I encountered partialmethod() at work, and I didn’t understand what they were so I looked it up.
functools
partialmethod() comes from functools builtin library. “The functools module is for higher-order functions:
functions that act on or return other functions. In general, any callable object can be treated as a function
for the purposes of this module.”
partialmethod()
“Return a new partialmethod descriptor which behaves like partial except that it is designed to be used as a method
definition rather than being directly called.”
# partialmethod() signature
functools.partialmethod(func, /, *args, **keywords)
# func must be a descriptor or a callable
# if descriptor:
# - calls to `__get__` are delegated to the underlying descriptor and
# an appropriate partial object returned as the result.
# if non-descriptor callable:
# - an appropriate bound method is created dynamically. This behaves like
# a normal Python function when used as a method: the `self` argument
# will be inserted as the first positional argument, even before the
# `args` and `keywords` supplied to the `partialmethod` constructor.
Example
from functools import partialmethod
class Cell:
def __init__(self):
self._alive = False
@property
def alive(self):
return self._alive
def set_state(self, state):
self._alive = bool(state)
set_alive = partialmethod(set_state, True)
set_dead = partialmethod(set_state, False)
>>> c = Cell()
>>> c.alive
False
>>> c.set_alive()
>>> c.alive
True