NAME Exception::Base - Lightweight exceptions SYNOPSIS # Use module and create needed exceptions use Exception::Base 'Exception::Runtime', # create new module 'Exception::System', # load existing module 'Exception::IO', => { isa => 'Exception::System' }, # create new based on existing 'Exception::FileNotFound' => { isa => 'Exception::IO', # create new based on previous message => 'File not found', # override default message has => [ 'filename' ], # define new rw attribute stringify_attributes => [ 'message', 'filename' ], }; # output message and filename # eval/$@ (fastest method) eval { open my $file, '/etc/passwd' or Exception::FileNotFound->throw( message=>'Something wrong', filename=>'/etc/passwd'); }; if ($@) { my $e = Exception::Base->catch; # convert $@ into exception if ($e->isa('Exception::IO')) { warn "IO problem"; } elsif ($e->isa('Exception::Eval')) { warn "eval died"; } elsif ($e->isa('Exception::Runtime')) { warn "some runtime was caught"; } elsif ($e->matches({value=>9})) { warn "something happened"; } elsif ($e->matches(qr/^Error/)) { warn "some error based on regex"; } else { $e->throw; } # rethrow the exception } # alternative syntax for Perl 5.10 use feature 'switch'; if ($@) { given (my $e = Exception::Base->catch) { when (['Exception::IO']) { warn "IO problem"; } when (['Exception::Eval']) { warn "eval died"; } when (['Exception::Runtime']) { warn "some runtime was caught"; } when ({value=>9}) { warn "something happened"; } when (qr/^Error/) { warn "some error based on regex"; } default { $e->throw; } # rethrow the exception } } # try/catch (15x slower) use Exception::Base ':all'; # import try/catch/throw try eval { open my $file, '/etc/passwd' or throw 'Exception::FileNotFound' => message=>'Something wrong', filename=>'/etc/passwd'; }; if (catch my $e) { # $e is an exception object so no need to check if is blessed if ($e->isa('Exception::IO')) { warn "IO problem"; } elsif ($e->isa('Exception::Eval')) { warn "eval died"; } elsif ($e->isa('Exception::Runtime')) { warn "some runtime was caught"; } elsif ($e->matches({value=>9})) { warn "something happened"; } elsif ($e->matches(qr/^Error/)) { warn "some error based on regex"; } else { $e->throw; } # rethrow the exception } # $@ has to be recovered ASAP! eval { die "this die will be caught" }; my $e = Exception::Base->catch; eval { die "this die will be ignored" }; if ($e) { (...) } # try/catch can be separated with another eval try eval { die "this die will be caught" }; do { eval { die "this die will be ignored" } }; catch my $e; # only first die is recovered # the exception can be thrown later my $e = Exception::Base->new; # (...) $e->throw; # try returns eval's value for scalar or array context $v = try eval { do_something_returning_scalar(); }; @v = try [eval { do_something_returning_array(); }]; # ignore our package in stack trace package My::Package; use Exception::Base '+ignore_package' => __PACKAGE__; # define new exception in separate module package Exception::My; use Exception::Base (__PACKAGE__) => { has => ['myattr'], }; # run Perl with changed verbosity for debugging purposes $ perl -MException::Base=verbosity,4 script.pl DESCRIPTION This class implements a fully OO exception mechanism similar to Exception::Class or Class::Throwable. It provides a simple interface allowing programmers to declare exception classes. These classes can be thrown and caught. Each uncaught exception prints full stack trace if the default verbosity is uppered for debugging purposes. The features of Exception::Base: * fast implementation of the exception class * fully OO without closures and source code filtering * does not mess with $SIG{__DIE__} and $SIG{__WARN__} * no external modules dependencies, requires core Perl modules only * implements error stack, the try/catch blocks can be nested * the default behaviour of exception class can be changed globally or just for the thrown exception * matching the exception by class, message or other attributes * matching with string, regex or closure function * creating automatically the derived exception classes ("use" interface) * easly expendable, see Exception::System class for example * prints just an error message or dumps full stack trace * can propagate (rethrow) an exception AUTHOR Piotr Roszatycki LICENSE Copyright (C) 2007, 2008 by Piotr Roszatycki . This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See http://www.perl.com/perl/misc/Artistic.html