From: Gavin Kistner <gavin@...>
Date: 2005-09-29T00:52:53+09:00
Subject: Re: creating independent lambdas in loops

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On Sep 28, 2005, at 9:29 AM, Eric Mahurin wrote:
> --- Gavin Kistner <gavin@refinery.com> wrote:
>> On Sep 28, 2005, at 7:47 AM, Eric Mahurin wrote:
>>>> Completely true. If a variable of that name is already
>>>> defined it is used (and no local variables are created).
>>> Does anyone else find this "feature" useful?
>> All the time! I would say that at least half the programs I
>> write use this feature of the blocks-as-closures.
>
> I'm talking about specifically block arguments (the only
> variables in a block that can be local to the block).

Ah, right. Sorry, I was responding only to the bit I quoted, not  
properly following the thread of the conversation.

No, I don't think I have ever personally used that and wanted it, and  
it has bitten me before (at least twice). It's like this sort of  
mistake in JS:

for (var i=0, len=myArray.length; i<len; ++i ){
     for ( var j=0, len2=myArray.length; j<len2; ++j ){
         #lots
         #of
         #code
         for ( var i=0, len=myArray.length; i<len; ++i ){
             #OOPS
         }
       }
}

In the same way that I hate having to come up with unique names for  
nested iterators variables, and be sure I'm using the right one, and  
never copy/paste code with the wrong one into place...well, I  
similarly dislike being unable to re-use the same local variable name  
for a block when doing iterations-in-iterations.

I, for one, would be fine with block arguments always being block- 
local, even if it means they mask access to local variables outside  
the closure.


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