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Something few non-lawyers understand is that to actually protect your code, works of art, ... you have to publish them!
The (temporary) protection you get from copyright law, patent law, trademarks, ... is given in trade for the author making their works, inventions, ... public and thus adding to the state of the art.
There are even some legal systems (most notably under European Union Law) that deny any protection at all for works which could have applied for specific protection (such as patents or design protection) but failed to do so.
So if you want to make sure, you get adequate protection go and see your friendly lawyer!
Of course some other legal systems (such as the US) make it a criminal offence to break any copy-protection or code-scheme. So hide your perl-code behind a simple source filter and send the decoders/re-engineers to jail, but don't hope that other legal systems will accept this.
"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law