From: Didier Prophete <didier.prophete@...>
Date: 2006-01-20T18:04:18+09:00
Subject: Re: invalid_arity method similar to method missing ?

Logan,

> I don't believe there is a way to get the argument names from inside
> ruby.

yeah... I am afraid this is impossible in ruby...

> Can you define these methods (f1 and friends) to take a hash
> ...
> mentioned. Still not quite sure what you are asking.

ahah... well, thanks for helping me anyway. I really appreciate that.

Let me try to explain what my goal was:

Think about how controllers are handled in rails for a second. You end 
up having methods after methods which are like:

    def meth1
      name = params[:name]
      data = params[:data]
      ...
    end

    def meth2
      arg1 = params[:arg1]
      arg2 = params[:arg2]
      arg3 = params[:arg3]
      ...
    end

Well, this is a little tedious, so I wanted to instead declare these as:

    def meth1(name, data)
      ...
    end

    def meth2(arg1, arg2, arg3)
      ...
    end

(see how the arguments are passed to the methods rather than being 
manually extracted from the 'params' object)

Well, it turns out that these controller methods are always called from 
the same place, using:
     send(action_name)
(where here, action_name is :meth1, or :meth2)

Now, in order to introduce my change and keep the framework working, I 
would want to replace this little piece of code by something like:
     arg_names = <figure out the argument names for the method I want to 
call>
     args = arg_names.map { |name| params[name] }
     send(action_name, *args)

Or something like that. The idea being that the caller extracts the 
parameter values from the 'params' object and invoke the appropriate 
method with these parameters...

Now, because getting the argument names of a method might not be 
possible in ruby, this whole thing will not work... But hey, thanks for 
helping me (thank also to Eero for his slightly off-topic comment :-)

-Didier

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