C++ for Scientists - Technische Universität Dresden

5.4. META-TUNING: WRITE YOUR OWN COMPILER OPTIMIZATION 159
The print-outs shall show us the execution. For convenience, one can templatize the operator
on the argument types:
template
struct fsize assign
{
template
void operator()(Target& tar, const Source& src)
{
fsize assign()(tar, src);
std::cout ≪ ”assign entry ” ≪ N ≪ ’\n’;
tar[N]= src[N];
}
};
template
struct fsize assign
{
template
void operator()(Target& tar, const Source& src)
{
std::cout ≪ ”assign entry ” ≪ 0 ≪ ’\n’;
tar[0]= src[0];
}
};
Then the vector types can by deduced by the compiler when the operator is called. Instead of
the previous loop, we call the assignment functor in the operator:
template
class fsize vector
{
BOOST STATIC ASSERT((my size > 0));
};
self& operator=( const self& that )
{
fsize assign()(∗this, that);
return ∗this;
}
template
self& operator=( const Vector& that )
{
fsize assign()(∗this, that);
return ∗this;
}
The execution of the following code fragment
yields
fsize vector v, w;
v[0]= v[1]= 1.0; v[2]= 2.0; v[3]= −3.0;
w= v;