AbstractChannel is currently not parametric

[donm]

The AbstractChannel type is not parametric; it's defined as

abstract type AbstractChannel end # channels.jl: 3

But should it be parametric? Will something with the Channel interface ever require more flexibility than would be allowed by this?:

abstract type AbstractChannel{T} end

The reason why this came up is because Channel and RemoteChannel do not share a common supertype below Any, and I'd like to create a type union for functions that accept anything with the channel interface. This is valid and catches most (all?) of the built-in cases:

 AnyChannel{T} = Union{Channel{T}, RemoteChannel{Channel{T}}}  

but trying to expand that definition to AbstractChannels is not valid

 AnyChannel{T} = Union{AbstractChannel{T}, RemoteChannel{AbstractChannel{T}}}  # -> TypeError

[StefanKarpinski]

This seems like a good idea; also shouldn't AbstractChannel be a supertype of RemoteChannel?

[donm]

That would be excellent, and it would also be great if RemoteChannel supported what seems to be the full Channel interface (it's missing iteration, isopen, ....). But currently RemoteChannel is a Base.Distributed.AbstractRemoteRef. It could instead just have a RemoteRef, but be an AbstractChannel. But that's a bigger change and I haven't thought through the implications.

[StefanKarpinski]

The immediate change to Base (as opposed to stdlib/Distributed) is just adding the type parameter.

[JeffBezanson]

Sounds good.