From: Dave Burt <dave@...>
Date: 2006-05-02T09:17:56+09:00
Subject: Re: getting the name of arguments a method takes

Guest wrote:
> Didier Prophete wrote:
>> I am wondering if there is a way to programatically get the name of the 
>> arguments a function take.
>>
>> Say, I have this code:
>>   class MyClass
>>       def my_fct(a, b, c)
>>      end
>>   end
>>
>> Now, I can easily get a handle to the method 'my_fct' using:
>>   mc = MyClass.new
>>   meth = mc.method(:my_fct)
>>
>> But how do I get to the list of arguments of 'my_fct' ? I couldn't find 
>> anything like:
>>   meth.arg_list
>> which would return [ :a, :b, :c ], or something like that.
>>
>> Is this even possible in ruby ?
>>
>> -Didier
> 
> i also would like to do this. anybody know if it's possible, and also
> getting arg names from a proc? if so it would be very handy for
> metaprogramming.

The short answer: no, it's not possible. What do you want it for?

There's always this way, though:

def method_arg_names(method_name, file)
  File.read(file)[/def #{Regexp.escape method_name}(.*(\)|$))/, 1]
end

p method_arg_names("method_arg_names", $0)  #=> "(method_name, file)"

Cheers,
Dave