dlang.org/spec/function.html#pure-functions example

[Paul]

On Sunday, 22 October 2023 at 00:50:33 UTC, Jonathan M Davis 
wrote:
>>
>> Can I say in the general sense that when the word static is 
>> used it means that something is defined/declared at compile 
>> time?
>
> Hmmm. It seems like my message got eaten. So, I'll write it out 
> again.
>
> In any case, no, in general, static really doesn't have much to 
> with runtime vs compile time. It means different things in 
> different contexts. Off the top of my head, the only contexts 
> where static specifically has anything to do with compile time 
> are with static if and static foreach, in which case, those 
> constructs become compile-time constructs instead of runtime 
> constructos. Other contexts have very different meanings for 
> static.
>
> For instance, a static member function is a member function 
> that doesn't have an implicit this reference/pointer and thus 
> is pretty much just a function that's scoped to the 
> class/struct rather than being a function that operates on 
> instances of that class or struct.
>
> On the other hand, static member variables are variables which 
> are associated with the class or struct and not with an 
> instance of that class or struct. So, there is only one 
> instance of that variable for all objects of that class or 
> struct on a single thread, as opposed to non-static member 
> variables which are specific to each object.
>
> static in functions has similar but different meanings. On a 
> nested function, it makes it so that the function has no 
> implicit parameter which is a reference to the context of the 
> outer function, meaning that it's pretty much just a function 
> within another function, whereas a non-static nested function 
> actually has access to the outer function's scope and thus can 
> access the variables in the outer scope.
>
> On the other hand, a static variable within a function is a 
> variable where there is only one instance of that variable for 
> every call to that function on a single thread, as opposed to 
> normal function variables which get a new instance every time 
> that the function is called.
>
> And there are other meanings for static in other contexts. 
> There are similarities between them, but if there is a 
> definition that can be given for what static means which covers 
> all of those contexts (and there may be - C manages that in 
> spite of the fact that static means very different things in 
> different contexts there too), it's not an obvious definition. 
> You mostly just have to learn what static means in each context 
> that it's used rather than memorizing a general definition for 
> it that can be applied in each context.
>
> - Jonathan M Davis

Very helpful.  Thanks Jonathan.

Wow. Sorry.  I just found this unsent draft!