JT Smith > Ouch-0.0401 > Ouch



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Module Version: 0.0401   Source   Latest Release: Ouch-0.0410


Ouch - Exceptions that don't hurt.


version 0.0401


 use Ouch;

 eval { ouch(404, 'File not found.'); };

 if (kiss 404) {

 say $@;           # These two lines do the
 say $@->scalar;   # same thing.


Ouch provides a class for exception handling that doesn't require a lot of boilerplate, nor any up front definition. If Exception::Class is working for you, great! But if you want something that is faster, easier to use, requires less typing, and has no prereqs, but still gives you much of that same functionality, then Ouch is for you.

Why another exception handling module?

It really comes down to Carp isn't enough for me, and Exception::Class does what I want but makes me type way too much. Also, I tend to work on a lot of protocol-based systems that use error codes (HTTP, FTP, SMTP, JSON-RPC) rather than error classes, so that feels more natural to me. Consider the difference between these:


 use Ouch;
 ouch 404, 'File not found.', 'file';


 use Exception::Class (
    'FileNotFound' => {
        fields  => [ 'code', 'field' ],
 FileNotFound->throw( error => 'File not found.', code => 404, field => 'file' );

And if you want to catch the exception you're looking at:


 if (kiss 404) {
   # do something


 my $e;
 if ($e = Exception::Class->caught('FileNotFound')) {
   # do something

Those differences may not seem like a lot, but over any substantial program with lots of exceptions it can become a big deal.


Most of the time, all you need to do is:

 ouch $code, $message, $data;
 ouch -32700, 'Parse error.', $request; # JSON-RPC 2.0 error
 ouch 441, 'You need to specify an email address.', 'email'; # form processing error
 ouch 'missing_param', 'You need to specify an email address.', 'email';

You can also go long form if you prefer:

 die Ouch->new($code, $message, $data);

Functional Interface


Some nice sugar instead of using the object oriented interface.

 ouch 2121, 'Did not do the big thing.';

An error code. An integer or string representing error type. Try to stick to codes used in whatever domain you happen to be working in. HTTP Status codes. JSON-RPC error codes, etc.


A human readable error message.


Optional. Anything you want to attach to the exception to help a developer catching it decide what to do. For example, if you're doing form processing, you might want this to be the name of the field that caused the exception.

WARNING: Do not include objects or code refs in your data. This should only be stuff that is easily serializable like scalars, array refs, and hash refs.


Some nice sugar to trap an Ouch.

 if (kiss $code) {
    # make it go

The code you're looking for.


Optional. If you like you can pass the exception into kiss. If not, it will just use whatever is in $@. You might want to do this if you've saved the exception before running another eval, for example.


Some nice sugar to trap any exception.

 if (hug) {
   # make it stop

Optional. If you like you can pass the exception into hug. If not, it will just use whatever is in $@.


A little sugar to make exceptions human friendly. Returns a clean error message from any exception, including an Ouch.

 File not found.

Rather than:

 File not found. at /Some/File.pm line 63.

Optional. If you like you can pass the exception into bleep. If not, it will just use whatever is in $@.

Calls bleep, and then exits with error code


Optional. You can pass an exception into barf which then gets passed to bleep otherwise it will use whatever's in $@

Object-Oriented Interface


Constructor for the object-oriented interface. Takes the same parameters as ouch.

 Ouch->new($code, $message, $data);


Returns the scalar form of the error message:

 Crap! at /Some/File.pm line 43.

Just as if you had done:

 die 'Crap!';

Rather than:

 ouch $code, 'Crap!'; 


Call this if you want the full stack trace that lead up to the ouch.


Returns a formatted hash reference of the exception, which can be useful for handing off to a serializer like JSON.

   code     => $code,
   message  => $message,
   data     => $data,


Returns the code passed into the constructor.


Returns the messsage passed into the constructor.


Returns the data passed into the constructor.

Traditional Interface

Some people just can't bring themselves to use the sugary cuteness of Ouch. For them there is the :traditional interface. Here's how it works:

 use Ouch qw(:traditional);

 my $e = try {
   throw 404, 'File not found.';

 if ( catch 404, $e ) {
   # do the big thing
 elsif ( catch_all $e ) {
   # make it stop
 else {
   # make it go

NOTE: try also populates $@, and catch and catch_all will also use $@ if you don't specify an exception.


Returns an exception. Is basically just a nice wrapper around eval.


Try accepts a code ref, anonymous subroutine, or a block.

NOTE: You need a semi-colon at the end of a try block.


Works exactly like ouch. See ouch for details.


Works exactly like kiss. See kiss for details.


Works exactly like hug. See hug for details.


Many Ouch users, like to use Ouch with Try::Tiny, and some of them are sticks in the mud who can't bring themselves to ouch and kiss, and don't like that :traditional walks all over try and catch For them, there is the :trytiny interface. Here's how it works:

 use Try::Tiny;
 use Ouch qw(:trytiny);

 try {
    throw(404, 'File not found!';
 catch {
    if (caught($_)) {
        # do something
    else {
        throw($_); # rethrow




Bug Reports



If you're looking for something lighter, check out Carp that ships with Perl. Or if you're looking for something heavier check out Exception::Class.


JT Smith <jt_at_plainblack_dot_com>


Ouch is Copyright 2011 Plain Black Corporation (http://www.plainblack.com) and is licensed under the same terms as Perl itself.

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