Re: singleton initialization

Fei Liu <>
Wed, 16 May 2007 09:48:41 CST
{ Edits: quoted signature removed. -mod }

Alf P. Steinbach wrote:

* Fei Liu:

Eric wrote:

class CTestClass
    static CTestClass& instance()
        static CTestClass* m_instance = new CTestClass;

This doesn't make sense. How can the compiler create this object at
compile time?

The object is created at run time.

Change this to:
static CTestClass& instance()
    static CTestClass* m_instance;
    if(!m_instance) m_instance = new CTestClass;
    return m_instance;

This merely replicates the code generated by the compiler for the
original, but in a more verbose and possibly less efficient way.

See ?6.7/4, "is initialized the first time control passes through its

Ah, so this is the C++ way of doing it...I may be wrong, but in C at
least for plain old datatype, function static variable initialization
happens at compile time.


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