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ap_decorators.py

+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+
+"""
+:module: ap2_decorators  
+:author: FIL - Faculté des Sciences et Technologies -  Univ. Lille <http://portail.fil.univ-lille1.fr>_
+:date: 2018, september
+
+"""
+
+from functools import wraps
+
+
+def trace(fct):
+    '''
+    Decorator for tracing every call to fct.
+    Recursive calls are indented.
+
+    :Example:
+
+    >>> @trace
+    ... def fact(n):
+    ...     if n == 0:
+    ...         return 1
+    ...     else:
+    ...         return n * fact(n - 1)
+    
+    >>> fact(5)
+     -> fact((5,), {})
+    ... -> fact((4,), {})
+    ...... -> fact((3,), {})
+    ......... -> fact((2,), {})
+    ............ -> fact((1,), {})
+    ............... -> fact((0,), {})
+    ............... <- 1
+    ............ <- 1
+    ......... <- 2
+    ...... <- 6
+    ... <- 24
+    <- 120
+    120
+    '''
+    @wraps(fct)
+    def wrapper(*args, **kwargs):
+        dots = '...' * wrapper.__depth
+        print('{:s} -> {:s}{:s}'.format(dots, wrapper.__name__, repr((args, kwargs))))
+        wrapper.__depth += 1
+        y = fct(*args, **kwargs)
+        wrapper.__depth -= 1
+        print('{:s} <- {:s}'.format(dots, repr(y)))
+        return y
+    wrapper.__depth = 0
+    return wrapper
+
+def count(fct):
+    '''
+    decorator for counting  calls to  function fct
+    
+    :Example:
+
+    >>> @count
+    ... def fact(n):
+    ...     if n == 0:
+    ...         return 1
+    ...     else:
+    ...         return n * fact(n - 1)
+    
+    >>> fact.counter
+    0
+    >>> fact(5)
+    120
+    >>> fact.counter
+    6
+    '''
+    @wraps(fct) 
+    def wrapper(*args, **kwargs):
+        y = fct(*args, **kwargs)
+        wrapper.counter += 1
+        return y
+    wrapper.counter = 0
+    return wrapper
+
+
+def memoize(fct):
+    '''
+    decorator for memoizing computed values of  function fct
+    
+    :Example:
+
+    >>> @count
+    ... @memoize
+    ... def fact(n):
+    ...     if n == 0:
+    ...         return 1
+    ...     else:
+    ...         return n * fact(n - 1)
+    
+    >>> fact.counter
+    0
+    >>> fact(5)
+    120
+    >>> fact.counter
+    6
+    >>> fact.counter = 0
+    >>> fact(5)
+    120
+    >>> fact.counter
+    1
+    '''
+    cache = dict()
+    @wraps(fct)
+    def wrapper(*args, **kwargs):
+        key = repr((args, kwargs))
+        if key in cache:
+            return cache[key]
+        else:
+            y = fct(*args, **kwargs)
+            cache[key] = y
+            return y
+    return wrapper
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod(optionflags=doctest.NORMALIZE_WHITESPACE | doctest.ELLIPSIS, verbose=False)
+    
+    
+
+
+
+
+
+
+