Provided by: libouch-perl_0.0501-2_all 
NAME
Ouch - Exceptions that don't hurt.
VERSION
version 0.0501
SYNOPSIS
use Ouch;
eval { ouch(404, 'File not found.'); };
if (kiss 404) {
check_elsewhere();
}
say $@; # These two lines do the
say $@->scalar; # same thing.
DESCRIPTION
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:
Ouch
use Ouch;
ouch 404, 'File not found.', 'file';
Exception::Class
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:
Ouch
if (kiss 404) {
# do something
}
Exception::Class
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.
Usage
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);
If you want to rethrow an Ouch, you can simply "die" it.
eval { ouch(404, 'File not found.'); } ;
die $@;
Functional Interface
ouch
Some nice sugar instead of using the object oriented interface.
ouch 2121, 'Did not do the big thing.';
code
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.
message
A human readable error message.
data
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.
kiss
Some nice sugar to trap an Ouch.
if (kiss $code) {
# make it go
}
code
The code you're looking for.
exception
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.
hug
Some nice sugar to trap any exception.
if (hug) {
# make it stop
}
exception
Optional. If you like you can pass the exception into "hug". If not, it will just use
whatever is in $@.
bleep
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.
exception
Optional. If you like you can pass the exception into "bleep". If not, it will just
use whatever is in $@.
barf
Calls "bleep", and then exits with error code
exception
Optional. You can pass an exception into "barf" which then gets passed to "bleep"
otherwise it will use whatever's in $@
Object-Oriented Interface
new
Constructor for the object-oriented interface. Takes the same parameters as "ouch".
Ouch->new($code, $message, $data);
scalar
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!';
trace
Call this if you want the full stack trace that lead up to the ouch.
hashref
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,
}
code
Returns the "code" passed into the constructor.
message
Returns the "messsage" passed into the constructor.
data
Returns the "data" passed into the constructor.
Try::Tiny
Many Ouch users like to use Ouch with Try::Tiny.
use Try::Tiny;
use Ouch;
try {
ouch 404, 'File not found!';
}
catch {
if (kiss(401, $_)) {
# do something
}
else {
die $_; # rethrow
}
};
Some users are sticks in the mud who can't bring themselves to "ouch" and "kiss". 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(401, $_)) {
# do something
}
else {
die $_; # rethrow
}
};
Using Try::Tiny has some impedence mismatch in that the exception is propagated through $_
instead of $@ (the default used by Ouch). This forces to always include $_ when calling
functions in Ouch, which is suboptimal. It's possible to do this:
use Try::Tiny;
use Ouch qw(:trytiny_var); # use Try::Tiny's variable $_
try {
throw 404, 'File not found!';
}
catch {
if (kiss 401) {
# do something
}
else {
die $_; # rethrow
}
};
i.e. you can use the regular Ouch syntax.
This behaviour is localized to the import, i.e. if Ouch is then imported in another place
it is possible to decide again which is the default exception variable in that specific
import:
package I::Want::Try::Tiny;
use Try::Tiny;
use Ouch qw(:trytiny_var);
# ... $_ is the default exception for kiss, hug, barf, and bleep
package Gimme::Regular::Ouch;
use Ouch;
# ... $@ is the default exception object here
It's also possible to mix the two approaches, i.e. use both ":trytiny" and ":trytiny_var".
throw
See "ouch" for details.
caught
See "kiss" for details.
caught_all
See "hug" for details.
DEPRECATED
This functionality is deprecated and will be removed in a future release. Use Try::Tiny
instead.
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.
try
Returns an exception. Is basically just a nice wrapper around "eval".
block
Try accepts a code ref, anonymous subroutine, or a block.
NOTE: You need a semi-colon at the end of a "try" block.
throw
Works exactly like "ouch". See "ouch" for details.
catch
Works exactly like "kiss". See "kiss" for details.
catch_all
Works exactly like "hug". See "hug" for details.
REQUIREMENTS
Requires Perl 5.12 or higher.
SUPPORT
Repository
<http://github.com/rizen/Ouch>
Bug Reports
<http://github.com/rizen/Ouch/issues>
SEE ALSO
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.
AUTHOR
JT Smith <jt_at_plainblack_dot_com>
LEGAL
Ouch is Copyright 2011 Plain Black Corporation (<http://www.plainblack.com>) and is
licensed under the same terms as Perl itself.