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Rocky Bernstein


Devel::Trepan -- A new modular Perl debugger


A modular, testable, gdb-like debugger in the family of the Ruby trepanning debuggers.


  • extensive online-help

  • syntax highlighting of Perl code

  • context-sensitive command completion

  • out-of-process and remote debugging

  • interactive shell support

  • code disassembly

  • gdb syntax

  • easy extensibility at several levels: aliases, commands, and plugins

  • comes with extensive tests

  • is not as ugly as perl5db

Some of the features above require additional modules before they take effect. See "Plugins" and "Recommended Modules" below.


From a shell:

    $ trepan.pl [trepan-opts] -- perl-program [perl-program-opts]

Or for those who prefer the traditional Perlish way:

    $ perl -d:Trepan perl-program [perl-program-opts]

Calling the debugger from inside your Perl program using Joshua ben Jore's Enbugger:

    # This needs to be done once and could even be in some sort of 
    # conditional code
    require Enbugger; Enbugger->load_debugger( 'trepan' );

    # Alternatively, to unconditionally load Enbugger and trepan:
    use Enbugger 'trepan';

    # work, work, work...
    # Oops! there was an error! Enable the debugger now!
    Enbugger->stop;  # or Enbugger->stop if ... 

Or if you just want POSIX-shell-like set -x line tracing:

    $ trepan.pl -x -- perl-program [perl-program-opts]

Inside the debugger tracing is turned on using the command set trace print. There is extensive help from the help command.


Because this should be useful in all sorts of environments such as back to perl 5.008, we often can make use of newer Perlisms nor can we require by default all of the modules, say for data printing, stack inspection, or interactive terminal handling. That said, if you have a newer Perl or the recommended modules or install plugins, you'll get more.

Although modular, this program is even larger than perl5db and so it loads a little slower. I think part of the slowness is the fact that there are over 70 or so (smallish) files (rather than one nearly 10K file) and because relative linking via rlib is used to glue them together.


Rocky Bernstein


My Devel::Trepan blogs and wiki


Other Debuggers

  • perldebug is perl's built-in tried-and-true debugger that other debuggers will ultimately be compared with

  • Devel::ebug

  • DB is a somewhat abandoned debugger API interface. I've tried to use some parts of this along with perl5db.


Copyright (C) 2011, 2012 Rocky Bernstein <rocky@cpan.org>

This program is distributed WITHOUT ANY WARRANTY, including but not limited to the implied warranties of merchantability or fitness for a particular purpose.

The program is free software. You may distribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation (either version 2 or any later version) and the Perl Artistic License as published by O'Reilly Media, Inc. Please open the files named gpl-2.0.txt and Artistic for a copy of these licenses.