c++模板函数的重载

 代码来自于facebook的folly库。
cursor.h

#pragma once
#include <iostream>
namespace zsy{
template <class Derived>
class Writable{
public:
  template <class T>
  typename std::enable_if<std::is_arithmetic<T>::value>::type write(T value) {
    const uint8_t* u8 = reinterpret_cast<const uint8_t*>(&value);
    Derived* d = static_cast<Derived*>(this);
    d->push(u8, sizeof(T));
  }
  template <class T>
  void writeLE(T value) {
    Derived* d = static_cast<Derived*>(this);
    d->write(value);
  }
  void push(const uint8_t* buf, size_t len) {
    Derived* d = static_cast<Derived*>(this);
    if (d->pushAtMost(buf, len) != len) {
    }
  }
};
class RWCursor:public Writable<RWCursor>{
public:
    size_t pushAtMost(const uint8_t* buf, size_t len){
        std::cout<<__FUNCTION__<<std::endl;
        return len;
    }
};
class QueueAppender:public Writable<QueueAppender>{
public:
  template <class T>
  typename std::enable_if<std::is_arithmetic<T>::value>::type write(T value){
    std::cout<<"queue "<<__FUNCTION__<<value<<std::endl;
  }
    size_t pushAtMost(const uint8_t* buf, size_t len){
        std::cout<<"queue "<<__FUNCTION__<<std::endl;
        return len;
    }
};
}

test.cc

#include <iostream>
#include "cursor.h"
int main(){
    zsy::RWCursor rw;
    uint32_t len=32;
    rw.writeLE(len);
    zsy::QueueAppender appender;
    appender.writeLE(len+1);
    return 0;
}