SYMPTOMS
当在一个使用多继承类作为event_receiver的未托管应用程序中unhook (__unhook) 一个native events时, 将会失败。__unhook将返回1(表明没有成功地unhook。在应用程序结束以后native event机制造成了内存泄漏.CAUSE
这个问题发生在事件的接受者(event_receiver)是多继承类的情况下。在unhook的时候event的注入代码无法正确比较成员函数指针。WORKAROUND
这个问题可以使用下面的代码重现:
#include
class A
{
?int a;
};
class B
{
?int b;
};
[event_source(native)]
class CSource
{
public:
?? __event void MyEvent(int nValue);
};
[event_receiver(native)]
class CReceiver : public A, public B //多继承
{
public:
?? void MyHandler1(int nValue) {
????? printf("MyHandler1 was called with value %d.\n", nValue);
?? }
?? void MyHandler2(int nValue) {
????? printf("MyHandler2 was called with value %d.\n", nValue);
?? }
};
int main() {
?? CSource source;
?? CReceiver receiver;
?? __unhook(&CSource::MyEvent, &source, &CReceiver::MyHandler2, &receiver);
?? __hook(&CSource::MyEvent, &source, &CReceiver::MyHandler1, &receiver);
?? __raise source.MyEvent(1);
?? __unhook(&CSource::MyEvent, &source, &CReceiver::MyHandler1, &receiver);//失败
?? __hook(&CSource::MyEvent, &source, &CReceiver::MyHandler2, &receiver);
?? __raise source.MyEvent(2);
?? __unhook(&CSource::MyEvent, &source, &CReceiver::MyHandler2, &receiver);//失败
?
}
运行结果
MyHandler1 was called with value 1.
MyHandler2 was called with value 2.
MyHandler1 was called with value 2.
MyHandler2没有被正确unhook。
The information in this article applies to:
- Microsoft Visual C++ .NET (2002)
- Microsoft Visual C++ .NET (2003)
- Visual C++ 2005 Express Edition Beta
打印 | 张贴于 2004-07-07 11:10:00 | Tag:软件 C++