Hide Enumeration Members

Hiding enumeration members enables class authors to change enumeration member names without causing incompatibilities in existing code. To hide members, create an enumeration block that sets the Hidden attribute. Members defined in a Hidden enumeration block are not visible when enumeration members are queried using the enumeration function.

When an enumeration class derives from another class, such as a numeric or logical class, then each member can have a value associated with it. If two members have the same value assigned to them, then the member defined first in the class definition masks the second member. Both names are valid enumeration members, but the first one defined is the primary member. While masking makes it possible to use one member name in place of another, it does not hide the secondary name from the class users.

Using the Hidden attribute removes the masked member names from user view. For example, the HighlightColor class defines enumeration members that represent syntax highlighting colors.

classdef HighlightColor < int32
    enumeration
        red   (1)
        green (2)
        blue  (3)
    end
end

A new version of the class uses more descriptive member names, but the class needs to avoid breaking existing code that uses the original member names, red, green, and blue. Using the Hidden attribute for enumeration members enables the class to hide the original members.

classdef HighlightColor < int32
    enumeration
        error   (1)
        comment (2)
        keyword (3)
    end
    enumeration (Hidden)
        red   (1)
        green (2)
        blue  (3)
    end
end

Code that uses the original member names continues to work. For example, existing references to the now-hidden member HighlightColor.blue is compatible with the same-valued nonhidden member HighlightColor.keyword.

a = HighlightColor.blue

a = 

  HighlightColor enumeration

    keyword

a == HighlightColor.Keyword

ans =

  logical

   1

For enumeration members that represent values, the first member defined in the class is the primary member for that value. For example, in the HighlightColor class, keyword is the primary member and blue is the secondary member, both representing the value 3. Typically, the primary member is not hidden while the secondary member is hidden. However, if the class design requires that the primary member is hidden, then the secondary member must be hidden too.

classdef PCComponents
    enumeration
        USBSlots
        CDPlayer
    end
    enumeration (Hidden)
        FloppyDrive
    end
end

mc =?HighlightColor

mc = 

  Class with properties:

                     Name: 'HighlightColor'
              Description: ''
      DetailedDescription: ''
                   Hidden: 0
                   Sealed: 0
                 Abstract: 0
              Enumeration: 1
          ConstructOnLoad: 0
         HandleCompatible: 0
          InferiorClasses: [1×1 matlab.metadata.Class]
                Namespace: [0×0 matlab.metadata.Namespace]
                  Aliases: [0×1 string]
     RestrictsSubclassing: 0
             PropertyList: [0×1 matlab.metadata.Property]
               MethodList: [145×1 matlab.metadata.Method]
                EventList: [0×1 matlab.metadata.Event]
    EnumerationMemberList: [6×1 matlab.metadata.EnumerationMember]
           SuperclassList: [1×1 matlab.metadata.Class]]

mc.EnumerationMemberList(4)

ans = 

  EnumeratedValue with properties:

                   Name: 'red'
            Description: ''
    DetailedDescription: ''
                 Hidden: 1

 findobj(mc.EnumerationMemberList,'Hidden',true).Name

ans =

    'red'


ans =

    'green'


ans =

    'blue'

See Also

findobj | enumeration