B::Deparse

B::Deparse(3)          Perl Programmers Reference Guide          B::Deparse(3)



NAME
       B::Deparse - Perl compiler backend to produce perl code

SYNOPSIS
       perl -MO=Deparse[,-uPACKAGE][,-p][,-l][,-sLETTERS] prog.pl

DESCRIPTION
       B::Deparse is a backend module for the Perl compiler that generates
       perl source code, based on the internal compiled structure that perl
       itself creates after parsing a program. The output of B::Deparse won't
       be exactly the same as the original source, since perl doesn't keep
       track of comments or whitespace, and there isn't a one-to-one
       correspondence between perl's syntactical constructions and their
       compiled form, but it will often be close. When you use the -p option,
       the output also includes parentheses even when they are not required by
       precedence, which can make it easy to see if perl is parsing your
       expressions the way you intended.

       Please note that this module is mainly new and untested code and is
       still under development, so it may change in the future.

OPTIONS
       As with all compiler backend options, these must follow directly after
       the '-MO=Deparse', separated by a comma but not any white space.

       -p  Print extra parentheses. Without this option, B::Deparse includes
           parentheses in its output only when they are needed, based on the
           structure of your program. With -p, it uses parentheses (almost)
           whenever they would be legal. This can be useful if you are used to
           LISP, or if you want to see how perl parses your input. If you say

               if ($var & 0x7f == 65) {print "Gimme an A!"}
               print ($which ? $a : $b), "\n";
               $name = $ENV{USER} or "Bob";

           B::Deparse,-p will print

               if (($var & 0)) {
                   print('Gimme an A!')
               };
               (print(($which ? $a : $b)), '???');
               (($name = $ENV{'USER'}) or '???')

           which probably isn't what you intended (the '???' is a sign that
           perl optimized away a constant value).

       -uPACKAGE
           Normally, B::Deparse deparses the main code of a program, all the
           subs called by the main program (and all the subs called by them,
           recursively), and any other subs in the main:: package. To include
           subs in other packages that aren't called directly, such as
           AUTOLOAD, DESTROY, other subs called automatically by perl, and
           methods, which aren't resolved to subs until runtime, use the -u
           option. The argument to -u is the name of a package, and should
           follow directly after the 'u'. Multiple -u options may be given,
           separated by commas.  Note that unlike some other backends,
           B::Deparse doesn't (yet) try to guess automatically when -u is
           needed -- you must invoke it yourself.

       -l  Add '#line' declarations to the output based on the line and file
           locations of the original code.

       -sLETTERS
           Tweak the style of B::Deparse's output. At the moment, only one
           style option is implemented:

       C       Cuddle elsif, else, and continue blocks. For example, print

                   if (...) {
                        ...
                   } else {
                        ...
                   }

               instead of

                   if (...) {
                        ...
                   }
                   else {
                        ...
                   }

               The default is not to cuddle.

BUGS
       See the 'to do' list at the beginning of the module file.

AUTHOR
       Stephen McCamant <alias@mcs.com>, based on an earlier version by
       Malcolm Beattie <mbeattie@sable.ox.ac.uk>.
















3rd Berkeley Distribution    perl 5.005, patch 02                B::Deparse(3)