cola/models/base.py

   1 # Copyright (c) 2009 David Aguilar
   2 """Provides a serializable data container"""
   3 import types
   4 import copy
   5
   6 from cola import serializer
   7 from cola.compat import set
   8
   9 class BaseModel(object):
  10     def param_names(self, export=False):
  11         """Returns a list of serializable attribute names.
  12
  13         >>> m = BaseModel()
  14         >>> m._question = 'unknown'
  15         >>> m.answer = 42
  16
  17         >>> m.param_names()
  18         ['answer']
  19
  20         >>> m.param_names(export=True)
  21         ['_question', 'answer']
  22
  23         """
  24         names = []
  25         for k, v in self.__dict__.iteritems():
  26             if is_atom(v) or is_dict(v) or is_seq(v):
  27                 if k.strip('_') != k:
  28                     if not export:
  29                         continue
  30                 names.append(k)
  31         names.sort()
  32         return names
  33
  34     def has_param(self,param):
  35         """Returns true if a parameter exists in a model.
  36
  37         >>> m = BaseModel()
  38         >>> m.answer = 42
  39         >>> m.has_param('answer')
  40         True
  41
  42         >>> m.has_param('question')
  43         False
  44
  45         """
  46         return param in self.__dict__
  47
  48     def param(self, param, default=None):
  49         """Returns the value of a model parameter.
  50
  51         >>> m = BaseModel()
  52         >>> m.answer = 42
  53         >>> m.param('answer')
  54         42
  55
  56         >>> m.param('another answer', 42)
  57         42
  58         """
  59         return self.__dict__.get(param, default)
  60
  61     def __getattr__(self, param):
  62         """Provides set_<attribute>(value) append methods.
  63
  64         This provides automatic convenience methods for handling
  65         setattrs with notification.
  66
  67         >>> m = BaseModel()
  68         >>> m.answer = 42
  69         >>> m.set_answer(41)
  70         >>> # Observers are notified
  71         >>> m.answer
  72         41
  73
  74         """
  75         # Base case: we actually have this param
  76         if param in self.__dict__:
  77             return getattr(self, param)
  78
  79         # Return a closure over param for calling set_param;
  80         # Concrete classes subclass set_param to provide notification
  81         if param.startswith('set_'):
  82             return lambda v: self.set_param(param[4:], v)
  83
  84         errmsg  = ("'%s' object has no attribute '%s'" %
  85                     (self.__class__.__name__, param))
  86         raise AttributeError(errmsg)
  87
  88     def set_param(self, param, value):
  89         """Wrapper around setattr()
  90
  91         >>> m = BaseModel()
  92         >>> m.answer = 41
  93         >>> m.set_param('answer', 42)
  94         >>> m.answer
  95         42
  96
  97         """
  98         setattr(self, param, value)
  99
 100     def copy_params(self, model, params_to_copy=None):
 101         """Copies params from one model to another.
 102
 103         >>> m = BaseModel()
 104         >>> m.answer = 42
 105         >>> m._question = 'unknown'
 106         >>> m2 = BaseModel()
 107         >>> m2.copy_params(m)
 108         >>> m2._question
 109         'unknown'
 110
 111         >>> m2.answer
 112         42
 113
 114         """
 115         # Loop over all attributes and copy them over
 116         for k in params_to_copy or model.param_names(export=True):
 117             self.__dict__[k] = copy.copy(model.__dict__[k])
 118
 119
 120 def is_dict(item):
 121     return type(item) is types.DictType
 122
 123
 124 def is_seq(item):
 125     return (type(item) is types.ListType or
 126             type(item) is types.TupleType or
 127             type(item) is set)
 128
 129 def is_atom(item):
 130     return(item is None or
 131         type(item) in types.StringTypes or
 132         type(item) is types.BooleanType or
 133         type(item) is types.IntType or
 134         type(item) is types.LongType or
 135         type(item) is types.FloatType or
 136         type(item) is types.ComplexType)