Include an integer `setindex` for `NamedTuple`

[rafaqz]

We have both Symbol and Int getindex for a NamedTuple, but only Symbol setindex.

Is there a reason for this? its seems like we should have both in both cases.

[Xnartharax]

Hi, I would like to work on this if no one else is currently on it. That would be my first real contribution to an open source project.

[Xnartharax]

So my proposed method is something like this:

function setindex(nt::NamedTuple{names, T}, v, idx::Int)
     NamedTuple(zip(names, setindex(Tuple(nt), v, idx)))
end

[rafaqz]

You want to make sure that is type stable. I would use names in the constructor i.e NamedTuple{names}(...)

And check what is commonly used for names in other methods in Base.

[Xnartharax]

The method you suggested unfortunately doesn't work and will return the following:

julia> Base.setindex((a=1, b=2), 3, 1)
(a = (:a, 3), b = (:b, 2))

[Xnartharax]

However after some experimentation I noticed this will work:

function setindex(nt::NamedTuple{names, T}, val::X, idx::Int) where {names, T, X}
      NamedTuple{names}(Base.setindex(Tuple(nt), val, idx))
end

This is also an order of magnitude faster. Thanks for the suggestion will update my pull request.
Also, names is the common name for this parameter.

[rafaqz]

Yes, that's what I mean ;).

Also it shouldnt be "faster" it should be essentially a compile-time operation with no allocations. Anything else shouldnt be merged.

[Xnartharax]

Also it shouldnt be "faster" it should be essentially a compile-time operation with no allocations.

I'm not sure what you mean by this. setindex requires at least the allocation of the new named tuple since it is not an inplace function.

[rafaqz]

NamedTuple is allocated on the stack, or not at all.

Allocations that show in benchmarks are heap allocations. Thats what we want to be zero.

[Xnartharax]

Thanks for that insight and yes indeed benchmark shows 0 heap allocations.

[Hitansh-Shah]

Hi! I am new to Julia and I want to contribute to the Julia community. I completed the Julia basics course from JuliaAcademy. I am also looking forward to Gsoc'22 with Julia. Can anyone guide on how I can start contributing to the good first issues because as a beginner in Julia they seem pretty overwhelming too. 😅

[srvjha]

hey I want to contribute to this , could u please assign me

[oscardssmith]

We don't generally assign issues. Make a PR and we'll review it.

[rafaqz]

Also the code from @Xnartharax is pretty much all of it. The real work is writing tests and docs.