Programming Perl, 3rd Edition

Code Generators

The three current backends that convert Perl opcodes into some other format are all emphatically experimental. (Yes, we said this before, but we don't want you to forget.) Even when they happen to produce output that runs correctly, the resulting programs may take more disk space, more memory, and more CPU time than than they would ordinarily. This is an area of ongoing research and development. Things will get better.

The Bytecode Generator

The B::Bytecode module writes the parse tree's opcodes out in a platform-independent encoding. You can take a Perl script compiled down to bytecodes and copy that to any other machine with Perl installed on it.

The standard but currently experimental perlcc (1) command knows how to convert Perl source code into a byte-compiled Perl program. All you have to do is:

% perlcc -b -o pbyscript srcscript

And now you should be able to directly "execute" the resulting pbyscript. The start of that file looks somewhat like this:

#!/usr/bin/perl
use ByteLoader 0.03;
^C^@^E^A^C^@^@^@^A^F^@^C^@^@^@^B^F^@^C^@^@^@^C^F^@^C^@^@^@
B^@^@^@^H9^A8M-^?M-^?M-^?M-^?7M-^?M-^?M-^?M-^?6^@^@^@^A6^@
^G^D^D^@^@^@^KR^@^@^@^HS^@^@^@^HV^@M-2W<^FU^@^@^@^@X^Y@Z^@
…

There you find a small script header followed by purely binary data. This may seem like deep magic, but its dweomer, er, dwimmer is at most a minor one. The ByteLoader module uses a technique called a source filter to alter the source code before Perl gets a chance to see it. A source filter is a kind ...