B::Showlex(3perl)      Perl Programmers Reference Guide      B::Showlex(3perl)


NAME
       B::Showlex - Show lexical variables used in functions or files

SYNOPSIS
               perl -MO=Showlex[,-OPTIONS][,SUBROUTINE] foo.pl

DESCRIPTION
       When a comma-separated list of subroutine names is given as options,
       Showlex prints the lexical variables used in those subroutines.
       Otherwise, it prints the file-scope lexicals in the file.

EXAMPLES
       Traditional form:

        $ perl -MO=Showlex -e 'my ($i,$j,$k)=(1,"foo")'
        Pad of lexical names for comppadlist has 4 entries
        0: (0x8caea4) undef
        1: (0x9db0fb0) $i
        2: (0x9db0f38) $j
        3: (0x9db0f50) $k
        Pad of lexical values for comppadlist has 5 entries
        0: SPECIAL #1 &PL_sv_undef
        1: NULL (0x9da4234)
        2: NULL (0x9db0f2c)
        3: NULL (0x9db0f44)
        4: NULL (0x9da4264)
        -e syntax OK

       New-style form:

        $ perl -MO=Showlex,-newlex -e 'my ($i,$j,$k)=(1,"foo")'
        main Pad has 4 entries
        0: (0x8caea4) undef
        1: (0xa0c4fb8) "$i" = NULL (0xa0b8234)
        2: (0xa0c4f40) "$j" = NULL (0xa0c4f34)
        3: (0xa0c4f58) "$k" = NULL (0xa0c4f4c)
        -e syntax OK

       New form, no specials, outside O framework:

        $ perl -MB::Showlex -e \
           'my ($i,$j,$k)=(1,"foo"); B::Showlex::compile(-newlex,-nosp)->()'
        main Pad has 4 entries
        1: (0x998ffb0) "$i" = IV (0x9983234) 1
        2: (0x998ff68) "$j" = PV (0x998ff5c) "foo"
        3: (0x998ff80) "$k" = NULL (0x998ff74)

       Note that this example shows the values of the lexicals, whereas the
       other examples did not (as they're compile-time only).

   OPTIONS
       The "-newlex" option produces a more readable "name => value" format,
       and is shown in the second example above.

       The "-nosp" option eliminates reporting of SPECIALs, such as "0:
       SPECIAL #1 &PL_sv_undef" above.  Reporting of SPECIALs can sometimes
       overwhelm your declared lexicals.

SEE ALSO
       B::Showlex can also be used outside of the O framework, as in the third
       example.  See B::Concise for a fuller explanation of reasons.

TODO
       Some of the reported info, such as hex addresses, is not particularly
       valuable.  Other information would be more useful for the typical
       programmer, such as line-numbers, pad-slot reuses, etc..  Given this,
       -newlex is not a particularly good flag-name.

AUTHOR
       Malcolm Beattie, "mbeattie@sable.ox.ac.uk"

perl v5.38.2                      2024-02-11                 B::Showlex(3perl)