Module::Compile(3) User Contributed Perl Documentation Module::Compile(3)NAMEModule::Compile - Perl Module Compilation
SYNOPSIS
package Foo;
use Module::Compile -base;
sub pmc_compile {
my ($class, $source) = @_;
# Convert $source into (most likely Perl 5) $compiled_output
return $compiled_output;
}
In Bar.pm:
package Bar;
use Foo;
...
no Foo
or (implied "no Foo;"):
package Bar;
{
use Foo;
...
}
To compile Bar.pm into Bar.pmc:
perl -c Bar.pm
DESCRIPTION
This module provides a system for writing modules that compile other
Perl modules.
Modules that use these compilation modules get compiled into some
altered form the first time they are run. The result is cached into
".pmc" files.
Perl has native support for ".pmc" files. It always checks for them,
before loading a ".pm" file.
EXAMPLE
You can declare a "v6.pm" compiler with:
package v6;
use Module::Compile -base;
sub pmc_compile {
my ($class, $source) = @_;
# ... some way to invoke pugs and give p5 code back ...
}
and use it like:
# MyModule.pm
use v6-pugs;
module MyModule;
# ...some p6 code here...
no v6;
# ...back to p5 land...
On the first time this module is loaded, it will compile Perl 6 blocks
into Perl 5 (as soon as the "no v6" line is seen), and merge it with
the Perl 5 blocks, saving the result into a MyModule.pmc file.
The next time around, Perl 5 will automatically load MyModule.pmc when
someone says "use MyModule". On the other hand, Perl 6 can run
MyModule.pm s a Perl 6 module just fine, as "use v6-pugs" and "no v6"
both works in a Perl 6 setting.
The v6.pm module will also check if MyModule.pmc is up to date. If it
is, then it will touch its timestamp so the ".pmc" is loaded on the
next time.
BENEFITSModule::Compile compilers gives you the following benefits:
· Ability to mix many source filterish modules in a much more sane
manner. Module::Compile controls the compilation process, calling
each compiler at the right time with the right data.
· Ability to ship precompiled modules without shipping
Module::Compile and the compiler modules themselves.
· Easier debugging of compiled/filtered code. The ".pmc" has the real
code you want to see.
· Zero additional runtime penalty after compilation, because "perl"
has already been doing the ".pmc" check on every module load since
1999!
PARSING AND DISPATCH
NOTE: *** NOT FULLY IMPLEMENTED YET ***
Module::Compile attempts to make source filtering a sane process, by
parsing up your module's source code into various blocks; so that by
the time a compiler is called it only gets the source code that it
should be looking at.
This section describes the rather complex algorithm that
Module::Compile uses.
First, the source module is preprocessed to hide heredocs, since the
content inside heredocs can possibly confuse further parsing.
Next, the source module is divided into a shallow tree of blocks:
PREAMBLE:
(SUBROUTINE | BAREBLOCK | POD | PLAIN)S
PACKAGES:
PREFACE
(SUBROUTINE | BAREBLOCK | POD | PLAIN)S
DATA
All of these blocks begin and end on line boundaries. They are
described as follows:
PREAMBLE - Lines before the first C<package> statement.
PACKAGES - Lines beginning with a C<package statement and continuing
until the next C<package> or C<DATA> section.
DATA - The DATA section. Begins with the line C<__DATA__> or
C<__END__>.
SUBROUTINE - A top level (not nested) subroutine. Ending '}' must be
on its own line in the first column.
BAREBLOCK - A top level (not nested) code block. Ending '}' must be
on its own line in the first column.
POD - Pod sections beginning with C<^=\w+> and ending with C<=cut>.
PLAIN - Lines not in SUBROUTINE, BAREBLOCK or POD.
PREFACE - Lines before the first block in a package.
Next, all the blocks are scanned for lines like:
use Foo qw'x y z';
no Foo;
Where Foo is a Module::Compile subclass.
The lines within a given block between a "use" and "no" statement are
marked to be passed to that compiler. The end of an inner block
effectively acts as a "no" statement for any compile sections in that
block. "use" statements in a PREFACE apply to all the code in a
PACKAGE. "use" statements in a PREAMBLE apply to all the code in all
PACKAGES.
After all the code has been parsed into blocks and the blocks have been
marked for various compilers, Module::Compile dispatches the code
blocks to the compilers. It does so in a most specific to most general
order. So inner blocks get compiled first, then outer blocks.
A compiler may choose to declare that its result not be recompiled by
some other containing parser. In this case the result of the
compilation is replaced by a single line containing the hexadecimal
digest of the result in double quotes followed by a semicolon. Like:
"f1d2d2f924e986ac86fdf7b36c94bcdf32beec15";
The rationale of this is that randoms strings are usally left alone by
compilers. After all the compilers have finished, the digest lines will
be expanded again.
Every bit of the default process described above is overridable by
various methods.
DISTRIBUTION SUPPORT
Module::Install makes it terribly easy to prepare a module distribution
with compiled .pmc files. Module::Compile installs a
Module::Install::PMC plugin. All you need to do is add this line to
your Makefile.PL:
pmc_support;
Any of your distrbution's modules that use Module::Compile based
modules will automatically be compiled into .pmc files and shipped with
your distribtution precompiled. This means that people who install your
module distribtution do not need to have the compilers installed
themselves. So you don't need to make the compiler modules be
prerequisites.
SEE ALSO
Module::Install
AUTHORS
Ingy dA~Xt Net <ingy@cpan.org>
Audrey Tang <autrijus@autrijus.org>
COPYRIGHT
Copyright (c) 2006. Ingy dA~Xt Net. All rights reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See <http://www.perl.com/perl/misc/Artistic.html>
perl v5.14.1 2006-10-17 Module::Compile(3)
