python - 访问子类中覆盖方法的签名

Question

在 python3.8.5 中，我正在使用一个superCl定义了方法的现有类f，以及多个现有的子类sub1， ......用不同数量的变量sub2覆盖。f基于如何通过向多个类添加相同的方法来创建新的子类，我想g通过超类向所有子类添加一个新函数。新函数应该调用f它并用它做事。问题是每个子类都有不同的签名f。我怎样才能解决这个问题？示例代码如下：

import numpy as np

class superCl(object): # Exists already
    def f(self, x): return x

class sub1(superCl): # Exists already
    def f(self, x, a, b): return x / (b - a)
        
class sub2(superCl): # Exists already
    def f(self, x, tau): return 1/tau * np.exp(-x/tau)
        
sc = superCl()
print(sc.f(0))

s1 = sub1()
print(s1.f(0, 1, 2))

s2 = sub2()
print(s2.f(0, 1))

def g(self, x1, x2, ...): # New, calls existing method.  Is there some way to get the signatures and values from the subclasses, eg self.args?
    print('Extra meth')
    self.f(x1, ...) - self.f(x2, ...) # How to adapt to proper arguments for f for each sublcass?

superCl.g = g # New method gets added to new and existing instances

print(sc.g(0, 1))
print(s1.g(0, 1, 1, 2))
print(s2.g(0, 1, 1))

编辑：超类定义了一组通用函数；子类是特殊情况，每个都有不同的变量。函数f返回子类参数的函数值；g我正在尝试创建的函数评估f两个不同点的差异。

标签： pythoninheritancesignature

Answer 1

看起来像使用*args或**kwds这样做（位置参数与关键字参数）：

import numpy as np

class superCl(object): # Exists already
    def f(self, x): return x

class sub1(superCl): # Exists already
    def f(self, x, a, b): return x / (b - a)
        
class sub2(superCl): # Exists already
    def f(self, x, tau): return 1/tau * np.exp(-x/tau)
        
sc = superCl()
print(sc.f(0))

s1 = sub1()
print(s1.f(0, 1, 2))

s2 = sub2()
print(s2.f(0, 1))

print('===========================================')
def g(self, x1, x2, *args): 
    print("args", *args)
    return self.f(x2, *args) - self.f(x1, *args)
superCl.g = g
print("--------------------\n"); print("sc", sc.f(1), '-', sc.f(0), "=", sc.g(0, 1))
print("--------------------\n"); print("s1", s1.f(1, 0, 4), '-', s1.f(0, 0, 4), "=", s1.g(0, 1, 0, 4))
print("--------------------\n"); print("s2", s2.f(1, 5), '-', s2.f(0, 5), "=", s2.g(0, 1, 5))

print('===========================================')
def h(self, x1, x2, **args): 
    print("args", args)
    return self.f(x2, **args) - self.f(x1, **args)
superCl.h = h
print("--------------------\n"); print("sc", sc.f(1), '-', sc.f(0), "=", sc.h(0, 1))
print("--------------------\n"); print("s1", s1.h(0, 1, a=0, b=4))
print("--------------------\n"); print("s2", s2.h(0, 1, tau=5))