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@wrapt 使用装饰器进行条件猴子修补

Wrapt有两个特点

  • 装饰师的最佳实践
  • 猴子补丁

我这样做是为了能够有条件地更改调用的方法。我提供了一个基于 pandas 版本的示例。虽然这可行，但我使用了准系统猴子补丁，而不是使用 wrapt 功能。如何使用 wrapt 来修补替代方法？

import pandas as pd
import wrapt, inspect
from distutils.version import StrictVersion
def alt_impl(alt_fn, cond):
    @wrapt.decorator
    def wrapper(wrapped, instance, args, kwargs):
        nonlocal alt_fn
        if cond():
            # @staticmethod and @classmethod need to navigate to actual function
            if not inspect.isfunction(alt_fn):
                alt_fn = alt_fn.__func__
            # class instance methods need to be bound to class instance
            if instance is not None:
                alt_fn = alt_fn.__get__(instance, instance.__class__)
            return alt_fn(*args, **kwargs)
        else:
            return wrapped(*args, **kwargs)
    return wrapper

示例用法

class alt_impl_example():
    def upgraded_pandas(self, args):
        print(f"upgraded {pd.__version__}") 

    @alt_impl(upgraded_pandas, lambda: StrictVersion(pd.__version__) >= StrictVersion("1.0.0")) 
    def pandas(self, args): 
        print(pd.__version__) 

t = alt_impl_example()
t.pandas({})
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