I posted this on Slack, but looking for some detailed answers. I recently saw a code snippet in Julia struct _GLOBAL_RNG <: AbstractRNG global const GLOBAL_RNG = _GLOBAL_RNG.instance end Jeff described this as basically defining a global const, but doing it inside a struct suppresses the defau…

[image] affans: Mason replied that this is equivalent (it’s not) How is it not equivalent, what’s the difference? Anyway, I’m not acquainted with Julia’s internals, but maybe this helps somewhat: julia> struct S return nothing end julia> S() # The default constructor …

I also ran into this, see here: [image] Global const in struct General Usage In #32407 I saw struct _GLOBAL_RNG <: AbstractRNG global const GLOBAL_RNG = _GLOBAL_RNG.instance end Can someone please explain what this does?

Or maybe it is. I am not sure. Just trying to get an overview of what is happening here.

This trick is also used with missing, see here . """ Missing A type with no fields whose singleton instance [`missing`](@ref) is used to represent missing values. """ struct Missing end """ missing The singleton instance of type [`Missing`](@ref) representing a missing value. """ const miss…

I think this is slightly different right? This actually sets up a default constuctor. Jeff, on Slack, said there are some uses to not have a default constructor as well. For example, in my original code, you’d want to prevent people from writing out _GLOBAL_RNG()p as it can be misunderstood as setti…

Return statements and global consts in a struct

General Usage

Tamas_Papp March 20, 2021, 8:06am 3

I also ran into this, see here:

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Return statements and global consts in a struct

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