in reply to Re: howto strip the first char of a string?
in thread howto strip the first char of a string?

Did you try running that? Perhaps you meant the pseudo-code reverse; chop; reverse; which spelled out in Perl would be $_ = reverse; chop; $_ = reverse;?

If not, I don't understand how you'd expect chop reverse; reverse; to do anything useful.

ihb

Read argumentation in its context!

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Re^3: howto strip the first char of a string?
by etcshadow (Priest) on Sep 08, 2004 at 18:15 UTC
    Well, in the insane-o universe where reverse was an lvalue, chop reverse is all you'd need. That, however is certainly not the case. It's funny just to think, though, about someone implementing an lvalue reverse function... can you lvalue a tied scalar? I should look into that :-p 
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      And, amazingly... it completely works! 
      package Tie::ReverseScalar;

sub TIESCALAR {
    my $class = shift;
    return bless \$_[0] => $class;
}

sub FETCH {
    return reverse ${$_[0]};
}

sub STORE {
    ${$_[0]} = reverse $_[1];
}

sub DESTROY {
    undef ${$_[0]};
}

1;

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      and then: 
      use Tie::ReverseScalar;
sub Reverse :lvalue { 
    my $x = @_ ? \$_[0] : \$_;
    tie $x, 'Tie::ReverseScalar', $$x; $x
}

$_ = 'foo';
chop Reverse;
print;

__END__
oo

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      Now, of course, that's not the way that reverse actually works... but isn't that fun?

      Update: oops, I had written that this output "fo" (which wouldn't have been interesting at all), but it actually outputs "oo" (which is what makes it cool). Thanks, BrowserUK, for pointing out the typo. 

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        Colour me confused but isn't: 

        $_ = 'foo';
chop Reverse;
print;

__END__
fo

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        a complicated way of doing?: 

        $_ = 'foo'; chop; print;

fo

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        Examine what is said, not who speaks.
        "Efficiency is intelligent laziness." -David Dunham
        "Think for yourself!" - Abigail
        "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon
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      Yes you can. You don't even need to go as far as you're thinking about.

      BEGIN {
    sub funky_reverse : lvalue {}
    *CORE::GLOBAL::reverse = \&funky_reverse;
}

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      It doesn't help you, though. You really want to return an alias (or a list thereof), not any old lvalue(s). And that's not something you can do in vanilla Perl. You need something like Data::Alias.

      Makeshifts last the longest.

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