http://www.perlmonks.org?node_id=290854


in reply to multiple keys - one value
in thread using a hash of functions

If you're only duplicating one value, you can use 
my %h = (
    HELP => $_ = sub {print "help\n"},
    "?"  => $_,
    SAVE => sub {print "save\n"},
);

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You have to use one variable per value though: 
my ($help, $save);
my %h = (
    HELP => $help = sub {print "help\n"},
    "?"  => $help,
    SAVE => $save = sub {print "save\n"},
    EXIT => $save,
);

[download]

Replies are listed 'Best First'.
Re: Re: multiple keys - one value
by NetWallah (Canon) on Dec 04, 2003 at 06:39 UTC
    I'm trying to improve on sandfly's code by eliminating the need for temp variables, but getting into trouble. Why does the following code produce
    "Use of uninitialized value in subroutine entry at -e line 1.
    Undefined subroutine &main:: called at -e line 1." 
    my %h=(   HELP => sub {print qq(help\n)},
                  Q=>$h{HELP},
                SAVE=>sub{print qq(save\n)} ); 
print $h{Q}();

    [download]
    I have also tried it by separating the declaration and population of %h, to no avail.
[reply]
[d/l]
      I suspect it's because $h{HELP} doesn't exist when you create the tuple Q=>$h{HELP}, as %h hasn't been assigned to at that time.

      Perhaps this will work for you: 

      use Data::Dumper;
my %h=(   HELP => sub {print qq(help\n)},

                SAVE=>sub{print qq(save\n)} ); 
$h{Q} = $h{HELP};
print Dumper(%h);
print $h{Q}();

      [download]
      Result: 
      $VAR1 = 'Q';
$VAR2 = sub { "DUMMY" };
$VAR3 = 'HELP';
$VAR4 = $VAR2;
$VAR5 = 'SAVE';
$VAR6 = sub { "DUMMY" };
help
1

      [download]
      Note that HELP and Q both use the same sub.

      -QM
      --
      Quantum Mechanics: The dreams stuff is made of

[reply]
[d/l]
[select]
Re: Re: multiple keys - one value
by NetWallah (Canon) on Dec 05, 2003 at 05:58 UTC
    OK I answered my own question based on one of my old writeups. It IS possible to eliminate the temporary variable by coding as follows: 
    use strict;
my %h; #Pre-declare so it can be referenced inside populating code
%h=(      HELP => sub {print qq(help\n)},
          '?'=>sub{$h{HELP}()},
          SAVE=>sub{print qq(save\n)},
          EXIT=>sub{$h{SAVE}()}  );
 $h{'?'}();
 $h{EXIT}();

    [download]
    This prints the lines:
    help
    save
[reply]
[d/l]

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