在父类中检查子级不同的参数（不同数量的参数）是否为负？

Question

Let's suppose we have this parent class:

class Parent:
    def __init__(self):
        pass      

And these two children:

class Child1(Parent):
    def __init__(self, 1stparam):
        pass

class Child2(Parent):
    def __init__(self, 1stparam, 2ndparam):
        pass   

I would like a method for class Parent to check if the arguments passed are negative. For example:

class Parent:
    def __init__(self):
        pass   

    def check_data( allparameters ):
        if allparameters <0:
            return false

I would like to check_data for all childs by inheriting this method, for example:

mychild1 child1(-1)
mychild2 child2(1, -1)
[mychild1.check_data(), mychild2.check_data()]

This should return, of course, [False, False] .

Answer 1

You need function with *args . Sample example:

def check_negative(*args):
    for item in args:
        if item < 0:
            return False
    else:
        return True

Sample run:

>>> check_negative(1)
True
>>> check_negative(-1)
False
>>> check_negative(1, 1)
True
>>> check_negative(1, -1)
False
>>> check_negative(-1, -1)
False

For more details, read: What do *args and **kwargs mean?

Answer 2

You could do something like this:

class Parent(object):
    def __init__(self):
        self.data = []

    def check_data(self):
        return all(map(lambda arg: arg >= 0, self.data))


class Child1(Parent):
    def __init__(self, param_1):
        self.data = [param_1]


class Child2(Parent):
    def __init__(self, param_1, param_2):
        self.data = [param_1, param_2]


print(Child1(1).check_data())  # True
print(Child1(-1).check_data())  # False
print(Child2(1, 1).check_data())  # True
print(Child2(1, -1).check_data())  # False
print(Child2(-1, 1).check_data())  # False
print(Child2(-1, -1).check_data())  # False

• The map function applies a function on each element of an iterable an returns the results in a iterable.
• The lambda function returns False when provided with a negative number.
• The all function returns True if all elements in the given list are True.