From: Matthew Moss <matt@...>
Date: 2008-12-13T05:58:20+09:00
Subject: Re: parallel method return value


On Dec 12, 2008, at 2:21 PM, Louis-Philippe wrote:

> Thanks Matthew,
>
>    "No, because what was provided before wasn't wrong."
>
> Yeah... I believe you, but would really like it to be else!


Think of it this way...

     def foo
       return 1, 2, 3
     end

     a = foo

Now, you want a to be 1, but Ruby would need the power to read minds  
to accommodate that. See, because if I do the same, I want a to be [1,  
2, 3]. How is foo supposed to figure that out? Or why should your want  
be more/less preferable than my want?

Simply, the interpreter can't know. There has to be some syntax or  
something that gives foo, or the assignment to a, that key information.

Telling foo would be passing an arg:

     def foo(nargs)
       return [1, 2, 3][0...nargs]
     end

     a = foo(1)

Any of the other examples come after foo is done, so:

     def foo
	return 1, 2, 3
     end

     a, = foo
     a = foo[0]
     a = foo.first

All three of those do the same... assign 1 to a. The latter two  
request specifically the first item, while the first does parallel  
assignment (of array components to particular variables... in this  
case, only a). Since you seem interested in parallel assignment to a  
variable number of variables, the first seems appropriate. Granted,  
forgetting the comma might be easy, but there's no way for foo to know  
that you want a = foo to return 1 and that someone else that does a =  
foo wants [1, 2, 3].