Possible to set the type of Dict entries for specific keys?

General Usage
1

Hi all,

I would like to use a Dict (or a similar structure) with values that can have different, but concrete types for given keys. For example:

mydict = Dict(:a=> 2, :b=>[1.0, 3.0], :c=> "hello type")

In general, this means typeof(mydict) is Dict{Symbol, Any}, so entries of mydict are type Any. However, I want to use mydict in a way, that the type of key :a is always Int, the type of key :b is always Vector{Float64} and so on.

Is there a way to set a specific type of the entries for the keys :a, :b and :c? Or could one implement a custom “Dict” that can do so?

I hope I made my question clear. I’m happy for answers!

Best

2

Dict doesn’t support this, but this sounds like exactly what mutable struct already does. Can you do something like this?

mutable struct MyType
  a::Int 
  b::Vector{Float64}
end
3

yes, that makes sense. What I need is a bit more complex however. If b inside of MyType is in turn something like a mutable struct, that would probably do it for me. Is this a good approach / style?

4

yeah sure, just like class, struct can and should be used when needed to have hierarchy.

5

Absolutely!

6

perfect, thanks both of you!