NAME

Gtk2::Ex::FormFactory::Rules - Rule checking in a FormFactory framework

SYNOPSIS

Gtk2::Ex::FormFactory::Rules->new (
  rules          => Hashref of rules and their implemenation CODEREF's,
  rules_messages => Hashref of the rules' error messages,
  message_format => Format of the "Invalid rules" message thrown
  		      on the GUI,
);

DESCRIPTION

This class implements rule checking in a Gtk2::Ex::FormFactory framework. Each widget can have on or more rules (combined with the locical and operator, except for the special "or-empty" rule described beyond) which are checked against the widget's value when the user changes it. This way you can prevent the user from entering illegal data at a high level.

Once the user entered illegal data, the old (legal) value is restored and a corresponding error dialog pops up.

OBJECT HIERARCHY

Gtk2::Ex::FormFactory::Rules

ATTRIBUTES

Attributes are handled through the common get_ATTR(), set_ATTR() style accessors.

rules = HASHREF [optional]

This is a hash of user specified rules. A rule has a name (the hash key) and a CODREF (the hash value) which implements the rule. The CODEREF has the following prototype:

$error = &$CODEREF ($value)

If $value doesn't match the rule, $error is the corresponding error message. $error is undef, if $value is Ok.

rules_messages = HASHREF [optional]

This is a hash of the error messages of the user specified rules. A message should read read as follows:

{field} is an odd value.

When presented to the user, the {field} place holder is replaced with the label of the widget in question.

message_format = SCALAR [optional]

This is the format string for the error message which is displayed to the user. The default is:

Data entered is invalid.\n\n[MESSAGES]\nOld value restored.

where [MESSAGES] is replaced with the actual list of error messages.

BUILTIN RULES

This is a verbatim snapshot of the builtin rules and rules_messages hashes. Please take a look at Gtk2::Ex::FormFactory::Rules' source code for a recent list of builtin rules:

my %RULES = (
  "empty"			=> sub { $_[0] eq ''			},
  "not-empty"			=> sub { $_[0] ne ''			},

  "alphanumeric"		=> sub { $_[0] =~ /^\w+$/		},
  "identifier"		=> sub { $_[0] =~ /^[a-z_]\w*$/i	},
  "no-whitespace"		=> sub { $_[0] !~ /\s/			},

  "zero"                      => sub { $_[0] =~ /^0(\.0*)?$/		},
  "not-zero"			=> sub { $_[0] !~ /^0(\.0*)?$/		},

  "integer"			=> sub { $_[0] =~ /^[+-]?\d+$/		},
  "positive-integer"		=> sub { $_[0] =~ /^[+]?\d+$/ 		},
  "negative-integer"		=> sub { $_[0] =~ /^-\d+$/		},

  "float"			=> sub { $_[0] =~ /^[+-]?\d+(\.\d+)?$/	},
  "positive-float"		=> sub { $_[0] =~ /^\+?\d+(\.\d+)?$/	},
  "negative-float"		=> sub { $_[0] =~ /^-\d+(\.\d+)?$/	},

  "odd"			=> sub {   $_[0] % 2			},
  "even"			=> sub { !($_[0] % 2)			},
  
  "file-executable"		=> sub { (!-d $_[0] && -x $_[0])	},
  "file-writable"		=> sub { (!-d $_[0] && -w $_[0])	},
  "file-readable"		=> sub { (!-d $_[0] && -r $_[0])	},
  
  "dir-writable"		=> sub { (-d $_[0] && -w $_[0])		},
  "dir-readable"		=> sub { (-d $_[0] && -r $_[0])		},

  "parent-dir-writable"	=> sub { -w dirname($_[0]) 		},
  "parent-dir-readable"	=> sub { -r dirname($_[0])		},

  "executable-command"	=> "_rule_result",
);

my %RULES_MESSAGES = (
  "empty"			=> "{field} is not empty.",
  "not-empty"			=> "{field} is empty.",

  "alphanumeric"		=> "{field} is not alphanumeric.",
  "identifier"		=> "{field} is no identifier.",
  "no-whitespace"		=> "{field} contains whitespace.",

  "zero"			=> "{field} is not zero",
  "not-zero"			=> "{field} is zero",

  "integer"			=> "{field} is no integer.",
  "positive-integer"		=> "{field} is no positive integer.",
  "negative-integer"		=> "{field} is no negative integer.",

  "float"			=> "{field} is no float.",
  "positive-float"		=> "{field} is no positive float.",
  "negative-float"		=> "{field} is no negativ float.",

  "odd"			=> "{field} is not odd.",
  "even"			=> "{field} is not even.",
  
  "file-executable"		=> "{field} is no file and/or not executable.",
  "file-writable"		=> "{field} is no file and/or not writable.",
  "file-readable"		=> "{field} is no file and/or not readable.",
  
  "dir-writable"		=> "{field} is no directory and/or not writable.",
  "dir-readable"		=> "{field} is no directory and/or not readable.",

  "parent-dir-writable"	=> "{field} has no writable parent directory.",
  "parent-dir-readable"	=> "{field} has no readable parent directory.",
);

Special "or-empty" rule

There is a special rule called "or-empty". If this rule occurs everywhere in the list of rules and the actual value is empty, rule checking quits immediately with a positive result, discarding error states from earlier rules.

Example: [ "positive-integer", "or-empty" ]

All rules are combined with "and", which is usually sufficient, but without this special "or-empty" case the common case optionally empty fields can't be done.

AUTHORS

Jörn Reder <joern at zyn dot de>

COPYRIGHT AND LICENSE

Copyright 2004-2005 by Jörn Reder.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details.

You should have received a copy of the GNU Library General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307 USA.