You are right, that example is silly, which is why I said so. :^) It's useful (as that thread was discussing btw) for something like $_ eq "pot" and ($_ = "kettle") for $some->{deeply}{nested}{data}{structure}; The straight alternative is 
$some->{deeply}{nested}{data}{structure} = "kettle"
    if $some->{deeply}{nested}{data}{structure} eq "pot";

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which irritates my hubris. Localizing here is better than that, but it's just too much red tape for my taste: 
{
    local *_ = \$some->{deeply}{nested}{data}{structure};
    $_ = "kettle" if $_ eq "pot";
}

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local *_ = \$something; is not a language construct, I have to brainparse it and understand what's going on to read the code.

I see where you object to a loop that has only one iteration, although I find the use of redo in a naked block far worse than a single-iteration for loop: the redo conceils the loop character because you don't know that that naked block is one until you read to an arbitrary point inside it. for used as a topicalizer on the other hand makes it immediately obvious that we're only looking at a single iteration.

The example you gave where a function's return value is topicalized misses the point. You topicalize a variable when you intend to modify it - doing that to a function return value you haven't saved is pointless. You might of course do something like this:

my $stuff;
for(return_value()) {
    chomp;
    s/foo//g;
    tr/x/y/;
    $stuff = $_;
}

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But if I had to maintain that I'd hunt you down and kill you. That obviously should have been 
my $stuff = return_value();
for($stuff) {
    chomp;
    s/foo//g;
    tr/x/y/;
}

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For the record, I actually don't use the long construct with the for block frequently either. It does come in very handy when it's appropriate though. (I got the idea of using for as a topicalizer from the man himself actually - he mentioned this in an interview, where he said it Perl has a topicalizer, for, which lets people say "it", ie $_, without specifying the subject over and over.)

That's what I have to say on the issue. YMMV :-)

Makeshifts last the longest.

In reply to Re^4: Using $_ as a temp var, especially in functions by Aristotle
in thread Using $_ as a temp var, especially in functions by BUU

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