Scalar::Readonly - functions for controlling whether any scalar variable is read-only

       Philippe M. Chiasson, <gozer@cpan.org>

       Copyright (C) 2004 by Philippe M. Chiasson

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself, either Perl version 5.8.3 or, at your option, any later version of Perl 5 you may have available.

perl v5.40.0                                       2024-10-20                              Scalar::Readonly(3pm)

       This simple module can make scalars read-only. Useful to protect configuration variables, for example.

       This module can also be used to subvert Perl's many read-only variables to potential evil trickery.

   readonly
       Ths function takes a scalar variable and tells you whether it is read-only. It returns 0 if the scalar
       isn't read-only, and a positive number if it is.

   readonly_on
       Makes the passed scalar variable read-only. If you try and modify a read-only scalar, your code will die
       with the following error message:

         Modification of a read-only value attempted at

   readonly_off
       Makes the passed scalar variable read-write. You can even do this to read-only special variables, though
       you almost certainly don't want to do that.

   EXPORT
       ':all' => readonly, readonly_on, readonly_off

       Scalar::Readonly - functions for controlling whether any scalar variable is read-only

       Scalar::Util, Attribute::Constant, Const::Fast.

         use Scalar::Readonly ':all';
         my $foo = "foo";
         readonly_on($foo);
         $foo = "bar";  #ERROR!

         if (readonly($foo)) {
           readonly_off($foo);
         }

         readonly_off($]);
         $] = "6.0";

         print "This is Perl v$]";