Perl Programming Documentation
Download Perl
Explore

Manual

- Overview
- Tutorials
- FAQs
- History / Changes
- License

Reference

- Language
- Functions
- Operators
- Special Variables
- Pragmas
- Utilities
- Internals
- Platform Specific

Modules

- A • B • C • D • E
- F • G • H • I • L
- M • N • O • P • S
- T • U • X

Tools

- Preferences

# B::Showlex

Perl 5 version 26.0 documentation
Go to top
Show page index • Show recent pages
Recently read

# B::Showlex

- NAME
- SYNOPSIS
- DESCRIPTION
- EXAMPLES
  - OPTIONS
- SEE ALSO
- TODO
- AUTHOR

# 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`

Page index

- NAME
- SYNOPSIS
- DESCRIPTION
- EXAMPLES
  - OPTIONS
- SEE ALSO
- TODO
- AUTHOR