New Singlton Scheme

From:
Dmitriy Vyukov <dvyukov@gmail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Wed, 29 Aug 2007 07:10:20 CST
Message-ID:
<1188385425.894221.72980@w3g2000hsg.googlegroups.com>
I propose new implementation scheme for singltons.

Mayers singleton have following advantages and drawbacks:
+ created by first request
- no guarantee that will be created "before main()"

Plain old global object:
+ guarantee that will be created "before main()"
- no guarantee that will be created before first request

New scheme:
+ created by first request
+ guarantee that will be created "before main()"
- not noted yet

// some_service.h

/** Service interface
 */
struct some_service
{
    void make_something() {}
};

/** Service interface getter
 */
some_service& get_service();

// some_service.cpp

some_service& get_service()
{
    static some_service instance;
    return instance;
}

static some_service& local = some_service(); // <-----------------

This implementation eliminate problems with multithreaded creation,
because instance guaranteed will be created "before main()" (in
singlethreaded envirionment).

I propose to call this Vyukov's Singleton :)
Any comments?

Dmitriy Vyukov

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