Dear monks,

I am trying to understand how to use Exception::Class in a large-ish multimodule application. As part of the set of modules I made one package where I am planning to define all exceptions, i.e.:

package Bio::Phylo::Exceptions;
use Exception::Class (
    'Bio::Phylo::Exceptions',
    'Bio::Phylo::Exceptions::BadNumber' =>
    { isa => 'Bio::Phylo::Exceptions' },
    'Bio::Phylo::Exceptions::BadString' =>
    { isa => 'Bio::Phylo::Exceptions' },
    'Bio::Phylo::Exceptions::BadFormat' =>
    { isa => 'Bio::Phylo::Exceptions' },
    'Bio::Phylo::Exceptions::ObjectMismatch' =>
    { isa => 'Bio::Phylo::Exceptions' }
);
1;
[download]

So then, elsewhere in the modules, there might be OO getters and setters like this:

use Scalar::Util qw(looks_like_number);

sub set_number {
   my ( $self, $number ) = @_;
   looks_like_number $number 
   ? $self->{'NUMBER'} = $number 
   : Bio::Phylo::Exceptions::BadNumber->throw(error => 'bad number');
}
[download]

And then the user has to go through a contortion like:

# try
eval { $obj->set_number(sdf7897) };

# catch
if (UNIVERSAL::isa($@,'Bio::Phylo::Exceptions::BadNumber')){
   # do something
}
[download]

Is that how it works? Or are the exceptions caught inside the object methods?

Pardon my ignorance, but I've never worried about this before, and I wish to learn.

Thank you!

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.