There should be a single connection to the "outside"

[abelsiqueira]

The pipeline should be clearer.

We should have a single "final" function, i.e., the last function in the pipeline, that will call solve!. This solve! call should resolve to the specific solver definition, while all others should dispatch to internal calls.
Right now there are at least three places that call external functions:

• minimize in solve.jl
• solve! in solve-model.jl
• minimize in ipopt_solve.jl

To simplify argument passing, we should focus on a simpler pipeline. Something like

1. minimize(args...; kwargs...) # Maybe some variants
2. minimize(solver, nlp; kwargs...) with no variants
3. solve!(solver, nlp, ...) external call

Then internally, we can a new function _create_problem that dispatches on the arguments, instead of minimize.

Then we have function 1 to create nlp, call select_optimizers, define the solver, and call function 2.
Function 2 serves mainly to define our interface to call solve! (function 3).

Maybe we'll need an intermediary function.

[tmigot]

Ok, so minimize call _create_problem (if the argument is not an NLPModel) and then solve?
I like the idea.