NAME

Exception::System - The exception class for system or library calls

SYNOPSIS

# The simplest usage
use Exception::Base 'Exception::System';
open my $file, "/notfound"
  or Exception::System->throw(message=>"Can not open file");

# The Exception::System class can be a base class for others
#
# Loaded automatically if used as Exception::Base's argument
use Exception::Base,
  'Exception::System',
  'Exception::File' => {
      isa => 'Exception::System',
      has => 'filename',
      string_attributes => [ 'message', 'errstr', 'filename' ],
  };

eval {
  my $filename = "/notfound";
  open my $fh, $filename
      or Exception::File->throw(
             message=>"Can not open file",
             filename=>$filename,
         );
};
if ($@) {
  my $e = Exception::Base->catch;
  if ($e->isa('Exception::File')) { warn "File error:".$e->errstr; }
  if ($e->matches({errname=>'ENOENT'})) { warn "Caught not found error"; }
}

DESCRIPTION

This class extends standard Exception::Base with handling system or library errors. The additional attributes of the exception object are filled on throw and contain the error message and error codes.

BASE CLASSES

• Exception::Base

CONSTANTS

ATTRS

Declaration of class attributes as reference to hash.

See Exception::Base for details.

ATTRIBUTES

Class attributes are implemented as values of blessed hash. The attributes of base class are inherited. See Exception::Base to see theirs description.

message (rw, default: 'Unknown system exception')

Contains the message of the exception. This class overrides the default value from Exception::Base class.

errstr (ro)

Contains the system error string fetched at exception throw. It is the part of the string representing the exception object. It is the same as $! variable in string context.

eval { Exception::System->throw( message=>"Message" ) };
my $e = Exception::Base->catch
  and print $e->errstr;

errstros (ro)

Contains the extended system error string fetched at exception throw. It is the same as $^E variable.

eval { Exception::System->throw( message=>"Message" ); };
if ($@) {
  my $e = Exception::Base->catch;
  if ($e->errstros ne $e->errstr) {
    print $e->errstros;
  }
}

errno (ro)

Contains the system error number fetched at exception throw. It is the same as $! variable in numeric context. This attribute represents numeric value of the exception object in numeric context.

use Errno ();
eval { Exception::System->throw( message=>"Message" ); };
if ($@) {
  my $e = Exception::Base->catch;
  if ($e->errno == &Errno::ENOENT) {  # explicity
    warn "Not found";
  }
  elsif ($e == &Errno::EPERM) {       # numeric context
    warn "Bad permissions";
  }
}

errname (ro)

Contains the system error constant from the system error.h include file.

eval { Exception::System->throw( message=>"Message" ); };
my $e = Exception::Base->catch
  and $e->errname eq 'ENOENT'
  and $e->throw;

string_attributes (default: ['message', 'errstr'])

Meta-attribute contains the format of string representation of exception object. This class overrides the default value from Exception::Base class.

numeric_attribute (default: 'errno')

Meta-attribute contains the name of the attribute which contains numeric value of exception object. This class overrides the default value from Exception::Base class.

PRIVATE METHODS

_collect_system_data

Collect system data and fill the attributes of exception object. This method is called automatically if exception if throwed. This class overrides the method from Exception::Base class.

SEE ALSO

Exception::Base.

BUGS

If you find the bug, please report it.

AUTHOR

Piotr Roszatycki <dexter@debian.org>

LICENSE

Copyright (C) 2007, 2008 by Piotr Roszatycki <dexter@debian.org>.

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