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Text File | 2006-04-25 | 5KB | 206 lines

package B::Showlex;

our $VERSION = '1.02';

use strict;
use B qw(svref_2object comppadlist class);
use B::Terse ();
use B::Concise ();

#
# Invoke as
#     perl -MO=Showlex,foo bar.pl
# to see the names of lexical variables used by &foo
# or as
#     perl -MO=Showlex bar.pl
# to see the names of file scope lexicals used by bar.pl
#


# borrowed from B::Concise
our $walkHandle = \*STDOUT;

sub walk_output { # updates $walkHandle
    $walkHandle = B::Concise::walk_output(@_);
    #print "got $walkHandle";
    #print $walkHandle "using it";
    $walkHandle;
}

sub shownamearray {
    my ($name, $av) = @_;
    my @els = $av->ARRAY;
    my $count = @els;
    my $i;
    print $walkHandle "$name has $count entries\n";
    for ($i = 0; $i < $count; $i++) {
    my $sv = $els[$i];
    if (class($sv) ne "SPECIAL") {
        printf $walkHandle "$i: %s (0x%lx) %s\n", class($sv), $$sv, $sv->PVX;
    } else {
        printf $walkHandle "$i: %s\n", $sv->terse;
        #printf $walkHandle "$i: %s\n", B::Concise::concise_sv($sv);
    }
    }
}

sub showvaluearray {
    my ($name, $av) = @_;
    my @els = $av->ARRAY;
    my $count = @els;
    my $i;
    print $walkHandle "$name has $count entries\n";
    for ($i = 0; $i < $count; $i++) {
    printf $walkHandle "$i: %s\n", $els[$i]->terse;
    #print $walkHandle "$i: %s\n", B::Concise::concise_sv($els[$i]);
    }
}

sub showlex {
    my ($objname, $namesav, $valsav) = @_;
    shownamearray("Pad of lexical names for $objname", $namesav);
    showvaluearray("Pad of lexical values for $objname", $valsav);
}

my ($newlex, $nosp1); # rendering state vars

sub newlex { # drop-in for showlex
    my ($objname, $names, $vals) = @_;
    my @names = $names->ARRAY;
    my @vals  = $vals->ARRAY;
    my $count = @names;
    print $walkHandle "$objname Pad has $count entries\n";
    printf $walkHandle "0: %s\n", $names[0]->terse unless $nosp1;
    for (my $i = 1; $i < $count; $i++) {
    printf $walkHandle "$i: %s = %s\n", $names[$i]->terse, $vals[$i]->terse
        unless $nosp1 and $names[$i]->terse =~ /SPECIAL/;
    }
}

sub showlex_obj {
    my ($objname, $obj) = @_;
    $objname =~ s/^&main::/&/;
    showlex($objname, svref_2object($obj)->PADLIST->ARRAY) if !$newlex;
    newlex ($objname, svref_2object($obj)->PADLIST->ARRAY) if  $newlex;
}

sub showlex_main {
    showlex("comppadlist", comppadlist->ARRAY)    if !$newlex;
    newlex ("main", comppadlist->ARRAY)        if  $newlex;
}

sub compile {
    my @options = grep(/^-/, @_);
    my @args = grep(!/^-/, @_);
    for my $o (@options) {
    $newlex = 1 if $o eq "-newlex";
    $nosp1  = 1 if $o eq "-nosp";
    }

    return \&showlex_main unless @args;
    return sub {
    my $objref;
    foreach my $objname (@args) {
        next unless $objname;    # skip nulls w/o carping

        if (ref $objname) {
        print $walkHandle "B::Showlex::compile($objname)\n";
        $objref = $objname;
        } else {
        $objname = "main::$objname" unless $objname =~ /::/;
        print $walkHandle "$objname:\n";
        no strict 'refs';
        die "err: unknown function ($objname)\n"
            unless *{$objname}{CODE};
        $objref = \&$objname;
        }
        showlex_obj($objname, $objref);
    }
    }
}

1;

__END__

=head1 NAME

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

=head1 SYNOPSIS

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

=head1 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.

=head1 EXAMPLES

Traditional form:

 $ 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

New-style form:

 $ 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).

=head2 OPTIONS

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

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

=head1 SEE ALSO

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

=head1 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 isnt a particularly good flag-name.

=head1 AUTHOR

Malcolm Beattie, C<[e-mail]>

=cut