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Original post by SteveC
Besides, using a scope-based locking technique inside of GetInstance() would only last for the duration of the call - so it would not protect the singleton once the method call returns.

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One way maybe you could consider doing it would be to return a kind of smart-pointer/mutex object from the GetInstance() method. That way each call to GetInstance would return a temporary automatic variable which locked the mutex until the call to the real class's method ( accessed via operator-> ) occurred.

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Original post by Stoffel Exactly. It's like trying to make an internally-synchronized container; the container has no way of knowing over which calls each thread needs exclusive access. It must be externally synchronized.

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Practical experience suggests than it is often possible to redesign so the singleton becomes a member variable or local static variable. Indeed, this should be a worthy goal to strive for.

Do we really need the graphics renderer to be global? Can it be a member variable of an Application object instead?

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Original post by Void
The application does not have to be a singleton. At the top upper most level, it can be just an auto variable.

If you need to pass renderer to subsystems, let them take a reference.

There are certain situations where a singleton would really be useful. For the renderer, IMO, it doesn't qualify.

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Original post by Kerion
Maybe I am just missing the point entirely, but whatever ever happened to good old fashion explicit creation/destruction? Its very simple to add an explicit static Create/Destroy function to your singletons which then creates/destroys the static instance of the class.

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Original post by Outworlder
Can someone give some examples of these situations?

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There are certain situations where a singleton would really be useful. For the renderer, IMO, it doesn't qualify.

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Main INIT
MyClass CTOR
Method called
Main EXIT
Method called
Press any key to continue
 

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Original post by SteveC
The double-checked locking pattern combined with a mutex/critical section can solve this problem.

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struct X
{
    ~X();
};

X x;

#include "MyClass.h"

X::~X()
{
    MyClassNiftyCounter::Get_Instance().Method();
}

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Initialization of static objects is well defined with each translation unit (ie. .cpp file), but not across multiple files. This is why we need singletons.

TrackNew( T* ptr, const char* file, int line );
TrackDelete( T* ptr, const char* file, int line );

#define NEW( T ) MemoryTracker::Instance().TrackNew( new T, __FILE__, __LINE__ )
#define DELETE( ptr ) delete MemoryTracker::Instance().TrackDelete( ptr, __FILE__, __LINE__ )

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Original post by Eisenbart Hi everyone, I have just discovered the "Nifty Counter" type of singleton in the article being discussed and I almost thought that this would the solution to a common order of destruction problem.

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Original post by Eisenbart I am using a singleton for a logger, too. It's a memory tracking mechanism that stores information about allocated memory in a database object, which offers methods like TrackNew( T* ptr, const char* file, int line ); TrackDelete( T* ptr, const char* file, int line ); These methods are called from macros like #define NEW( T ) MemoryTracker::Instance().TrackNew( new T, __FILE__, __LINE__ ) #define DELETE( ptr ) delete MemoryTracker::Instance().TrackDelete( ptr, __FILE__, __LINE__ ) How would you implement that with global functions within namespaces? And isn't that pretty much the same, because a class also acts somewhat (or in this case even exactly) like a namespace?

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Original post by Anonymous Poster The global functions fire off a message to the event handler asking for a pointer to the Memory Manager class. They then use that and log the information into that the database.

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Original post by Anonymous Poster Someone might argue that you cannot remove your memory manager and place it into another application easily. Mine also has the ability to use a local copy of the manager if my engine library isn't detected. It can also save/read from a file all the data also. It logs pointers etc to the file. Bit more work but its a very robust memory manager.