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