函数关闭与可调用类 [英] Function closure vs. callable class

问题描述

在许多情况下，有两种实现选择：闭包和可调用类。例如，

In many cases, there are two implementation choices: a closure and a callable class. For example,

class F:
  def __init__(self, op):
    self.op = op
  def __call__(self, arg1, arg2):
    if (self.op == 'mult'):
      return arg1 * arg2
    if (self.op == 'add'):
      return arg1 + arg2
    raise InvalidOp(op)

f = F('add')

或

def F(op):
  if op == 'or':
    def f_(arg1, arg2):
      return arg1 | arg2
    return f_
  if op == 'and':
    def g_(arg1, arg2):
      return arg1 & arg2
    return g_
  raise InvalidOp(op)

f = F('add')

在选择一个方向时，应该考虑哪些因素？

What factors should one consider in making the choice, in either direction?

我可以想到两个：

• 闭包似乎总是会有更好的性能（
  不能想到一个反例）。

• It seems a closure would always have better performance (can't think of a counterexample).

我认为在某些情况下，关闭无法完成任务（例如，如果
的状态随时间而变化）。

I think there are cases when a closure cannot do the job (e.g., if its state changes over time).

我在这些内容中正确吗？

Am I correct in these? What else could be added?

推荐答案

关闭速度更快。类更灵活（即，可用的方法不仅仅是__call __）。

Closures are faster. Classes are more flexible (i.e. more methods available than just __call__).

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