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copied!<p>It can be done in pure Python with this incredibly clever module:</p> <p><a href="https://pypi.python.org/pypi/forbiddenfruit">https://pypi.python.org/pypi/forbiddenfruit</a></p> <p>For example:</p> <pre><code>import functools import ctypes import __builtin__ import operator class PyObject(ctypes.Structure): pass Py_ssize_t = hasattr(ctypes.pythonapi, 'Py_InitModule4_64') and ctypes.c_int64 or ctypes.c_int PyObject._fields_ = [ ('ob_refcnt', Py_ssize_t), ('ob_type', ctypes.POINTER(PyObject)), ] class SlotsPointer(PyObject): _fields_ = [('dict', ctypes.POINTER(PyObject))] def proxy_builtin(klass): name = klass.__name__ slots = getattr(klass, '__dict__', name) pointer = SlotsPointer.from_address(id(slots)) namespace = {} ctypes.pythonapi.PyDict_SetItem( ctypes.py_object(namespace), ctypes.py_object(name), pointer.dict, ) return namespace[name] def die(message, cls=Exception): """ Raise an exception, allows you to use logical shortcut operators to test for object existence succinctly. User.by_name('username') or die('Failed to find user') """ raise cls(message) def unguido(self, key): """ Attempt to find methods which should really exist on the object instance. """ return functools.partial((getattr(__builtin__, key, None) if hasattr(__builtin__, key) else getattr(operator, key, None)) or die(key, KeyError), self) class mapper(object): def __init__(self, iterator, key): self.iterator = iterator self.key = key self.fn = lambda o: getattr(o, key) def __getattribute__(self, key): if key in ('iterator', 'fn', 'key'): return object.__getattribute__(self, key) return mapper(self, key) def __call__(self, *args, **kwargs): self.fn = lambda o: (getattr(o, self.key, None) or unguido(o, self.key))(*args, **kwargs) return self def __iter__(self): for value in self.iterator: yield self.fn(value) class foreach(object): """ Creates an output iterator which will apply any functions called on it to every element in the input iterator. A kind of chainable version of filter(). E.g: foreach([1, 2, 3]).__add__(2).__str__().replace('3', 'a').upper() is equivalent to: (str(o + 2).replace('3', 'a').upper() for o in iterator) Obviously this is not 'Pythonic'. """ def __init__(self, iterator): self.iterator = iterator def __getattribute__(self, key): if key in ('iterator',): return object.__getattribute__(self, key) return mapper(self.iterator, key) def __iter__(self): for value in self.iterator: yield value proxy_builtin(list)['foreach'] = property(foreach) import string print string.join([1, 2, 3].foreach.add(2).str().add(' cookies').upper(), ', ') >>> 3 COOKIES, 4 COOKIES, 5 COOKIES </code></pre> <p>There, doesn't that feel good?</p>

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