使用Python装饰器跟踪递归深度 [英] Tracking recursion depth with Python decorators
问题描述
我正在尝试编写一个装饰器,以跟踪Python中递归函数的递归深度.
I am trying to write a decorator that tracks the recursion depth of a recursive function in Python.
例如,使用
def fib(n):
if n == 0:
return 0
if n == 1:
return 1
else:
return fib(n-1) + fib(n-2)
通常,要跟踪递归深度,您可以编写如下内容
Usually, to track recursion depth you could write something like so
def fib(n, level=0):
print(level)
if n == 0:
return 0
if n == 1:
return 1
else:
return fib(n-1, level=level+1) + fib(n-2, level=level+1)
但是,在与装饰者摆弄了一段时间并进行了很多搜索之后,我不确定这是否有可能.
However, after fiddling around with decorators for a while and a lot of googling, I'm not sure this is even possible.
我尝试过类似的事情
def visualise(func):
def modify(*args, **kwargs):
kwargs["count"] += 1
print(kwargs["count"])
return func(*args, **kwargs)
return modify
@visualise
def fib(n):
...
fib(4, count=0)
但是它抱怨 count
是一个意外的关键字参数,我不太理解,因为我印象是包装器 modify
替换了所有出现的 fib
,但我猜不是吗?
But it complains that count
is an unexpected keyword argument, which I don't really understand because I was under the impression that the wrapper modify
replaces all occurrences of fib
but I guess not?
指针将不胜感激.
推荐答案
您可以为装饰器指定级别变量,然后在如下的函数调用中使用它:
You can specify level variable for decorator and then use it in function calls like this:
def visualise(func):
visualise.level = 0
def wrapper(*args, **kwargs):
print("In:", visualise.level)
visualise.level += 1
result = func(*args, **kwargs)
visualise.level -= 1
print("Out:", visualise.level)
return result
return wrapper
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