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Intercept function and method calls

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Build Status PyPI license

Intercepts allows you to intercept any function call in Python and handle it in any manner you choose. For example, you can pre-process the inputs to a function, or apply post-processing on its output. Intercepts also allows you to completely replace a function with a custom implementation.

>>> increment(41)
>>> intercepts.register(increment, handler)
>>> increment(41)
>>> intercepts.unregister(increment)
>>> intercepts.register(increment, handler2)
>>> increment(41)
'The answer is: 42'
>>> intercepts.unregister_all()

Handler functions receive the intercepted function as their first argument, as well as all of the arguments to the intercepted function.

>>> def handler(func, num):
...  result = func(num)
...  return num - (result - num)
>>> def handler2(func, *args, **kwargs):
...  return "The answer is: %s" % func(*args, **kwargs)

The intercepts module also allows intercepting python built-in functions, such as print and sorted. For best results, the intercepts module should be the first module imported.

>>> def print_handler(print_func, message):
...     return print_func(''.join(reversed(message)))
>>> print("Hello world")
Hello world
>>> intercepts.register(print, print_handler)
>>> print("Hello world")
dlrow olleH


Intercepts requires python 3.5+. There are currently no additional dependencies.


Intercepts can be installed using pip.

$ pip install intercepts

Or, use pip to install the latest version from the github source.

$ pip install -U git+


Some documentation is available here.

This software is in early stages of development and may be unstable.

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