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ru.perl
- RU.PERL ----------------------------------------------------------------------
From : Nick Kostirya 2:5020/400 11 Feb 2004 11:01:54
To : Yury Kopyl
Subject : Re: C-style Logical Defined-Or
--------------------------------------------------------------------------------
>
> NK>>> Привет.
> NK>>> А что "C-style Logical Defined-Or" убрали?
>
> NK>>> В http://search.cpan.org/~nwclark/perl-5.8.3/pod/perlop.pod не
> NK>>> могу найти.
>
>
> NK> http://search.cpan.org/~nwclark/perl-5.8.3/pod/perlop.pod#C-style_
> NK> Logical_Or
>
> NK> Что то не вижу там оператора //
>
>
http://search.cpan.org/~nwclark/perl-5.8.3/pod/perlop.pod#Assignment_Operato
> rs
Hашел!
Это в http://search.cpan.org/src/HVDS/perl-5.9.0/pod/perlop.pod
Вот цитата
=head2 C-style Logical Defined-Or
Although it has no direct equivalent in C, Perl's C<//> operator is related
to its C-style or. In fact, it's exactly the same as C<||>, except that it
tests the left hand side's definedness instead of its truth. Thus, C<$a //
$b>
is similar to C<defined($a) || $b> (except that it returns the value of
C<$a>
rather than the value of C<defined($a)>) and is exactly equivalent to
C<defined($a) ? $a : $b>. This is very useful for providing default values
for variables. If you actually want to test if at least one of C<$a> and
C<$b> is defined, use C<defined($a // $b)>.
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