ubelt.util_func module

Helpers for functional programming. Currently this module contains an identify function that simply returns its own inputs and a function to “inject” another function into a class instance as a method. This is useful for monkey patching.


The identity function. Simply returns its inputs.

Parameters:arg (object) – some value
Returns:arg: the same value
Return type:object


>>> assert identity(42) == 42
ubelt.util_func.inject_method(self, func, name=None)[source]

Injects a function into an object instance as a bound method

The main use case of this function is for monkey patching. While monkey patching is sometimes necessary it should generally be avoided. Thus, we simply remind the developer that there might be a better way.

  • self (object) – instance to inject a function into
  • func (func) – the function to inject (must contain an arg for self)
  • name (str) – name of the method. optional. If not specified the name of the function is used.


>>> class Foo(object):
>>>     def bar(self):
>>>         return 'bar'
>>> def baz(self):
>>>     return 'baz'
>>> self = Foo()
>>> assert self.bar() == 'bar'
>>> assert not hasattr(self, 'baz')
>>> inject_method(self, baz)
>>> assert not hasattr(Foo, 'baz'), 'should only change one instance'
>>> assert self.baz() == 'baz'
>>> inject_method(self, baz, 'bar')
>>> assert self.bar() == 'baz'