C++ template samples

C++ template samples

#include <boost/format.hpp>
#include <boost/shared_ptr.hpp>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
#include <list>

using namespace std;

// declare start for 5-1
struct widget {
	typedef int value_type;
};

template <class T>
void something(typename T::value_type*)
{
	cout << "has value_type" << endl;
}

template <class T>
void something(...)
{
	cout << "other" << endl;
}

void sample5_1()
{
	cout << "SFINAE p120 5-1" << endl;
	something<widget>(0);
	something<int>(0);
}
// declare end for 5-1


// declare start for 5-3
template <class T>
struct _is_void {
	static const bool value = false;
};

template <>
struct _is_void<void> {
	static const bool value = true;
};

void sample5_3()
{
	cout << "SFINAE p122 5-3" << endl;
	cout << boolalpha;
	cout << _is_void<void>::value << endl;
	cout << _is_void<int>::value << endl;
	cout << _is_void<char*>::value << endl;
}
// declare end for 5-3


// declare start for 5-33
// ☆☆☆ constexpr is not available for disabled test ☆☆☆
//template <class T>
//class has_iterator {
//	template <class U>
//	static constexpr bool check(typename U::iterator*)
//	{ return true; }
//
//	template <class U>
//	static constexpr bool check(...)
//	{ return false; }
//
//public:
//	static const bool vazlue = check<T>(nullptr);
//};
//
//void sample5_33()
//{
//	cout << "SFINAE p125 5-33" << endl;
//
//	static_assert(
//		has_iterator<std::vector<int>>::value,
//		"vector has iterator.");
//
//	static_assert(
//		!has_iterator<int>::value,
//		"int has not iterator.");
//}
// declare end for 5-33


// declare start for 6-1
struct debug_log {
	static void print(const string &value) {
		cout << value << endl;
	}
};

struct release_log {
	static void print(const string &value) {}
};

template <class LogPolicy>
struct Hoge {
	void foo() const {
		LogPolicy::print("Fatal Error!!!");
	}
};

// Static member function
void sample6_1()
{
	Hoge<debug_log>().foo();
	Hoge<release_log>().foo();
}

// 非静的メンバ関数
struct policy6_8 {
	void foo()
	{
		cout << "policy call foo." << endl;
	}
};

template <class Policy>
class widget6_8 {
	Policy _policy;
public:
	void do_something()
	{
		_policy.foo();
	}
};

void sample6_8()
{
	widget6_8<policy6_8> hoge;
	hoge.do_something();
}

// Inheritance
class policy6_9 {
protected:
	void foo() {
		cout << "policy6_9 class call foo." << endl;
	}

public:
	virtual void abc() {
		cout << "policy6_9 class call abc." << endl;
	}

	void first() {
		cout << "policy6_9 class call first." << endl;
	}
};

class fakePolicy {
public:
	void hoge() {
		cout << "fakePolicy class call hoge." << endl;
	}
};

template <class Policy>
class widget6_9 : public Policy
{
public:
	void do_something()
	{
		//foo();
	}

	virtual void abc() {
		cout << "widget6_9 class call abc." << endl;
	}
};

void sample6_9()
{
	widget6_9<policy6_9> hoge;
	hoge.do_something();
	hoge.abc();
	hoge.first();

	widget6_9<fakePolicy> fuga;
	fuga.hoge();
}

// declare start for 6-1

void sample2_20()
{
	vector<int> v;
	v.push_back(1);
	v.push_back(2);
	v.push_back(3);

	copy(begin(v), end(v) - 1, ostream_iterator<int>(std::cout, ","));
	cout << v.back() << endl;

	list<double> dl;
	dl.push_back(0.1);
	dl.push_back(0.2);
	dl.push_back(0.3);

	//copy(begin(dl), end(dl), ostream_iterator<double>(std::cout, ","));
}

void sample_boost()
{
	std::cout << boost::format("%s¥n") % "hello world";

	boost::shared_ptr<int> pInt(new int);

}


int main()
{
	cout << "C++ Template Samples." << endl;

	//sample5_1();
	//sample5_3();
	//sample5_33();
	//sample6_1();
	//sample6_8();
	//sample6_9();
	//sample2_20();
	sample_boost();

	//cout << hex;
	//cout << 12334;

	cout << "Finished" << endl;
	return 0;
}