Patch built-in python objects

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Forbidden Fruit

Forbidden Fruit

This project aims to help you reach heaven while writing tests, but it may lead you to hell if used on production code.

It basically allows you to patch built-in objects, declared in C through python. Just like this:

>>> from forbiddenfruit import curse
>>> def words_of_wisdom(self):
...     return self * "blah "
>>> curse(int, "words_of_wisdom", words_of_wisdom)
>>> assert (2).words_of_wisdom() == "blah blah "

Boom! That's it, your int class now has the words_of_wisdom method. Do you want to add a classmethod to a built-in class? No problem, just do this:

>>> from forbiddenfruit import curse
>>> def hello(self):
...     return "blah"
>>> curse(str, "hello", classmethod(hello))
>>> assert str.hello() == "blah"

Reversing a curse

If you want to free your object from a curse, you can use the reverse() function. Just like this:

>>> from forbiddenfruit import curse, reverse
>>> curse(str, "test", "blah")
>>> assert 'test' in dir(str)
>>> # Time to reverse the curse
>>> reverse(str, "test")
>>> assert 'test' not in dir(str)


Forbidden Fruit runs on all cpython versions I tested so far, which includes the versions 2.5, 2.6, 2.7, 3.2 and 3.3. Since Forbidden Fruit is fundamentally dependent on the C API, this library won't work on other python implementations, such as Jython, PyPy, etc.

I might add support for PyPy in the future, but It's unlikely that I'll do it for Jython. But I could happily accept patches for them.


License (GPLv3)

Copyright (C) 2013 Lincoln Clarete

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see

Logo by

Kimberly Chandler, from The Noun Project