Is create a instance inside another class possible?

Question

chen cui 2021-8-10

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/895447-is-create-a-instance-inside-another-class-possible

回答： Yongjian Feng 2021-8-11

I wonder if a function in a class could create another class?

For example, surposing that there is a Point class, and a Vector class, i translate the properties Point.x, Point.y, Point.z in a Point instance with vector.x, vector.y, vector.z. The translate fuction creates a new Point instance instead of change the origin Point instance.

In python, i wrote like this,

class Point:

def __init__(self,x,y,z):

self.x,self.y,self.z = x, y, z

def translate(self,vector):

return Point(self.x+vector.x,self.y+vector.y,+self.z+vector.z)

or create another instance from the class

class Vector:

pass

class Point:

def __init__(self,x,y,z):

self.x,self.y,self.z = x, y, z

def vec(self):

return Vector(self.x,self.y,self.z)

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Answer 1

Yongjian Feng 2021-8-11

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/895447-is-create-a-instance-inside-another-class-possible#answer_764817

在 MATLAB Online 中打开

Yes, it is doable:

classdef Apoint < handle
    properties (Access=public)
        x
        y
    end
    methods
        function ap = Apoint(x, y)
            ap.x = x;
            ap.y = y;
        end
        function np = translate(obj, x, y)
            np = Apoint(obj.x + x, obj.y + y);
        end
    end
end

Then

>> p = Apoint(10, 10)
p = 
  Apoint with properties:
    x: 10
    y: 10
>> np = p.translate(5, 5)
np = 
  Apoint with properties:
    x: 15
    y: 15
>> 