Source Code for Module turbogears.decorator

  1  """Decorator tools""" 
  2   
  3  import itertools 
  4  from inspect import getargspec, formatargspec 
  5   
  6   
  7 -def decorate(func, caller, signature=None): 
  8      """Decorate func with caller. 
  9   
 10      Inspired by Michele Simionato's decorator library: 
 11      http://www.phyast.pitt.edu/~micheles/python/documentation.html 
 12   
 13      """ 
 14      argnames, varargs, kwargs, defaults = \ 
 15          signature is None and getargspec(func) or signature 
 16      if defaults is None: 
 17          defaults = () 
 18      parameters = formatargspec(argnames, varargs, kwargs, defaults)[1:-1] 
 19      defval = itertools.count(len(argnames) - len(defaults)) 
 20      args = formatargspec(argnames, varargs, kwargs, defaults, 
 21          formatvalue=lambda value:"=%s" % argnames[defval.next()])[1:-1] 
 22      exec_dict = dict(func=func, caller=caller) 
 23      exec "\ndef %s(%s):\n\treturn caller(func, %s)\n" % ( 
 24          func.__name__, parameters, args) in exec_dict 
 25      new_func = exec_dict[func.__name__] 
 26      new_func.__doc__ = func.__doc__ 
 27      new_func.__dict__ = func.__dict__.copy() 
 28      new_func.__module__ = func.__module__ 
 29      new_func.__composition__ = getattr(func, '__composition__', 
 30          [func]) + [new_func] 
 31      return new_func 
 32   
 33   
 34 -def decorator(entangler, signature=None): 
 35      """Decorate function with entangler. 
 36   
 37      Use new signature or preserve original signature if signature is None. 
 38   
 39      """ 
 40      def entangle(func): 
 41          return decorate(func, entangler(func), signature) 
 42      return entangle 
 43   
 44   
 45 -def weak_signature_decorator(entangler): 
 46      """Decorate function with entangler and weak signature. 
 47   
 48      Changes signature to accept arbitrary additional arguments. 
 49   
 50      """ 
 51      def entangle(func): 
 52          return decorate(func, entangler(func), make_weak_signature(func)) 
 53      return entangle 
 54   
 55   
 56 -def simple_decorator(caller, signature=None): 
 57      """Decorate function with caller.""" 
 58      def entangle(func): 
 59          return decorate(func, caller, signature) 
 60      return entangle 
 61   
 62   
 63 -def simple_weak_signature_decorator(caller): 
 64      """Decorate function with caller and weak signature. 
 65   
 66      Changes signature to accept arbitrary additional arguments. 
 67   
 68      """ 
 69      def entangle(func): 
 70          return decorate(func, caller, make_weak_signature(func)) 
 71      return entangle 
 72   
 73   
 74 -def make_weak_signature(func): 
 75      """Change signature to accept arbitrary additional arguments.""" 
 76      argnames, varargs, kwargs, defaults = getargspec(func) 
 77      if kwargs is None: 
 78          kwargs = "_decorator__kwargs" 
 79      if varargs is None: 
 80          varargs = "_decorator__varargs" 
 81      return argnames, varargs, kwargs, defaults 
 82   
 83   
 84 -def compose(*decorators): 
 85      """Compose decorators.""" 
 86      return lambda func: reduce(lambda f, g: g(f), decorators, func) 
 87   
 88   
 89 -def func_composition(func): 
 90      """Return composition (decorator wise) of function.""" 
 91      return getattr(func, "__composition__", [func]) 
 92   
 93   
 94 -def func_original(func): 
 95      """Return original (undecorated) function.""" 
 96      return func_composition(func)[0] 
 97   
 98   
 99 -def func_id(func): 
100      """Return identity of function. 
101   
102      If decorator was created with decorator() or weak_signature_decorator(), 
103      identity is invariant under decorator application. 
104   
105      """ 
106      return id(func_original(func)) 
107   
108   
109 -def func_eq(f, g): 
110      """Check if functions are identical.""" 
111      return func_id(f) == func_id(g) 
112   
113   
114  __all__ = ["decorate", "make_weak_signature", "compose", 
115      "decorator", "weak_signature_decorator", 
116      "simple_decorator", "simple_weak_signature_decorator", 
117      "func_id", "func_eq", "func_original", "func_composition"] 
118