Source Code for Module smartcard.ClassLoader

 1  """ClassLoader allows you to load modules from packages without
 
 2  hard-coding their class names in code; instead, they might be
 
 3  specified in a configuration file, as command-line parameters,
 
 4  or within an interface.
 
 5  
 
 6  Source: Robert Brewer at the Python Cookbook:
 
 7  http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/223972
 
 8  
 
 9  License: PSF license (http://docs.python.org/license.html).
 
10  """ 
11  
 
12 -def get_mod(modulePath): 
13      """Import a module.""" 
14      return __import__(modulePath, globals(), locals(), ['']) 
15  
 
16  
 
17 -def get_func(fullFuncName): 
18      """Retrieve a function object from a full dotted-package name.""" 
19  
 
20      # Parse out the path, module, and function
 
21      lastDot = fullFuncName.rfind(u".") 
22      funcName = fullFuncName[lastDot + 1:] 
23      modPath = fullFuncName[:lastDot] 
24  
 
25      aMod = get_mod(modPath) 
26      aFunc = getattr(aMod, funcName) 
27  
 
28      # Assert that the function is a *callable* attribute.
 
29      assert callable(aFunc), u"%s is not callable." % fullFuncName 
30  
 
31      # Return a reference to the function itself,
 
32      # not the results of the function.
 
33      return aFunc 
34  
 
35  
 
36 -def get_class(fullClassName, parentClass=None): 
37      """Load a module and retrieve a class (NOT an instance).
 
38  
 
39      If the parentClass is supplied, className must be of parentClass
 
40      or a subclass of parentClass (or None is returned).
 
41      """ 
42      aClass = get_func(fullClassName) 
43  
 
44      # Assert that the class is a subclass of parentClass.
 
45      if parentClass is not None: 
46          if not issubclass(aClass, parentClass): 
47              raise TypeError(u"%s is not a subclass of %s" %
 
48                              (fullClassName, parentClass)) 
49  
 
50      # Return a reference to the class itself, not an instantiated object.
 
51      return aClass 
52