Re: true/false condition - what am I doing wrong?

[Marshall]

This is an abuse of the ternary operator.

Normally in this situation, you want to choose between 3 choices, not two!

Use the ternary operator to set a variable dependent upon a true/ false condition.
A common use would be like this:
($today eq 'Monday') ? $firstDay =1 : $firstDay =0;

That would be preferred over:
$firstDay=0;
$firstDay=1 if ($today eq 'Monday');

Use if and if/elsif/else conditions for more complicated things.

#!/usr/bin/perl -w
use strict;

decide ('add');
decide ('edit');
decide ('bad input nothing');

print "\n";

decide2 ('add');
decide2 ('edit');
decide2 ('bad input nothing');


sub decide
{
   my $input = shift;
   
   print "invalid input\n" if ($input ne "add" and $input ne "edit");
   print "doing an add\n"  if $input eq "add";
   print "doing an edit\n" if $input eq "edit";
}

sub decide2
{
   my $input = shift;
   if ($input eq 'add')
   {
      print "the add code goes here\n";
   }
   elsif ($input eq 'edit')
   {
      print "the edit code goes here\n";
   }
   else
   {
      print "the invalid input code goes here\n";
   }
}

__END__
doing an add
doing an edit
invalid input

the add code goes here
the edit code goes here
the invalid input code goes here

[choroba]

A common use would be like this:

($today eq 'Monday') ? $firstDay =1 : $firstDay =0;

I have always thought the common use is

$firstDay = $today eq 'Monday' ? 1 : 0;

[Marshall]

correct - tired this morning.. been pulling late nights on a db project...
main point is that this is not the right place for 'edit' vs 'add'.

Update: even more uses are possible:

#!/usr/bin/perl -w
use strict;

sub is_name_valid
{
   return $_[0]; #just a dummy
}

print "the name ",is_name_valid(0) ? "was" :"was not"," valid\n";
# the name was not valid
print "the name ",is_name_valid(1) ? "was" :"was not"," valid\n";
# the name was valid

[Anonymous Monk]

3 choices or more?

These also seem relevant: dispatch table and Term::Interact example

[Perlbotics]

The ternary operator is stackable. So for three choices, the following might be bearable:

use strict;
use warnings;

for my $type ( qw(add edit nada) ) {

  my $redo = $type eq 'add'  ? 'wiki_add2'
           : $type eq 'edit' ? 'wiki_edit2'
           :                   'error';

  print "$type -> $redo\n";
}

__END__
add -> wiki_add2
edit -> wiki_edit2
nada -> error

But as AM points out, the OP's task seems to call for a dispatch table.