From: dblack@...
Date: 2007-09-10T23:52:07+09:00
Subject: Re: Bug in lambda?

Hi --

On Mon, 10 Sep 2007, Robert Klemme wrote:

> 2007/9/9, dblack@wobblini.net <dblack@wobblini.net>:
>> Definitely not a bug. Block parameters use assignment semantics, with
>> regard to the scope in which the block appears. In your example,
>> you're assigning 1 to a. If you create a local variable inside the
>> block, however, it only exists for the duration of the block.
>>
>> As far as remember, Guy Decoux and I are the only two people who think
>> that this makes perfect sense, once you learn it, and should not be
>> changed :-)
>
> Now I'm curious: how often do you have use for this feature?  I mean,
> if block parameters were locally scoped you just had to punch in one
> more assignment to get the same effect like the current version:
>
> def foo
>  x=1
>  lambda {|a| x=a}
> end
>
> Do I miss something?

I don't think so, but part of the problem for me is that there's no
problem -- in other words, I learned that it works with assignment
syntax, and probably haven't made all that much use of it but never
thought there was any reason for it *not* to work that way. I suppose
it's possible to clobber variables, but then it's possible to do that
without blocks, too, if you're not careful about variable names.


David

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