John Siirola

These issues become moot if we only allow out-of-place transformations. If we start by cloning the (sub)block that we are transforming, that will break any external references to the Expression...

> Hi @blnicho and @jsiirola . Do you know how to resolve the following 'gams' not found issue? Yup: use `SolverFactory('gams').available(False)` (That is passing `exception_flag=False`, which suppresses the exception. In...

I am pretty sure it is not mathematically valid to have a scaling factor for an `Expression`. That said, I see a value in scaling the variables in the Expression...

I believe the other reason we removed named expressions was that we couldn't guarantee that there weren't other Constriaints / Objectives outside of the scope of the block that was...

(Looking back through older issues). I am very confused by this. I am not actually sure what version of Pyomo you are running. The `Component.__getstate__` definition was removed in 6.4.3...

Overall, I don't see a huge problem with supporting a library of useful external functions; however, some concerns with this implementation: - the `ampl_function_demo` module is really meant to be...

> I have a general question about this functionality: Would this even work with IPOPT currently, which is using the NL interface (via files) to communicate the problem? Yes. In...

@eslickj, we discussed this at yesterday's dev call. The consensus was that we should move this to a separate contrib package. The package could host multiple ASL external libraries, and...

`calculate_variable_from_constraint` is meant to be a fast, lightweight solver. As such it does *no* interrogation of the underlying expression. My feeling is that adding that kind of processing would be...

@michaelbynum: That seems like a reasonable enhancement, but for performance reasons shouldn't we only do that if an initial call to `calculate_variable_from_constraint` fails?