C++ singleton Post: 302710857

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Top Forums Programming C++ singleton Post 302710857 by JohnGraham on Friday 5th of October 2012 04:14:22 AM

10-05-2012

Registered User

No - make a private static variable that is a pointer to your object type. Make sure it's NULL initially. Then at each request, check if this pointer is NULL - if it is, then no instance of your object has been initialized, so construct one and return it. If it is non-NULL, just return it:

Code:

class Single
{
private:
    static Single *single;  // Initialize to NULL at definition.
    Single();
public:
    static Single *getSingle() {
        if (!single)
            single = new Single();  // Only gets called once, then if() statemenet is false.
        return single;
    }
};

JohnGraham

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sbthreadautolock

SbThreadAutoLock(3)						       Coin						       SbThreadAutoLock(3)

NAME

       SbThreadAutoLock -

       Simple convenience class for locking access to a function.

       This class provides a simple convenience mechanism for automatically locking access to a function that is not re-entrant.

SYNOPSIS

       #include <Inventor/threads/SbThreadAutoLock.h>

   Public Member Functions
       SbThreadAutoLock (SbMutex *mutexptr)
       SbThreadAutoLock (SbThreadMutex *mutexptr)
       ~SbThreadAutoLock ()

   Protected Attributes
       SbMutex * mutex
       SbThreadMutex * recmutex

Detailed Description
       Simple convenience class for locking access to a function.

       This class provides a simple convenience mechanism for automatically locking access to a function that is not re-entrant.

       Usage example:

	 void
	 myfunction(void)
	 {
	   SbThreadAutoLock lock(aMutexPtr);

	   // [other code]
	 }

       In the class constructor, SbMutex::lock() is called on the mutex, and when the function exits (this is the convenience part) the destructor
       will automatically be invoked, calling SbMutex::unlock() on the same mutex.

Constructor &; Destructor Documentation
   SbThreadAutoLock::SbThreadAutoLock (SbMutex *mutex) [inline]
       The constructor calls SbMutex::lock() on mutex.

   SbThreadAutoLock::SbThreadAutoLock (SbThreadMutex *mutex) [inline]
       The constructor calls SbThreadMutex::lock() on mutex.

   SbThreadAutoLock::~SbThreadAutoLock () [inline]
       The destructor calls unlock() on the mutex passed in as a parameter to the constructor.

Member Data Documentation
   SbThreadAutoLock::recmutex [protected]
       This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Author
       Generated automatically by Doxygen for Coin from the source code.

Version 3.1.3							  Wed May 23 2012					       SbThreadAutoLock(3)