"successor" and "predecessor" functions for enumerated types

When working with enumerated types it is sometimes necessary to access the preceding enumerated value or the next enumerated value. There are no built-in methods for this so has anybody come up with user built methods? An example is the StateMate function enum_succ(in_value) that returns the enumerated value which is the successor to the in_value enumerated value

[Walter Roberson]

Would this be about... ummm, StateFlow at a guess?

Or about enumerated types for code generated from a Simulink model?

[Jim Johnson]

Yes indirectly about StateFlow, but specifically about embedded matlab functions EML in a StateFlow diagram. So if I can get a function that works in Matlab, chances are I can make the EML function work.

[Walter Roberson]

MATLAB itself does not offer any enumerated types (but such things could be defined by way of an OOP class, I suppose.)

Answer 1

[Andrew Newell]

You could make a linked list with an enumerated class as one of its properties. See Example — Implementing Linked Lists and How to Define Enumerated Data in a Stateflow Chart.

Answer 2

[Walter Roberson]

It appears to me that you could add your own methods to the enumeration; you are defining a class and there is not obvious barrier against it. See http://www.mathworks.com/help/toolbox/simulink/ug/brscgt1-1.html#brsebyf-1

The enumerations are described as not needing to be consecutive or even ordered, so there is no inherent succ() or pred() ordering (e.g., next higher or next lower integer value.) Might drive you to a switch statement that listed each case. Or if you could store a private array, list the values in order in a private array, then when called, find() the current value in the list and extract the next or previous as appropriate.