• Step 5 - Use a stringified ref. to provide straightforward visual comparison of 2, or more, ref.s - I've recently been using this to verify that a ref. in 2 different places is actually the same object.
• Step 7 - add use autodie; to provide default exception throwing on failure
• Step 7 & 8 - add use CGI::Carp; for CGI/WWW scripts
• Your final observation WRT IDEs etc. could, IMHO, suggest that the use of Eclipse, for perl dev't, isn't for the fainthearted...

To let the debugger do this automatically I use a debugger customization script:

sub afterinit 
{
    $::SIG{'__WARN__'} = sub {
        my $warning = shift;
        if ( $warning =~ m{\s at \s \S+ \s line \s \d+ \. $}xms ) {
            $DB::single = 1;    # debugger stops here automatically
        }
        warn $warning;
    };
    print "sigwarn handler installed!\n";
    return;
}
[download]

hexcoder++ :)

For further informations: afterinit , .perldb and other options are described in:

--> perldebug#Debugger Customization

Nice work, but may I suggest that

> Display the contents of variables using print or warn

> warn "$var\n";

is changed to

warn "<$var>";

?

Two reasons:

• I don't see the point of disabling line and file information from warn by default by appending "\n".

  A beginner might get lost where the error originates.

• A missing chomp is very common, surrounding brackets <...> helps finding them.

  A beginner should be made aware if his variable ends on a newline.

C:\>perl
$var = "abc\n";    # trailing newline

warn "$var\n";
warn "<$var>";
warn "$var";

__END__
abc

<abc
> at - line 4.
abc
[download]

update

I just realized that your point 3 covers chomp and detecting whitespace, but I'm still not sure why you're disabling the line info in warn.

On the subject of detecting unexpected whitespace, mention should also be made of another node that regularly appears in Selected Best Nodes:

Unbelievably Obvious Debugging Tip by dreadpiratepeter

Cheers,

Athanasius <°(((>< contra mundum

Iustus alius egestas vitae, eros Piratica,

I recently got bitten by doing this. The debugging messages were going to the web page. The code was misbehaving, but no debugging messages appeared. View Source explained why - because I had used < and >, they were being interpreted as HTML tags that made no sense & were ignored. Since then, I've been using square brackets.

Regards,

John Davies

yeah that's why CGI::Carp translates -> to -» and so on, which makes some dumps hard to read.

My preference to <...> over [...] stems from the fact that square brackets are easily confused as array syntax by the eye.

I'd suggest to either double or invert the angle brackets, I doubt that <<...>> or >...< are easily confused as HTML tags.

update

I was wrong with the simple doubling, this <<br>> would be a a break surrounded by angles.

Though this might help ->...<-

I'm open for other ASCII suggestions, i.e. avoiding unicode.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

I think the "\n" stems from (originally) just replacing print with warn.

It has always been well documented that warn or die, with a terminating newline, doesn't emit the line and file info. But warn with a newline is essentially the same as print STDERR, if a little more self-documenting.

-QM
--
Quantum Mechanics: The dreams stuff is made of

eval { do_something(); 1 } or warn $@;
[download]

Here's why: Bug in eval in pre-5.14

Not sure if your perl version is too old?

Use Perl::MinimumVersion/perlver

$ perlver foo.pl


   --------------------------------------
 | file   | explicit | syntax  | external |
 | -------------------------------------- |
 | foo.pl | ~        | v5.10.0 | n/a      |
 | -------------------------------------- |
 | Minimum explicit version : ~                             |
 | Minimum syntax version   : v5.10.0                       |
 | Minimum version of perl  : v5.10.0                       |
   --------------------------------------

$ perlver --blame foo.pl

 ------------------------------------------------------------
 File    : foo.pl
 Line    : 3
 Char    : 17
 Rule    : _perl_5010_operators
 Version : 5.010
 ------------------------------------------------------------
 ~~
 ------------------------------------------------------------

$ cat foo.pl
my $foo = 6;
my @bar = ( 3,6, 9 );
print 1 if $foo ~~ @bar;
[download]

Then you can add use v5.10.0; or <c> use 5.01000; to your foo.pl, and perl will do the version check

If you don't quite understand what you're looking at (output of deparse, perl syntax), then ppi_dumper can help you look at the right part of the manual, an example

$ ppi_dumper 2
PPI::Document
  PPI::Statement::Include
    PPI::Token::Word    'use'
    PPI::Token::Whitespace      ' '
    PPI::Token::Word    'constant'
    PPI::Token::Whitespace      ' '
    PPI::Token::Word    'X'
    PPI::Token::Whitespace      ' '
    PPI::Token::Operator        '=>'
    PPI::Token::Whitespace      ' '
    PPI::Token::Number          '1'
    PPI::Token::Operator        '/'
    PPI::Token::Number          '3'
    PPI::Token::Structure       ';'
  PPI::Token::Whitespace        '\n'
  PPI::Token::Whitespace        '\n'
[download]

So PPI::Token::Operator tells you "=>" is an operator

If you read perl/"perltoc" then you'll know that operators are documented in perlop

App::PPI::Dumper / ppi_dumper

wxPPIxregexplain.pl