Could anyone suggest how to make the following: struct A b::Int; c::Int end as = [A(1, 1), A(2, 2)] as[2].c = 3 work without resorting to: mutable types recreating A with a changed field Ideally the produced llvm code might be similar to C equivalent (*pointer).c = 3, so the solution may involv…

I would recommend the following procedure to you: struct A{T <: Integer} b::Vector{T} c::Vector{T} A(b::T, c::T) where T = new{T}([b], [c]) end as = [A(1, 1); A(2, 2)] as[2].c[1] = 3 Maybe it’s even possible to implement a specialized value to array conversion such that you do not have to use …

See these issues that give deep insights of what’s going on about this: https://github.com/JuliaLang/julia/pull/21912 https://github.com/JuliaLang/julia/issues/17115

In the meantime, you could try something like this struct A{T<:Integer} b::Base.RefValue{T} c::Base.RefValue{T} end A(b::T, c::T) where {T<:Integer} = A{T}(Ref(b), Ref(c)) Base.show(io::IO, a::A) = print(io, "A(", a.b[], ", ", a.c[], ")") as = [A(1, 1); A(2, 2)] as[2].c[] = 3

Thank you @cdsousa , but some code snippets which I encountered in these threads will be available in 1.0+, as I understood. At least methods mentioned are not available in 0.6. It is just very strange that there is no way to do something similar, even with some low-level code, in the current versio…

@PabloZubieta Is it possible to not uglify the struct definition, and obtain these RefValues in some other way?

@jonas-kr your solution introduces mutable objects (Vector), this makes the whole point of using immutable structs in array irrelevant.

Setting individual fields for struct in array

New to Julia

PabloZubieta August 9, 2017, 3:48pm 5

Also, see this previous post Mutable field in immutable type and this comment on Immutable vs Type: reassignment via arrays and performance - #10 by jameson.

Topic		Replies	Views
Trying to reference a struct field into an array New to Julia arrays , struct	7	1361	August 26, 2022
Modifying the fields of an immutable struct General Usage question	5	1387	January 2, 2024
Saving data into array having struct data type General Usage question	5	1854	August 8, 2020
What Julia type maps to a C type containing nested structs? General Usage question , ccall	2	1429	June 6, 2017
Mutable field in immutable type General Usage question	7	3937	December 22, 2019

Setting individual fields for struct in array

Related topics