[Reprinted] A basic class implementation of Singleton

I am going to interview a game company today. The pen test is called Designing and implementing a singleton base class. I have not seriously considered this issue before, And I have reprinted an article.

Address: http://blog.csdn.net/Blue_Light/archive/2008/07/13/2646266.aspx

 

 

 

In the creation mode, there is a design mode "Singleton ". The intention of this mode is to ensure that a class has only one instance and provide a global access point to access it. Under the guidance of gof, we often write some Singleton classes. Each class is similar.

BelowCodeDescribes a basic class of singleton and Its Usage:

Template<ClassT>

ClassAllocusingnew

{

Public:

StaticT * Create ()

{

Return NewT;

}

 

Static VoidDestroy (T * P)

{

DeleteP;

}

};

 

Template<ClassT>

ClassAllocusingstatic

{

Public:

StaticT * Create ()

{

StaticT;

Return New(& T) T;

}

 

Static VoidDestroy (T * P)

{

P-> ~ T ();

}

};

 

Template<ClassT,Template<Class>ClassAllocpolicy = allocusingstatic>

ClassSingleton

{

Public:

StaticT * instance ()

{

If(Null = m_pthis)

{

M_pthis = allocpolicy <t>: Create ();

Assert (m_pthis );

M_pthis-> initialize ();

}

ReturnM_pthis;

}

 

Static VoidDestroy ()

{

If(M_pthis)

{

M_pthis-> finalize ();

Allocpolicy <t >:: destroy (m_pthis );

M_pthis = NULL;

}

}

 

VoidInitialize ()

{

}

 

VoidFinalize ()

{

}

 

Protected:

Singleton (){}

~ Singleton (){}

Private:

Singleton (ConstSingleton &);

Singleton &Operator= (ConstSingleton &);

Friend ClassAllocpolicy <t>;

Private:

StaticT * m_pthis;

};

 

Template<ClassT,Template<Class>ClassAllocpolicy>

T * Singleton <t, allocpolicy>: m_pthis = NULL;

 

ClassMysingleton:PublicSingleton <mysingleton, allocusingnew>

{

Public:

VoidSetvalue (IntValue)

{

M_value = value;

}

 

VoidPrint ()

{

Cout <m_value <Endl;

}

 

VoidInitialize ()

{

M_value = 1000;

}

 

Private:

IntM_value;

};

 

 

Int_ Tmain (IntArgc, _ tchar * argv [])

{

Mysingleton: instance ()-> Print ();

Mysingleton: Destroy ();

 

System ("pause ");

 

Return0;

}