Your code looks overly complicated, it could be as simple as: 

#! perl -sw
use strict;

sub doit {
    local $^W;
    *doit = sub{ print } if m[^foo];
}

doit() while $_ = <DATA>;

=output
P:\test>junk4
fum
fiddlesticks
=cut

__DATA__
fee
fi
foo
fum
fiddlesticks

[download]

It's this kind of self-modifying code that horrified the CS types in the late 60's (early COBOL compilers used this extensively), and is what lead to 'structured programming' and eventually object orientation.

The funny thing is it is exactly this kind of technique that allows FP language compilers to produce efficient code from what appears horribly inefficient at the source code level. Goggle for a paper on the "The spineless tagless G-machine" for further reading.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.

In reply to Re: Doing "it" only once by BrowserUk
in thread Doing "it" only once by Limbic~Region

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