@TypeChecked 和 @CompileStatic 的区别

问题描述

谁能解释@TypeChecked 和@CompileStatic 的区别?

Can someone explain the difference between @TypeChecked and @CompileStatic?

我读到使用@TypeChecked 无法在运行时添加新方法.不允许使用哪些其他功能?

I read that with @TypeChecked it is not possible to add new methods at runtime. What other features are not allowed?

@CompileStatic 允许哪些 Groovy 特性?与 groovyc 和 @CompileStatic 相比，字节码是否与使用 javac 编译的相同?

Which Groovy Features are allowed with @CompileStatic? Is the bytecode same as compiled with javac in compare to groovyc and @CompileStatic?

推荐答案

主要区别在于 MOP(元对象协议):@TypeChecked 保持方法通过 MOP，而 @CompileStatic 生成类似于Java 字节码的方法调用.这意味着它们的语义不同，但也意味着您仍然可以在 @TypeChecked 代码之上应用元编程，只要可以在编译时解析方法调用即可.

The major difference is the MOP (Meta Object Protocol): @TypeChecked keep methods going through the MOP, while @CompileStatic generate method calls similar to Java's bytecode. This means their semantic are different, but it also means you can still apply metaprogramming on top of a @TypeChecked code, as long as the method call can be resolved at compile time.

以下代码显示了 MOP 作用于 @TypeChecked 代码，而不是作用于 @CompileStatic 代码:

The following code shows the MOP acting on a @TypeChecked code, and not on @CompileStatic code:

import groovy.transform.CompileStatic as CS
import groovy.transform.TypeChecked as TC

class Foo {
  def bar = "bar"
}

class TestTC {
  Foo foo

  TestTC() {
    foo = new Foo()
    foo.metaClass.getBar = { "metaClass'd bar" }
  }

  @TC
  def typed() {
    foo.bar
  }

  @CS 
  def compiled() {
    foo.bar
  }
}

assert new TestTC().typed() == "metaClass'd bar"
assert new TestTC().compiled() == "bar"

对于 @CompileStatic，是的，Groovy 尝试生成接近 javac 输出的字节码，因此，他们的表现非常接近，只有少数例外.

For @CompileStatic, yes, Groovy tries to generate bytecode close to what javac would output, thus, their performance are very close, with a few exceptions.

(更新于 2016-01-13)

@CompileStatic 和 @TypeChecked 都允许:

• 闭包(包括通过@DelegatesTo的闭包委托)；
• AST(可用于编译时元编程)；
• Groovy 的语法糖，例如正则表达式、列表、映射、运算符重载等；
• 扩展.

• Closures (including Closure delegations through @DelegatesTo);
• ASTs (which can be used for compile-time metaprogramming);
• Groovy's syntatic sugar, like those on regex, lists, maps, operator overload and the likes;
• Extensions.

对于 @TypeChecked，您还可以通过 类型检查扩展，提供更大的灵活性.@CompileStatic 也支持这一点，但它是一个 限制更多.

For @TypeChecked, you can also instruct the compiler to ignore some type checks through a Type Checking Extensions, allowing more flexibility. @CompileStatic also support this, but is a little more restrictive.

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