Beefy Boxes and Bandwidth Generously Provided by pair Networks
Think about Loose Coupling

Re^2: Mixing tied variables with goto label

by Limbic~Region (Chancellor)
on Nov 16, 2005 at 00:50 UTC ( #508858=note: print w/replies, xml ) Need Help??

in reply to Re: Mixing tied variables with goto label
in thread Mixing tied variables with goto label

I couldn't find it documented anywhere. So it is how the function is called that is causing the problem. I can still produce a fair amount of misdirection. I am not sure I have the time or energy to actually make the obfu, but I would be happy and impressed if someone did. Like most magic and misdirection, the most important part is the setup.

You will need to hide the tie, sub TIESCALAR, and friends. This should be possible using evil eval. The FETCH needs to be special too. Instead of using an internal goto to produce the magic, it will return the current value in the STORE the first time, but the second time it will return a different label.

my $label; # magic setup happens here $label = 'START'; print "$label\n"; # prints START goto $label; exit; START: print "Hello, world\n"; END: print "Goodbye, cruel world\n";
When it is run, the output will be unexpected:
START Goodbye, cruel world
In any case, if you happen to find some documentation explaining this behavior I would appreciate it.

Cheers - L~R

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://508858]
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others avoiding work at the Monastery: (3)
As of 2018-06-24 11:12 GMT
Find Nodes?
    Voting Booth?
    Should cpanminus be part of the standard Perl release?

    Results (126 votes). Check out past polls.