使用字符串按名称访问局部变量

问题描述：

我是新手，但我有以下代码:

I'm new to this but I have the following code:

when /^read (.+)$/
   puts "Reading #{$1}:"
   puts $1.description.downcase

我想使用 $1 作为我可以调用方法的变量，目前解释器返回一个 "NoMethodError: undefined method 'description' for "Door":String".

I would like to use $1 as a variable that I can call methods on, currently the interpreter returns a "NoMethodError: undefined method 'description' for "Door":String".

编辑:

例如:

door = Item.new( :name => "Door", :description => "a locked door" )
key  = Item.new( :name => "Key",  :description => "a key"         )

答

您需要提供代码设置的更多详细信息才能得到好的答案(或者让我找出哪个问题与 : 重复).$1 引用了哪些变量?以下是一些猜测:

You need to provide more details of your code setup to get a good answer (or for me to figure out which question this is a duplicate of :). What kind of variables are referenced by $1? Here are some guesses:

如果这实际上是同一实例上的一个方法，您可以通过以下方式调用此方法:

If this is actually a method on the same instance, you can invoke this method by:

# Same as "self.foo" if $1 is "foo"
self.send($1).description.downcase

如果这些是实例变量，则:

If these are instance variables, then:

# Same as "@foo.description.downcase"
instance_variable_get(:"@#{$1}").description.downcase

如果这些是局部变量，你不能直接做，你应该改变你的代码以使用哈希:

If these are local variables, you can't do it directly, and you should change your code to use a Hash:

objs = {
  'foo' => ...,
  'key' => Item.new( :name => "Key", :description => "a key" )
}
objs['jim'] = ...
case some_str
  when /^read (.+)$/
    puts "Reading #{$1}:"
    puts objs[$1].description.downcase
end

使用字符串按名称访问局部变量

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