块局部变量的语法 [英] Syntax for Block Local Variables

问题描述

我对定义块局部变量采用的好样式感到困惑.选择是:

I am confused about a good style to adopt to define block local variables. The choices are:

选择A:

method_that_calls_block { |v, w| puts v, w }

选择B:

method_that_calls_block { |v; w| puts v, w }

当我希望本地块具有默认值时，混乱就更加复杂了.我很困惑的选择是:

The confusion is compunded when I want the block local to have a default value. The choices I am confused about are:

选择C:

method_that_calls_block { |v, w = 1| puts v, w }

选择D:

method_that_calls_block { |v, w: 1| puts v, w }

是否有关于必须如何定义块局部变量的约定?

Is there a convention about how block local variables must be defined?

P.S.当我需要将默认值分配给块局部变量时，似乎; 语法也不起作用！奇怪的.

P.S. Also it seems the ; syntax does not work when I need to assign default value to a block local variable! Strange.

推荐答案

选择B无效.如@matt所示-这是有效的(尽管晦涩)语法(请参见此处:如何在Ruby中编写内联块以包含局部变量作用域?)

Choice B is not valid. As @matt indicated - it is a valid (though obscure) syntax (see here: How to write an inline block to contain local variable scope in Ruby?)

选择项C将默认值赋予 w ，这是常规值，而选择项D是默认值

Choice C gives a default value to w, which is a regular value, while Choice D is a syntax for default keyword argument.

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