python - 使用默认参数传入函数

Question

我在 Python f(a, b) 中有一个函数，我正在尝试定义一个接受 f 的新函数 g已经设置了一个参数，类似于 g(f(a = 5))。这将是一个简单的例子:

def sum(a, b):
   return a+b

def g(x, f):
   return f(x)

我希望能够计算 g(5, sum(b=0))。我该怎么做？

Answer 1

使用 functools.partial :

g(5, partial(sum, b=5))

Return a new partial object which when called will behave like func called with the positional arguments args and keyword arguments keywords. If more arguments are supplied to the call, they are appended to args. If additional keyword arguments are supplied, they extend and override keywords

The partial() is used for partial function application which “freezes” some portion of a function’s arguments and/or keywords resulting in a new object with a simplified signature. For example, partial() can be used to create a callable that behaves like the int() function where the base argument defaults to two:

basetwo = partial(int, base=2)