在另一个方法中计算 python 方法调用

Question

我实际上正在尝试在 Java 中执行此操作，但我正在自学 python，这让我想知道是否有一种简单/聪明的方法可以使用包装器或其他东西来做到这一点。

我想知道一个特定方法在另一个方法中被调用了多少次。例如：

def foo(z):
    #do something
    return result

def bar(x,y):
    #complicated algorithm/logic involving foo
    return foobar

因此，对于使用各种参数对 bar 的每次调用，我想知道 foo 被调用了多少次，可能输出如下：

>>> print bar('xyz',3)
foo was called 15 times
[results here]
>>> print bar('stuv',6)
foo was called 23 times
[other results here]

编辑：我意识到我可以在吧台内放一个柜台，然后当我返回时将其倾倒，但如果你可以用包装器做一些魔法来完成同样的事情，那就太酷了。这也意味着我可以在其他地方重用相同的包装器，而无需修改方法内的任何代码。

Answer 1

听起来几乎是装饰器的教科书示例！

def counted(fn):
    def wrapper(*args, **kwargs):
        wrapper.called += 1
        return fn(*args, **kwargs)
    wrapper.called = 0
    wrapper.__name__ = fn.__name__
    return wrapper

@counted
def foo():
    return

>>> foo()
>>> foo.called
1

您甚至可以使用另一个装饰器来自动记录一个函数在另一个函数中被调用的次数：

def counting(other):
    def decorator(fn):
        def wrapper(*args, **kwargs):
            other.called = 0
            try:
                return fn(*args, **kwargs)
            finally:
                print '%s was called %i times' % (other.__name__, other.called)
        wrapper.__name__ = fn.__name__
        return wrapper
    return decorator

@counting(foo)
def bar():
    foo()
    foo()

>>> bar()
foo was called 2 times

如果foo 或bar 最终可以调用自己，那么您需要一个涉及堆栈的更复杂的解决方案来应对递归。然后你将走向一个全面的分析器......

如果您仍在“自学 Python”，那么这种包装的装饰器可能不是理想的地方，它往往被用于魔法！

Answer 2

这定义了一个装饰器来做这件事：

def count_calls(fn):
    def _counting(*args, **kwargs):
        _counting.calls += 1
        return fn(*args, **kwargs)
    _counting.calls = 0
    return _counting

@count_calls
def foo(x):
    return x

def bar(y):
    foo(y)
    foo(y)

bar(1)
print foo.calls

Answer 3

在您回复后 - 这是装饰工厂的一种方式...

import inspect

def make_decorators():
    # Mutable shared storage...
    caller_L = []
    callee_L = []
    called_count = [0]
    def caller_decorator(caller):
        caller_L.append(caller)
        def counting_caller(*args, **kwargs):
            # Returning result here separate from the count report in case
            # the result needs to be used...
            result = caller(*args, **kwargs)
            print callee_L[0].__name__, \
                   'was called', called_count[0], 'times'
            called_count[0] = 0
            return result
        return counting_caller

    def callee_decorator(callee):
        callee_L.append(callee)
        def counting_callee(*args, **kwargs):
            # Next two lines are an alternative to
            # sys._getframe(1).f_code.co_name mentioned by Ned...
            current_frame = inspect.currentframe()
            caller_name = inspect.getouterframes(current_frame)[1][3]
            if caller_name == caller_L[0].__name__:
                called_count[0] += 1
            return callee(*args, **kwargs)
        return counting_callee

    return caller_decorator, callee_decorator

caller_decorator, callee_decorator = make_decorators()

@callee_decorator
def foo(z):
    #do something
    return ' foo result'

@caller_decorator
def bar(x,y):
    # complicated algorithm/logic simulation...
    for i in xrange(x+y):
        foo(i)
    foobar = 'some result other than the call count that you might use'
    return foobar


bar(1,1)
bar(1,2)
bar(2,2)

这是输出（使用 Python 2.5.2 测试）：

foo was called 2 times
foo was called 3 times
foo was called 4 times