NAME
Scalar::Readonly - functions for controlling whether any scalar variable is read-only
SYNOPSIS
my
$foo
=
"foo"
;
readonly_on(
$foo
);
$foo
=
"bar"
;
#ERROR!
if
(readonly(
$foo
)) {
readonly_off(
$foo
);
}
readonly_off($]);
$] =
"6.0"
;
"This is Perl v$]"
;
DESCRIPTION
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
SEE ALSO
Scalar::Util, Attribute::Constant, Const::Fast.
AUTHOR
Philippe M. Chiasson, <gozer@cpan.org>
COPYRIGHT AND LICENSE
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.