NAME

DB::Pluggable - Add plugin support for the Perl debugger

VERSION

version 1.101050

SYNOPSIS

$ cat ~/.perldb

use DB::Pluggable;
use Hook::Modular::Builder;
my $config = builder {
    log_level 'error';
    enable 'BreakOnTestNumber';
    enable 'StackTraceAsHTML';
    enable 'TypeAhead', type => [ '{l', 'c' ] if $ENV{DBTYPEAHEAD};
    enable 'Dumper';
};

$DB::PluginHandler = DB::Pluggable->new(config => $config);
$DB::PluginHandler->run;

Alternatively, build the configuration yourself, for example, using YAML:

$ cat ~/.perldb

use DB::Pluggable;
use YAML;

$DB::PluginHandler = DB::Pluggable->new(config => Load <<EOYAML);
global:
  log:
    level: error

plugins:
  - module: BreakOnTestNumber
EOYAML

$DB::PluginHandler->run;

Then:

$ perl -d foo.pl

DESCRIPTION

This class adds plugin support to the Perl debugger. It is based on Hook::Modular, so see its documentation for details.

You need to have a ~/.perldb file (see perldebug for details) that invokes the plugin mechanism. The one in the synopsis will do, and there is a more commented one in this distribution's etc/perldb file.

Plugins should live in the DB::Pluggable:: namespace, like DB::Pluggable::BreakOnTestNumber does.

METHODS

enable_watchfunction

Tells the debugger to call DB::watchfunction(), which in turn calls the db.watchfunction hook on all plugins that have registered it.

run

First it calls the plugin.init hook, then it enables hooks for the relevant debugger commands (see above for which hooks are available).

Each command-related hook should return the appropriate constant from DB::Pluggable::Constants - either HANDLED if the hook has handled the command, or DECLINED if it didn't. If no hook has HANDLED the command, the default command subroutine (e.g., DB::cmd_b()) from perl5db.pl will be called.

HOOKS

This class is very much in beta, so it's more like a proof of concept. Therefore, not all hooks imaginable have been added, only the ones to make this demo work. If you want more hooks or if the current hooks don't work for you, let me know.

The following hooks exist:

plugin.init

Called at the beginning of the run() method. The hook doesn't get any arguments.

db.watchfunction

Called from within DB::watchfunction(). If you want the debugger to call the function, you need to enable it by calling enable_watchfunction() somewhere within your plugin. It's a good idea to enable it as late as possible because it is being called very often. See the DB::Pluggable::BreakOnTestNumber source code for an example. The hook doesn't get any arguments.

db.cmd.b

Called when the b debugger command (used to set breakpoints) is invoked. See run() below for what the hook should return.

The hook passes these named arguments:

cmd

This is the first argument passed to DB::cmd_b().

line

This is the second argument passed to DB::cmd_b(). This is the most important argument as it contains the command line. See the DB::Pluggable::BreakOnTestNumber source code for an example.

dbline

This is the third argument passed to DB::cmd_b().

db.eval

The debugger's eval() function is overridden so we can hook into it. This is needed to define new debugger commands that take arguments. Each plugin that registered this hook will get a chance to inspect the command line, which is the last line in $DB::evalarg and act on it. Each hook gets passed a code reference in the original DB::eval() function. If a plugin decides the handle the command, it needs to call the original function and return HANDLED - see DB::Pluggable::Constants - to indicate that it has done so. If a plugin does not want to handle the command, it must return DECLINED.

The hook passes these named arguments:

eval

The code reference to the original DB::eval() function.

For example, if you wanted to define a new xx debugger command, you could use:

sub register {
    my ($self, $context) = @_;
    $context->register_hook(
        $self,
        'db.eval' => $self->can('eval'),
    );
}

sub eval {
    my ($self, $context, $args) = @_;
    return DECLINED unless $DB::evalarg =~ s/\n\s*xx\s+([^\n]+)$/\n $1/;
    ... # handle the actual command
    $args->{eval}->();
    HANDLED;
}

INSTALLATION

See perlmodinstall for information and options on installing Perl modules.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests through the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=DB-Pluggable.

AVAILABILITY

The latest version of this module is available from the Comprehensive Perl Archive Network (CPAN). Visit http://www.perl.com/CPAN/ to find a CPAN site near you, or see http://search.cpan.org/dist/DB-Pluggable/.

The development version lives at http://github.com/hanekomu/DB-Pluggable/. Instead of sending patches, please fork this project using the standard git and github infrastructure.

AUTHOR

Marcel Gruenauer <marcel@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2008 by Marcel Gruenauer.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

cpanm DB

perl -MCPAN -e shell
install DB