Re: Pre-main construction order in modules

On 3/30/25 2:20 PM, Mr Flibble wrote:

On Sun, 30 Mar 2025 20:17:23 +0200, Bonita Montero wrote:
 

Am 30.03.2025 um 20:11 schrieb Mr Flibble:
>

No what I meant was the Meyers Singleton which involves static local
variables NOT static member variables which is what YOU thought it
meant.

>
static local variables need double-checked locked initialization.
That's rather slow to just get a reference.

 But that is nevertheless what the Meyers Singleton involves.  Static local
initialisation has been threadsafe since C++11 and if performance is a
concern then you can always cache the result in a reference downstream in
any hot path that needs it.
 /Flibble

Yes, my typical implementation is a global pointer (or static member of a class, not significantly different in function), which code can do a check for zero, if it sees it zero calls the generator function which sets the variable to the address of the local static variable.
The check for zero needs no guard, as redundant calls to the function are harmless, costing only the extra interlocking operation, and will be limited to code that reaches that pointer within the time frame needed to initialize the object.