成员函数(member function)模板(template) 详解 及 代码

成员函数(member function)模板(template) 详解 及 代码

本文地址: http://blog.csdn.net/caroline_wendy/article/details/16918085

成员模板(member template) 既可以在普通类(ordinary class), 也可以在类模板(class
template);

在普通类中, 在使用成员函数时, 不用提供模板参数, 函数可以根据使用的参数,

自动推导(deduce)模板实参(template argument)对应模板形参(template parameter);

在类模板中, 成员函数的模板参数(template parameter)可以和类的模板参数不同, 但在定义(definition)中,

必须添加两个模板参数列表(template parameter list), 第一个为类的, 第二个为成员函数的;

代码如下:

[cpp] view
plain copy

print?





/*

* cppprimer.cpp

*

* Created on: 2013.11.24

* Author: Caroline

*/

/*eclipse cdt, gcc 4.8.1*/

#include <iostream>

#include <functional>

#include <memory>

#include <algorithm>

#include <string>

#include <vector>

#include <deque>

#include <iterator>

//函数模板默认参数

template <typename T, typename F = std::less<T>>

int compare (const T &v1, const T &v2, F f = F())

{

if (f(v1, v2)) return -1;

if (f(v2, v1)) return 1;

return 0;

}

class DebugDelete {

public:

DebugDelete (std::ostream &s = std::cerr) : os (s) { }

template <typename T> void operator() (T *p) const {

os << "deleting unique_ptr" << std::endl; delete p;

}

private:

std::ostream &os;

};

template <typename T> class Blob {

public:

template <typename It> Blob (It b, It e);

/*template <typename It> Blob (It b, It e) {

std::sort(b, e);

}*/

};

template <typename T>

template <typename It>

Blob<T>::Blob (It b, It e) {

std::sort(b, e); //容器需要允许被排序

}

int main (void) {

std::cout << "compare (0, 42) = " << compare (0, 42) << std::endl;

double* p = new double;

DebugDelete d;

d(p); //使用时, 可以自动推倒模板

int* ip = new int;

DebugDelete() (ip);

std::unique_ptr<int, DebugDelete> pi (new int, DebugDelete());

std::unique_ptr<std::string, DebugDelete> ps (new std::string, DebugDelete());

int ia[] = {9, 8, 7, 6, 5};

std::vector<long> vi = {5, 4, 3, 2, 1, 0};

std::deque<std::string> w = {"lady", "girl", "woman", "now"};

Blob<int> a1(std::begin(ia), std::end(ia));

Blob<int> a2(vi.begin(), vi.end());

Blob<std::string> a3(w.begin(), w.end());

std::cout << "int ia[] = ";

for (const auto i : ia) { std::cout << i << " "; }

std::cout << std::endl;

std::cout << "std::vector<long> vi = ";

for (const auto i : vi) { std::cout << i << " "; }

std::cout << std::endl;

std::cout << "std::list<const char*> w = ";

for (const auto i : w) { std::cout << i << " "; }

std::cout << std::endl;

return 0;

}

输出:

[plain] view
plain copy

print?





deleting unique_ptr

deleting unique_ptr

deleting unique_ptr

deleting unique_ptr

compare (0, 42) = -1

int ia[] = 5 6 7 8 9

std::vector<long> vi = 0 1 2 3 4 5

std::list<const char*> w = girl lady now woman