Re: Type traits
On Mar 1, 8:47 am, Asif Zaidi <asifnza...@gmail.com> wrote:
Hi:
I am following the dochttp://boost.cowic.de/rc/pdf/type_traits.pdf
and trying to do the example from pg 4. I want to create my own
'is_pointer' trait. I have done this as shown in code below, and am
trying to test it as shown below.
When I don't have the 'debug0' & 'debug1' statements in my is_pointer
templates, I can compile. But when I do have them, I get compile
errors. What am I missing - and how can I test my code ?
I want to see if 'a' is a pointer.
Plz advise.
Thanks
Asif
====
#include <iostream>
#include <boost/type_traits.hpp>
using namespace boost;
using namespace std;
namespace my_namespace
{
template <typename T> struct is_pointer : public =
false_type
{ cout << "debug0" << endl; };
template <typename T> struct is_pointer<T*> : public true=
_type { cout
<< "debug1" << endl; };
}
You can't have executable statements directly as part of a class.
They need
to be part of a member function.
Try:
template <typename T> struct is_pointer :
public false_type
{
is_pointer() { cout << "debug0" << endl; }
};
template <typename T> struct is_pointer<T*> :
public true_type
{
is_pointer() { cout<< "debug1" << endl; }
};
int main ( )
{
my_namespace::is_pointer<int> a;
return 0;
}