it seems to me that you have two problems: 1) You want to know that your value is always a number, so you add a constraint. 2) Your users will not always enter the correct value. 3) You want to KNOW what the bad value was. So I would separate out the input attribute and the used attribute. Moose (and mouse) makes this easy! Check out this example (I wrote it using 5.10 Perl, mainly as I am trying to practice using it...): #### Start use Mouse;use Mouse::Util::TypeConstraints;package MyApp::Room;use Carp qw(cluck);use Scalar::Util qw(looks_like_number); use feature 'switch'; # Subtype and coercionsubtype 'Price' => as 'Num'; coerce 'Price' => from 'Str' => via { given($_) { # Anything like a number is OK when (looks_like_number $_) { return $_; } # $9.99 is ok. when(/ \A \$(\d+\.?\d+?) \z /xms) { return $1; } # $.99 is ok when(/ \A \$(\d+?\.\d+) \z /xms) { return $1; } # Complain about anything else. default { cluck 'Price must be a number! Setting to $0.00'; return 0; } } }; has 'price_in' => ( is => 'rw', perdicate => 'has_price_in', trigger => sub { my ($self,$val) = @_; $self->price($val); }); has 'price' => ( is => 'rw', isa => 'Price', coerce => 1,); package main; use feature 'say'; # Says 3.50my $room = MyApp::Room->new( price_in => '3.50' );say "Room price: " . $room->price(); # Says 1000$room->price_in('1000');say "Room price: " . $room->price(); # Says 0 and complains$room->price_in('cheap');say "Room price: " . $room->price(); #### END --- Edward J. Allen III > Date: Fri, 10 Jun 2011 13:37:36 -0400 > Subject: Re: Moose Type Constraints violations to warnings? > From: chris@prather.org > To: barefootcoder@gmail.com > CC: publiustemp-catalyst@yahoo.com; moose@perl.org > > On Fri, Jun 10, 2011 at 1:14 PM, Buddy Burden <barefootcoder@gmail.com> wrote: > > Ovid, > > > > On Fri, Jun 10, 2011 at 3:06 AM, Ovid <publiustemp-catalyst@yahoo.com> wrote: > >> When I declare a parameter as follows: > >> > >> > >> has 'some_val' => ( > >> is => 'rw', > >> isa => 'Int', > >> ); > >> > >> Later if I do $object->some_value("foobar"), it blows up with a stack trace because of the type constraint violation. > >> > >> Without using signal handlers, is there some way I can convert that exception into a warning except when something like $ENV{HARNESS_ACTIVE} is true? Preferably on a per-attribute basis? > > > > Is it possible that Jesse's answer to my question here: > > > > http://www.mail-archive.com/moose@perl.org/msg01464.html > > > > could help? I know it isn't exactly the same problem that you're > > describing, but it seems that if there's a way to solve one, there > > must be a way to solve the other as well. Possibly the code of the > > module he mentions would be illuminating. > > > > Apologies if this isn't actually helpful. > > Karen also suggested MooseX::Constructor::AllErrors but discarded it > because it was Moose only. A Mouse port would probably be pretty > simple. > But it only covers the constructor case. > > For accessors, if the issue is that you "don't want type constraints > to throw out *everything*" you'll need to show a better example of the > parsing code because I'm not sure how a judicious use of Try::Tiny > wouldn't be the natural solution there. Accessors never really operate > on the entire object, so you'd only throw an exception for a specific > attribute. Wrapping the block in Try::Tiny will leave the object in a > partial state (whatever had been mutated until the exception was > thrown) and give you an error message you could then dispatch with. > > The particular phrase Ovid referred to in the Moose docs was written a > *long* time ago when Stevan still believed that you could potentially > safely turn off runtime type checks. My impression is that he's > re-considered this idea now. It also applies to Moose and not Mouse. > Mouse has it's own development community and goals. > > -ChrisThread Previous | Thread Next