SingletonPtr< T > Class Template Reference

Singleton smart pointer. More...

#include <singleton.h>

Collaboration diagram for SingletonPtr< T >:

List of all members.

Public Types
enum	memoryRelease { never = 0, nonarray, array }
	Define how the pointer is deleted. More...
Public Member Functions
	SingletonPtr (T *app)
	No memory management by default, callers responsibility to manage memory.
	SingletonPtr (T *app, SingletonPtr< T >::memoryRelease m)
	Specifies how to delete pointer.
	SingletonPtr ()
	Create a temporary to access the pointer.
	~SingletonPtr ()
	Cleanup.
T *	operator-> ()
	Access the object.
T &	operator() ()
	Access the object.
Static Public Attributes
static int	count = 0
	Count of the ojbects pointed to by ptr.

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Detailed Description

template<class T>
class SingletonPtr< T >

Singleton smart pointer.

A singleton is a pointer to a unique (only one) object.

I do not generally use this as C++ provides a low tech solution with static variables that is simpler or more primitive.

However this does a little more by supporting reference counting deletion, if the client so chooses for array and not array objects.

The class can also be used without memory management. References are still counted but they can become zero and still have a valid pointer, because it is the clients responsibility. The following is an example of this technique.

Example

  //Initialize the pointer.
  SingletonPtr< A > init(&app);  // Be aware of app object's lifetime
  // Let init die.

  //... Access the object anywhere in the C++ universe.
  SingletonPtr< A >()-> A's methods/data

Definition at line 49 of file singleton.h.

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Member Enumeration Documentation

template<class T>

enum SingletonPtr::memoryRelease

Define how the pointer is deleted.

Enumerator:

never
nonarray
array

Definition at line 58 of file singleton.h.

{ never=0, nonarray, array };

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Constructor & Destructor Documentation

template<class T >

SingletonPtr< T >::SingletonPtr

(

T *

app

)

[inline, explicit]

No memory management by default, callers responsibility to manage memory.

Definition at line 99 of file singleton.h.

References SingletonPtr< T >::count, and SingletonPtr< T >::never.

{
   assert(ptr==0);

  ptr = app;
  count = 1;
  memorystate = never;
}

template<class T >

SingletonPtr< T >::SingletonPtr	(	T *	app,
		SingletonPtr< T >::memoryRelease	m
	)			[inline, explicit]

Specifies how to delete pointer.

Definition at line 111 of file singleton.h.

{

  assert(ptr==0);

  memorystate = m;

  ptr = app;
  count = 1;
}

template<class T >

SingletonPtr< T >::SingletonPtr

(

)

[inline]

Create a temporary to access the pointer.

Definition at line 124 of file singleton.h.

References SingletonPtr< T >::count, and SingletonPtr< T >::never.

{
  assert(ptr!=0);
  assert( (count>=1) || (memorystate==never));

  ++count;
}

template<class T >

SingletonPtr< T >::~SingletonPtr

(

)

[inline]

Cleanup.

Definition at line 149 of file singleton.h.

References SingletonPtr< T >::array, SingletonPtr< T >::count, SingletonPtr< T >::never, and SingletonPtr< T >::nonarray.

{
  --count;
  if (count<=0)
  {

assert(count==0);

    switch(memorystate)
    {
      case never: break;
      case array: delete[] ptr; break;
      case nonarray: delete ptr; break;
    }

    if (memorystate!=never)
      ptr=0;
  }
}

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Member Function Documentation

template<class T >

T & SingletonPtr< T >::operator()

(

)

[inline]

Access the object.

Definition at line 141 of file singleton.h.

{
  assert(ptr!=0);

  return *ptr;
}

template<class T >

T * SingletonPtr< T >::operator->

(

)

[inline]

Access the object.

Definition at line 133 of file singleton.h.

{
  assert(ptr!=0);

  return ptr;
}

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Member Data Documentation

template<class T>

int SingletonPtr< T >::count = 0 [inline, static]

Count of the ojbects pointed to by ptr.

Definition at line 55 of file singleton.h.

Referenced by SingletonPtr< T >::SingletonPtr(), and SingletonPtr< T >::~SingletonPtr().

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The documentation for this class was generated from the following file:

• misclib/singleton.h