[英]c++ template: Create a specialized function for a specific data type
I have a template Node
below for storing some data in an array. 我在下面有一个模板Node
,用于在数组中存储一些数据。 Before adding I want to check if an entry is present with the same value (my insert logic needs it). 在添加之前,我想检查条目是否存在具有相同的值(我的插入逻辑需要它)。 For string type, i want to implement a specific method for comparison. 对于字符串类型,我想实现一个特定的比较方法。
template <class T> class Node
{
private:
short noOfEntries;
T data[MAX_VALUES];
public:
Node () { noOfEntries = 0; }
int Compare(int index, T *key);
int Insert(T *key);
};
template <class T>
int Node<T>::Compare(int index, T *key)
{
if(data[index] > *key)
return 1;
else if(data[index] == *key)
return 0;
return -1;
}
template <>
class Node <string> {
public:
int Compare(int index, string *key)
{
return (data[index].compare(*key));
}
};
This gives error as the attributes 'data' and 'noOfEntries' are not in class Node <string>
. 这会产生错误,因为属性'data'和'noOfEntries'不在Node <string>
。 It seems that I will have to put ALL the attributes from Node to the specialized version for string. 似乎我必须将Node的所有属性都放到字符串的专用版本中。 Same thing for methods too. 方法也是如此。
Is there a better way so that I will have just one insert method defined for Node which will invoke correct compare() method depending on the actual type of T ? 有没有更好的方法,以便我只有一个为Node定义的插入方法,它将调用正确的compare()方法,具体取决于T的实际类型? I want to avoid duplication of the methods. 我想避免重复这些方法。
Just specialize the one member: 只专注一个成员:
template <> int Node<std::string>::Compare(int index, std::string *key)
{
return (data[index].compare(*key));
}
A more idiomatic way to do this would be to use a comparison policy template argument, or possibly a traits describing the default comparison policy for the element type. 更常用的方法是使用比较策略模板参数,或者可能使用描述元素类型的默认比较策略的特征。
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