On Saturday 25 July 2009 11:10:03 Mike Friedman wrote: > Hi, > > I'm working on a module to provide some syntactic sugar for creating > exceptions with throw/catch semantics in a Moose-ish way. The basic > idea is: >
Before I comment on your code, let me ask - how will your effort differ from these previous efforts: * http://search.cpan.org/dist/Error/ * http://search.cpan.org/dist/Exception-Class/ * http://search.cpan.org/dist/TryCatch/ I should note that I have once used Error.pm and have adopted it and now am one of its maintainers. However, I no longer recommend using it because its syntactic sugar breaks often. Just today I found the following code in an old codebase of mine: {{{{{{{{{{{{{{{{{{{{ sub run { my $self = shift; try { return $self->real_run(); } catch $error_class with { my $e = shift; print STDERR "Quad-Pres Error: ", $e->text(), "\n"; return (-1); } otherwise { my $e = shift; print STDERR "$e\n"; return (-1); }; } }}}}}}}}}}}}}}}}}}}} The problem here is that I return inside the clauses which are sub {...}'s in disguise and so it's not very correct. Recently, I've started using Exception::Class and can recommend it. Less syntactic sugar, but it's still convenient, and it doesn't break as often. Now for your code. > package MyApp; > > use Moose; > use MooseX::Exceptions; > > exception 'MyApp::Ex::Foo' => ( error => 'A foobar exploded' ); > exception 'MyApp::Ex::Bar' => ( error => 'barf', extends => > 'MyApp::Ex::Foo' ); > I feel these too lines are two wordy. You may wish to have a construct that accepts a list of exceptions so you can omit the "exception" keywords. This would be similar to Exception::Class. "error" is too generic. How about "msg"? Make sure the exceptions contain a record of the status of caller() and everything when thrown. > sub do_something { > ... > throw MyApp::Ex::Foo; > # or > throw MyApp::Ex::Foo => 'custom error message'; > } > Again, you may wish to specify several parameters other that an error message. > sub catcher { > my $self = shift; > eval { > $self->do_something; > } > > if ( my $e = catch 'MyApp::Ex::Foo' ) { # exception isa > MyApp::Ex::Foo # or > if ( my $e = catch ) { # catch anything > .... > throw $e; # rethrow exception object; > } > $@ may be clobbered. I suggest Doing something like: {{{{ my $ExceptionHandler = MooseX::Exception->handle($@); }}}} And then call methods on $ExceptionHandler which will have its own safe copy of $...@. > > I haven't implemented all the features that I want just yet, and I'm > pretty new to Moose and Class::MOP. So I'd love to hear any > suggestions from the community regarding feature ideas and ways to > improve my code. > > The woefully incomplete code and POD as it currently exists can be found > here: > > code: http://www.friedo.com/MooseX-Exceptions/lib/MooseX/Exceptions.pm > POD: http://www.friedo.com/MooseX-Exceptions/lib/MooseX/Exceptions.html > > There aren't any real unit tests or anything yet. I hope to have > something CPAN-worthy in a week or two, depending on how much time I > have to work on it. > > Thanks for any comments. > I hope you found mine to be insightful. Regards, Shlomi Fish > > > Mike -- ----------------------------------------------------------------- Shlomi Fish http://www.shlomifish.org/ What Makes Software Apps High Quality - http://xrl.us/bkeuk God gave us two eyes and ten fingers so we will type five times as much as we read.
