Piotr Roszatycki

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

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