How can I define a composite type
mutable struct Foo
bar::Int64
end
such that when I create an instance of it, bar gets a default value, let's say 42?
I know I can create the instance with
Foo(42)
but I would like to do something like
Foo()
You can just define a constructor with a default value:
julia> struct Foo; bar::Int64; end
julia> Foo() = Foo(42)
Foo
julia> Foo()
Foo(42)
You could use Base.@kwdef like so:
Base.@kwdef mutable struct Foo
bar::Int64 = 42
end
julia> foo = Foo()
Foo(42)
julia> foo.bar
42
julia> foo = Foo(bar = 423)
Foo(423)
julia> foo.bar
423
And if you need more functionality, then you could check out a package called Parameters.jl
For information on how to implement various constructors you can check out the documentation: https://docs.julialang.org/en/v1/manual/constructors/