Ruby块中的怪异功能不足 [英] Weird imoperfection in Ruby blocks

问题描述

可能重复:
有什么区别或价值Ruby中有哪些块编码样式?

Possible Duplicate:
What is the difference or value of these block coding styles in Ruby?

# This works

method :argument do
  other_method
end

# This does not

method :argument {
  other_method
}

为什么?

解释器似乎很困惑，并认为{...}是一个哈希.

It seems like the interpreter is confused and thinks that the { ... } is a hash.

当翻译无法理解实际有效的代码时，我总是会生气.它类似于具有许多此类问题的PHP.

I always get angry when an interpreter can't understand a code that is actually valid. It resembles PHP that had many problems of this kind.

推荐答案

它不认为它是哈希，而是一个优先问题. {}的绑定比do end紧密，因此method :argument { other_method }解析为method(:argument {other_method})，在语法上无效(但是如果不是符号，则参数将是另一个方法调用).

It doesn't think it's a hash - it's a precedence issue. {} binds tighter than do end, so method :argument { other_method } is parsed as method(:argument {other_method}), which is not syntactically valid (but it would be if instead of a symbol the argument would be another method call).

如果添加括号(method(:argument) { other_method })，它将可以正常工作.

If you add parentheses (method(:argument) { other_method }), it will work fine.

不，该代码实际上无效.如果是这样，它将起作用.

And no, the code is not actually valid. If it were, it would work.

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