How can I call same class twice using super() in other class?

Question

I got class Z which has 5 attributes:

ID
actual x
actual y
future x
future y

actual x and actual y I can replace using Position class(using class inheritance). The problem is that I want to replace future position using same method. How can I do it to avoid namespace conflict? Do I really need to create new Position class with slightly changed namespace ?

I know I can do (but i dont like this solution):

class Position: def __init__(self,x , y): self.x = x self.y = y class Position2: def __init__(self,x , y): self.fx = x self.fy = y class Z(Position,Position2): def __init__(self, x, y, f_x, f_y, Id): super().__init__(x, y) super().__init__(f_x,f_y) self.Id = Id

actual code:

class Position: def __init__(self,x , y): self.x = x self.y = y class Z(Position): def __init__(self, x, y, f_x, f_y, Id): super().__init__(x, y) self.Id = Id

I would like to get something like:

class Position: def __init__(self,x , y): self.x = x self.y = y class Z(Position): def __init__(self, x, y, f_x, f_y, Id): super().__init__(x, y) super().__init__(f_x, f_y) self.Id = Id

that I could easy print actual and future parameters.

What is Z? Is it a thing with two positions? or a Position with two positions? — wwii
– wwii, Commented Aug 2, 2019 at 23:24
why are you even trying to use inheritance here? Just use composition — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Aug 3, 2019 at 0:14

Mad Physicist · Accepted Answer · 2019-08-02 23:10:13Z

It looks like you are looking for composition rather than inheritance. Position is a concept. You have a class that references two positions:

class Position: def __init__(self, x, y): self.x = x self.y = y class Z: def __init__(self, x, y, fx, fy, id): self.p = Position(x, y) self.fp = Position(fx, fy) self.id = id

You should only inherit from Position if you want Z to have access to the behavior of Position. If that were the case, you could either define fx and fy as attributes of Z, or use composition as before:

class Z(Position): def __init__(self, x, y, fx, fx, id): super.__init__(x, y) self.fx = fx self.fy = fy self.id = id

Or

class Z(Position): def __init__(self, x, y, fx, fx, id): super.__init__(x, y) self.fp = Position(fx, fy) self.id = id

By the way, if your Position class is really just a simple container, consider using collections.namedtuple to hold the values. For example:

Position = namedtuple('Position', ['x', 'y'])

This version of Position inherits from the built in tuple, so it is much more efficient at storing values.

Sarath Padakandla · Accepted Answer · 2019-08-02 22:59:39Z

0

why not list in Position constructor,

class Position: def __init__(self,x , y): self.x_lst.append(x) self.y_lst.append(y) class Z(Position): def __init__(self, x, y, f_x, f_y, Id): super().__init__(x, y) super().__init__(f_x, f_y) self.Id = Id

x_lst and y_lst are lists. Not sure if this idea works for you.

answered Aug 2, 2019 at 22:59

Sarath Padakandla

202 bronze badges

3 Comments

Mad Physicist Over a year ago

You'll get an AttributeError if you try to run this. x_lst and y_lst need to be defined.

snamef Over a year ago

second init accesses the same class, he has mult inheritence here

Mad Physicist Over a year ago

@snamef. Multiple inheritance is when your class inserts from two classes. This only inherits from one. __init__ is just a regular method in this context, and you can call it as often as you want. The second call just overwrites the attributes set by the first one.

snamef · Accepted Answer · 2019-08-02 23:19:22Z

You can also call Type.init(self,args) for a parent class init

class First(object): def __init__(self, x): print ("First(): entering") self. x = x print ("First(): exiting") class Second(object): def __init__(self , y ): print ("Second(): entering") self. y = y print ("Second(): exiting") class Third(First, Second): def __init__(self,x,y): print ("Third(): entering") First.__init__(self,x) Second.__init__(self,y) #super(Third, self).__init__(x,y) print ("Third(): exiting") def __repr__(self): return f'{self.x} { self.y}' a = Third(10,20) print(a)

OP has a solution with three classes but stated they did not want the third class.
This is a correct solution (excerpt the indentation), but does not capture the concept of OP's intent.

Collectives™ on Stack Overflow

How can I call same class twice using super() in other class?

3 Answers 3

Comments

3 Comments

2 Comments

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

3 Comments

2 Comments

Related