Source code for track

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Functions for creating classes with access tracking facilities.
This can e.g. be use to detect if the contents of a list or dict
has been changed.
from __future__ import absolute_import, division, print_function

_attributes_ = ['track_methods']

track_methods = [
    '__setitem__', '__setslice__', '__delitem__', 'update', 'append', 'extend',
    'add', 'insert', 'pop', 'popitem', 'remove', 'setdefault', '__iadd__'
List of names of methods that can possibly change an object
of type dict or list.

[docs]def track_decorator(func): """Create a wrapper function for tracked class methods. The wrapper function increases the 'hits' attribute of the class and then executes the wrapped method. Note that the class is passed as the first argument. """ def wrapper(*args, **kw): """Wrapper function for a class method.""" # print "NOTIF %s %s" % (func.__name__, id(args[0])) args[0].hits += 1 return func(*args, **kw) wrapper.__name__ = func.__name__ return wrapper
[docs]def track_class_factory(cls, name='', methods=track_methods): """Create a wrapper class with method tracking facilities. Tracking a class counts the number of times any of the specified class methods has been used. Given an input class, this will return a class with tracking facilities. The tracking occurs on all the specified methods. The default will Parameters ---------- cls: class The class to be tracked. name: str, optional The name of the class wrapper. If not provided, the name will be 'Tracked' followed by the capitalized class name. methods: list of str List of class method names that should be taken into account in the tracking. Calls to any of these methods will increment the number of hits. The methods should be owned by the class itself, not by a parent class. The default list will track all methods which could possibly change a 'list' or a 'dict'. Returns ------- class A class wrapping the input class and tracking access to any of the specified methods. The class has an extra attribute 'hits' counting the number accesses to one of these methods. This value can be reset to zero to track changes after some breakpoint. Examples -------- >>> TrackedDict = track_class_factory(dict) >>> D = TrackedDict({'a':1,'b':2}) >>> print(D.hits) 0 >>> D['c'] = 3 >>> print(D.hits) 1 >>> D.hits = 0 >>> print(D.hits) 0 >>> D.update({'d':1,'b':3}) >>> del D['a'] >>> print(D.hits) 2 """ new_dct = cls.__dict__.copy() if 'hits' in new_dct: raise ValueError("The input class should not have an attribute 'hits'") for key in new_dct: if key in track_methods: value = new_dct[key] new_value = track_decorator(value) new_dct[key] = new_value new_dct['hits'] = 0 new_dct['__doc__'] = """Tracked %s class """ % cls.__name__ if not name: name = 'Tracked' + cls.__name__.capitalize() return type(name, (cls,), new_dct)
TrackedDict = track_class_factory(dict) TrackedList = track_class_factory(list) # End