我正在尝试创建一个函数装饰器,该函数装饰器将指定值的函数参数记录在可访问的python对象中。我已经可以使用代码了,但是我缺少完成这一工作的一部分。
首先,我有对象日志,可以在其中正确保存内容:
class Borg:
_shared_state = {}
def __init__(self):
self.__dict__ = self._shared_state
class Log(Borg):
def __init__(self):
Borg.__init__(self)
if not hasattr(self, 'tape'):
self.tape = []
def add(self, this):
self.tape.append(this)
def __str__(self):
return '\n'.join([str(line) for line in self.tape])
然后我有一个通用调用对象和装饰器实现(缺少代码):
import inspect
import functools
class Call:
def __init__(self, name, **saved_arguments):
self.name = name
self.saved_arguments = saved_arguments
def __str__(self):
return f'Call(name={self.name}, saved_arguments={self.saved_arguments})'
def record(func, save_args_names=None):
if save_args_names is None:
save_args_names = {}
name = func.__name__
args = inspect.getfullargspec(func).args
if save_args_names and not set(save_args_names).issubset(set(args)):
raise ValueError(f'Arguments not present in function: {set(save_args_names) - set(args)}')
log = Log()
@functools.wraps(func)
def wrapper(*func_args, **func_kwargs):
# **here** I am missing something to replace 0 with the correct values!
saved_arguments = {a: 0 for a in save_args_names}
log.add(Call(name, **saved_arguments))
return_value = func(*func_args, **func_kwargs)
return return_value
return wrapper
要对此进行测试,我设置了以下功能:
def inner(x, add=0):
return sum(x) + add
def outer(number, add=0):
x = range(number)
return inner(x, add)
和基本用例(不保存参数)有效:
inner = record(inner)
print(outer(1), outer(2), outer(3))
print(Log())
它正确输出:
0 1 3
Call(name=inner, saved_arguments={})
Call(name=inner, saved_arguments={})
Call(name=inner, saved_arguments={})
我所缺少的是使用此案例的一种方式:
inner = record(inner, save_args_names=['x'])
print(outer(1), outer(2), outer(3))
print(Log())
输出:
0 1 3
Call(name=inner, saved_arguments={'x': range(0, 1)})
Call(name=inner, saved_arguments={'x': range(0, 2)})
Call(name=inner, saved_arguments={'x': range(0, 3)})
这也应适用于关键字参数,例如:
inner = record(inner, save_args_names=['x', 'add'])
print(outer(1, 2), outer(2, 3), outer(3, 4))
print(Log())
应输出:
2 4 7
Call(name=inner, saved_arguments={'x': range(0, 1), 'add': 2})
Call(name=inner, saved_arguments={'x': range(0, 2), 'add': 3})
Call(name=inner, saved_arguments={'x': range(0, 3), 'add': 4})
我觉得我已经很接近了,inspect
库应该可以帮助我解决这个问题,但是一点帮助将不胜感激!
答案 0 :(得分:2)
您要寻找的功能是Signature.bind
。像这样定义您的wrapper
函数:
@functools.wraps(func)
def wrapper(*func_args, **func_kwargs):
signature = inspect.signature(func)
bound_args = signature.bind(*func_args, **func_kwargs)
saved_arguments = {a: bound_args.arguments[a] for a in save_args_names}
log.add(Call(name, **saved_arguments))
return_value = func(*func_args, **func_kwargs)
return return_value