From: Paul Brannan <paul@...>
Date: 2002-03-19T01:52:07+09:00
Subject: Re: instance_respond_to?

On Mon, Mar 18, 2002 at 03:36:44AM +0900, Thomas Sondergaard wrote:
> Shouldn't module have an instance_respond_to? method?

I'm not sure why it is needed, when Object#respond_to? works 99% of the
time.

> I'd like to use it in a state pattern, where I'd like to do something
> like:
> 
> class ClosedState
>   def method_missing(aSymbol, *args)
>     raiseClosedError if Impl.instance_respond_to? aSymbol
>     super
>   end
> end
> 
> For now I will add it myself. Shouldn't the following do fine?

Why add it to Module?  Modifying built-in classes is something that
should only be done when absolutely necessary.  IMO, you should make
this a standalone method.

> class Module
>   def instance_respond_to? aSymbol
>     return Module.public_instance_methods.include?(aSymbol.to_s)
>   end
> end

This will work, but I think it's an O(n) operation.

Paul