How to treat one of the function arguments as a constant during broadcasting

New to Julia
1

I wonder what is the correct way to create objects that are iterable (or broadcastable?). The code below works as expected.

struct A 
x::Float64
y::Float64
end 

function foo(n,m,s::A)
u = n^2 + s.x^2
v = m + s.y
return u,v
end

a = A(1,2)
u,v = foo(4,5,a)

However now I would like to be able to pass vectors to foo so it can also return vectors eg:

x = collect(1:10)
y = collect(2:11)
u,v = foo.(x,y,a)

Note here that ‘a’ is still a single object of type ‘A’. I have tried to extend length and iterate among others but to no avail. Thanks!

2

u,v = foo.(x,y,Ref(a))

You’re asking how to NOT “expand” your struct during broad cast. You’re not iterating over your object

1 Like
3

Precisely, thank you!

4

maybe you want to revise your title a bit, but I’m not sure what’s the most likely titled to appear in google when someone searches this

1 Like
5

To make this work without the Ref (i.e., to always treat objects of type A as scalars when broadcasting), you can define

Base.Broadcast.broadcastable(a::A) = Ref(a)
6 Likes