Tie::Scalar::Sticky - Block assignments to scalars

   use strict;
   use Tie::Scalar::Sticky;

   tie my $sticky, 'Tie::Scalar::Sticky';

   $sticky = 42;
   $sticky = '';       # still 42
   $sticky = undef;    # still 42
   $sticky = 0;        # now it's zero

   tie my $sticky, 'Tie::Scalar::Sticky' => qw/ foo bar /;

   $sticky = 42;
   $sticky = 'foo';    # still 42
   $sticky = 'bar';    # still 42
   $sticky = 0;        # now it's zero

Scalars tie'ed to this module will 'reject' any assignments of undef or the empty string or any of the extra arugments provided to tie(). It simply removes the need for you to validate assignments, such as:

   $var = $val unless grep $val eq $_, qw(not one of these);

Actually, that is the exact idea used in this module ...

So, why do this? Because i recently had to loop through a list where some items were undefined and the previously defined value should be used instead. In a nutshell:

   tie my $sticky, 'Tie::Scalar::Sticky' => 9, 'string';
   for (3,undef,'string',2,'',1,9,0) {
      $sticky = $_;
      print $sticky, ' ';
   }

Should print: 3 3 2 2 1 0

If you have found a bug, typo, etc. please visit Best Practical Solution's CPAN bug tracker at http://rt.cpan.org:

<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Tie-Scalar-Sticky>

or send mail to <bug-Tie-Scalar-Sticky#rt.cpan.org>

(you got this far ... you can figure out how to make that a valid address ... and note that i won't respond to bugs sent to my personal address any longer)

Jeffrey Hayes Anderson

Dan [broquaint] Brook Dan added support for user-defined strings by changing $self to a glob. His patch was applied to Version 1.02 verbatim, i later 'simplified' the code by assuming that undef and the empty strings (the only two items Version 1.00 will block) are already waiting inside @$$self. Dan then removed undef from @$$self, and i added a simple check that returns from STORE unless $val is defined.

PerlMonks for the education.

Copyright (c) 2004 Jeffrey Hayes Anderson.

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