progress(simulation) is not always called during run!

[glwagner]

This line:

https://github.com/climate-machine/Oceananigans.jl/blob/6502f078c8f7698a2fb6cd398d9e96cfacccc787/src/Simulations.jl#L166

prevents the method progress(simulation) from being called if progress is not a subtype of the abstract type Function.

This makes using callable objects for progress more complicated (at least, these callable objects would have to subtype Function, which seems like an arbitrary requirement for such objects).

What is the reasoning behind requiring progress to subtype Function (and furthermore enforcing this with an if-statement)? If progress does not subtype function, the keyword argument is unused (despite the desperate efforts of flailing users, such as myself).

Callable objects are nice for progress. For example, a callable object is a good way to keep track of wall time, make plots, automatically format strings containing diagnostics information, or otherwise reference objects outside simulation for the purposes of logging.

[ali-ramadhan]

Isn't this a duplicate of #642?

I agree that callable objects should work. I think the solution we discussed in #642 should work:

iscallable(sim.progress) && sim.progress(sim) 

[glwagner]

Yep, dup of #642 (more or less)