• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Misery

Partial template specialization

7 posts in this topic

Hello,

I am trying to create a matrix template class. I would like Sum() function to act differently for bool types. What I need to make it elegant class is partial template specialization. How do I do it?

[code]

template <class DATA,class INT_TYPE>
class TMatrix
{
private:
DATA *d;
INT_TYPE rows,cols;

public:
DATA Sum(); //count the sum of element
// for bool data type I would like to get:
INT_TYPE Sum(); //counts the number of elements that are true, so it cannot return bool, but INT_TYPE instead
}

[/code]

And how do I create definition of such function outside the class?

Thanks in advance,
Regards,
Misery
0

Share this post


Link to post
Share on other sites
You could do something like this:
[code]
template<typename T>
struct sum_traits;

template<typename T>
class matrix {
public:
typedef typename sum_traits<T>::sum_type sum_type;

sum_type sum() const;
};
[/code]
The nice thing about this is that it is general - the sum_type for char/short should probably be longer than the data type itself - at least a full int if not a long.

Example:
[code]

#include <vector>
#include <cstdlib>
#include <iostream>

template<typename T>
struct sum_traits;

template<typename T>
class example {
public:
void add(T item) {
data.push_back(item);
}

typedef typename sum_traits<T>::sum_type sum_type;

sum_type sum() const {
sum_type result = 0;
for(int i = 0 ; i < data.size() ; ++i) {
result += data[i];
}
return result;
}

private:
std::vector<T> data;
};

template<>
struct sum_traits<int> {
typedef long sum_type;
};

template<>
struct sum_traits<bool> {
typedef int sum_type;
};

int main() {
example<int> a;
for(int i = 0 ; i < 10 ; ++i ) {
a.add(std::rand());
}
a.add(0xffffff00);

std::cout << "Sum<int>: " << a.sum() << '\n';

example<bool> b;
for(int i = 0 ; i < 10000 ; ++i) {
b.add(std::rand() > (RAND_MAX / 2));
}
std::cout << "Sum<bool>: " << b.sum() << '\n';
}
[/code]
2

Share this post


Link to post
Share on other sites
It looks qute nice, but i would like to use usual template specialization in manner like:
[code]
template <class INT_TYPE>
INT_TYPE Matrix<bool,INT_TYPE>::Sum()
{
//sum all true elements
}
[/code]

How doI do that? My compiler always returnsan error saying that this function template requires two elements.
0

Share this post


Link to post
Share on other sites
You can't specialize individual member functions of a template class without specializing the entire class.
1

Share this post


Link to post
Share on other sites
A somewhat cheap trick to get around "specialize the whole class" thing is to create a helper class that only contains the sum functionality and inherit from that, that way you only have to specialize that one. The other way around works too obviously put the non special functionality into a base class and only specialize classes that inherit from it.
1

Share this post


Link to post
Share on other sites
Well, thinking on this again, the simpler solution that might suffice is default template arguments:
[code]

#include <vector>
#include <cstdlib>
#include <iostream>

template <typename type, typename size_type, typename sum_type = type>
class example
{
public:
sum_type sum() const {
sum_type result = 0;
for(int i = 0 ; i < data.size() ; ++i) {
result += data[i];
}
return result;
}

void add(type item) {
data.push_back(item);
}


private:
std::vector<type> data;
};

int main() {
example<int> a;
for(int i = 0 ; i < 10 ; ++i ) {
a.add(std::rand());
}
a.add(0xffffff00);

std::cout << "Sum<int>: " << a.sum() << '\n';

example<bool> b;
for(int i = 0 ; i < 10000 ; ++i) {
b.add(std::rand() > (RAND_MAX / 2));
}
std::cout << "Sum<bool>: " << b.sum() << '\n';
}
[/code]
You can now create a typedef for bool_matrix as something like matrix<bool, size_t, size_t>.
1

Share this post


Link to post
Share on other sites
Actually, at last I decided to derive BoolMatrix class from Matrix class. The main problem I was trying to work around was that I wanted to use BoolMatrix argument in one of the Matrix methods. And the second problem was that I needed to make it possible to change the INT_TYPE used to matrix indexing, because in MSVC OpenMP works only on signed long int and I also use GCC and Intel Compiler.
Anyway, as always, thanks to You Guys I have tested a few very clever solutions and achieved the goal.
Thanks and regards [img]http://public.gamedev.net//public/style_emoticons/default/biggrin.png[/img]
0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0