Extending the behavior of an inherited function in Python

Question

Let's say we have the following classes:

class Base(object):

    def load(self):
        # do logic A

        # do logic B

class Child(Base):

    def load(self):
        # do logic C

I know decorators can be used to extend function behavior in Python but I don't know how I can apply it in my case. When Child's load() is called, how can I get the following code executions in this order?:

logic A

logic C

logic B

What I don't want to do

class Base(object)

    def logicA()
       pass

    def logicB()
       pass

    def load()
       pass

class Child(Base):

    def load(self):
        super.logicA()

        # do logic C

        super.logicB()

I just want to code up logic C, without having to explicitly call logic A and B

Solution

You mean something like this:

class Base(object):

    def load(self):
        print('do logic A')
        print('do logic B')


class Child(Base):

    def load(self):
        super().load()
        print('do logic C')


c = Child()
c.load()   

This will print:

do logic A
do logic B
do logic C

The only other way I can think of is this one:

class Base(object):

    def load(self):
        print('do logic A')
        self.new_logic() # call new logic from child class, if exist.
        print('do logic B')

    def new_logic(self):
        # overwrite this one in child class 
        pass


class Child(Base):

    def new_logic(self):
        print('do logic C')


c = Child()
c.load()   

This prints:

do logic A
do logic C
do logic B

Comments

[thefourtheye]

Split logic A and B in to two different functions?

[lambda]

Close, but I am aiming for logic C to be called before B

[lambda]

But the thing is, I don't want to explicitly be calling logic A or B...logic C is basically just an extension of the Base load()

[Paul Rooney]

@Unit978 You are saying you want the child function to execute in the middle of the base classes function ?

[Paul Rooney]

Maybe pass a function to perform logic C to the base class function and call it in between logic A and Logic B?

[lambda]

The thing is, I don't want to explicitly call anything from the Base class.

[Marcin]

@Unit978 I amended the answer with other possibility.