NAME

BPM::Engine::Exceptions - Exception classes used in BPM::Engine

VERSION

0.01

SYNOPSIS

Throw an exception when something is wrong

use BPM::Engine::Exceptions qw/throw_plugin/;

sub set_length {
    my ($self, $length) = @_;

    # throw an exception
    throw_plugin("Whoops!") unless $length =~ /\d+/;

    # ...
    }    

Now let's try something illegal and catch the exception

# use the is_Exception() function exported from the types library
use BPM::Engine::Types qw/Exception/;    

eval {
    $obj->set_length( 'non-numerical value' ); # this throws the error
    #...
};

# handle any exception, cathing them in various ways
if(my $err = $@) {
    # encountered an error
    
    if( Exception::Class->caught('BPM::Engine::Exception::Engine') ) {
        #... use the thrown error obj
        warn $err->error;
        print $err->as_html;
        }
    elsif(my $err = BPM::Engine::Exception::Plugin->caught() ) {
        warn $err->trace->as_string;
        }
    # the type tests blessed $@ && $@->isa('BPM::Engine::Exception')
    elsif( is_Exception($err) ) {
        $err->rethrow();
        }
    else {
        # something bad happened!
        die $@;
        }
    }

BPM::Engine::Exception stringifies to something reasonable, so if you don't need detailed error information, you can simply treat $@ as a string:

eval { $engine->update($status) };
if ( $@ ) {
    warn "update failed because: $@\n";
}

DESCRIPTION

This module creates the hierarchy of exception objects used by other BPM::Engine modules and provides shortcuts to make raising an exception easier and more readable.

The exceptions are subclasses of Exception::Class::Base, created by the interface defined by Exception::Class. See Exception::Class for more information on how this is done.

EXCEPTIONS

Each of the exception classes created by BPM::Engine::Exceptions has a functional alias for its throw class method. In the SYNOPSIS example, we use the throw_plugin function to throw a BPM::Engine::Exception::Plugin exception.

These may be imported by passing a list of the function names to import:

use BPM::Engine::Exceptions qw(throw_component);

Some of the exceptions mentioned above have additional fields, which are available via accessors.

The exception classes created by BPM::Engine::Exceptions are as follows:

• BPM::Engine::Exception

  This is the base class for all generated exceptions.

• BPM::Engine::Exception::Engine

  Engine exception. Aliased as throw_engine.

• BPM::Engine::Exception::Runner

  ProcessRunner exception. Aliased as throw_runner.

• BPM::Engine::Exception::Database

  Datastore exception. Aliased as throw_store.

• BPM::Engine::Exception::IO

  IO exception. Aliased as throw_io.

• BPM::Engine::Exception::Parameter

  Invalid parameters was given to method/function. Aliased as throw_param.

• BPM::Engine::Exception::Condition

  Condition false error. Aliased as throw_condition.

• BPM::Engine::Exception::Expression

  Exception evaluator error. Aliased as throw_expression.

• BPM::Engine::Exception::Plugin

  Plugin exception. Extra field: plugin. Aliased as throw_plugin.

• BPM::Engine::Exception::Model

  Model exception. Aliased as throw_model.

• BPM::Engine::Exception::Install

  Installation/configuration exception. Aliased as throw_install.

• BPM::Engine::Exception::NotImplemented

  Abstract method. Aliased as throw_abstract.

DEPENDENCIES

• Exception::Class

AUTHOR

Peter de Vos <sitetech@cpan.org>

COPYRIGHT AND LICENSE

Copyright (c) 2010, 2011 Peter de Vos <sitetech@cpan.org>.

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