org.dmfs.srcless.annotations.composable.Composable Maven / Gradle / Ivy

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Generate code too trivial to write it down.

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package org.dmfs.srcless.annotations.composable;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;


/**
 * Generate an abstract class for compositions.
 * 
 * The resulting class is abstract. Its constructor takes an instance of the same type and each method is final and delegates to the same
 * method of the delegate.
 *
 * 
Example
 *
 *  * {@literal @}Composable
 *  public interface FooBar<T>
 *  {
 *      void foo(T foo);
 *
 *      T bar(String bazz) throws IOException;
 *  }
 * 
 * 
 * will generate this code
 *
 * 
{@code
 * public abstract class FooBarComposition implements FooBar {
 *     private final FooBar mDelegate;
 *
 *     public FooBarComposition(FooBar delegate) {
 *         mDelegate = delegate;
 *     }
 *
 *     public final void foo(T foo) {
 *         mDelegate.foo(foo);
 *     }
 *
 *     public final T bar(String bazz) throws IOException {
 *         return mDelegate.bar(bazz);
 *     }
 * }
 * }
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.SOURCE)
public @interface Composable
{
    /**
     * The package name of the generated class.
     * 
     * Defaults to the package name of the annotated interface.
     */
    String packageName() default "";

    /**
     * The name of the generated class.
     * 
     * Defaults to the name of the annotated interface plus the word "Composition".
     */
    String className() default "";
}