There must be a routine that returns the MD5. Let's call this "giveMD5" in package Foo. Then the following code will replace that routine by another routine, without the outside world knowing about it. 
{
my $giveMD5 = \&Foo::giveMD5;
my %givenMD5;
*Foo::giveMD5 = sub {
    my $md5 = $givenmd5{@_} ||= $giveMD5->( @_ ); # execute old to obt
+ain "real" MD5
# do evil things to op tree for given parameters if first time
    return $md5; # the "right" value
};
}

[download]

Of course, this is more or less pseudo-code to give you the idea.

By the way, this "wrapping" technique is used in all sorts of Perl modules, so disabling this feature in Perl is basically impossible.

Liz

In reply to Re: Re: Re: Locking PERL code another way by liz
in thread Locking PERL code another way by Anonymous Monk

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