` is required. `value` or `defaultValue` are required except when deleting.
+-  For `Type.DATE`, the `now` keyword can be used as the property value.
 
-## Operations
+## Functions
 
-The following operations are available:
-
-| Operation              | Description                                                               |
-|:-----------------------|:--------------------------------------------------------------------------|
-| `Operations.ADD`       | Adds a value to an entry.                                                 |
-| `Operations.DELETE`    | Deletes an entry.                                                         |
-| `Operations.SET`       | Sets the entry value. This is the default operation.                      |
-|  `Operations.SUBTRACT` | Subtracts a value from the entry. For `Types.INT` and `Types.DATE` only.  |
+The following function are available:
 
+| Function   | Example                                                                                                 | Description                                |
+|:-----------|:--------------------------------------------------------------------------------------------------------|:-------------------------------------------|
+| `calc()`   | `calc(ADD)`<br/>`calc(v -> v + 1)`<br/>`calc(SUB)`<br/>`calc(v -> v - 1)`                               | Perform a calculation with an entry value. |
+| `modify()` | `modify("-foo", String::concat)`<br/>`modify("-foo", (v, s) -> v + s)`<br/>`modify((v, s) -> v.trim())` | Modify an entry value.                     |
+| `delete()` | `delete()`                                                                                              | Delete an entry.                           |
 ## Units
 
-The following units are available for `Types.DATE` with `Operations.ADD` and `Operations.SUBTRACT`:
+The following units are available for `Types.DATE`:
 
 * `Units.MILLISECOND`
 * `Units.SECOND`
@@ -98,18 +97,6 @@ The following units are available for `Types.DATE` with `Operations.ADD` and `Op
 * `Units.MONTH`
 * `Units.YEAR`
 
-## Rules
-
-The rules used when setting a property value are:
-
-* If only `value` is specified, the property is set to it regardless of its previous value.
-* If only `defaultValue` is specified and the property previously existed, it is unchanged.
-* If only `defaultValue` is specified and the property did not exist, the property is set to `defaultValue`.
-* If `value` and `defaultValue` are both specified and the property previously existed, the property is set to `value`.
-* If `value` and `defaultValue` are both specified and the property did not exist, the property is set to `defaultValue`.
-
-Operations occur after the rules are evaluated.
-
 ## Differences with the [ant PropertyFile task](https://ant.apache.org/manual/Tasks/propertyfile.html)
 
 * The comments and layout of the original property file will not be preserved.
diff --git a/examples/.idea/libraries/bld.xml b/examples/.idea/libraries/bld.xml
index a0a25eb..0d30585 100644
--- a/examples/.idea/libraries/bld.xml
+++ b/examples/.idea/libraries/bld.xml
@@ -2,12 +2,12 @@
   <library name="bld">
     <CLASSES>
       <root url="file://$PROJECT_DIR$/lib/bld" />
-      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.14.jar!/" />
+      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.16.jar!/" />
       <root url="file://$PROJECT_DIR$/lib/bld" />
     </CLASSES>
     <JAVADOC />
     <SOURCES>
-      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.14-sources.jar!/" />
+      <root url="jar://$USER_HOME$/.rife2/dist/rife2-1.5.16-sources.jar!/" />
       <root url="file://$PROJECT_DIR$/lib/bld" />
     </SOURCES>
     <jarDirectory url="file://$PROJECT_DIR$/lib/bld" recursive="false" />
diff --git a/examples/.idea/misc.xml b/examples/.idea/misc.xml
index 4af0048..7010ea3 100644
--- a/examples/.idea/misc.xml
+++ b/examples/.idea/misc.xml
@@ -1,10 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="EntryPointsManager">
+    <list size="1">
+      <item index="0" class="java.lang.String" itemvalue="rife.bld.BuildCommand" />
+    </list>
     <pattern value="com.example.PropertyFileExampleBuild" />
     <pattern value="com.example.PropertyFileExampleBuild" method="updateMajor" />
     <pattern value="com.example.PropertyFileExampleBuild" method="updateMinor" />
     <pattern value="com.example.PropertyFileExampleBuild" method="updatePatch" />
+    <pattern value="com.example.PropertyFileExampleBuild" method="deleteVersion" />
   </component>
   <component name="PDMPlugin">
     <option name="skipTestSources" value="false" />
diff --git a/examples/.vscode/settings.json b/examples/.vscode/settings.json
index bce4c6c..2aea7f2 100644
--- a/examples/.vscode/settings.json
+++ b/examples/.vscode/settings.json
@@ -7,7 +7,7 @@
     ],
     "java.configuration.updateBuildConfiguration": "automatic",
     "java.project.referencedLibraries": [
-        "${HOME}/.rife2/dist/rife2-1.5.14.jar",
+        "${HOME}/.rife2/dist/rife2-1.5.16.jar",
         "lib/compile/*.jar",
         "lib/runtime/*.jar",
         "lib/test/*.jar"
diff --git a/examples/lib/bld/bld-wrapper.jar b/examples/lib/bld/bld-wrapper.jar
index b372bbc..ca16d0f 100644
Binary files a/examples/lib/bld/bld-wrapper.jar and b/examples/lib/bld/bld-wrapper.jar differ
diff --git a/examples/lib/bld/bld-wrapper.properties b/examples/lib/bld/bld-wrapper.properties
index b61179e..3689138 100644
--- a/examples/lib/bld/bld-wrapper.properties
+++ b/examples/lib/bld/bld-wrapper.properties
@@ -1,6 +1,6 @@
 #Sun Apr 02 10:32:44 PDT 2023
 bld.extension=com.uwyn.rife2:bld-property-file:0.9.0
-bld.repositories=MAVEN_LOCAL,https\://repo1.maven.org/maven2/
+bld.repositories=MAVEN_LOCAL,RIFE2,https\://repo1.maven.org/maven2/
 bld.downloadExtensionSources=true
 rife2.downloadLocation=
-rife2.version=1.5.14
\ No newline at end of file
+rife2.version=1.5.16
\ No newline at end of file
diff --git a/examples/src/bld/java/com/example/PropertyFileExampleBuild.java b/examples/src/bld/java/com/example/PropertyFileExampleBuild.java
index 966a217..12d44ed 100644
--- a/examples/src/bld/java/com/example/PropertyFileExampleBuild.java
+++ b/examples/src/bld/java/com/example/PropertyFileExampleBuild.java
@@ -3,7 +3,6 @@ package com.example;
 import rife.bld.BuildCommand;
 import rife.bld.Project;
 import rife.bld.extension.propertyfile.Entry;
-import rife.bld.extension.propertyfile.Entry.Operations;
 import rife.bld.extension.propertyfile.Entry.Types;
 import rife.bld.extension.propertyfile.PropertyFileOperation;
 
@@ -12,9 +11,10 @@ import java.util.List;
 import static rife.bld.dependencies.Repository.MAVEN_CENTRAL;
 import static rife.bld.dependencies.Repository.SONATYPE_SNAPSHOTS;
 import static rife.bld.dependencies.Scope.test;
+import static rife.bld.extension.propertyfile.Calc.ADD;
 
 public class PropertyFileExampleBuild extends Project {
-    final Entry buildDateEntry = new Entry("build.date").value("now").pattern("yyyy-MM-dd").type(Types.DATE);
+    final Entry buildDateEntry = new Entry("build.date").set("now").pattern("yyyy-MM-dd").type(Types.DATE);
 
     public PropertyFileExampleBuild() {
         pkg = "com.example";
@@ -27,7 +27,6 @@ public class PropertyFileExampleBuild extends Project {
         scope(test)
                 .include(dependency("org.junit.jupiter", "junit-jupiter", version(5, 9, 2)))
                 .include(dependency("org.junit.platform", "junit-platform-console-standalone", version(1, 9, 2)));
-
     }
 
     public static void main(String[] args) {
@@ -39,11 +38,11 @@ public class PropertyFileExampleBuild extends Project {
         new PropertyFileOperation(this)
                 .file("version.properties")
                 // set the major version to 1 if it doesn't exist, increase by 1
-                .entry(new Entry("version.major").defaultValue(0).type(Types.INT).operation(Operations.ADD))
+                .entry(new Entry("version.major").defaultValue(0).type(Types.INT).calc(ADD))
                 // set the minor version to 0
-                .entry(new Entry("version.minor").value(0))
+                .entry(new Entry("version.minor").set(0))
                 // set the patch version to 0
-                .entry(new Entry("version.patch").value(0))
+                .entry(new Entry("version.patch").set(0))
                 // set the build date to the current date
                 .entry(buildDateEntry)
                 .execute();
@@ -56,9 +55,9 @@ public class PropertyFileExampleBuild extends Project {
                 // set the major version to 1 if it doesn't exist
                 .entry(new Entry("version.major").defaultValue(1))
                 // set the minor version to 0 if it doesn't exist, increase by 1
-                .entry(new Entry("version.minor").defaultValue(-1).type(Types.INT).operation(Operations.ADD))
+                .entry(new Entry("version.minor").defaultValue(-1).type(Types.INT).calc(ADD))
                 // set the patch version to 0
-                .entry(new Entry("version.patch").value(0))
+                .entry(new Entry("version.patch").set(0))
                 // set the build date to the current date
                 .entry(buildDateEntry)
                 .execute();
@@ -73,9 +72,20 @@ public class PropertyFileExampleBuild extends Project {
                 // set the minor version to 0 if it doesn't exist
                 .entry(new Entry("version.minor").defaultValue(0))
                 // set the patch version to 10 if it doesn't exist, increase by 10
-                .entry(new Entry("version.patch").value(10).defaultValue(0).type(Types.INT).operation(Operations.ADD))
+                .entry(new Entry("version.patch").defaultValue(0).type(Types.INT).calc(v -> v + 10))
                 // set the build date to the current date
                 .entry(buildDateEntry)
                 .execute();
     }
+
+    @BuildCommand(summary = "Delete version properties")
+    public void deleteVersion() throws Exception {
+        new PropertyFileOperation(this)
+                .file("version.properties")
+                .entry(new Entry("version.major").delete())
+                .entry(new Entry("version.minor").delete())
+                .entry(new Entry("version.patch").delete())
+                .entry(buildDateEntry.delete())
+                .execute();
+    }
 }
\ No newline at end of file
diff --git a/lib/bld/bld-wrapper.jar b/lib/bld/bld-wrapper.jar
index d80796e..dece4d4 100644
Binary files a/lib/bld/bld-wrapper.jar and b/lib/bld/bld-wrapper.jar differ
diff --git a/lib/bld/bld-wrapper.properties b/lib/bld/bld-wrapper.properties
index f40fc3f..6f6b0bc 100644
--- a/lib/bld/bld-wrapper.properties
+++ b/lib/bld/bld-wrapper.properties
@@ -1,2 +1,2 @@
 #Sat Apr 01 10:09:33 PDT 2023
-rife2.version=1.5.14
+rife2.version=1.5.16
diff --git a/src/bld/java/rife/bld/extension/propertyfile/PropertyFileBuild.java b/src/bld/java/rife/bld/extension/propertyfile/PropertyFileBuild.java
index 0708b54..bca5131 100644
--- a/src/bld/java/rife/bld/extension/propertyfile/PropertyFileBuild.java
+++ b/src/bld/java/rife/bld/extension/propertyfile/PropertyFileBuild.java
@@ -24,6 +24,8 @@ public class PropertyFileBuild extends Project {
                 .url("https://github.com/rife2/bld-property-file")
                 .developer(new PublishDeveloper().id("ethauvin").name("Erik C. Thauvin").email("erik@thauvin.net")
                         .url("https://erik.thauvin.net/"))
+                .developer(new PublishDeveloper().id("gbevin").name("Geert Bevin").email("geert@uwyn.com")
+                        .url("https://github.com/gbevin"))
                 .license(new PublishLicense().name("The Apache License, Version 2.0")
                         .url("http://www.apache.org/licenses/LICENSE-2.0.txt"))
                 .scm(new PublishScm().connection("scm:git:https://github.com/rife2/bld-property-file.git")
diff --git a/src/main/java/rife/bld/extension/propertyfile/Calc.java b/src/main/java/rife/bld/extension/propertyfile/Calc.java
new file mode 100644
index 0000000..9e90642
--- /dev/null
+++ b/src/main/java/rife/bld/extension/propertyfile/Calc.java
@@ -0,0 +1,50 @@
+/*
+ *  Copyright 2023 the original author or authors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package rife.bld.extension.propertyfile;
+
+import java.util.function.IntFunction;
+
+/**
+ * Implements the calculation functions.
+ *
+ * @author <a href="https://github.com/gbevin">Geert Bevin</a>
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public final class Calc {
+    public static final IntFunction<Integer> ADD = Calc::add;
+    public static final IntFunction<Integer> SUB = Calc::sub;
+
+    /**
+     * Adds {@code 1} to the value.
+     *
+     * @param v the value
+     */
+    public static Integer add(int v) {
+        return v + 1;
+    }
+
+    /**
+     * Subtracts {@code 1} to the value.
+     *
+     * @param v the value
+     */
+    public static Integer sub(int v) {
+        return v - 1;
+    }
+}
+
diff --git a/src/main/java/rife/bld/extension/propertyfile/Entry.java b/src/main/java/rife/bld/extension/propertyfile/Entry.java
index 7dafd76..a75993a 100644
--- a/src/main/java/rife/bld/extension/propertyfile/Entry.java
+++ b/src/main/java/rife/bld/extension/propertyfile/Entry.java
@@ -16,35 +16,30 @@
 
 package rife.bld.extension.propertyfile;
 
+import java.util.function.BiFunction;
+import java.util.function.IntFunction;
+
 /**
- * <p>Declares the edits to be made to a {@link java.util.Properties Properties} file.</p>
- *
- * <p>The rules used when setting a {@link java.util.Properties property} value are:</p>
- *
- * <ul>
- * <li>If only value is specified, the property is set to it regardless of its previous value.</li>
- * <li>If only default value is specified and the property previously existed, it is unchanged.</li>
- * <li>If only default value is specified and the property did not exist, the property is set to the default value.</li>
- * <li>If value and default value are both specified and the property previously existed, the property is set to value.</li>
- * <li>If value and default value are both specified and the property did not exist, the property is set to the default value.</li>
- * </ul>
- *
- * <p>{@link Operations Operations} occur after the rules are evaluated.</p>
+ * Declares the modifications to be made to a {@link java.util.Properties Properties} file.
  *
  * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @author <a href="https://github.com/gbevin">Geert Bevin</a>
  * @since 1.0
  */
 public class Entry {
     private String key;
-    private String value;
     private String defaultValue;
+    private String newValue;
+    private String modifyValue;
+    private boolean isDelete;
     private Types type = Types.STRING;
-    private Operations operation = Operations.SET;
     private String pattern = "";
     private Units unit = Units.DAY;
+    private IntFunction<Integer> calc;
+    private BiFunction<String, String, String> modify;
 
     /**
-     * Creates a new {@link Entry entry} Entry.
+     * Creates a new {@link Entry entry}.
      *
      * @param key the required property key
      */
@@ -53,14 +48,116 @@ public class Entry {
     }
 
     /**
-     * Returns the name of the {@link java.util.Properties property} name/value pair.
+     * Creates a new {@link Entry entry}.
+     *
+     * @param key  the required property key
+     * @param type the value {@link Types Type}
+     */
+    public Entry(String key, Types type) {
+        this.key = key;
+        this.type = type;
+    }
+
+    /**
+     * Returns the value to be used in the {@link #modify} function.
+     */
+    public String getModifyValue() {
+        return modifyValue;
+    }
+
+    /**
+     * Returns the modify function.
+     */
+    public BiFunction<String, String, String> getModify() {
+        return modify;
+    }
+
+    /**
+     * Set the modify function.
+     */
+    public void setModify(BiFunction<String, String, String> modify) {
+        this.modify = modify;
+    }
+
+    /**
+     * Set the modify function.
+     *
+     * @param value the value to perform a modification with
+     */
+    public void setModify(String value, BiFunction<String, String, String> modify) {
+        this.modifyValue = value;
+        this.modify = modify;
+    }
+
+    /**
+     * Creates a new {@link Entry entry}.
+     *
+     * @param value  the value to perform a modification with
+     * @param modify the modification function
+     */
+    public Entry modify(String value, BiFunction<String, String, String> modify) {
+        modifyValue = value;
+        setModify(modify);
+        return this;
+    }
+
+    /**
+     * Creates a new {@link Entry entry}.
+     *
+     * @param modify the modification function
+     */
+    public Entry modify(BiFunction<String, String, String> modify) {
+        setModify(modify);
+        return this;
+    }
+
+    /**
+     * Returns {@code true} if the {@link Entry} is to be deleted.
+     */
+    public boolean isDelete() {
+        return isDelete;
+    }
+
+    /**
+     * Sets whether the {@link Entry} should be deleted.
+     */
+    public void setDelete(boolean delete) {
+        isDelete = delete;
+    }
+
+    /**
+     * Returns the calculation function.
+     */
+    public IntFunction<Integer> getCalc() {
+        return calc;
+    }
+
+    /**
+     * Sets the calculation function.
+     */
+    public void setCalc(IntFunction<Integer> calc) {
+        this.calc = calc;
+    }
+
+    /**
+     * Creates a new {@link Entry entry}.
+     *
+     * @param calc the calculation function.
+     */
+    public Entry calc(IntFunction<Integer> calc) {
+        setCalc(calc);
+        return this;
+    }
+
+    /**
+     * Returns the key of the {@link java.util.Properties property}.
      */
     public String getKey() {
         return key;
     }
 
     /**
-     * Sets the name of the {@link java.util.Properties property} name/value pair.
+     * Sets the key of the {@link java.util.Properties property}.
      *
      * @param key the {@link java.util.Properties property} key
      */
@@ -68,22 +165,6 @@ public class Entry {
         this.key = key;
     }
 
-    /**
-     * Returns the value of the {@link java.util.Properties property}.
-     */
-    public String getValue() {
-        return value;
-    }
-
-    /**
-     * Sets the value of the {@link java.util.Properties property}.
-     *
-     * @param value the {@link java.util.Properties property} value
-     */
-    public void setValue(String value) {
-        this.value = value;
-    }
-
     /**
      * Returns the default value.
      */
@@ -92,7 +173,7 @@ public class Entry {
     }
 
     /**
-     * <p>Sets the initial value to set for the {@link java.util.Properties property} if not already defined.</p>
+     * <p>Sets the initial value to set the {@link java.util.Properties property} to, if not already defined.</p>
      *
      * <p>The {@code now} keyword can be used for {@link Types#DATE Types.DATE}</p>
      *
@@ -103,7 +184,7 @@ public class Entry {
     }
 
     /**
-     * Return the value {@link Types Type}/
+     * Return the value {@link Types Type}.
      */
     public Types getType() {
         return type;
@@ -118,22 +199,6 @@ public class Entry {
         this.type = type;
     }
 
-    /**
-     * Return the {@link Operations Operation}.
-     */
-    public Operations getOperation() {
-        return operation;
-    }
-
-    /**
-     * Sets the {@link Operations Operation} to be performed on the {@link java.util.Properties property} value,
-     *
-     * @param operation the entry {@link Operations Operation}
-     */
-    public void setOperation(Operations operation) {
-        this.operation = operation;
-    }
-
     /**
      * Returns the pattern.
      */
@@ -142,9 +207,8 @@ public class Entry {
     }
 
     /**
-     * <p>Parses the value of {@link Types#INT Types.INT} and {@link Types#DATE Types.DATE} to
-     * {@link java.text.DecimalFormat DecimalFormat} and {@link java.text.SimpleDateFormat SimpleDateFormat}
-     * respectively.</p>
+     * Sets the {@link java.text.DecimalFormat DecimalFormat} or {@link java.text.SimpleDateFormat SimpleDateFormat}
+     * pattern to be used with {@link Types#INT Types.INT} or {@link Types#DATE Types.DATE} respectively.
      *
      * @param pattern the pattern
      */
@@ -160,8 +224,8 @@ public class Entry {
     }
 
     /**
-     * Sets the {@link Units unit} value to apply to {@link Operations#ADD Operations.ADD}
-     * and {@link Operations#SUBTRACT Operations.SUBTRACT} for {@link Types#DATE Types.DATE}.
+     * Sets the {@link Units unit} value to apply to {@link Calc#ADD add} and {@link Calc#SUB subtract} calculations
+     * for {@link Types#DATE Types.DATE}.
      *
      * @param unit the {@link Units unit}
      */
@@ -170,11 +234,10 @@ public class Entry {
     }
 
     /**
-     * Sets the name of the {@link java.util.Properties property} name/value pair.
+     * Sets the key of the {@link java.util.Properties property}.
      *
      * @param key the {@link java.util.Properties property} key
      */
-
     @SuppressWarnings("unused")
     public Entry key(String key) {
         setKey(key);
@@ -182,22 +245,31 @@ public class Entry {
     }
 
     /**
-     * Sets the value of the {@link java.util.Properties property}.
+     * Returns the new value to set the {@link java.util.Properties property)} to.
+     */
+    public String getNewValue() {
+        return newValue;
+    }
+
+    /**
+     * Sets a new value to set the {@link java.util.Properties property} to, regardless of its previous value.
      *
-     * @param value the {@link java.util.Properties property} value
+     * <p>The {@code now} keyword can be used for {@link Types#DATE Types.DATE}</p>
+     *
+     * @param newValue the {@link java.util.Properties property} new value
      */
     @SuppressWarnings("unused")
-    public Entry value(Object value) {
-        if (value != null) {
-            setValue(String.valueOf(value));
+    public Entry set(Object newValue) {
+        if (newValue != null) {
+            this.newValue = String.valueOf(newValue);
         } else {
-            setValue(null);
+            this.newValue = null;
         }
         return this;
     }
 
     /**
-     * <p>Sets the initial value to set for the {@link java.util.Properties property} if not already defined.</p>
+     * <p>Sets the initial value to set the {@link java.util.Properties property} to, if not already defined.</p>
      *
      * <p>The {@code now} keyword can be used for {@link Types#DATE Types.DATE}</p>
      *
@@ -224,18 +296,7 @@ public class Entry {
     }
 
     /**
-     * Sets the {@link Operations Operation} to be performed on the {@link java.util.Properties property} value,
-     *
-     * @param operation the entry {@link Operations Operation}
-     */
-    @SuppressWarnings("unused")
-    public Entry operation(Operations operation) {
-        setOperation(operation);
-        return this;
-    }
-
-    /**
-     * <p>Parses the value of {@link Types#INT Types.INT} and {@link Types#DATE Types.DATE} to
+     * <p>Sets the pattern for {@link Types#INT Types.INT} and {@link Types#DATE Types.DATE} to
      * {@link java.text.DecimalFormat DecimalFormat} and {@link java.text.SimpleDateFormat SimpleDateFormat}
      * respectively.</p>
      *
@@ -247,8 +308,8 @@ public class Entry {
     }
 
     /**
-     * Sets the {@link Units unit} value to apply to {@link Operations#ADD Operations.ADD}
-     * and {@link Operations#SUBTRACT Operations.SUBTRACT} for {@link Types#DATE Types.DATE}.
+     * Sets the {@link Units unit} value to apply to {@link Calc#ADD add} and {@link Calc#SUB subtract} calculations
+     * for {@link Types#DATE Types.DATE}.
      *
      * @param unit the {@link Units unit}
      */
@@ -258,6 +319,14 @@ public class Entry {
         return this;
     }
 
+    /**
+     * Sets the {@link Entry entry} up for deletion.
+     */
+    public Entry delete() {
+        isDelete = true;
+        return this;
+    }
+
     /**
      * The available datatypes.
      *
@@ -272,23 +341,8 @@ public class Entry {
     }
 
     /**
-     * The operations available for all {@link Types Types}.
-     *
-     * <uL>
-     * <li>{@link Operations#ADD ADD} adds a value to an {@link Entry entry}</li>
-     * <li>{@link Operations#DELETE DELETE} deletes an entry</li>
-     * <li>{@link Operations#SET SET} sets the entry value. This is the default operation</li>
-     * <li>{@link Operations#SUBTRACT SUBTRACT} subtracts a value from the {@link Entry entry}.
-     * For {@link Types#INT Types.INT} and {@link Types#DATE Types.DATE} only.</li>
-     * </uL>
-     */
-    public enum Operations {
-        ADD, DELETE, SET, SUBTRACT
-    }
-
-    /**
-     * The units available for {@link Types#DATE Type.DATE} with {@link Operations#ADD Operations>ADD}
-     * and {@link Operations#SUBTRACT Operations.SUBTRACT}.
+     * The units available for {@link Types#DATE Type.DATE} {@link Calc#ADD add}
+     * and {@link Calc#SUB subtract} calculations.
      *
      * <uL>
      * <li>{@link Units#SECOND SECOND}</li>
diff --git a/src/main/java/rife/bld/extension/propertyfile/PropertyFileOperation.java b/src/main/java/rife/bld/extension/propertyfile/PropertyFileOperation.java
index 1692a99..bd6757a 100644
--- a/src/main/java/rife/bld/extension/propertyfile/PropertyFileOperation.java
+++ b/src/main/java/rife/bld/extension/propertyfile/PropertyFileOperation.java
@@ -17,8 +17,6 @@
 package rife.bld.extension.propertyfile;
 
 import rife.bld.Project;
-import rife.bld.extension.propertyfile.Entry.Operations;
-import rife.bld.extension.propertyfile.Entry.Types;
 import rife.bld.operations.AbstractOperation;
 
 import java.io.File;
@@ -36,9 +34,9 @@ import java.util.Properties;
 public class PropertyFileOperation extends AbstractOperation<PropertyFileOperation> {
     private final List<Entry> entries = new ArrayList<>();
     private final Project project;
-    private File file = null;
+    private File file;
     private String comment = "";
-    private boolean failOnWarning = false;
+    private boolean failOnWarning;
 
     public PropertyFileOperation(Project project) {
         this.project = project;
@@ -122,17 +120,13 @@ public class PropertyFileOperation extends AbstractOperation<PropertyFileOperati
                     success = false;
                 } else {
                     var key = entry.getKey();
-                    var value = entry.getValue();
+                    var value = entry.getNewValue();
                     var defaultValue = entry.getDefaultValue();
-                    if ((value == null || value.isBlank()) && (defaultValue == null || defaultValue.isBlank())
-                            && entry.getOperation() != Operations.DELETE) {
-                        PropertyFileUtils.warn(commandName, "An entry value or default must be specified: " + key);
-                        success = false;
-                    } else if (entry.getType() == Types.STRING && entry.getOperation() == Operations.SUBTRACT) {
-                        PropertyFileUtils.warn(commandName, "Subtraction is not supported for String properties: " + key);
-                        success = false;
-                    } else if (entry.getOperation() == Operations.DELETE) {
+                    if (entry.isDelete()) {
                         properties.remove(key);
+                    } else if ((value == null || value.isBlank()) && (defaultValue == null || defaultValue.isBlank())) {
+                        PropertyFileUtils.warn(commandName, "An entry must be set or have a default value: " + key);
+                        success = false;
                     } else {
                         switch (entry.getType()) {
                             case DATE ->
diff --git a/src/main/java/rife/bld/extension/propertyfile/PropertyFileUtils.java b/src/main/java/rife/bld/extension/propertyfile/PropertyFileUtils.java
index f3d6869..eb47799 100644
--- a/src/main/java/rife/bld/extension/propertyfile/PropertyFileUtils.java
+++ b/src/main/java/rife/bld/extension/propertyfile/PropertyFileUtils.java
@@ -16,7 +16,6 @@
 
 package rife.bld.extension.propertyfile;
 
-import rife.bld.extension.propertyfile.Entry.Operations;
 import rife.bld.extension.propertyfile.Entry.Units;
 import rife.tools.Localization;
 
@@ -45,7 +44,7 @@ import java.util.logging.Logger;
 public final class PropertyFileUtils {
     private final static Logger LOGGER = Logger.getLogger(PropertyFileUtils.class.getName());
 
-    private final static Map<Units, Integer> calendarFields =
+    private final static Map<Units, Integer> CALENDAR_FIELDS =
             Map.of(Units.MILLISECOND, Calendar.MILLISECOND,
                     Units.SECOND, Calendar.SECOND,
                     Units.MINUTE, Calendar.MINUTE,
@@ -70,8 +69,8 @@ public final class PropertyFileUtils {
     public static boolean processDate(String command, Properties p, Entry entry, boolean failOnWarning) {
         var success = true;
         var cal = Calendar.getInstance();
-        var value = PropertyFileUtils.currentValue(p.getProperty(entry.getKey()), entry.getValue(),
-                entry.getDefaultValue(), entry.getOperation());
+        String value = PropertyFileUtils.currentValue(p.getProperty(entry.getKey()), entry.getDefaultValue(),
+                entry.getNewValue());
 
         var pattern = entry.getPattern();
         SimpleDateFormat fmt;
@@ -80,6 +79,7 @@ public final class PropertyFileUtils {
         } else {
             fmt = new SimpleDateFormat(entry.getPattern(), Localization.getLocale());
         }
+
         if ("now".equalsIgnoreCase(value) || value.isBlank()) {
             cal.setTime(new Date());
         } else {
@@ -92,74 +92,36 @@ public final class PropertyFileUtils {
             }
         }
 
-        if (entry.getOperation() != Entry.Operations.SET) {
-            var offset = 0;
+        var offset = 0;
 
-            try {
-                offset = Integer.parseInt(entry.getValue());
-                if (entry.getOperation() == Entry.Operations.SUBTRACT) {
-                    offset *= -1;
-                }
-            } catch (NumberFormatException nfe) {
-                warn(command, "Non-date value for \"" + entry.getKey() + "\" --> " + nfe.getMessage(), nfe,
-                        failOnWarning);
-                success = false;
-            }
-
-            //noinspection MagicConstant
-            cal.add(calendarFields.getOrDefault(entry.getUnit(), Calendar.DATE), offset);
+        if (entry.getCalc() != null) {
+            offset = entry.getCalc().apply(offset);
         }
 
+        //noinspection MagicConstant
+        cal.add(CALENDAR_FIELDS.getOrDefault(entry.getUnit(), Calendar.DATE), offset);
+
         p.setProperty(entry.getKey(), fmt.format(cal.getTime()));
 
         return success;
     }
 
     /**
-     * Return the current value, new value or default value based on the specified {@link Operations operation}.
+     * Returns the new value, value or default value depending on which is specified.
      *
      * @param value        the value
      * @param newValue     the new value
      * @param defaultValue the default value
-     * @param operation    the {@link Operations operation}
      * @return the current value
      */
-    public static String currentValue(String value, String newValue, String defaultValue, Operations operation) {
-        String result = null;
-
-        if (operation == Entry.Operations.SET) {
-            if (newValue != null && defaultValue == null) {
-                result = newValue;
-            }
-            if (defaultValue != null) {
-                if (newValue == null && value != null) {
-                    result = value;
-                }
-
-                if (newValue == null && value == null) {
-                    result = defaultValue;
-                }
-
-                if (newValue != null && value != null) {
-                    result = newValue;
-                }
-
-                if (newValue != null && value == null) {
-                    result = defaultValue;
-                }
-            }
+    public static String currentValue(String value, String defaultValue, String newValue) {
+        if (newValue != null) {
+            return newValue;
+        } else if (value == null) {
+            return defaultValue;
         } else {
-            if (value == null) {
-                result = defaultValue;
-            } else {
-                result = value;
-            }
+            return value;
         }
-
-        if (result == null) {
-            result = "";
-        }
-        return result;
     }
 
     /**
@@ -172,28 +134,18 @@ public final class PropertyFileUtils {
      */
     public static boolean processInt(String command, Properties p, Entry entry, boolean failOnWarning) {
         var success = true;
-        int intValue;
+        int intValue = 0;
         try {
             var fmt = new DecimalFormat(entry.getPattern());
-            var value = PropertyFileUtils.currentValue(p.getProperty(entry.getKey()), entry.getValue(),
-                    entry.getDefaultValue(), entry.getOperation());
+            String value = PropertyFileUtils.currentValue(p.getProperty(entry.getKey()), entry.getDefaultValue(),
+                    entry.getNewValue());
 
-            if (value.isBlank()) {
-                intValue = fmt.parse("0").intValue();
-            } else {
+            if (value != null) {
                 intValue = fmt.parse(value).intValue();
             }
 
-            if (entry.getOperation() != Entry.Operations.SET) {
-                var opValue = 1;
-                if (entry.getValue() != null) {
-                    opValue = fmt.parse(entry.getValue()).intValue();
-                }
-                if (entry.getOperation() == Entry.Operations.ADD) {
-                    intValue += opValue;
-                } else if (entry.getOperation() == Entry.Operations.SUBTRACT) {
-                    intValue -= opValue;
-                }
+            if (entry.getCalc() != null) {
+                intValue = entry.getCalc().apply(intValue);
             }
             p.setProperty(entry.getKey(), fmt.format(intValue));
         } catch (NumberFormatException | ParseException e) {
@@ -213,15 +165,13 @@ public final class PropertyFileUtils {
      * @return {@code true} if successful
      */
     public static boolean processString(Properties p, Entry entry) {
-        var value = PropertyFileUtils.currentValue(p.getProperty(entry.getKey()), entry.getValue(),
-                entry.getDefaultValue(), entry.getOperation());
+        var value = PropertyFileUtils.currentValue(p.getProperty(entry.getKey()), entry.getDefaultValue(),
+                entry.getNewValue());
 
-        if (entry.getOperation() == Entry.Operations.SET) {
-            p.setProperty(entry.getKey(), value);
-        } else if (entry.getOperation() == Entry.Operations.ADD) {
-            if (entry.getValue() != null) {
-                p.setProperty(entry.getValue(), "$value${entry.value}");
-            }
+        p.setProperty(entry.getKey(), value);
+
+        if (entry.getModify() != null && entry.getModifyValue() != null) {
+            p.setProperty(entry.getKey(), entry.getModify().apply(p.getProperty(entry.getKey()), entry.getModifyValue()));
         }
 
         return true;
diff --git a/src/test/java/rife/bld/extension/propertyfile/PropertyFileUtilsTest.java b/src/test/java/rife/bld/extension/propertyfile/PropertyFileUtilsTest.java
index 4448272..5471073 100644
--- a/src/test/java/rife/bld/extension/propertyfile/PropertyFileUtilsTest.java
+++ b/src/test/java/rife/bld/extension/propertyfile/PropertyFileUtilsTest.java
@@ -27,6 +27,8 @@ import java.util.Properties;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatCode;
+import static rife.bld.extension.propertyfile.Calc.ADD;
+import static rife.bld.extension.propertyfile.Calc.SUB;
 
 /**
  * PropertyFileUtilsTest class
@@ -38,151 +40,131 @@ class PropertyFileUtilsTest {
     final Properties p = new Properties();
     final String t = "test";
 
-    @Test
-    void currentValueTest() {
-        String prev = "previous";
-        String value = "value";
-        String defaultValue = "defaultValue";
-        var operation = Entry.Operations.SET;
-
-        // If only value is specified, the property is set to it regardless of its previous value.
-        assertThat(PropertyFileUtils.currentValue(prev, value, null, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(value);
-
-        // If only defaultValue is specified and the property previously existed, it is unchanged.
-        assertThat(PropertyFileUtils.currentValue(prev, null, defaultValue, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(prev);
-
-        // If only defaultValue is specified and the property did not exist, the property is set to defaultValue.
-        assertThat(PropertyFileUtils.currentValue(null, null, defaultValue, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(defaultValue);
-
-        // If value and defaultValue are both specified and the property previously existed, the property is set to value.
-        assertThat(PropertyFileUtils.currentValue(prev, value, defaultValue, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(value);
-
-        // If value and defaultValue are both specified and the property did not exist, the property is set to defaultValue.
-        assertThat(PropertyFileUtils.currentValue(null, value, defaultValue, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(defaultValue);
-
-        // ADD
-        operation = Entry.Operations.ADD;
-
-        assertThat(PropertyFileUtils.currentValue(null, value, defaultValue, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(defaultValue);
-
-        assertThat(PropertyFileUtils.currentValue(prev, value, null, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(prev);
-
-        assertThat(PropertyFileUtils.currentValue(null, value, null, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo("");
-
-        assertThat(PropertyFileUtils.currentValue(null, value, defaultValue, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo(defaultValue);
-
-        assertThat(PropertyFileUtils.currentValue(null, null, null, operation))
-                .as(String.format("currentValue(%s,%s,%s,%s)", prev, value, defaultValue, operation)).isEqualTo("");
-    }
-
     @Test
     void processStringTest() {
-        var entry = new Entry("version.major").value("1");
+        var entry = new Entry("version.major").set("1");
 
         PropertyFileUtils.processString(p, entry);
 
-        assertThat(entry.getValue()).as("processString(entry.getKey(), entry.getValue())").isEqualTo(p.getProperty(entry.getKey()));
+        assertThat(entry.getNewValue()).as(String.format("processString(%s, %s)", entry.getKey(), entry.getNewValue()))
+                .isEqualTo(p.getProperty(entry.getKey()));
 
         entry.setKey("version.minor");
-        entry.setValue("0");
 
+        PropertyFileUtils.processString(p, entry.set(0));
+        assertThat(entry.getNewValue()).as(String.format("processString(%s, %s)", entry.getKey(), entry.getNewValue()))
+                .isEqualTo(p.getProperty(entry.getKey()));
+
+        // APPEND
+        PropertyFileUtils.processString(p, entry.modify("-foo", String::concat));
+        assertThat(p.getProperty(entry.getKey())).as(String.format("processString(%s, %s)", entry.getKey(), entry.getNewValue()))
+                .isEqualTo("0-foo");
+
+        // PREPEND
+        PropertyFileUtils.processString(p, entry.modify("foo-", (v, s) -> s + v));
+        assertThat(p.getProperty(entry.getKey())).as(String.format("processString(%s, %s)", entry.getKey(), entry.getNewValue()))
+                .isEqualTo("foo-0");
+        // CAP
+        PropertyFileUtils.processString(p, entry.set(t).modify((v, s) -> v.toUpperCase(Localization.getLocale())));
+        assertThat(p.getProperty(entry.getKey())).as("capitalize").isEqualTo(t.toUpperCase(Localization.getLocale()));
+
+        // REPLACE
+        entry.set(t).setModify("T", (v, s) -> v.replace("t", s));
         PropertyFileUtils.processString(p, entry);
-        assertThat(entry.getValue()).as("processString(entry.getKey(), entry.getValue())").isEqualTo(p.getProperty(entry.getKey()));
+        assertThat(p.getProperty(entry.getKey())).as("replace").isEqualTo("TesT");
+
+        // SUBSTRING
+        entry.set(t).setModify((v, s) -> v.substring(1));
+        PropertyFileUtils.processString(p, entry);
+        assertThat(p.getProperty(entry.getKey())).as("substring").isEqualTo(t.substring(1));
     }
 
     @Test
     void processIntTest() {
-        var entry = new Entry("version.patch").value("a").type(Entry.Types.INT);
-        assertThat(PropertyFileUtils.processInt(t, p, entry, false)).as("parseInt(entry.getKey(), a)");
+        var entry = new Entry("version.patch").type(Entry.Types.INT);
 
         // ADD
-        entry.setOperation(Entry.Operations.ADD);
-
-        entry.setValue("1");
+        entry.calc(ADD);
         entry.setDefaultValue("-1");
         PropertyFileUtils.processInt(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processInt(entry.getKey(), 0)").isEqualTo("0");
+        assertThat(p.getProperty(entry.getKey())).as("add(-1)").isEqualTo("0");
 
         entry.setKey("anint");
-        entry.setValue(null);
         entry.setDefaultValue("0");
         PropertyFileUtils.processInt(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processInt(entry.getKey(), 1)").isEqualTo("1");
+        assertThat(p.getProperty(entry.getKey())).as("add(0)").isEqualTo("1");
         PropertyFileUtils.processInt(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processInt(entry.getKey(), 2)").isEqualTo("2");
+        assertThat(p.getProperty(entry.getKey())).as("add(1)").isEqualTo("2");
 
         entry.setKey("formated.int");
-        entry.setValue(null);
         entry.setDefaultValue("0013");
         entry.setPattern("0000");
         PropertyFileUtils.processInt(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processInt(entry.getKey(), 0014)").isEqualTo("0014");
+        assertThat(p.getProperty(entry.getKey())).as("add(0013)").isEqualTo("0014");
         PropertyFileUtils.processInt(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processInt(entry.getKey(), 0015)").isEqualTo("0015");
+        assertThat(p.getProperty(entry.getKey())).as("add(0014)").isEqualTo("0015");
 
         entry.setKey("formated.int");
-        entry.setValue("2");
+        entry.calc(v -> v + 2);
         entry.setDefaultValue("0013");
         entry.setPattern("0000");
         PropertyFileUtils.processInt(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processInt(entry.getKey(), 0017)").isEqualTo("0017");
+        assertThat(p.getProperty(entry.getKey())).as("add(0013)+2").isEqualTo("0017");
 
         // SUBTRACT
-        entry.setOperation(Entry.Operations.SUBTRACT);
-        entry.setValue(null);
-        entry.setDefaultValue("0013");
+        entry.calc(SUB);
         entry.setPattern("0000");
         PropertyFileUtils.processInt(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processInt(entry.getKey(), 0016)").isEqualTo("0016");
+        assertThat(p.getProperty(entry.getKey())).as("sub(0017)").isEqualTo("0016");
+
+        PropertyFileUtils.processInt(t, p, entry.calc(v -> v - 3), true);
+        assertThat(p.getProperty(entry.getKey())).as("sub(0017)-3").isEqualTo("0013");
     }
 
     @Test
     void processDateTest() {
-        var entry = new Entry("adate").type(Entry.Types.DATE).pattern("D").value("1");
+        var entry = new Entry("adate", Entry.Types.DATE).pattern("D");
         var day = new SimpleDateFormat(entry.getPattern(), Localization.getLocale()).format(new Date());
         var dayInt = Integer.parseInt(day);
 
-        entry.setValue("a");
-        assertThat(PropertyFileUtils.processDate(t, p, entry, false)).as("processDate(entry.getKey(), a)").isFalse();
+        assertThat(PropertyFileUtils.processDate(t, p, entry.set("a"), false)).as("processDate(a)").isFalse();
 
-        entry.setValue("99");
-        PropertyFileUtils.processDate(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processDate(entry.getKey(), 99)").isEqualTo("99");
+        PropertyFileUtils.processDate(t, p, entry.set("99"), true);
+        assertThat(p.getProperty(entry.getKey())).as("processDate(99)").isEqualTo("99");
 
-        entry.setValue("now");
-        PropertyFileUtils.processDate(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processDate(entry.getKey(), now)").isEqualTo(day);
+        PropertyFileUtils.processDate(t, p, entry.set("noew"), true);
+        assertThat(p.getProperty(entry.getKey())).as("processDate(now)").isEqualTo(day);
 
         // ADD
-        entry.setOperation(Entry.Operations.ADD);
+        entry.setCalc(ADD);
+        PropertyFileUtils.processDate(t, p, entry.set(dayInt), true);
+        assertThat(p.getProperty(entry.getKey())).as("processDate(now+1)").isEqualTo(String.valueOf(dayInt + 1));
 
-        entry.setValue("1");
-        PropertyFileUtils.processDate(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processDate(entry.getKey(), now+1)").isEqualTo(String.valueOf(dayInt + 1));
-
-        entry.setValue("2");
-        PropertyFileUtils.processDate(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processDate(entry.getKey(), now+3)").isEqualTo(String.valueOf(dayInt + 3));
+        entry.setCalc(v -> v + 3);
+        PropertyFileUtils.processDate(t, p, entry.set(dayInt), true);
+        assertThat(p.getProperty(entry.getKey())).as("processDate(now+3)").isEqualTo(String.valueOf(dayInt + 3));
 
         // SUBTRACT
-        entry.setOperation(Entry.Operations.SUBTRACT);
-        entry.setValue("3");
-        PropertyFileUtils.processDate(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processDate(entry.getKey(), now-3)").isEqualTo(String.valueOf(dayInt));
+        entry.setCalc(SUB);
+        PropertyFileUtils.processDate(t, p, entry.set(dayInt), true);
+        assertThat(p.getProperty(entry.getKey())).as("processDate(now-3)").isEqualTo(String.valueOf(dayInt - 1));
 
-        entry.setOperation(Entry.Operations.SUBTRACT);
-        entry.setValue("2");
-        PropertyFileUtils.processDate(t, p, entry, true);
-        assertThat(p.getProperty(entry.getKey())).as("processDate(entry.getKey(), now-2)").isEqualTo(String.valueOf(dayInt - 2));
+        entry.setCalc(v -> v - 2);
+        PropertyFileUtils.processDate(t, p, entry.set(dayInt), true);
+        assertThat(p.getProperty(entry.getKey())).as("processDate(now-2)").isEqualTo(String.valueOf(dayInt - 2));
+    }
+
+    @Test
+    void testCurrentValue() {
+        var value = "value";
+        var defaultValue = "default";
+        var newValue = "new";
+
+        assertThat(PropertyFileUtils.currentValue(value, defaultValue, newValue)).as("all").isEqualTo(newValue);
+        assertThat(PropertyFileUtils.currentValue(value, null, null)).as("value").isEqualTo(value);
+        assertThat(PropertyFileUtils.currentValue(value, defaultValue, null)).as("value not default").isEqualTo(value);
+        assertThat(PropertyFileUtils.currentValue(null, defaultValue, null)).as("default").isEqualTo(defaultValue);
+        assertThat(PropertyFileUtils.currentValue(null, null, newValue)).as("new").isEqualTo(newValue);
     }
 
     @Test