写模版多了的人,必然会遇到这样那样的问题,模版特例化就是解决了一个经常碰见的问题:如果我们需要根据某些特殊的模版参数类型来重新实现一下算法的话,该怎么办呢?说的多了那也没什么用,我们就写一个会做除法的类吧。这个类在做整数除法的时候会同时求出余数,而在算其他类型时是不求的。代码如下:
1
#include <iostream>
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4
template<typename Ty>
5
class Division
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{
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public:
8
Division(Ty dividend, Ty divisor)
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:mDividend(dividend), mDivisor(divisor)
{}
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public:
11
void show()
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{
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std::cout<<"结果 = "<<mDividend/mDivisor<<std::endl;
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}
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Ty mDividend, mDivisor;
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};
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template<>
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inline void Division<int>::show()
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{
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std::cout<<"结果 = "<<mDividend/mDivisor<<std::endl;
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std::cout<<"余数 = "<<mDividend%mDivisor<<std::endl;
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}
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int _tmain(int argc, _TCHAR* argv[])
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{
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Division<int> a(20, 11);
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a.show();
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Division<float> b(20.0f, 11.0f);
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b.show();
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return 0;
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}
以上这种方式就叫做局部特化,关于全部特化和局部特化、全特化和偏特化,我认为他们之间的关系很紧密,界限也很模糊,硬要分类的话,以上面的Division类为例,就看下面的代码对全部特化和局部特化的区别吧:
1 /**
2 @remark
3 Division的全部特化
4 */
5 template<>
6 class Division<int>
7 {
8 public:
9 Division(Ty dividend, Ty divisor)
10 :mDividend(dividend), mDivisor(divisor){}
11 public:
12 void show()
13 {
14 std::cout<<"结果 = "<<mDividend/mDivisor<<std::endl;
15 std::cout<<"余数 = "<<mDividend%mDivisor<<std::endl;
16 }
17
18 Ty mDividend, mDivisor;
19 };
20
21 /**
22 @remark
23 Division的局部特化
24 */
25 template<>
26 inline void Division<int>::show()
27 {
28 std::cout<<"结果 = "<<mDividend/mDivisor<<std::endl;
29 std::cout<<"余数 = "<<mDividend%mDivisor<<std::endl;
30 }
上面的代码只是说明了全部特化和局部特化,并没有说明什么事全特化和偏特化。其实,对于只有一个参数的模版类型来说,并没有什么全特化和偏特化的区别,但如果是一个以上的模板参数,那就是由区别的了,如下:
1 /**
2 @remark
3 原始模板类
4 */
5 template<typename Ty, typename TyEx>
6 class ObjectData
7 {
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9 };
10
11 /**
12 @remark
13 Object的全特化
14 */
15 template<>
16 class ObjectData<int, float>
17 {
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19 };
20
21 /**
22 @remark
23 Object的偏特化,只特化第一个参数
24 */
25 template<typename TyEx>
26 class ObjectData<int, TyEx>
27 {
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29 };
以上仅为个人观点,错误之处请指正。