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

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.

POD ERRORS

Hey! The above document had some coding errors, which are explained below:

Around line 349:: Non-ASCII character seen before =encoding in 'Jörn'. Assuming CP1252