create_external_param!

[davidanthoff]

See discussion here.

@ckingdon95 rightly pointed out that this is less of a problem with models that are packaged as composite components. I still think, though, that there is a valid use case for this kind of pattern when folks are not using composite components. I think we should just support both cases.

Is the existing, private function set_external_param! essentially what we are talking about already?

I guess one question is what function name would be good in this scenario.

[corakingdon]

yes, I think that the private set_external_param! function is what we are talking about. I think we will want to discuss any possible corner cases and make sure we write up a test file that has examples of when this would error etc. (what happens if you use this function, then try to call set_param! with the same parameter name, for example)

I think I like the name create_external_param! or maybe just create_param!

[davidanthoff]

Yes!

The error conditions I can think of right now would essentially be that whenever an external parameter already exists, and one tries to create it again, we error. So that would imply that if one calls create_param! twice with the same name, it errors. Given that set_param! internally would also call create_param!, calling any combination of these two that would end up creating parameters with the same name would also error, right? Beyond that I can't really think of anything right now...

Do we use the terminology of "external parameter" in the docs anywhere, or is that really a concept that we just use in the dev team? If the latter, then create_param! looks better to me as well. Essentially the story would simply be that set_param! is a shortcut for the create_param! & connect_param! combo.

[davidanthoff]

We could use set_param!(m, :name, value, auto_connect=false).