Hello perl-diddler,

I have no experience with the PPI modules, but I can get (a slightly simplified version of) your code to work by adding a backslash before $ARGV[0] in the call to PPI::Document->new:

#! perl
use warnings;
use strict;
use PPI;
use PPI::Dumper;

printf "parse: >%s<\n", $ARGV[0];

my $doc   = PPI::Document->new(\$ARGV[0])
    or die "PPI::Document->new failed: $!";

my $dumpr = PPI::Dumper->new($doc)
    or die "PPI::Dumper->new failed: $!";

$dumpr->print;
[download]

Output:

14:25 >perl 1688_SoPW.pl "print qq[Hello world!\n];"
parse: >print qq[Hello world!\n];<
PPI::Document
  PPI::Statement
    PPI::Token::Word    'print'
    PPI::Token::Whitespace      ' '
    PPI::Token::Quote::Interpolate      'qq[Hello world!\n]'
    PPI::Token::Structure       ';'

14:25 >
[download]

Note that it’s good practice to die on failure: in this case, it identifies the call to PPI::Document->new as the location of the problem.

Also note that I use double quotes on the command line because I’m on Windows.

Hope that helps,