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Re: Sequential defined-or operators

by Util (Priest)
on Jan 14, 2008 at 22:21 UTC ( [id://662388]=note: print w/replies, xml ) Need Help??


in reply to Sequential defined-or operators

While you remain pre-5.10, you might like this technique: 

use List::Util qw( first );
my $theme = first { defined $_ } (
    $global_config->{modes}{$current_mode}{theme},
    $theme_config->{current_theme},
    $default_theme,
    'none',
);

[download]

Replies are listed 'Best First'.
Re^2: Sequential defined-or operators
by plobsing (Friar) on Jan 15, 2008 at 02:39 UTC
    Thats all fine and good until your default value is ask_user(). Then this fails due to eager evaluation. // fixes this fortunately.
[reply]
[d/l]
[select]
      It took me a second to understand that you are referring to the short-circuiting nature of //. If you needed the short-circuiting behaviour pre-5.10, here's one solution: 
      sub first(&@) {
   my $cb = shift(@_);
   for (@_) {
      my $i = ref eq 'CODE' ? $_->() : $$_;
      my $rv;
      $rv = $cb->() for $i;
      return $i if $rv;
   }
   return;
}

my $theme = first { defined }
   \$global_config->{modes}{$current_mode}{theme},
   \$theme_config->{current_theme},
   \&ask_user,
   \'none';

      [download]
[reply]
[d/l]
[select]

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