Add description to `@mtkmodel`

[tpdsantos]

Question❓

I know you can add a description for every variable and parameter inside a model, but what about a description of the entire model? I know that a model created with @mtkbuild has a field description but how to I set a value for it?

[hersle]

Descriptions were added in #3132, but I don't think it's handled by the (special) @mtkmodel macro yet. You can do it without the macro:

using ModelingToolkit
using ModelingToolkit: t_nounits as t, D_nounits as D
@variables x(t)
@named sys = ODESystem([D(x) ~ 0], t; description = "A component with a constant variable")

Model sys: A component with a constant variable
Equations (1):
  1 standard: see equations(sys)
Unknowns (1): see unknowns(sys)
  x(t)

[tpdsantos]

I see... I already have several models written using @mtkmodel and I probably won't change it just to add a description in that way... Is there a way to add a docstring for a model? Some text that could would be shown when running ?sys?

[tpdsantos]

Never mind, just found out. I'll close this question.

[hersle]

Ok. Just a quick suggestion from me would be to hack it for now (until @mtkmodel supports @description) with e.g.

using ModelingToolkit
using ModelingToolkit: t_nounits as t, D_nounits as D

@mtkmodel FOL begin
    @parameters begin
        τ = 3.0 # parameters
    end
    @variables begin
        x(t) = 0.0 # dependent variables
    end
    @equations begin
        D(x) ~ (1 - x) / τ
    end
end
@mtkbuild fol = FOL()

using Setfield
@set! fol.description = "This is a description of the system"

Model fol: This is a description of the system
Equations (1):
  1 standard: see equations(fol)
Unknowns (1): see unknowns(fol)
  x(t) [defaults to 0.0]
Parameters (1): see parameters(fol)
  τ [defaults to 3.0]

It's far from perfect, but it works.

[baggepinnen]

Let's keep this issue open until @mtkmodel supports adding descriptions :)