Implement iteration of Struct

General Usage
1

Hi,

I’m trying to implement iteration on a small struct:

struct Coordinate
    x::Float64
    y::Float64
    Coordinate(x, y) = new(x, y)
end

So that I can unpack its members like this:

x, y = Coordinate(1,1)

Any help is welcome :slight_smile:

2

I think all you need to do is use

https://github.com/mauro3/UnPack.jl

2 Likes
3

Nice!,

But just as an excercise, it would be great to know how to do it “by hand”.

Also, the package you mention does not allow me to do

xc, yc = Coordinate(1,1)
4

All you need to do is fulfill the iteration interface by defining a Base.iterate method, like this one:

function Base.iterate(c::Coordinate, state = 0)
    state >= nfields(c) && return
    return Base.getfield(c, state+1), state+1
end

(Note this one actually works for any number of fields!).

You can also define other methods mentioned in the interface like

Base.length(c::Coordinate) = nfields(c)

which allows e.g. collect to work with it.

6 Likes
5

Just to complement this, see StaticArrays.FieldVector which is exactly for use cases like this.

2 Likes