[c++] Template Programming

typedef double T1;
typedef add_const<T1>::type T2;
T2 x = 3.14;
bool b1 = is_const<T2>::value;

typedef double T3[4];
typedef add_const<T3>::type T4;
T4 a = {1,2,3,4};

bool b2 = is_const<T4>::value;
bool b4 = is_const<T3>::value;


int main()
{
         cout << "type T2: " << typeid(T2).name() << endl;
         cout << "type T4: " << typeid(T4).name() << endl;
         cout << "b1: " << b1 << endl; //true
         cout << "b2: " << b2 << endl; //true
    return (0);
}

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qualifiers applied to a reference are ignored
tricky const with typeid.

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undefined template type : C++ Meta P.171

class<>

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There's NO partial template friendship!
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Bad coding style:
1. Lack of non-virtual protected destructor in (empty) base class
2. implementing cast operators

operator T() const

3.Declaring a non-explicit constructor with a singl argument.
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