Source Code for Module MinimalMatch

  1  # Copyright (C) 2005, 2006 Joint Institute for VLBI in Europe 
  2  # 
  3  # This program is free software; you can redistribute it and/or modify 
  4  # it under the terms of the GNU General Public License as published by 
  5  # the Free Software Foundation; either version 2 of the License, or 
  6  # (at your option) any later version. 
  7  # 
  8  # This program is distributed in the hope that it will be useful, 
  9  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 10  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 11  # GNU General Public License for more details. 
 12   
 13  # You should have received a copy of the GNU General Public License 
 14  # along with this program; if not, write to the Free Software 
 15  # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 16   
 17  """ 
 18  This modules provides the MinimalMatch class.  Subclasses from this 
 19  class have the special property that attribute names can be 
 20  abbreviated: 
 21   
 22  >>> class MyClass(MinimalMatch): 
 23  ...     user = 'root' 
 24  ...     start = 'yesterday' 
 25  ...     stop = 'tomorrow' 
 26  ...  
 27  >>> my_instance = MyClass() 
 28   
 29  For instance the following command will set the 'user' attribute: 
 30   
 31  >>> my_instance.u = 'nobody' 
 32  >>> print my_instance.user 
 33  nobody 
 34   
 35  But of course you can always use the full attribute name: 
 36   
 37  >>> my_instance.user = 'root' 
 38  >>> print my_instance.us 
 39  root 
 40   
 41  Never type more than the full attribute name: 
 42   
 43  >>> print my_instance.users 
 44  Traceback (most recent call last): 
 45    ... 
 46  AttributeError: MyClass instance has no attribute 'users' 
 47   
 48  Abbreviations should not be ambiguous: 
 49   
 50  >>> my_instance.st = 'now' 
 51  Traceback (most recent call last): 
 52    ... 
 53  AttributeError: MyClass instance attribute 'st' is ambiguous 
 54   
 55  And setting instance attributes that are not class attributes is not 
 56  possible: 
 57   
 58  >>> my_instance.group = 'nobody' 
 59  Traceback (most recent call last): 
 60    ... 
 61  AttributeError: MyClass instance has no attribute 'group' 
 62   
 63  >>> print my_instance.stop 
 64  tomorrow 
 65   
 66  Getting and setting private attributes should just work: 
 67   
 68  >>> my_instance._private = ('do', 'not', 'touch') 
 69  >>> print my_instance._private 
 70  ('do', 'not', 'touch') 
 71   
 72  And accesing non-existent private attributes should fail (and not land 
 73  us in an infinite loop): 
 74   
 75  >>> print my_instance._does_not_exist 
 76  Traceback (most recent call last): 
 77    ... 
 78  AttributeError: MyClass instance has no attribute '_does_not_exist' 
 79   
 80  """ 
 81   
 82 -class MinimalMatch: 
 83      """ Allow class attribute names to be abbreviated. """ 
 84   
 85 -    def _findattr(self, name): 
 86          # Disregard private attributes. 
 87          if name.startswith('_'): 
 88              return name 
 89   
 90          match_attr = None 
 91          if name in self.__dict__: 
 92              match_attr = name 
 93          else: 
 94              for dict in self.__dict__, self.__class__.__dict__: 
 95                  for attr in dict: 
 96                      if attr.startswith(name): 
 97                          if match_attr and attr != match_attr: 
 98                              msg = "%s instance attribute '%s' is ambiguous" \ 
 99                                    % (self.__class__.__name__, name) 
100                              raise AttributeError, msg 
101                          else: 
102                              match_attr = attr 
103   
104          if not match_attr: 
105              msg = "%s instance has no attribute '%s'" \ 
106                    % (self.__class__.__name__, name) 
107              raise AttributeError, msg 
108   
109          return match_attr 
110   
111 -    def __getattr__(self, name): 
112          attr = self._findattr(name) 
113          if hasattr(self, attr): 
114              return getattr(self, attr) 
115   
116          msg = "%s instance has no attribute '%s'" \ 
117                % (self.__class__.__name__, name) 
118          raise AttributeError, msg 
119   
120 -    def __setattr__(self, name, value): 
121          attr = self._findattr(name) 
122          self.__dict__[attr] = value 
123   
124   
125  # Tests. 
126  if __name__ == '__main__': 
127      import doctest, sys 
128      results = doctest.testmod(sys.modules[__name__]) 
129      sys.exit(results[0]) 
130