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User Rating: Rated by: |
Good (3.8/5) 5 user(s) |
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Want description |
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Want is a Perl module created to implement the `want' command. Want is a Perl module created to implement the `want' command.
SYNOPSIS
use Want; sub foo :lvalue { if (want(qw'LVALUE ASSIGN')) { print "We have been assigned ", want('ASSIGN'); lnoreturn; } elsif (want('LIST')) { rreturn (1, 2, 3); } elsif (want('BOOL')) { rreturn 0; } elsif (want(qw'SCALAR !REF')) { rreturn 23; } elsif (want('HASH')) { rreturn { foo => 17, bar => 23 }; } return }
This module generalises the mechanism of the wantarray function, allowing a function to determine in some detail how its return value is going to be immediately used.
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EXAMPLES
use Carp 'croak'; use Want 'howmany'; sub numbers { my $count = howmany(); croak("Can't make an infinite list") if !defined($count); return (1..$count); } my ($one, $two, $three) = numbers();
use Want 'want'; sub pi () { if (want('ARRAY')) { return [3, 1, 4, 1, 5, 9]; } elsif (want('LIST')) { return (3, 1, 4, 1, 5, 9); } else { return 3; } } print pi->[2]; # prints 4 print ((pi)[3]); # prints 1
sub backstr :lvalue { if (want(qw'LVALUE ASSIGN')) { my ($a) = want('ASSIGN'); $_[0] = reverse $a; return undef; } elsif (want('RVALUE')) { my $t = scalar reverse $_[0]; } else { carp("Not in ASSIGN context"); } return } print "foo -> ", backstr("foo"), "n"; # foo -> oof backstr(my $robin) = "nibor"; print "$robin is now $robinn"; # $robin is now robin Requirements:
· Perl
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