Low-Lock Singletons In D

[Steven Schveighoffer]

On Mon, 06 May 2013 17:36:00 -0400, Andrej Mitrovic  
<andrej.mitrovich at gmail.com> wrote:

> On 5/6/13, Diggory <diggsey at googlemail.com> wrote:
>> Although that's only a single-per-thread-ton :P
>
> My bad.
>
>> final abstract class singleton
>> {
>> __gshared:
>>     void foo() { }
>>     int f;
>> }

The point that is missed is the lazy creation.  Imagine if it's not just  
an int but a whole large resource, which takes a long time to create/open.

If all we cared about is access, and you *know* you are going to need it,  
you can just create it eagerly via shared static this().  That is not what  
the singleton pattern is for.

-Steve