Forbidden Fruit

This project allows Python code to extend built-in types.

If that's a good idea or not, you tell me. The first need this project attended was allowing a Python assertion library to implement a similar API to RSpec Expectations and should.js. But people got creative and used it to among other things spy on things or to integrate profiling.

Tiny Example

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

Add a new method to the int class:

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 "

Add a classmethod to the str class:

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)

Beware: reverse() only deletes attributes. If you curse()'d to replace a pre-existing attribute, reverse() won't re-install the existing attribute.

Context Manager / Decorator

cursed() acts as a context manager to make a curse(), and then reverse() it on exit. It uses contextlib.contextmanager(), so on Python 3.2+ it can also be used as a function decorator. Like so:

from forbiddenfruit import cursed

with cursed(str, "test", "blah"):
    assert str.test == "blah"

assert "test" not in dir(str)


@cursed(str, "test", "blah")
def function():
    assert str.test == "blah"


function()

assert "test" not in dir(str)

Compatibility

Forbbiden Fruit is tested on CPython 2.7, 3.0, and 3.3-3.7.

Since Forbidden Fruit is fundamentally dependent on the C API, this library won't work on other python implementations, such as Jython, pypy, etc.

License

This software is available under two different licenses at your choice:

GPLv3

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 http://www.gnu.org/licenses/.

MIT

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

clarete/forbiddenfruit