我可以使用 Java 注释来定义编译时检查吗？
Can I use Java annotations to define compile time checks?
例如，我想为目标参数创建注解@Out。然后我会以某种方式使用编译器检查参数值是否设置在函数 returns 之前。这可能吗？
还考虑了一个 @Immutable 注释，它不允许调用任何未使用 @Const 注释的方法或访问任何 public 字段。 （编译时间和可能的运行时间？）
到目前为止我有这个：
//I'm assuming Class retention is a subset of Runtime retention
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface Out
{
//no idea what to go in here.
}
这是另一个注释。同样，我没有完整的定义：
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Immutable
{
}
我想我可以开始设计一种策略，在运行时使用反射来实现它，但我想指示编译器或预处理器为我检查这些东西，这样我的注释就会有零开销。
这是您认为的事情之一 "if this could've been done, it would already be out there, and if it is, where can I grab it"。
编辑：在进一步思考 @Const 和 @Immutable 并记住 java 按值传递对象指针之后，我扩展了@Const 的定义，删除了 @Immutable，并更改了 @Out 的定义，如下所示：
/**
* When Applied to a method, ensures the method doesn't change in any
* way the state of the object used to invoke it, i.e., all the fields
* of the object must remain the same, and no field may be returned,
* unless the field itself is marked as {@code @Const}. A method
* annotated with {@code @Const} can only invoke other {@code @Const}
* methods of its class, can only use the class's fields to invoke
* {@code @Const} methods of the fields classes and can only pass fields
* as parameters to methods that annotate that formal parameter as
* {@code @Const}.
*
* When applied to a formal parameter, ensures the method will not
* modify the value referenced by the formal parameter. A formal
* parameter annotated as {@code @Const} will not be aliased inside the
* body of the method. The method is not allowed to invoke another
* method and pass the annotated parameter, save if the other method
* also annotates the formal parameter as {@code @Const}. The method is
* not allowed to use the parameter to invoke any of its type's methods,
* unless the method being invoked is also annotated as {@code @Const}
*
* When applied to a field, ensures the field cannot be aliased and that
* no code can alter the state of that field, either from inside the
* class that owns the field or from outside it. Any constructor in any
* derived class is allowed to set the value of the field and invoke any
* methods using it. As for methods, only those annotated as
* {@code @Const} may be invoked using the field. The field may only be
* passed as a parameter to a method if the method annotates the
* corresponding formal parameter as {@code @Const}
*
* When applied to a local variable, ensures neither the block where the
* variable is declared or any nested block will alter the value of that
* local variable. The local variable may be defined only once, at any
* point where it is in scope. Only methods annotated as
* {@code @Const} may be invoked using this variable, and the variable
* may only be passed as a parameter to another method if said method
* annotates its corresponding formal parameter as {@code @Const}
*
*/
@Retention(RetentionPolicy.SOURCE)
@Target({ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD,
ElementType.LOCAL_VARIABLE})
@Inherited
public @interface Const
{
}
现在 @Out:
/**
* The formal parameter annotated with {@code @Out} must be undefined in
* the scope of the caller, and it's the responsibility of the method to
* define it. If allowNull is true, the parameter can be explicitly set
* to null in the body of the method.
*/
@Retention(RetentionPolicy.SOURCE)
@Target(ElementType.PARAMETER)
public @interface Out
{
boolean allowNull() default false;
}
编辑： 我正在尝试将其实现为 eclipse 插件，但我完全无法阅读手册。我编写了一个插件，其中包含用于访问 AST 和访问方法和字段的基本逻辑。然后我做了一堆我的插件应该检测到的虚拟注释，然后我尝试打印结果，但我什至不确定会发生什么。我的插件是 "Incremental Build" 插件。这是它的代码，如果有人可以看一下并向我解释一些事情。我完全迷失在这个 API.
javac 编译器支持用户可定义的插件，称为注解处理器，可以完全满足您的需求。您可以将注释视为语言扩展。
定义public @interface Immutable { ... } 定义了语法：@Immutable 你可以在程序中编写的注解。注释处理器（编译器插件）定义语义：它强制执行语义规则并在您的程序违反规则时发出编译器警告。
Checker Framework, and it contains definitions for annotations like @NonNull and @Immutable. Here are two tutorials about how to use the Checker Framework to validate code: tutorial 1, tutorial 2.
可以轻松编写此类注释处理器的一个框架。
普通Java注释处理在每个声明上调用，例如classes、字段、方法和方法参数，普通Java使注释处理器无法访问程序的完整 AST。您可以将 Checker Framework 视为扩展 Java 注释处理功能的库。它使您可以访问每个 class 的完整 AST，并允许您为程序中的每个语句定义规则。因此，当语句在 @Immutable 对象上调用非 @Const 方法时，您的注释处理器可以发出警告。
您的注释处理器应该是模块化的，一次处理一个 class。注释处理器可以访问当前 class 的 AST，以及它使用的所有 class 的签名，包括注释。注释处理为您提供该信息（但不是一次性提供给整个项目的 AST）。
例如，我想为目标参数创建注解@Out。然后我会以某种方式使用编译器检查参数值是否设置在函数 returns 之前。这可能吗？
还考虑了一个 @Immutable 注释，它不允许调用任何未使用 @Const 注释的方法或访问任何 public 字段。 （编译时间和可能的运行时间？）
到目前为止我有这个：
//I'm assuming Class retention is a subset of Runtime retention
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface Out
{
//no idea what to go in here.
}
这是另一个注释。同样，我没有完整的定义：
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Immutable
{
}
我想我可以开始设计一种策略，在运行时使用反射来实现它，但我想指示编译器或预处理器为我检查这些东西，这样我的注释就会有零开销。
这是您认为的事情之一 "if this could've been done, it would already be out there, and if it is, where can I grab it"。
编辑：在进一步思考 @Const 和 @Immutable 并记住 java 按值传递对象指针之后，我扩展了@Const 的定义，删除了 @Immutable，并更改了 @Out 的定义，如下所示：
/**
* When Applied to a method, ensures the method doesn't change in any
* way the state of the object used to invoke it, i.e., all the fields
* of the object must remain the same, and no field may be returned,
* unless the field itself is marked as {@code @Const}. A method
* annotated with {@code @Const} can only invoke other {@code @Const}
* methods of its class, can only use the class's fields to invoke
* {@code @Const} methods of the fields classes and can only pass fields
* as parameters to methods that annotate that formal parameter as
* {@code @Const}.
*
* When applied to a formal parameter, ensures the method will not
* modify the value referenced by the formal parameter. A formal
* parameter annotated as {@code @Const} will not be aliased inside the
* body of the method. The method is not allowed to invoke another
* method and pass the annotated parameter, save if the other method
* also annotates the formal parameter as {@code @Const}. The method is
* not allowed to use the parameter to invoke any of its type's methods,
* unless the method being invoked is also annotated as {@code @Const}
*
* When applied to a field, ensures the field cannot be aliased and that
* no code can alter the state of that field, either from inside the
* class that owns the field or from outside it. Any constructor in any
* derived class is allowed to set the value of the field and invoke any
* methods using it. As for methods, only those annotated as
* {@code @Const} may be invoked using the field. The field may only be
* passed as a parameter to a method if the method annotates the
* corresponding formal parameter as {@code @Const}
*
* When applied to a local variable, ensures neither the block where the
* variable is declared or any nested block will alter the value of that
* local variable. The local variable may be defined only once, at any
* point where it is in scope. Only methods annotated as
* {@code @Const} may be invoked using this variable, and the variable
* may only be passed as a parameter to another method if said method
* annotates its corresponding formal parameter as {@code @Const}
*
*/
@Retention(RetentionPolicy.SOURCE)
@Target({ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD,
ElementType.LOCAL_VARIABLE})
@Inherited
public @interface Const
{
}
现在 @Out:
/**
* The formal parameter annotated with {@code @Out} must be undefined in
* the scope of the caller, and it's the responsibility of the method to
* define it. If allowNull is true, the parameter can be explicitly set
* to null in the body of the method.
*/
@Retention(RetentionPolicy.SOURCE)
@Target(ElementType.PARAMETER)
public @interface Out
{
boolean allowNull() default false;
}
编辑： 我正在尝试将其实现为 eclipse 插件，但我完全无法阅读手册。我编写了一个插件，其中包含用于访问 AST 和访问方法和字段的基本逻辑。然后我做了一堆我的插件应该检测到的虚拟注释，然后我尝试打印结果，但我什至不确定会发生什么。我的插件是 "Incremental Build" 插件。这是它的代码，如果有人可以看一下并向我解释一些事情。我完全迷失在这个 API.
javac 编译器支持用户可定义的插件，称为注解处理器，可以完全满足您的需求。您可以将注释视为语言扩展。
定义public @interface Immutable { ... } 定义了语法：@Immutable 你可以在程序中编写的注解。注释处理器（编译器插件）定义语义：它强制执行语义规则并在您的程序违反规则时发出编译器警告。
Checker Framework, and it contains definitions for annotations like @NonNull and @Immutable. Here are two tutorials about how to use the Checker Framework to validate code: tutorial 1, tutorial 2.
普通Java注释处理在每个声明上调用，例如classes、字段、方法和方法参数，普通Java使注释处理器无法访问程序的完整 AST。您可以将 Checker Framework 视为扩展 Java 注释处理功能的库。它使您可以访问每个 class 的完整 AST，并允许您为程序中的每个语句定义规则。因此，当语句在 @Immutable 对象上调用非 @Const 方法时，您的注释处理器可以发出警告。
您的注释处理器应该是模块化的，一次处理一个 class。注释处理器可以访问当前 class 的 AST，以及它使用的所有 class 的签名，包括注释。注释处理为您提供该信息（但不是一次性提供给整个项目的 AST）。