How do we find the input arguments required by a handle class constructor?

Question

Vignesh Ramakrishnan 2019-9-20

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https://ww2.mathworks.cn/matlabcentral/answers/481320-how-do-we-find-the-input-arguments-required-by-a-handle-class-constructor

回答： Guillaume 2019-9-21

采纳的回答： Guillaume

I am getting an error " too many input arguments"

So I wished to match my input arguments with the constructor arguments

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Adam 2019-9-20

They are listed in the function definition of the constructor, or if there is no defined constructor then it takes 0 arguments. Since you haven't shown any class definition code or calling code it's hard to say much more though.

Vignesh Ramakrishnan 2019-9-21

Thanks Adam. I am actually working on fixing some legacy code by my employer, so I cannot share the source code. Also, the information of 0 arguments considered by the default constructor was helpful, as I realized that the class involved had no user defined constructors.

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Answer 1

Guillaume 2019-9-21

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在 MATLAB Online 中打开

It sounds like the problem has already been resolved and as Adam said, the easiest is to look at the function definition.

If, for some reason, that's not possible, you can use the methods function (for display at the command line) with the -'full' option, or the methodsview function (for display in a separate window) to see the list of all the methods of the class and their inputs and outputs.

methods('classname', '-full')
%or
methodsview('classname')

If even more details are needed, you can also use introspection classes such as meta.class and meta.method.

%demo for class string
>> mc = meta.class.fromName('string');
>> mm = mc.MethodList(strcmp({mc.MethodList.Name}, 'string'))  %find constructor in method list and display properties
mm = 
  method with properties:
                   Name: 'string'
            Description: ''
    DetailedDescription: ''
                 Access: 'public'
                 Static: 0
               Abstract: 0
                 Sealed: 0
     ExplicitConversion: 0
                 Hidden: 1
             InputNames: {'rhs1'}
            OutputNames: {'lhs1'}
          DefiningClass: [1×1 meta.class]