From: Eric Hodel <drbrain@...7.net>
Date: 2007-11-17T12:19:20+09:00
Subject: Re: "&prock", not "&block"

On Nov 16, 2007, at 02:01 , Greg Weeks wrote:
> Eric Hodel wrote:
>>> It may be that "&foo" is pedagogically described as the "foo"
>>> parameter with an "&" modifier.  But that is misleading.
>>
>> This is correct, and this is what happens.  Its not misleading.
>
> I take your point.  Thanks for the correction.
>
> Nevertheless, even though the argument is a block, the parameter  
> foo is
> not.  If you want to use the *block* argument in the method body, you
> use the expression &foo, not foo.

If by 'use the block argument in the method body' you mean 'call  
methods on the block argument', you must use 'foo', as  
'&foo.some_method' is a syntax error.  If by 'use [...]' you mean  
'pass foo as a block argument to another method' (like the array- 
splat * syntax) you are correct.

> foo is a proc; &foo -- an expression, not a parameter as I  
> erroneously said -- is a block.

&foo is not an expression, & can only be used to modify argument  
passing:

$ ruby
def x(&foo) &foo end
-:1: parse error
def x(&foo) &foo end
              ^
def x(&foo) (&foo) end
-:2: parse error
def x(&foo) (&foo) end
               ^

--
Poor workers blame their tools. Good workers build better tools. The
best workers get their tools to do the work for them. -- Syndicate Wars