Case insensitive enumeration class

Question

Phillip 2016-9-19

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/303643-case-insensitive-enumeration-class

编辑： Sean de Wolski 2016-9-20

采纳的回答： Brendan Hamm

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Hi,

How does one create a case insensitive enumeration class?

So that one could call it as:

aRed = colourEnum.RED;
aRed = colourEnum.red;
aRed = colourEnum.ReD;

I would also like to confirm that enumerations must follow variable naming conventions. Ie you can't have an enum that is:

enumclass.A/B

Am I right in this?

Regards, Phillip

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Answer 1

Brendan Hamm 2016-9-19

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Why would you want to have your enumeration be able to have any case?

The only place I could consider this, is if the user has to specify the string via some form of text input e.g. an inputdlg. If this is the case, then you should simply do a case insensitive string validation and with this result dynamically create your object:

val = validatestring('red',{'Red'})  
aRed = colourEnum.(val)

Other than this, the MATLAB command prompt will alert the user of the correct case of the characters involved.

Yes. Enumerations must conform to the MATLAB variable naming convention.

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Phillip 2016-9-19

Hi Brendan

I hear you and I think you are right (need to give it some thought). The enumeration is unique in itself and should be treated as such. The only problem I have is that I need to code that validation outside of the enumeration object, where somehow naturally i wanted to do it within the object (so that the object handles it). Ie RED is ReD is red and it should be able to accept that.

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Answer 2

Sean de Wolski 2016-9-19

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You could use a containers.Map to use non-MATLAB variable names if you want:

mapper = containers.Map('enumclass.A/B','A')
mapper('enumclass.A/B')

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Sean de Wolski 2016-9-20

编辑：Sean de Wolski 2016-9-20

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Hi Phillip,

What I was suggesting won't work the way you have it above. For best looks, what you're doing is probably best. I was thinking more like a factory function to generate the enumerations given any key. disp can be overloaded to make it look right. This is probably not a good idea, but it is possible.

e = genEnum('Hello World')
e = 
Hello World

Function

function enumObj = genEnum(key)
mapper = containers.Map({'enumclass.A/B','Hello World'},{'A','B'});
enum = mapper(key);
enumObj = EnumClass.(enum);
end

And

classdef EnumClass
  enumeration
      A
      B
  end
  methods
      function disp(obj)
          mapper = containers.Map({'A','B'},{'enumclass.A/B','Hello World'});
          label = mapper(char(obj));
          disp(label)
      end
  end
end