NAME

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

SYNOPSIS

   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

DESCRIPTION

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

BUGS

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)

AUTHOR

Jeffrey Hayes Anderson

CREDITS

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

Copyright (c) 2004 Jeffrey Hayes Anderson.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.