NAME
Acme::landmine - variables that explode
SYNOPSIS
use Acme::landmine; # crucial, this line
tie $scalar, "Acme::landmine" => "first use of \$scalar";
tie @array, "Acme::landmine" => "first use of \@array";
tie %hash, "Acme::landmine" => "first use of \%hash";ABSTRACT
variables that "explode", which useful for locating the first
use of a variable after a checkpoint, while debugging.DESCRIPTION
a tie interface that C<confess>es. This is useful
for creating out-of-bounds markers when modeling data structures,
or setting a checkpoint when you want to know the next time
a variable is accessed after some point.
DESTROY is not mined, but everything else is. EXPORT
None.
HISTORY
2002 - released version 0.01
2006 - cleaned up the documentation to describe how I actually use this module in production work, bumped version to 1.00
how it works
we've got two functions, DESTROY, which is just there so AUTOLOAD isn't called at DESTROY time, and AUTOLOAD, which behaves differently if you are calling TIE-something or if you are using your tied variable. at tie time, the AUTOLOAD function blesses the tie argument, if any, as a scalar reference, so the argument is saved as the "sin" to "confess" (that is, die with a stack-trace) when the exploding variable is used any other way.
If you look at the source code of this module, which is very short, you will see that the sin variable is associated with the named autoloaded function with a string evaluation, which might appear to allow executing arbitrary code, as long as it is well-formed and begins with an r-value, but this is not the case: the argument is never interpolated into the string, and the TIE functions are abstracted in this way to avoid having to duplicate code for TIESCALAR, TIEARRAY, TIEHASH, TIEFILE, TIESCARF, and any other future TIE* possibilities that might happen to appear.
COPYRIGHT AND LICENSE
copyright 2002, 2006 David Nicol davidnico@cpan.org
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
please feedback and bugreport via
https://rt.cpan.org/Ticket/Create.html?Queue=Acme-landmine