MATLAB's flexible nature is very convenient in most situations. However, this flexibility can also be the cause of hard-to-find bugs.
In many cases, it is desirable to have a data type which is CONST. That is, a datatype which cannot be changed after the first assignment. MATLAB has seen heavy criticism due to its lack of a CONST data type. Although the basic functionality of CONST variables can be achieved through a class with constant properties, that approach leaves much to be desired.

That is where this file comes in. It implements all the functionality of a basic, scalar MATLAB structure, but after a field has been added and assigned a value, that field can no longer be changed.

That means, it strikes a middle ground by offering the flexibility of adding fields dynamically, but disallowing *changing* of fields values.

A simple example session:

C = const; % empty const
C.myField = 'test'; % first assignment; OK
C.myField = 4; % ERROR!

Much more is possible; have a look at the function documentation inside const.m for more information.