我有以下最小的示例代码:
#include <functional>
#include <iostream>
#include <vector>
template<class ReadFileCallback>
void fileMgr_ReadWithCallback(std::string filename, ReadFileCallback callback) {
callback("OK");
}
void globalReadResult(std::string result) {
std::cout << "ReadResult in global function: result=" << result << std::endl;
}
class MyClass {
public:
MyClass() {};
~MyClass() {};
void Read() {
fileMgr_ReadWithCallback("file", globalReadResult);
//fileMgr_ReadWithCallback("file", this->ReadResult);
}
void ReadResult(std::string result) {
std::cout << "ReadResult in member function: result=" << result << std::endl;
}
};
int main()
{
MyClass c;
c.Read();
return 0;
}
对于回调函数，我希望使用非静态类成员MyClass::ReadResult。 在调用回调之前知道对象是否仍然有效（未被破坏）也会很好，因为否则我猜程序会失败。
如何更改此代码以使其能够使用MyClass对象的ReadResult作为回调？
您可以将其包装成lambda:
class MyClass {
public:
MyClass() {};
~MyClass() {};
void Read() {
fileMgr_ReadWithCallback("file", [this](const std::string& result){ this->ReadResult(result); });
}
void ReadResult(std::string result) {
std::cout << "ReadResult in member function: result=" << result << std::endl;
}
};
您可以使用std::函数。 这是一个很好的解决办法:
#include <functional>
#include <iostream>
#include <vector>
#include <functional>
template<class ReadFileCallback>
void fileMgr_ReadWithCallback(std::string filename, ReadFileCallback callback) {
callback("OK");
}
void globalReadResult(std::string result) {
std::cout << "ReadResult in global function: result=" << result << std::endl;
}
class MyClass {
public:
MyClass() {};
~MyClass() {};
void Read() {
using std::placeholders::_1;
std::function<void(std::string)> func = std::bind( &MyClass::ReadResult, this, _1);
fileMgr_ReadWithCallback("file", func);
}
void ReadResult(std::string result) {
std::cout << "ReadResult in member function: result=" << result << std::endl;
}
};
int main()
{
MyClass c;
c.Read();
return 0;
}
