Re: Unrolling loops using templates
On 3/3/2011 12:32 PM, Ashley wrote:
I'm trying to unroll a loop that prints down numbers from the given
number down to 0. I get the following error on Sun C++ 5.5 Patch
113817-12.
-------------------------
"tmp.cpp", line 15: Error: explicit specialization is not allowed in
the current scope.
"tmp.cpp", line 24: Where: While specializing
"printDownContainer<int>".
"tmp.cpp", line 24: Where: Specialized in non-template code.
"tmp.cpp", line 24: Error: Template parameter T requires a type
argument.
-------------------------
How can I correct this? I want to generalize the type of the counter
i. Here's the code.
-------------------------
#include<iostream>
template< typename T>
struct printDownContainer
{
template< T i>
struct printDown {
static void run(void) {
std::cout<< i<< "\n";
printDown< i - 1>::run();
}
};
template< >
struct printDown< 0> {
static void run(void) {
std::cout<< 0<< "\n";
}
};
};
int main(void)
{
printDownContainer< int>::printDown< 10>::run();
return 0;
}
-------------------------
You can't define/declare a specialization in the class template body.
And you can't specialize a member without specializing the class. What
you could do is to extract your 'printDown' functionality into a
separate template with two arguments and provide a partial
specialization for it:
template<class T, T i> struct printDownHelper {
...
};
template<class T> struct printDownHelper<T,0> {
...
};
And then in your 'printDownContainer' just forward the request to the
helper:
tempate<class T> struct printDownContainer {
tempate<T i> printDown {
static void run() {
printDownHelper<T,i>::doit();
}
}
};
V
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