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destroying singleton instances ?

Started by bg3ntl Jan 14, 2002 at 6:30 AM 3 replies 450+ views

Original Post

Jan 14, 2002 at 6:30 AM

well ok i understand singletons now and how to use them etc. when do they get destroyed ? do u create a destroy function and call that when u want to release the instance you have created ? or can u just put a call to delete m_singleton in the destructor. when the app quits will it automatically call the destructor for any remaining objects ? thanks for your help bg3ntl

Sandman

209

Sandman

Jan 14, 2002 at 6:43 AM

A lot depends on how you implemented your singleton. If you do it the ''usual'' way, using a static member pointer to a CSingleton, which you create using new the first time the GetInstance() function is called, the destructor never gets called unless you explicitly delete the singleton . For this reason, I prefer to use this method for my singletons - its cleaner and the destructor is called automagically when the program exits.

  
class CSingleton
{
  private:
  CSingleton()
  {
    // constructor stuff goes here

  }
  public
  ~CSingleton()
  {
    // Destructor stuff goes here

  }
  CSingleton* GetInstance()
  {
    static CSingleton instance;
    return &instance
  }
};

bg3ntl

Author

bg3ntl

Jan 14, 2002 at 7:42 AM

why is the destructor called in your case ?

yes you are right, i am doing it the usual way with a static class member m_singleton and a static accessor function.

is it because you are creating a static variable that has a lifetime equal to that of the program exectution ?

if that is true, how come a static member variable doesnt behave the same way ?

bg3ntl

kvh

Jan 14, 2002 at 8:17 AM

try this post

bg3ntl

Author

bg3ntl

Jan 14, 2002 at 9:10 PM

thnx kvh, that post was excellent. i never knew that static vars were destroyed in FILO manner. now i see the difference between the two implementations, one is created in free space and one is just a static var destroyed at the end of program execution.

thnx a lot!

bg3ntl

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