groovy.transform.builder.Builder Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of groovy Show documentation
Show all versions of groovy Show documentation
Groovy: A powerful, dynamic language for the JVM
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
*
* http://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 groovy.transform.builder;
import groovy.transform.Undefined;
import org.codehaus.groovy.transform.GroovyASTTransformationClass;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import static org.codehaus.groovy.transform.BuilderASTTransformation.BuilderStrategy;
/**
* The {@code @Builder} AST transformation is used to help write classes that can be created using fluent api calls.
* The transform supports multiple building strategies to cover a range of cases and there are a number
* of configuration options to customize the building process.
*
* In addition, a number of annotation attributes let you customise the building process. Not all annotation attributes
* are supported by all strategies. See the individual strategy documentation for more details.
* If you're an AST hacker, you can also define your own strategy class.
*
* The following strategies are bundled with Groovy:
*
* - {@link SimpleStrategy} for creating chained setters
* - {@link ExternalStrategy} where you annotate an explicit builder class while leaving some buildee class being built untouched
* - {@link DefaultStrategy} which creates a nested helper class for instance creation
* - {@link InitializerStrategy} which creates a nested helper class for instance creation which when used with {@code @CompileStatic} allows type-safe object creation
*
*
* Note that Groovy provides other built-in mechanisms for easy creation of objects, e.g. the named-args constructor:
*
* new Person(firstName: "Robert", lastName: "Lewandowski", age: 21)
*
* or the with statement:
*
* new Person().with {
* firstName = "Robert"
* lastName = "Lewandowski"
* age = 21
* }
*
* so you might not find value in using the builder transform at all. But if you need Java integration or in some cases improved type safety, the {@code @Builder} transform might prove very useful.
*
* @see groovy.transform.builder.SimpleStrategy
* @see groovy.transform.builder.ExternalStrategy
* @see groovy.transform.builder.DefaultStrategy
* @see groovy.transform.builder.InitializerStrategy
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.TYPE, ElementType.CONSTRUCTOR, ElementType.METHOD})
@GroovyASTTransformationClass("org.codehaus.groovy.transform.BuilderASTTransformation")
public @interface Builder {
/**
* A class for which builder methods should be created. It will be an error to leave
* this attribute with its default value for some strategies.
*/
Class forClass() default Undefined.CLASS.class;
/**
* A class capturing the builder strategy
*/
Class builderStrategy() default DefaultStrategy.class;
/**
* The prefix to use when creating the setter methods.
* Default is determined by the strategy which might use "" or "set" but you can choose your own, e.g. "with".
* If non-empty the first letter of the property will be capitalized before being appended to the prefix.
*/
String prefix() default Undefined.STRING;
/**
* For strategies which create a builder helper class, the class name to use for the helper class.
* Not used if using {@code forClass} since in such cases the builder class is explicitly supplied.
* Default is determined by the strategy, e.g. TargetClass + "Builder" or TargetClass + "Initializer".
*/
String builderClassName() default Undefined.STRING;
/**
* For strategies which create a builder helper class that creates the instance, the method name to call to create the instance.
* Default is determined by the strategy, e.g. build or create.
*/
String buildMethodName() default Undefined.STRING;
/**
* The method name to use for a builder factory method in the source class for easy access of the
* builder helper class for strategies which create such a helper class.
* Must not be used if using {@code forClass}.
* Default is determined by the strategy, e.g. builder or createInitializer.
*/
String builderMethodName() default Undefined.STRING;
/**
* List of field and/or property names to exclude from generated builder methods.
* Must not be used if 'includes' is used. For convenience, a String with comma separated names
* can be used in addition to an array (using Groovy's literal list notation) of String values.
*/
String[] excludes() default {};
/**
* List of field and/or property names to include within the generated builder methods.
* Must not be used if 'excludes' is used. For convenience, a String with comma separated names
* can be used in addition to an array (using Groovy's literal list notation) of String values.
* The default value is a special marker value indicating that no includes are defined; all fields
* are included if includes remains undefined and excludes is explicitly or implicitly an empty list.
*/
String[] includes() default {Undefined.STRING};
/**
* By default, properties are set directly using their respective field.
* By setting {@code useSetters=true} then a writable property will be set using its setter.
* If turning on this flag we recommend that setters that might be called are
* made null-safe wrt the parameter.
*
* @since 2.5.0
*/
boolean useSetters() default false;
/**
* Generate builder methods for properties from super classes.
*
* @since 2.5.0
*/
boolean includeSuperProperties() default false;
/**
* Whether the generated builder should support all properties, including those with names that are considered internal.
*
* @since 2.5.0
*/
boolean allNames() default false;
/**
* Whether to include all properties (as per the JavaBean spec) in the generated builder.
* Groovy recognizes any field-like definitions with no explicit visibility as property definitions
* and always includes them in the {@code @Builder} generated classes. Groovy also treats any explicitly created getXxx() or isYyy()
* methods as property getters as per the JavaBean specification. Old versions of Groovy did not.
* So set this flag to false for the old behavior or if you want to explicitly exclude such properties.
* Currently only supported by DefaultStrategy and ExternalStrategy.
*
* @since 2.5.0
*/
boolean allProperties() default true;
/**
* Whether to always include helper constructors. Currently only supported by InitializerStrategy.
* By default, the InitializerStrategy only adds a needed helper tuple constructor if no {@code @TupleConstructor}
* annotations are present. If such annotations are present, it is assumed they will provide the helper constructor
* that this strategy needs. If made true, the helper constructor will be generated and it is up to you to make sure
* this doesn't conflict with any other generated constructors.
*
* @since 2.5.0
*/
boolean force() default false;
}