How do I call a function which I have defined within a class?

Question

Daniel Pollard 2020-11-27

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/665228-how-do-i-call-a-function-which-i-have-defined-within-a-class

回答： Steven Lord 2020-11-27

I'm trying to learn how to use classes in Matlab, having never used them in any language before, so apologies if this is a bit basic.

I have defined a class called car, with the properties of colour, type, serial number and speed, with a function to change the speed.

classdef car <handle
   properties
      colour
      type
      speed
   end 
   properties (SetAccess = private)
      SerialNumber
   end
   methods
       function faster(obj, v)
           obj.speed = obj.speed + v;
       end
   end
end

In another script I can type

car.colour = "red",

and when I disp(car), the class has the property colour with label "red". When I call faster(100) however, instead of setting car.speed=100, it throws the error

Check for missing argument or incorrect argument data type in call to function 'faster'.

I built the class and method using the same sort of code structure as in this question:

https://www.mathworks.com/matlabcentral/answers/395472-how-to-call-a-method-from-a-class-called-a-within-another-method-from-a

where the user seemed to not have the issue I do. I'm not sure where I'm going wrong - my function seems like it should work. Can anybody point me in the right direction?

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Answer 1

Daniel Pollard 2020-11-27

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https://ww2.mathworks.cn/matlabcentral/answers/665228-how-do-i-call-a-function-which-i-have-defined-within-a-class#answer_557863

This question has now been answered on Stack Overflow:

https://stackoverflow.com/questions/65038867/matlab-how-do-i-call-a-function-which-i-have-defined-within-a-class.

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Answer 2

Steven Lord 2020-11-27

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在 MATLAB Online 中打开

When you call a non-Static method of a class, at least one of the inputs to that method must be an instance of that class. With your car class's definition:

% Create a car
y = car
% Set its colour
y.colour = 'red'
% Set its initial speed
y.speed = 30
% Update the speed with the method
faster(y, 10)
% Alternately you could use
% y.faster(10)
% Display the updated object
y