How to dynamically choose between two methods with parameters using a property in Python

Question

I have a Python class that needs to dynamically choose between two methods based on a condition. Both methods take parameters. I want to use a property to determine which method to call. How can I achieve this?

class MyClass:
    def __init__(self, condition):
        self.condition = condition

    def _method_1(self, param1, param2):
        # Implementation for the first add_way method
        print(f"_method_1 called with {param1} and {param2}")

    def _method_2(self, param1, param2):
        # Implementation for the second add_way method
        print(f"_method_2 called with {param1} and {param2}")

    @property
    def method(self):
        # How to return the correct method based on self.condition?
        pass

# Example usage:
manager = WayManager(condition=True)
manager.method('value1', 'value2')  # Should call _method_1 with 'value1' and 'value2'

manager.condition = False
manager.method('value3', 'value4')  # Should call _method_2 with 'value3' and 'value4'

How can I implement the method property to achieve this behavior?

AKX · Accepted Answer · 2024-12-11 12:38:28Z

2

Simply return the correct method from your method property. (It will be bound to the same self instance automatically, so you don't need to worry about anything like that.)

class MyClass:
    def __init__(self, condition):
        self.condition = condition

    def _method_1(self, param1, param2):
        print(f"{self}._method_1 called with {param1=} and {param2=}")

    def _method_2(self, param1, param2):
        print(f"{self}._method_2 called with {param1=} and {param2=}")

    @property
    def method(self):
        return self._method_1 if self.condition else self._method_2


manager = MyClass(condition=True)
manager.method("value1", "value2")
manager.condition = False
manager.method("value3", "value4")

prints out

<__main__.MyClass object at 0x1031c91f0>._method_1 called with param1='value1' and param2='value2'
<__main__.MyClass object at 0x1031c91f0>._method_2 called with param1='value3' and param2='value4'

answered Dec 11, 2024 at 12:38

AKX

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1 Comment

Mikhail Goussarov Dec 11, 2024 at 12:57

Ah, very nice. Thank you for the very quick answer!

Allprod · Accepted Answer · 2024-12-11 13:03:00Z

Your mistake is thinking that the method is the property.

What you should do is just change the method function to check what the value of condition is and run the appropriate function.

If you truly do need to watch for changes in the condition, you could do so as follows:

class MyClass:
    def __init__(self, condition):
        self.condition(condition)

    def _method_1(self, param1, param2):
        # Implementation for the first add_way method
        print(f"_method_1 called with {param1} and {param2}")

    def _method_2(self, param1, param2):
        # Implementation for the second add_way method
        print(f"_method_2 called with {param1} and {param2}")
    
    @property
    def condition(self):
        return self._condition

    @condition.setter
    def condition(self, new_condition):
        self._value = new_value
       
    def method(self, param1, param2):
        method1(param1,param2) if condition else method2(param1,param2)

Though I do not see the benefit of doing so unless you need to do something special on every value change. Other wise the following solution without any properties is more apt for the problem:

class MyClass:
    def __init__(self, condition):
        self.condition = condition

    def _method_1(self, param1, param2):
        # Implementation for the first add_way method
        print(f"_method_1 called with {param1} and {param2}")

    def _method_2(self, param1, param2):
        # Implementation for the second add_way method
        print(f"_method_2 called with {param1} and {param2}")

    def method(self, param1, param2):
        method1(param1,param2) if condition else method2(param1,param2)

tldr: pass the parameters to method, and call method1 if condition is true else call method2.

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