Deepcopy of the module

[jlperla]

No description provided.

[jlperla]

For now, add the following

import Base.deepcopy_internal
deepcopy_internal(x::Module,stackdict::IdDict) = x

Note that this basically makes Module's shallow copy. i.e., treats them as references. This is very unlikely to cause issues globally since right now it errors.

I tried to see if tehre was a way to "stop" the recursiion to copy a weak reference but it doesn't seem immediately possible. Later we can revisit this hack.

[jlperla]

This is triggering a compilation warning, so we should revsit at some point:

[ Info: Precompiling DifferentiableStateSpaceModels [beacd9db-9e5e-4956-9b09-459a4b2028df]
WARNING: Method definition deepcopy_internal(Module, Base.IdDict{K, V} where V where K) in module Base at deepcopy.jl:33 overwritten in module DifferentiableStateSpaceModels at c:\Users\jesse\Documents\GitHub\DifferentiableStateSpaceModels.jl\src\types.jl:2.
  ** incremental compilation may be fatally broken for this module **

[wupeifan]

Yeah, essentially we overrode that line in deepcopy.jl

[cpfiffer]

Def. low priority for now, or at least it seems that way. One performance hit we could be exposing ourself to is that we're overwriting a fairly core Julia function, which could trigger a bunch of recompilations. Either way, the hit we're taking is at JIT spinup time and not runtime, so I'm not terribly worried for now.

[jlperla]

Exactly. Yeah, this was intended as a hack to get us through, and we would need to revsit. What I didn't realize was that it was overwriting anything - rather than just adding in something that didn't already exist. But I don't think it will cause any immediate issues with the runtime.

The other things I tried (e.g. storing a Ref{Module} had the same problems since it didn't seem like there was any other convenient way to stop the recusion without a custom type.

So the next stage in the hack is to add in a wrapper DontDeepCopyMe{Module} which stops the deepcopy recusiion at the custom type so then piracy is no longer required. But this whole thing was just temporary anyways, so we shall see.