


lib::B::Deparse(3Perl Programmers Reference Gulib::B::Deparse(3p)


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



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lib::B::Deparse(3Perl Programmers Reference Gulib::B::Deparse(3p)


           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>.











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