Serialize ponters in Opt

[papamarkou]

@stevenj is it easy to write a serialize function for Opt type objects? I need it when I run some functions in parallel. See also this Julia issue:

JuliaLang/julia#5954 (comment)

[stevengj]

No, it is rather difficult to do in a completely general way, because Opt contains a pointer to a C struct that itself contains pointers to C structs as well as C function pointers.

It would be better to serialize the parameters you used to create the Opt object, and then just create a new one.

[papamarkou]

Thanks @stevengj. I created a type called NLoptimizer holding some parameters that are passed to Opt and a convert function that maps NLoptimizer ojbects to Opt objects. This workaround allows me to use NLopt in parallel. If you think that this could be useful to other users too, I could open a pull request. Here is the code:

https://github.com/scidom/ChaosCommunications.jl/blob/master/src/optimizers/NLoptimizer.jl