It might sound a bit weird but I am facing the following issue quite often:
Given a largish struct:
struct Foo
a
b
c
d
e
f
g
h
i
j
end
And a bunch of them in a Vector
foos = [Foo(rand(10)...) for _ ∈ 1:10]
I’d like to “alter” e.g. one field (e.g. subtracting 23 from each .h), by creating an exact copy with the new values of .h.
Something like
altered_foos = copy(foos, but = :h=>x->x-23)
Is there a somewhat convenient method/package or whatever to do this other than writing out the a new constructor? I’d like to avoid code repetition and also tried it via meta programming but I have the feeling this has been solved before.
Edit: no, I don’t want to make it mutable 
