docs(about): add about Property

Author: paul58914080

docs/pages/about/core-concepts/property/index.md

@@ -1 +1,131 @@
-We know that you are waiting, we will have this section ready very soon.
+# Property
+
+Property represents a configuration parameter that can be associated with features or used
+independently within the FF4J framework. Properties allow you to store various types of data, such
+as strings, integers, booleans, and more, which can be utilized to control feature behavior or
+application settings.
+
+## Overview
+
+A [**`Property`**](https://github.com/ff4j/ff4j/blob/main/ff4j-core/src/main/java/org/ff4j/property/Property.java)
+is an entity representing any kind of value or configuration. It has an unique name and a value.
+This value can be of any type and this the reason why, in ff4j, we chose to implement it with
+generics **`Property<?>`**. There is a Property implementation for each Java Raw Type as shown in
+the example below.
+
+## Property object
+
+```mermaid
+classDiagram
+    direction TB
+
+    class Property~T~ {
+        <<abstract>>
+        -readOnly: boolean
+        -name: String
+        -description: String
+        -type: String
+        -value: T
+        -fixedValues: Set~T~
+        +Property()
+        +Property(name: String)
+        +Property(name: String, valueStr: String)
+        +Property(name: String, value: T, fixed: Set~T~)
+        +add2FixedValueFromString(v: String)
+        +add2FixedValue(value: T)
+        +abstract fromString(v: String): T
+        +parameterizedType(): Class
+        +asString(): String
+        +asInt(): int
+        +asDouble(): double
+        +asBoolean(): boolean
+        +getValue(): T
+        +setValue(value: T)
+        +setValueFromString(value: String)
+        +getName(): String
+        +setName(name: String)
+        +getFixedValues(): Set~T~
+        +setFixedValues(fixedValues: Set~T~)
+        +toString(): String
+        +toJson(): String
+        +getType(): String
+        +setType(type: String)
+        +getDescription(): String
+        +setDescription(description: String)
+        +isReadOnly(): boolean
+        +setReadOnly(readOnly: boolean)
+    }
+```
+
+## Examples
+
+### Create and Manage Properties
+
+```java title="Snippet for creating and managing properties"
+public void createAndManageProperty() {
+  // Create a new String property
+  PropertyString myProp = new PropertyString("myStringProp", "defaultValue");
+  ff4j.getPropertyStore().create(myProp);
+  // Retrieve the property
+  PropertyString retrievedProp = (PropertyString) ff4j.getPropertyStore().read("myStringProp");
+  // Update the property value
+  retrievedProp.setValue("newValue");
+  ff4j.getPropertyStore().update(retrievedProp);
+  // Delete the property
+  ff4j.getPropertyStore().delete("myStringProp");
+}
+```
+
+### Using Properties in Features
+
+```java title="Snippet for using properties in features"
+public void usePropertyInFeature() {
+  // Create a feature with a custom property
+  Feature featureWithProp = new Feature("featureWithProp", true);
+  PropertyInt timeoutProp = new PropertyInt("timeout", 30);
+  featureWithProp.addProperty(timeoutProp);
+  ff4j.getFeatureStore().create(featureWithProp);
+  // Retrieve and use the property
+  Feature retrievedFeature = ff4j.getFeatureStore().read("featureWithProp");
+  PropertyInt retrievedTimeoutProp = (PropertyInt) retrievedFeature.getProperty("timeout");
+  int timeoutValue = retrievedTimeoutProp.getValue();
+}
+```
+
+### Custom Property Implementation
+
+```java title="Snippet for creating a custom property type"
+import org.ff4j.property.Property;
+import org.ff4j.test.property.CardinalPoint.Point;
+
+public class CardinalPoint extends Property<Point> {
+
+  private static final long serialVersionUID = 1792311055570779010L;
+
+  public static enum Point {NORTH, SOUTH, EAST, WEST};
+
+  public CardinalPoint(String uid, Point lvl) {
+    super(uid, lvl, Point.values());
+  }
+
+  public Point fromString(String v) {
+    return Point.valueOf(v);
+  }
+
+  public void north() {
+    setValue(Point.NORTH);
+  }
+
+  public void south() {
+    setValue(Point.SOUTH);
+  }
+
+  public void east() {
+    setValue(Point.EAST);
+  }
+
+  public void west() {
+    setValue(Point.WEST);
+  }
+}
+```