I have a template class (for numerical processing) that was originally
written for real data that I need to extend to complex data, and I am
running into a problem. The current version (greatly simplified) has
something like
template <class T>
class FOO {
T A;
T B;
};
which works fine with T as any floating point type (float, double, etc.).
With complex data however, I would want A to be type complex<T> and B to
be type T. As the operations are identical for both real and complex
data (B represents the absolute value/magnitude of type of A) and the
actual template is quite large, I want to use the same template for both.
The obvious solution is to rewrite it as
template <class DATA, class ABS_TYPE>
class FOO {
DATA A;
ABS_TYPE B;
}
which can be instantiated with FOO<float, float>,
FOO<complex<double>, double>, etc., but that would break existing code
and add a possibility for error (FOO<complex<double>, float> would be
a disasterous loss of precision). Is there a way to get a template
to recognize automatically that B should be type T when A is instantiated
as either T or complex<T>? 2 1638
Jim West wrote in
news:sl**************************@jwest.ecen.oksta te.edu:
[snip] template <class T> class FOO { T A; T B; };
which works fine with T as any floating point type (float, double, etc.). With complex data however, I would want A to be type complex<T> and B to be type T. As the operations are identical for both real and complex data (B represents the absolute value/magnitude of type of A) and the actual template is quite large, I want to use the same template for both. The obvious solution is to rewrite it as
template <class DATA, class ABS_TYPE> class FOO { DATA A; ABS_TYPE B; }
which can be instantiated with FOO<float, float>, FOO<complex<double>, double>, etc., but that would break existing code and add a possibility for error (FOO<complex<double>, float> would be a disasterous loss of precision). Is there a way to get a template to recognize automatically that B should be type T when A is instantiated as either T or complex<T>?
template < typename T >
struct extract_real
{
typedef T type;
};
template < typename T >
struct extract_real< std::complex< T > >
{
typedef T type;
};
template < typename T >
class FOO
{
T A;
typename extract_real< T >::type B;
};
HTH
Rob. -- http://www.victim-prime.dsl.pipex.com/
In article <Xn**********************************@195.129.110. 131>, Rob Williscroft wrote:
<solution to my problem snipped>
Worked perfectly, of course. I never, ever would have come up with that.
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