为 Python 中的 function 传递相同的参数名称

Question

In python, I have a class with functions printing certain outputs, of which each has default parameters but those can be changed, like

def func1(self,a='a', b='b'):
    return something

def func2(self,c='c', d='d'):
    return something 

Lots of other functions of a similar kind too.

I created another function that can take those functions with parameters and can do something with them, ie

def foo(self, default,*args,**kwargs):
    df=self.df
    if default == True:
        args = self.list1
    else:
        for fname in args:
            getattr(self, fname)(*kwargs)
            df['appending_array'] = df.apply(lambda...

In the effect I'd like to be able to call something like object.foo(False, func2,func11,d='z') Unfortunately in the loop, when I change d to 'z', it changes the first argument of each function that is iterated, instead of the actual parameter d from the function I want.

Is there a possibility to either rearrange it so I can pass the original parameters of each passed function, or configure **kwarg so it can refer to the original parameters' names of each function?

Many thanks for any help/advice

Answer 1

You need to unpack the kwargs with dictionary unpacking using two stars:

getattr(self, fname)(**kwargs)

And I think you also need to provide self as the first argument since these are unbound methods:

getattr(self, fname)(self,**kwargs)

Answer 2

So, if I understand correctly, you want to write it such that if, for example, d is present in the foo call, it is solely passed to all functions in args that have d as an input argument (in this case, func2 )?

If so, then you want to determine all input arguments that each function can take. Luckily, Python has a function that allows you to do just that: inspect.signature .

So, you could rewrite it like this (I am assuming you wanted to pass the names of the functions as args , not the actual functions themselves):

from inspect import signature

def foo(self, default, *args, **kwargs):
    df=self.df

    if default:
        args = self.list1
    else:
        for fname in args:
            # Obtain function
            func = getattr(self, fname)

            # Obtain signature of this function
            f_sig = signature(func)

            # Create dict with values for this function, updating with values from kwargs
            # Make sure to skip 'self'
            f_kwargs = {argname: kwargs.get(argname, argpar.default)
                        for argname, argpar in f_sig.parameters.items()
                        if (argname != 'self')}

            # Call this function
            f_out = func(**f_kwargs)

            # Perform some operations on the output of this function
            df['appending_array'] = df.apply(lambda...

Keep in mind that this only works if every function that is ever passed as args solely takes optional arguments. If one argument is mandatory, it must be passed to kwargs .

PS: I am however unsure what the use of the args = self.list1 for if default is. Because that part is incompatible with everything else.