Attaching custom data (string tag) to a MATLAB cfit object

Question

I have a code where cfit objects are passed back and forth between functions\classes and I would like to have a "tag" that contains some information about my fit (i.e. its name), such that I instantiate it at some point and can access it later whenever it's needed.

Ideally, this would be right inside the object, so that whenever I need to access the information, it's available without the need to drag around (or in appdata) additional vectors\cells.

Attempts & Thoughts

Normally, one would simply subclass cfit and add a property that contains this data. However, the declaration of cfit (see below) tells us that it is Sealed, and therefore cannot be subclassed.

classdef (Sealed = true) cfit < fittype

Alternatively, we could try to "hijack" some property that is not used by the current objects and use it to store the required data (not that it's a technical problem, but this is equivalent to ignoring the developers' warnings that these properties shouldn't be touched).

Moreover, from the above classdef we also learn that this is a subclass of fittype which may have some properties\methods we could use for this purpose.

Finally, the question remains - what is the best place to save my additional bit of data, so that it is both convenient to set\get (convenient means that if I want to access it inside a loop, I don't have to use eval()), and doesn't interfere with the normal operation of cfit objects?

Answer 1

One way that seems to work is by accessing the .p structure of a cfit object and adding whatever to it:

Before:

>> F378

F378 = 

     Shape-preserving (pchip) interpolant:
       F378(x) = piecewise polynomial computed from p
     Coefficients:
       p = coefficient structure

>> F378.p

ans = 

      form: 'pp'
    breaks: [1x40 double]
     coefs: [39x4 double]
    pieces: 39
     order: 4
       dim: 1

After F378.p.tag = '3.78';:

F378.p

ans = 

  form: 'pp'
breaks: [1x40 double]
 coefs: [39x4 double]
pieces: 39
 order: 4
   dim: 1
   tag: '3.78'

I found this from the following error:

Error using cfit/subsref (line 18)
The name 'probnames' is not a coefficient or a problem parameter. You can only use dot 
notation to access the coefficients and problem parameters of a cfit or sfit, for example 
'f.p'.

For the current object the properties you can access like this are:

p

Caution is advised: I did not test whether this solution interferes with normal operation.