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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  
 
10  import sys 
11  import types 
12  
 
13  
 
14 -def get_mod(modulePath): 
15      """Import a module.""" 
16      return __import__(modulePath, globals(), locals(), ['']) 
17  
 
18  
 
19 -def get_func(fullFuncName): 
20      """Retrieve a function object from a full dotted-package name.""" 
21  
 
22      # Parse out the path, module, and function
 
23      lastDot = fullFuncName.rfind(u".") 
24      funcName = fullFuncName[lastDot + 1:] 
25      modPath = fullFuncName[:lastDot] 
26  
 
27      aMod = get_mod(modPath) 
28      aFunc = getattr(aMod, funcName) 
29  
 
30      # Assert that the function is a *callable* attribute.
 
31      assert callable(aFunc), u"%s is not callable." % fullFuncName 
32  
 
33      # Return a reference to the function itself,
 
34      # not the results of the function.
 
35      return aFunc 
36  
 
37  
 
38 -def get_class(fullClassName, parentClass=None): 
39      """Load a module and retrieve a class (NOT an instance).
 
40  
 
41      If the parentClass is supplied, className must be of parentClass
 
42      or a subclass of parentClass (or None is returned).
 
43      """ 
44      aClass = get_func(fullClassName) 
45  
 
46      # Assert that the class is a subclass of parentClass.
 
47      if parentClass is not None: 
48          if not issubclass(aClass, parentClass): 
49              raise TypeError(u"%s is not a subclass of %s" %
 
50                              (fullClassName, parentClass)) 
51  
 
52      # Return a reference to the class itself, not an instantiated object.
 
53      return aClass 
54   

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