FM / pod

/usr/share/perl5/pod

Name	Size	Mode	Actions
a2p.pod	6107	0644	edit dl rm
perl.pod	15748	0644	edit dl rm
perl56delta.pod	107184	0644	edit dl rm
perl58delta.pod	114908	0644	edit dl rm
perl561delta.pod	124697	0644	edit dl rm
perl570delta.pod	21655	0644	edit dl rm
perl571delta.pod	30382	0644	edit dl rm
perl572delta.pod	25551	0644	edit dl rm
perl573delta.pod	4644	0644	edit dl rm
perl581delta.pod	38060	0644	edit dl rm
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perl583delta.pod	6335	0644	edit dl rm
perl584delta.pod	7363	0644	edit dl rm
perl585delta.pod	5889	0644	edit dl rm
perl586delta.pod	4651	0644	edit dl rm
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perl589delta.pod	53905	0644	edit dl rm
perl590delta.pod	34951	0644	edit dl rm
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perl594delta.pod	12661	0644	edit dl rm
perl595delta.pod	18934	0644	edit dl rm
perl5004delta.pod	56240	0644	edit dl rm
perl5005delta.pod	34285	0644	edit dl rm
perl5100delta.pod	53922	0644	edit dl rm
perl5101delta.pod	43877	0644	edit dl rm
perlaix.pod	18128	0644	edit dl rm
perlamiga.pod	7031	0644	edit dl rm
perlapi.pod	169428	0644	edit dl rm
perlapio.pod	19332	0644	edit dl rm
perlapollo.pod	829	0644	edit dl rm
perlartistic.pod	6802	0644	edit dl rm
perlbeos.pod	2939	0644	edit dl rm
perlbook.pod	663	0644	edit dl rm
perlboot.pod	28355	0644	edit dl rm
perlbot.pod	11675	0644	edit dl rm
perlbs2000.pod	7929	0644	edit dl rm
perlcall.pod	55173	0644	edit dl rm
perlce.pod	9257	0644	edit dl rm
perlcheat.pod	4153	0644	edit dl rm
perlclib.pod	7684	0644	edit dl rm
perlcn.pod	4915	0644	edit dl rm
perlcommunity.pod	6398	0644	edit dl rm
perlcompile.pod	9516	0644	edit dl rm
perlcygwin.pod	28183	0644	edit dl rm
perldata.pod	36879	0644	edit dl rm
perldbmfilter.pod	4987	0644	edit dl rm
perldebguts.pod	31887	0644	edit dl rm
perldebtut.pod	21304	0644	edit dl rm
perldebug.pod	37535	0644	edit dl rm
perldelta.pod	43877	0644	edit dl rm
perldgux.pod	2821	0644	edit dl rm
perldiag.pod	183151	0644	edit dl rm
perldoc.pod	7310	0644	edit dl rm
perldos.pod	10853	0644	edit dl rm
perldsc.pod	25447	0644	edit dl rm
perlebcdic.pod	66607	0644	edit dl rm
perlembed.pod	38033	0644	edit dl rm
perlepoc.pod	3779	0644	edit dl rm
perlfaq.pod	24841	0644	edit dl rm
perlfaq1.pod	17762	0644	edit dl rm
perlfaq2.pod	21614	0644	edit dl rm
perlfaq3.pod	38534	0644	edit dl rm
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perlfaq5.pod	49201	0644	edit dl rm
perlfaq6.pod	38538	0644	edit dl rm
perlfaq7.pod	37588	0644	edit dl rm
perlfaq8.pod	46128	0644	edit dl rm
perlfaq9.pod	24191	0644	edit dl rm
perlfilter.pod	21140	0644	edit dl rm
perlfork.pod	11440	0644	edit dl rm
perlform.pod	16894	0644	edit dl rm
perlfreebsd.pod	1950	0644	edit dl rm
perlfunc.pod	291909	0644	edit dl rm
perlglossary.pod	112139	0644	edit dl rm
perlgpl.pod	18806	0644	edit dl rm
perlguts.pod	105182	0644	edit dl rm
perlhack.pod	121512	0644	edit dl rm
perlhaiku.pod	1504	0644	edit dl rm
perlhist.pod	38766	0644	edit dl rm
perlhpux.pod	28650	0644	edit dl rm
perlhurd.pod	1990	0644	edit dl rm
perlintern.pod	26408	0644	edit dl rm
perlintro.pod	21491	0644	edit dl rm
perliol.pod	33755	0644	edit dl rm
perlipc.pod	67761	0644	edit dl rm
perlirix.pod	4397	0644	edit dl rm
perljp.pod	8070	0644	edit dl rm
perlko.pod	7892	0644	edit dl rm
perllexwarn.pod	14435	0644	edit dl rm
perllinux.pod	1492	0644	edit dl rm
perllocale.pod	41616	0644	edit dl rm
perllol.pod	8252	0644	edit dl rm
perlmachten.pod	4500	0644	edit dl rm
perlmacos.pod	2111	0644	edit dl rm
perlmacosx.pod	11322	0644	edit dl rm
perlmint.pod	9539	0644	edit dl rm
perlmod.pod	24494	0644	edit dl rm
perlmodinstall.pod	13929	0644	edit dl rm
perlmodlib.pod	77333	0644	edit dl rm
perlmodstyle.pod	21114	0644	edit dl rm
perlmpeix.pod	15087	0644	edit dl rm
perlmroapi.pod	2959	0644	edit dl rm
perlnetware.pod	6488	0644	edit dl rm
perlnewmod.pod	11214	0644	edit dl rm
perlnumber.pod	8352	0644	edit dl rm
perlobj.pod	21813	0644	edit dl rm
perlop.pod	96225	0644	edit dl rm
perlopenbsd.pod	1207	0644	edit dl rm
perlopentut.pod	37997	0644	edit dl rm
perlos2.pod	92783	0644	edit dl rm
perlos390.pod	16074	0644	edit dl rm
perlos400.pod	4618	0644	edit dl rm
perlothrtut.pod	40657	0644	edit dl rm
perlpacktut.pod	51047	0644	edit dl rm
perlperf.pod	51328	0644	edit dl rm
perlplan9.pod	5125	0644	edit dl rm
perlpod.pod	21626	0644	edit dl rm
perlpodspec.pod	67792	0644	edit dl rm
perlport.pod	86302	0644	edit dl rm
perlpragma.pod	4320	0644	edit dl rm
perlqnx.pod	4246	0644	edit dl rm
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perlrecharclass.pod	21909	0644	edit dl rm
perlref.pod	26465	0644	edit dl rm
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perlrepository.pod	23453	0644	edit dl rm
perlrequick.pod	17617	0644	edit dl rm
perlreref.pod	11996	0644	edit dl rm
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perlrun.pod	49928	0644	edit dl rm
perlsec.pod	23542	0644	edit dl rm
perlsolaris.pod	29131	0644	edit dl rm
perlstyle.pod	8618	0644	edit dl rm
perlsub.pod	54222	0644	edit dl rm
perlsymbian.pod	16222	0644	edit dl rm
perlsyn.pod	31090	0644	edit dl rm
perlthrtut.pod	46510	0644	edit dl rm
perltie.pod	36665	0644	edit dl rm
perltoc.pod	642987	0644	edit dl rm
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perltooc.pod	51425	0644	edit dl rm
perltoot.pod	68625	0644	edit dl rm
perltrap.pod	41151	0644	edit dl rm
perltru64.pod	7736	0644	edit dl rm
perltw.pod	5384	0644	edit dl rm
perlunicode.pod	56169	0644	edit dl rm
perlunifaq.pod	12878	0644	edit dl rm
perluniintro.pod	32973	0644	edit dl rm
perlunitut.pod	7907	0644	edit dl rm
perlutil.pod	9881	0644	edit dl rm
perluts.pod	3180	0644	edit dl rm
perlvar.pod	59133	0644	edit dl rm
perlvmesa.pod	3952	0644	edit dl rm
perlvms.pod	52545	0644	edit dl rm
perlvos.pod	5567	0644	edit dl rm
perlwin32.pod	40809	0644	edit dl rm
perlxs.pod	74194	0644	edit dl rm
perlxstut.pod	49670	0644	edit dl rm

Edit: /usr/share/perl5/pod/perlcompile.pod (9516B)

=head1 NAME

perlcompile - Introduction to the Perl Compiler-Translator

=head1 DESCRIPTION

Perl has always had a compiler: your source is compiled into an
internal form (a parse tree) which is then optimized before being
run.  Since version 5.005, Perl has shipped with a module
capable of inspecting the optimized parse tree (C<B>), and this has
been used to write many useful utilities, including a module that lets
you turn your Perl into C source code that can be compiled into a
native executable.

The C<B> module provides access to the parse tree, and other modules
("back ends") do things with the tree.  Some write it out as
semi-human-readable text.  Another traverses the parse tree to build a
cross-reference of which subroutines, formats, and variables are used
where.  Another checks your code for dubious constructs.  Yet another back
end dumps the parse tree back out as Perl source, acting as a source code
beautifier or deobfuscator.

Because its original purpose was to be a way to produce C code
corresponding to a Perl program, and in turn a native executable, the
C<B> module and its associated back ends are known as "the
compiler", even though they don't really compile anything.
Different parts of the compiler are more accurately a "translator",
or an "inspector", but people want Perl to have a "compiler
option" not an "inspector gadget".  What can you do?

This document covers the use of the Perl compiler: which modules
it comprises, how to use the most important of the back end modules,
what problems there are, and how to work around them.

=head2 Layout

The compiler back ends are in the C<B::> hierarchy, and the front-end
(the module that you, the user of the compiler, will sometimes
interact with) is the O module.

Here are the important back ends to know about, with their status
expressed as a number from 0 (outline for later implementation) to
10 (if there's a bug in it, we're very surprised):

=over 4

=item B::Lint

Complains if it finds dubious constructs in your source code.  Status:
6 (it works adequately, but only has a very limited number of areas
that it checks).

=item B::Deparse

Recreates the Perl source, making an attempt to format it coherently.
Status: 8 (it works nicely, but a few obscure things are missing).

=item B::Xref

Reports on the declaration and use of subroutines and variables.
Status: 8 (it works nicely, but still has a few lingering bugs).

=back

=head1 Using The Back Ends

The following sections describe how to use the various compiler back
ends.  They're presented roughly in order of maturity, so that the
most stable and proven back ends are described first, and the most
experimental and incomplete back ends are described last.

The O module automatically enabled the B<-c> flag to Perl, which
prevents Perl from executing your code once it has been compiled.
This is why all the back ends print:

myperlprogram syntax OK

before producing any other output.

=head2 The Cross Referencing Back End

The cross referencing back end (B::Xref) produces a report on your program,
breaking down declarations and uses of subroutines and variables (and
formats) by file and subroutine.  For instance, here's part of the
report from the I<pod2man> program that comes with Perl:

Subroutine clear_noremap
    Package (lexical)
      $ready_to_print   i1069, 1079
    Package main
      $&                1086
      $.                1086
      $0                1086
      $1                1087
      $2                1085, 1085
      $3                1085, 1085
      $ARGV             1086
      %HTML_Escapes     1085, 1085

This shows the variables used in the subroutine C<clear_noremap>.  The
variable C<$ready_to_print> is a my() (lexical) variable,
B<i>ntroduced (first declared with my()) on line 1069, and used on
line 1079.  The variable C<$&> from the main package is used on 1086,
and so on.

A line number may be prefixed by a single letter:

=over 4

=item i

Lexical variable introduced (declared with my()) for the first time.

=item &

Subroutine or method call.

=item s

Subroutine defined.

=item r

Format defined.

=back

The most useful option the cross referencer has is to save the report
to a separate file.  For instance, to save the report on
I<myperlprogram> to the file I<report>:

$ perl -MO=Xref,-oreport myperlprogram

=head2 The Decompiling Back End

The Deparse back end turns your Perl source back into Perl source.  It
can reformat along the way, making it useful as a deobfuscator.  The
most basic way to use it is:

$ perl -MO=Deparse myperlprogram

You'll notice immediately that Perl has no idea of how to paragraph
your code.  You'll have to separate chunks of code from each other
with newlines by hand.  However, watch what it will do with
one-liners:

$ perl -MO=Deparse -e '$op=shift||die "usage: $0
  code [...]";chomp(@ARGV=<>)unless@ARGV; for(@ARGV){$was=$_;eval$op;
  die$@ if$@; rename$was,$_ unless$was eq $_}'
  -e syntax OK
  $op = shift @ARGV || die("usage: $0 code [...]");
  chomp(@ARGV = <ARGV>) unless @ARGV;
  foreach $_ (@ARGV) {
      $was = $_;
      eval $op;
      die $@ if $@;
      rename $was, $_ unless $was eq $_;
  }

The decompiler has several options for the code it generates.  For
instance, you can set the size of each indent from 4 (as above) to
2 with:

$ perl -MO=Deparse,-si2 myperlprogram

The B<-p> option adds parentheses where normally they are omitted:

$ perl -MO=Deparse -e 'print "Hello, world\n"'
  -e syntax OK
  print "Hello, world\n";
  $ perl -MO=Deparse,-p -e 'print "Hello, world\n"'
  -e syntax OK
  print("Hello, world\n");

See L<B::Deparse> for more information on the formatting options.

=head2 The Lint Back End

The lint back end (B::Lint) inspects programs for poor style.  One
programmer's bad style is another programmer's useful tool, so options
let you select what is complained about.

To run the style checker across your source code:

$ perl -MO=Lint myperlprogram

To disable context checks and undefined subroutines:

$ perl -MO=Lint,-context,-undefined-subs myperlprogram

See L<B::Lint> for information on the options.

=head1 Module List for the Compiler Suite

=over 4

=item B

This module is the introspective ("reflective" in Java terms)
module, which allows a Perl program to inspect its innards.  The
back end modules all use this module to gain access to the compiled
parse tree.  You, the user of a back end module, will not need to
interact with B.

=item O

This module is the front-end to the compiler's back ends.  Normally
called something like this:

$ perl -MO=Deparse myperlprogram

This is like saying C<use O 'Deparse'> in your Perl program.

=item B::Concise

This module prints a concise (but complete) version of the Perl parse
tree.  Its output is more customizable than the one of B::Terse or
B::Debug (and it can emulate them). This module useful for people who
are writing their own back end, or who are learning about the Perl
internals.  It's not useful to the average programmer.

=item B::Debug

This module dumps the Perl parse tree in verbose detail to STDOUT.
It's useful for people who are writing their own back end, or who
are learning about the Perl internals.  It's not useful to the
average programmer.

=item B::Deparse

This module produces Perl source code from the compiled parse tree.
It is useful in debugging and deconstructing other people's code,
also as a pretty-printer for your own source.  See
L</"The Decompiling Back End"> for details about usage.

=item B::Lint

This module inspects the compiled form of your source code for things
which, while some people frown on them, aren't necessarily bad enough
to justify a warning.  For instance, use of an array in scalar context
without explicitly saying C<scalar(@array)> is something that Lint
can identify.  See L</"The Lint Back End"> for details about usage.

=item B::Showlex

This module prints out the my() variables used in a function or a
file.  To get a list of the my() variables used in the subroutine
mysub() defined in the file myperlprogram:

$ perl -MO=Showlex,mysub myperlprogram

To get a list of the my() variables used in the file myperlprogram:

$ perl -MO=Showlex myperlprogram

[BROKEN]

=item B::Terse

This module prints the contents of the parse tree, but without as much
information as B::Debug.  For comparison, C<print "Hello, world.">
produced 96 lines of output from B::Debug, but only 6 from B::Terse.

This module is useful for people who are writing their own back end,
or who are learning about the Perl internals.  It's not useful to the
average programmer.

=item B::Xref

This module prints a report on where the variables, subroutines, and
formats are defined and used within a program and the modules it
loads.  See L</"The Cross Referencing Back End"> for details about
usage.

=back

=head1 KNOWN PROBLEMS

BEGIN{} blocks are executed while compiling your code.  Any external
state that is initialized in BEGIN{}, such as opening files, initiating
database connections etc., do not behave properly.  To work around
this, Perl has an INIT{} block that corresponds to code being executed
before your program begins running but after your program has finished
being compiled.  Execution order: BEGIN{}, (possible save of state
through compiler back-end), INIT{}, program runs, END{}.

=head1 AUTHOR

This document was originally written by Nathan Torkington, and is now
maintained by the perl5-porters mailing list
I<perl5-porters@perl.org>.

=cut

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