Thuban/Lib/classmapper.py

# Copyright (c) 2004 by Intevation GmbH
# Authors:
# Martin Schulze <[email protected]>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""
The provided class maintains a mapping between classes and objects.
Instances of the class are used as keys, not classes, though.

Usually layer classes and their instances are used in combination with
layer property dialog classes in order to utilise the proper dialog
for a given layer instance.

"""

__version__ = "$Revision$"
# $Source$
# $Id$


class ClassMapper:
    """
    Thuban class to implement a mapping of classes and objects,
    usually also classes.
    """

    mapping = None


    def __init__(self):
        """
        Initialises a mapping.
        """

        self.mapping = []


    def add(self, key_class, obj):
        """
        Register an object with a class.

        This method adds the provided pair (key_class,obj) to the
        internal list.  Subsequently instances of key_class are used
        to retrieved the stored object.
        """

        self.mapping.append((key_class, obj))


    def get(self, instance):
        """
        Retrieve a stored object corresponding to the provided class
        instance.
        """

        for key_class, obj in self.mapping:
            if isinstance(instance, key_class):
                return obj
        return None


    def has(self, instance):
        """
        Determine if the ClassMapper contains an object corresponding
        to the provided instance
        """

        return self.get(instance) is not None
1	joey	2299	# Copyright (c) 2004 by Intevation GmbH
2			# Authors:
3			# Martin Schulze <[email protected]>
4			#
5			# This program is free software; you can redistribute it and/or modify
6			# it under the terms of the GNU General Public License as published by
7			# the Free Software Foundation; either version 2 of the License, or
8			# (at your option) any later version.
9			#
10			# This program is distributed in the hope that it will be useful,
11			# but WITHOUT ANY WARRANTY; without even the implied warranty of
12			# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13			# GNU General Public License for more details.
14			#
15			# You should have received a copy of the GNU General Public License
16			# along with this program; if not, write to the Free Software
17			# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19			"""
20			The provided class maintains a mapping between classes and objects.
21			Instances of the class are used as keys, not classes, though.
22
23			Usually layer classes and their instances are used in combination with
24			layer property dialog classes in order to utilise the proper dialog
25			for a given layer instance.
26
27			"""
28
29			__version__ = "$Revision$"
30			# $Source$
31			# $Id$
32
33
34			class ClassMapper:
35			"""
36			Thuban class to implement a mapping of classes and objects,
37			usually also classes.
38			"""
39
40			mapping = None
41
42
43			def __init__(self):
44			"""
45			Initialises a mapping.
46			"""
47
48			self.mapping = []
49
50
51			def add(self, key_class, obj):
52			"""
53			Register an object with a class.
54
55			This method adds the provided pair (key_class,obj) to the
56			internal list. Subsequently instances of key_class are used
57			to retrieved the stored object.
58			"""
59
60			self.mapping.append((key_class, obj))
61
62
63			def get(self, instance):
64			"""
65			Retrieve a stored object corresponding to the provided class
66			instance.
67			"""
68
69			for key_class, obj in self.mapping:
70			if isinstance(instance, key_class):
71			return obj
72			return None
73
74
75			def has(self, instance):
76			"""
77			Determine if the ClassMapper contains an object corresponding
78			to the provided instance
79			"""
80
81			return self.get(instance) is not None
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