Re-use handles if model is closed and re-opened

This is in Matlab 2019b.

I have a function to read/calculate signal information from a Simulink model (model1.slx) and produce a list of matching signal handles. This function is quite time-consuming, so I save the output of signal handles to a table in a MAT file. The next time, I want to just read these handles from the MAT file rather than recalculate.

All of this works, except the signal handles are shown as invalid/deleted when I close model1.slx and re-open it. Nothing has changed in the model, but the handles are no longer valid. I have compared them one-by-one and the handle numbers are exactly the same before and after.

Is there any way to keep object handles 'persistent' for re-use when a model is closed and re-opened or across multiple sessions of Matlab? Any other suggestions to achieve this without having to re-compute each time would be greatly appreciated.

TIA

Joe

[Rik]

What you ask for may be fundamentally impossible.

If you have a handle to figure 1, then close figure 1, then open a new figure 1. Should the original handle still work? It is a new object that happens to have the same name, which is why it doesn't.

I hardly ever work with Simulink, but if you post the code you're using (or a rough sketch) I or someone else may be able to suggest something.

[Joe Rustan]

Thanks Rik. I'm not expecting the handles would work, but I would've thought the numeric identifiers of the handles would be the same so I could look them up between sessions. However, it turns these numeric identifiers are also different - sometimes just by a digit in the 3rd decimal place :) :) I was going to check the rounded-off integer but then realized sometimes even those can be different. Not sure the Mathworks logic to come up with these identifiers.

I can definitely do this with objects (in my case signal lines) that are named. I've decided to follow a different (and more cumbersome approach) of naming blank signals as Unnamed-1, Unnamed-2.... to get their handles between sessions.

Thanks again. Cheers!

[Walter Roberson]

The numbers you see are closely related to the old handle graphics numeric handles. Before handles got made into a class primarily in R2014b, the interface to the user was to represent them to the users as double precision numbers. The same double precision representation was used for Simulink objects.

The double precision representation for handles is still available internally. You can double() a handle to see the number and you can handle() a number to get the handle object it is associated with. You can still do things like figure(3) and that is treated like figure(handle(3))

The numbers you are seeing in Simulink are not random... they are equivalent to pointers. Items tend to get allocated different locations in memory when they are recreated.