Update deeply nested immutable structs.

We plan to maintain Setfield.jl for a long time (written 2020-09-21, reinforced 2021-08-01, 2022-09-08, 2024-02-15). We will however not add new features. For a successor, see Accessors.jl.

Updating deeply nested immutable structs was never easier:

using Setfield
@set obj.a.b.c = d

For more information, see the documentation and/or watch this video:

• VegaLite.jl overloads getproperty and lens API to manipulate JSON-based nested objects.

• Kaleido.jl is a library of additional lenses.

• PhaseSpaceIO.jl overloads getproperty and setproperties to get/set values from/in packed bits.