added jeep module, a general purpose class for objects acting like a list, a dictionary and a normal object with attributes

git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@1606 fd906abe-77d9-0310-91a1-e0d9ade77398

util/jeep.py

@@ -0,0 +1,70 @@
+#
+#  Copyright (c) 2007 Helmut Merz helmutm@cy55.de
+#
+#  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
+#
+
+"""
+A general purpose (thus 'Jeep') class that provides most of the interfaces
+of sequences and dictionaries and in addition allows attribute access to
+the dictionary entries.
+
+$Id$
+"""
+
+_notfound = object()
+
+class Jeep(object):
+
+    _attributes = ('_sequence',)
+
+    def __init__(self, init=None):
+        self._sequence = []
+        if init is not None:
+            for attr, value in init:
+                setattr(self, attr, value)
+
+    def __iter__(self):
+        for key in self._sequence:
+            yield key
+
+    def __setattr__(self, attr, value):
+        if not attr in self._attributes:
+            if getattr(self, attr, _notfound) is _notfound:
+                self._sequence.append(attr)
+        object.__setattr__(self, attr, value)
+
+    def __getitem__(self, key):
+        if type(key) is int:
+            return getattr(self, self._sequence[key])
+        value = getattr(self, key, _notfound)
+        if value is _notfound:
+            raise KeyError(key)
+        return value
+
+    def __setitem__(self, key, value):
+        setattr(self, key, value)
+
+    def keys(self):
+        return list(self)
+
+    def values(self):
+        return [self[k] for k in self]
+
+    def items(self):
+        return [(k, self[k]) for k in self]
+
+    def get(self, key, default=None):
+        return getattr(self, key, default)

util/jeep.txt

@@ -0,0 +1,89 @@
+==============================
+Jeep - a General Purpose Class
+==============================
+
+$Id$
+
+  >>> from cybertools.util.jeep import Jeep
+  >>> jeep = Jeep()
+
+  >>> jeep.first = 'first value'
+  >>> jeep.second = 'second value'
+
+  >>> jeep.first
+  'first value'
+
+In addition to the usual access via dot notation all attributes can be
+accessed via dictionary notation:
+
+The third type of interface provided by Jeep objects is the sequence or
+iterator interface. Converting a jeep object to a list iterates over the
+keys:
+
+  >>> list(jeep)
+  ['first', 'second']
+
+Direct index access to certain entries gives the corresponding value,
+not the key:
+
+  >>> jeep[1]
+  'second value'
+
+Changing Jeep Objects
+---------------------
+
+Assignment by dictionary or attribute access appends the newly assigned
+attribute:
+
+  >>> jeep['third'] = 'third value'
+  >>> jeep.third
+  'third value'
+
+  >>> list(jeep)
+  ['first', 'second', 'third']
+
+Assigning a new value to an already existing attribute does not change the
+order but only changes the attribute's value
+
+  >>> jeep.second = 'new second value'
+  >>> list(jeep)
+  ['first', 'second', 'third']
+  >>> jeep[1]
+  'new second value'
+
+More Dictionary Methods
+-----------------------
+
+  >>> jeep.keys()
+  ['first', 'second', 'third']
+
+  >>> jeep.values()
+  ['first value', 'new second value', 'third value']
+
+  >>> jeep.items()
+  [('first', 'first value'), ('second', 'new second value'), ('third', 'third value')]
+
+  >>> jeep.get('second')
+  'new second value'
+
+  >>> jeep.get('fourth', 'default')
+  'default'
+
+  >>> jeep.get('fourth') is None
+  True
+
+  >>> jeep['fourth']
+  Traceback (most recent call last):
+  ...
+  KeyError: 'fourth'
+
+  >>> dict(jeep)
+  {'second': 'new second value', 'third': 'third value', 'first': 'first value'}
+
+Constructors
+------------
+
+  >>> jeep2 = Jeep((('f', '1st'), ('s', '2nd'), ('t', '3rd')))
+  >>> list(jeep2)
+  ['f', 's', 't']
+

util/tests.py

@@ -21,6 +21,7 @@ def test_suite():
         doctest.DocFileSuite('adapter.txt', optionflags=flags),
         doctest.DocFileSuite('defer.txt', optionflags=flags),
         doctest.DocFileSuite('property.txt', optionflags=flags),
+        doctest.DocFileSuite('jeep.txt', optionflags=flags),
         ))
 
 if __name__ == '__main__':