From: MonkeeSage <MonkeeSage@...>
Date: 2007-12-07T23:40:07+09:00
Subject: Re: function like "function_exits"

On Dec 7, 8:16 am, Girard Fred <fred.gir...@gmail.com> wrote:
> Jordan Callicoat wrote:
> > On Dec 7, 7:31 am, Girard Fred <fred.gir...@gmail.com> wrote:
> >> > Regards,
> >> --------------------
>
> >> Posted viahttp://www.ruby-forum.com/.
> > But you don't really want that... ;)
>
> > You want respond_to? which Just Works everywhere. And really, you
> > probably don't even want to be asking if a method is defined (depends
> > on your code), but usually there are better ways of doing things (like
> > unit testing).
>
> > HTH,
> > Jordan
>
>  No it's ok, i am happy with that, if i really want, i can merge these 2
> methods:
>
> def foo()
>    puts 'test'
> end
>
> def function?(function_name)
>    return true if private_methods.include?(function_name)
>    return true if methods.include?(function_name)
>    return false
> end
>
> puts function?('foo') => true
> puts function?('notfoo') => false
> puts function?('puts') => true
>
> It's nice to learn a new language like that, thank you so much (and
> sorry for my  poor english)
> :)
>
> --
> Posted viahttp://www.ruby-forum.com/.

Your english is fine. :)

And I'm glad you like ruby!

But really, you want to use respond_to? ...that's why it was added to
the language:

http://www.ruby-doc.org/core/classes/Object.html#M000333

In rbuy, everything is an object, and every callable object is a
method. What it means when you say...

foo()

...is really this...

send(:foo) # actual ruby, try it!

In other words, you don't "call" a method in ruby, you send an object
a message that tells it to execute some code by that name. So, for
example, when you say...

[3,2,1].sort

...it really means...

[3,2,1].send(:sort) # try it!

So the way to check if an object can execute code with a certain name
("foo"), is to ask does it "respond_to?('foo')"...that means "can I
send the object with a message 'foo' and it knows how to execute it?"

If I don't make sense, just ignore me. ;)

Regards,
Jordan