NAME

Devel::ebug - A simple, extensible Perl debugger

SYNOPSIS

  use Devel::ebug;
  my $ebug = Devel::ebug->new;
  $ebug->program("calc.pl");
  $ebug->load;

  print "At line: "       . $ebug->line       . "\n";
  print "In subroutine: " . $ebug->subroutine . "\n";
  print "In package: "    . $ebug->package    . "\n";
  print "In filename: "   . $ebug->filename   . "\n";
  print "Code: "          . $ebug->codeline   . "\n";
  $ebug->step;
  $ebug->step;
  $ebug->next;
  $ebug->break_point(6);
  $ebug->break_point(6, '$e = 4');
  $ebug->break_point("t/Calc.pm", 29);
  $ebug->break_point("t/Calc.pm", 29, '$i == 2');
  $ebug->break_point_subroutine("main::add");
  my @filenames    = $ebug->filenames();
  my @break_points = $ebug->break_points();
  $ebug->watch_point('$x > 100');
  my $codelines = $ebug->codelines(@span);
  $ebug->run;
  my $pad  = $ebug->pad;
  foreach my $k (sort keys %$pad) {
    my $v = $pad->{$k};
    print "Variable: $k = $v\n";
  }
  my $v = $ebug->eval('2 ** $exp');
  print "Finished!\n" if $ebug->finished;
  $ebug->return;

DESCRIPTION

A debugger is a computer program that is used to debug other programs. Devel::ebug is a simple, extensible Perl debugger with a clean API. Using this module, you may easily write a Perl debugger to debug your programs. Alternatively, it comes with an interactive debugger, ebug.

The reasoning behind building Devel::ebug is that the current Perl debugger, perl5db.pl, is very crufty, hard to use and extend and has no tests. Devel::ebug provides a simple programmatic interface to debugging programs, which is well tested. This makes it easier to build debuggers on top of Devel::ebug, be they console-, curses-, GUI- or Ajax-based.

Devel::ebug is a work in progress.

Internally, Devel::ebug consists of two parts. The frontend is Devel::ebug, which you interact with. The frontend starts the code you are debugging in the background under the backend (running it under perl -d:ebug code.pl). The backend starts a TCP server, which the frontend then connects to, and uses this to drive the backend. This adds some flexibilty in the debugger. There is some minor security in the client/server startup (a secret word), and a random port is used from 3141-4165 so that multiple debugging sessions can happen concurrently.

CONSTRUCTOR

new

The constructor creats a Devel::ebug object:

  my $ebug = Devel::ebug->new;

program

The program method selects which program to load:

  $ebug->program("calc.pl");

load

The load method loads the program and gets ready to debug it:

  $ebug->load;

METHODS

break_point

The break_point method sets a break point in a program. If you are run-ing through a program, the execution will stop at a break point. Break points can be set in a few ways.

A break point can be set at a line number in the current file:

  $ebug->break_point(6);

A break point can be set at a line number in the current file with a condition that must be true for execution to stop at the break point:

  $ebug->break_point(6, '$e = 4');

A break point can be set at a line number in a file:

  $ebug->break_point("t/Calc.pm", 29);

A break point can be set at a line number in a file with a condition that must be true for execution to stop at the break point:

  $ebug->break_point("t/Calc.pm", 29, '$i == 2');

break_point_subroutine

The break_point_subroutine method sets a break point in a program right at the beginning of the subroutine. The subroutine is specified with the full package name:

  $ebug->break_point_subroutine("main::add");
  $ebug->break_point_subroutine("Calc::fib");

break_points

The break_points method returns a list of all the line numbers in the current file that have a break point set.

  my @break_points = $ebug->break_points();

codeline

The codeline method returns the line of code that is just about to be executed:

  print "Code: "          . $ebug->codeline   . "\n";

codelines

The codelines method returns lines of code.

It can return all the code lines in the current file:

  my @codelines = $ebug->codelines();

It can return a span of code lines from the current file:

  my @codelines = $ebug->codelines(1, 3, 4, 5);

It can return all the code lines in a file:

  my @codelines = $ebug->codelines("t/Calc.pm");

It can return a span of code lines in a file:

  my @codelines = $ebug->codelines("t/Calc.pm", 5, 6);

eval

The eval method evaluates Perl code in the current program and returns the result:

  my $v = $ebug->eval('2 ** $exp');

filename

The filename method returns the filename of the currently running code:

  print "In filename: "   . $ebug->filename   . "\n";

filenames

The filenames method returns a list of the filenames of all the files currently loaded:

  my @filenames = $ebug->filenames();

finished

The finished method returns whether the program has finished running:

  print "Finished!\n" if $ebug->finished;

line

The line method returns the line number of the statement about to be executed:

  print "At line: "       . $ebug->line       . "\n";

next

The next method steps onto the next line in the program. It executes any subroutine calls but does not step through them.

  $ebug->next;

package

The package method returns the package of the currently running code:

  print "In package: "    . $ebug->package    . "\n";

pad

  my $pad  = $ebug->pad;
  foreach my $k (sort keys %$pad) {
    my $v = $pad->{$k};
    print "Variable: $k = $v\n";
  }

return

The return subroutine returns from a subroutine. It continues running the subroutine, then single steps when the program flow has exited the subroutine:

  $ebug->return;

run

The run subroutine starts executing the code. It will only stop on a break point or watch point.

  $ebug->run;

step

The step method steps onto the next line in the program. It steps through into any subroutine calls.

  $ebug->step;

subroutine

The subroutine method returns the subroutine of the currently working code:

  print "In subroutine: " . $ebug->subroutine . "\n";

watch_point

The watch point method sets a watch point. A watch point has a condition, and the debugger will stop run-ing as soon as this condition is true:

  $ebug->watch_point('$x > 100');

SEE ALSO

perldebguts

AUTHOR

Leon Brocard, <acme@astray.com>

COPYRIGHT

Copyright (C) 2005, Leon Brocard

This module is free software; you can redistribute it or modify it under the same terms as Perl itself.

cpanm DB

perl -MCPAN -e shell
install DB