• 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
KaiserJohan

Interface woes, windows header and coupling

3 posts in this topic

Hello,

Kinda vague title, but I'll try to explain below:

I have two interfaces, IMutex and IConditionVariable, and behind them the concrete implementations.
These are created/destroyed by a factory class.

IMutex looks like this:

[CODE]class IMutex
{
public:
enum MutexState
{
UNLOCKED = 0,
LOCKED
};
virtual ~IMutex() { }
virtual int32_t Lock() = 0;
virtual int32_t Unlock() = 0;
virtual const MutexState& GetMutexState() const = 0;
};
[/CODE]

IConditionVariable looks like this:

[CODE]class IConditionVariable
{
public:
enum ConditionVariableState
{
READY,
WAITING
};
virtual ~IConditionVariable() { }
virtual void Wait(IMutex* mutex) = 0;
virtual void TimedWait(IMutex* mutex, uint32_t milliseconds) = 0;
virtual void Signal() = 0;
virtual void Broadcast() = 0;
virtual const ConditionVariableState& GetConditionVariableState() const = 0;
};
[/CODE]

Two question:

1.
In the implementation of condition variable, I need to have the native mutex handle behind the IMutex so I can pass it to pthreads/windows api. But currently there is no way to aquire it.

To this I have two solutions:[list]
[*]Make IConditionVariable a friend of IMutex, typedef the native handle and make it a protected member variable. Don't like this one very much, they shouldn't be coupled?
[*]Add a method to IMutex "GetNativeHandle" which returns the underlying platform handle. Also requries me to typedef the native handle. I like this one better, but I'd rather encapsulate the handle.
[/list]
I prefer the second option, but is there any other way?


2,
In both cases above, I need to typedef the native handle in the interface, either to return it or to declare it as a protected member

[CODE]#if defined _WIN32 || _WIN64
typedef CRITICAL_SECTION MutexHandle;
#else
typedef pthread_mutex_t MutexHandle;
#endif[/CODE]

But, for windows I need the definition of CRITICAL_SECTION. The only solution I have found is to include the <windows.h> with WIN32_LEAN_AND_MEAN... but I'd rather not have to include the windows header in an interface file.
How can I solve this one? Edited by KaiserJohan
0

Share this post


Link to post
Share on other sites
IMHO, it's not a big deal if those two classes are coupled, because they're both such small thin wrappers around different parts of the same API. I'd probably even implement them in the same file.
I wouldn't want to expose the native handle type via a typedef, as this requires that the user of "IMutex" has to include the windows headers -- preferably, only the CPP that implements the mutex interface should have to carry that burden.
Lastly, I wouldn't bother using polymorphism here, as you're deciding which implementation of the interface to use at compile-time, not run-time.

If the internal types are being hidden behind a factory API, I'd use something like:[code]//threadtypes.h
class Mutex
{
public:
int32_t Lock();
protected:
Mutex(){}
};
class ConditionVariable
{
public:
void Wait(Mutex* mutex);
protected:
ConditionVariable(){}
};

//threadtypes.cpp
class MutexWin32 : public Mutex
{
public:
CRITICAL_SECTION cs;
}
namespace {
MutexWin32& Members(Mutex& p) { return *(MutexWin32*)&p; }
}

int32_t Mutex::Lock() { EnterCriticalSection(&Members(*this).cs); }

void ConditionVariable::Wait(Mutex& mutex)
{
CRITICAL_SECTION& cs = Members(mutex).cs;
...
}[/code]
0

Share this post


Link to post
Share on other sites
How can you design this Without having a factory class creating it btw, and still avoiding having to include windows header? Edited by KaiserJohan
0

Share this post


Link to post
Share on other sites
Here's a few options:

1) Use factory functions[code]//threadtypes.h
class Mutex
{
public:
static Mutex* Create();
static void Release(Mutex*);
};

//threadtypes.cpp
Mutex* Mutex::Create() { return new MutexWin32; }
void Mutex::Release(Mutex* m) { delete (MutexWin32*)m; }[/code]
2) split it over two headers. Regular users of the mutex only need the regular "*.h", but creators of mutexes need the bloated "*_imp.h" header.
[code]
//threadtypes.h
class Mutex
{
...
protected:
Mutex(){}
};

//threadtypes_imp.h
#include "threadtypes.h"
#include "windows.h"
class MutexWin32 : public Mutex
{
...[/code]
3) Use PIMPL
[code]//threadtypes.h
class Mutex
{
public:
Mutex();
~Mutex();
int32_t Lock();

private://non-copyable:
Mutex(const Mutex&);
Mutex& operator=( const Mutex& );

void* pimpl;
};

//threadtypes.cpp
class MutexWin32
{
public:
int32_t Lock() {...}
private:
CRITICAL_SECTION cs;
}

Mutex::Mutex() : pimpl(new MutexWin32) {}
Mutex::~Mutex() { delete (MutexWin32*)pimpl; }
int32_t Mutex::Lock() { return (((MutexWin32*)pimpl)->Lock(); }[/code]
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