From: Tom Sawyer <transami@...>
Date: 2002-08-05T12:18:47+09:00
Subject: Re: Implicit local variables for do...end blocks

you know, if your going to do this, then just go all the away and spare
us further confusions. i.e the earlier example with capitalize makes
more sense to me than this perlishness. :-)

["john", "mary"].map { capitalize }

this would thus represent the simple deafulting to a single parameter
and the receiverless mehtods acting on that deafult parameter. although
i suspect there may be some issues with the self default here.

anyhow, that's my opinion. please no more perls.

~transami


On Sun, 2002-08-04 at 09:20, Gavin Sinclair wrote:
> In the thread "Should this work?", I proposed that :collect should be able
> to operate without an explicit block parameter.  For example:
> 
> ["john", "mary"].map { |name| name.capitalize }
>   CAN BE EXPRESSED AS
> ["john", "mary"].map { $_.capitalize }   # -> ["john", "mary"]
> 
> 
> [1, 2, 3, 4].map { |i| i ** 2 }          # -> [1, 4, 9, 16]
>   CAN BE EXPRESSED AS
> [1, 2, 3, 4].map { $_ ** 2 }             # -> [1, 4, 9, 16]
> 
> 
> Guy Decoux pointed out that the blocks are independent of the method calling
> them, so the above could only be done by allowing implicit assignment of the
> *local* variable $_ in *every* "do ... end" block.
> 
> Is this agreeable?
> 
> I would usually continue to name my parameters explicitly, just to make it
> clear what's being operated on (useful in a dynaically typed language!).
> However, the motivation for my proposal is very simple cases like the
> following:
> 
>    input = ARGV.map { |s| s.to_i }
> 
> And, of course, this whole discussion was prompted by such constructs as:
> 
>    [x, y, z].each { |arr| arr << nil }
>    [x, z, z].map  { |arr| arr == [nil] }
> 
> The above three examples would be more concisely written as:
> 
>    input = ARGV.map { $_.to_i }
> 
>    [x, y, z].each { $_ << nil }
> 
>    [x, y, z].map { $_ == [nil] }
> 
> Whether this terseness is useful is for discussion.
> 
> Cheers,
> Gavin
> 
> --
> Gavin Sinclair                                       Software Engineer
> Sydney, Australia                            Soyabean Software Pty Ltd
> 
> 
> 
-- 
~transami