动态获取/设置参数的默认值 [英] Getting/setting an argument's default value dynamically

问题描述

从以下情况开始:

class Foo
  def bar(baz={})
    p baz
  end
end

foo = Foo.new
p meth = foo.method(:bar) # => #<Method: Foo#bar>
p meth.parameters # => [[:opt, :baz]]

因此我可以确定方法bar是可选的，但是如何找到该方法的默认值({})?

So I can figure out that the method bar is optional, but how do I find the default value ({}) for the method?

推荐答案

只需执行以下操作:

foo.bar

由于您没有传递baz的值，它将打印出默认值.

Since you are not passing in a value for baz, it will print out the default value.

尽管如此，我敢打赌你想要一些适用于任何方法的东西.我知道的唯一一致的方法是查看源代码.

Although, I'm betting you want something that would apply to any method. The only consistent way I know of, is to look at the source code.

答案:有人写了一个脚本来完成它此处中获取方法参数和其他信息.

The Answer: Somebody wrote a script that does it here.

但是，查看脚本以尝试了解它如何提取默认值会让我头疼.

However, looking over the script to try and understand just how it pulls out the default values makes my head hurt.

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