B::Showlex - Show lexical variables used in functions or files
perl -MO=Showlex[,-OPTIONS][,SUBROUTINE] foo.pl
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.
$ perl -MO=Showlex -e 'my ($i,$j,$k)=(1,"foo")' Pad of lexical names for comppadlist has 4 entries 0: SPECIAL #1 &PL_sv_undef 1: PVNV (0x9db0fb0) $i 2: PVNV (0x9db0f38) $j 3: PVNV (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
$ perl -MO=Showlex,-newlex -e 'my ($i,$j,$k)=(1,"foo")' main Pad has 4 entries 0: SPECIAL #1 &PL_sv_undef 1: PVNV (0xa0c4fb8) "$i" = NULL (0xa0b8234) 2: PVNV (0xa0c4f40) "$j" = NULL (0xa0c4f34) 3: PVNV (0xa0c4f58) "$k" = NULL (0xa0c4f4c) -e syntax OK
New form, no specials, outside O framework:
$ perl -MB::Showlex -e \ 'my ($i,$j,$k)=(1,"foo"); B::Showlex::compile(-newlex,-nosp)->()' main Pad has 4 entries 1: PVNV (0x998ffb0) "$i" = IV (0x9983234) 1 2: PVNV (0x998ff68) "$j" = PV (0x998ff5c) "foo" 3: PVNV (0x998ff80) "$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).
-newlex option produces a more readable
name => value format, and is shown in the second example above.
-nosp option eliminates reporting of SPECIALs, such as
0: SPECIAL #1 &PL_sv_undef above. Reporting of SPECIALs can sometimes overwhelm your declared lexicals.
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 isnt a particularly good flag-name.