Supplement: C++ Code Examples
Example 16-3. C++ Code Fragment: Singleton Pattern
Class USTax {
public:
static USTax* getInstance();
private:
USTax();
static USTax* instance;
}
USTax* USTax::instance= 0;
USTax* USTax::getInstance () {
if (instance== 0) {
instance= new USTax;
}
return instance;
}
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Example 16-4. C++ Code Fragment: Double-Checked Locking Pattern
class USTax : public CalcTax {
public:
static USTax* getInstance();
private:
USTax();
static USTax* instance;
};
USTax* USTax::instance= 0;
USTax* USTax::getInstance () {
if (instance== 0) {
// do sync here
if (instance== 0) {
instance= new USTax;
}
}
return instance;
}
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