Object type: examples with methods saveobj(), loadobj(), delete()

General usage
1

Hello,

about object variables saving and loading, is there a few example how to implement saveobj(), loadobj() and delete() overloading function in classdefobject ? Currently there’s neither example nor details in the documentation.

Especially, the sentence about saveobj() is a bit obscure:

  • You have to return a native scilab variable (struct, list, …) except objects that contains all data you want to save.

thank you

David

2

Hello David,

The idea is to save only the properties (since the methods are in the classdef definition).

Here is a concise example:

classdef demosave
    properties
        a
        b
    end

    methods
        function demosave(a,b)
            this.a = a;
            this.b = b;
        end

        function st = saveobj()
            disp("save properties");
            st.a = this.a;
            st.b = this.b;
        end

        function loadobj(st)
            disp("reload properties")
            this.a = st.a;
            this.b = st.b;
        end

        function delete()
            disp("demosave destructor");
        end
    end
end

a = demosave(12, "test");
save("TMPDIR/save.sod", "a");
clear a; //call delete
load("TMPDIR/save.sod");
a

BUT, while writing this message, I noticed there’s a bug in loadobj: the data we receive (st in my example) doesn’t contain the struct but this instead.
I reported the issue (#17513)

Best regards,
Antoine

1 Like
3

Thank you Antoine, clear now !

Out of curiosity, is really needed the destructor since Scilab is not complaining when I perform a clear while there was an object variable in the memory stack ?

Maybe good to include in demo a case or a note about when it makes sense to perform special action when removing the object instance (link with a third party code for instance ?).

Thank you

David

4

Absolutely — use cases for a destructor will be very rare.
It might be used to release a hardware resource or close a connection, that kind of thing.
But as long as you only use standard Scilab variables, you’ll probably never need one.
Matrices, structs, lists, … will be deleted automatically when the instance is destroyed.