So i finnished writing some basic network code, and thought about the in game commands. I wanted to be able to turn, lets say
"app.quit()"
and in game make the game quit. I started now by writing
if(ClassDepth[0]=="app")
{
if(ClassDepth[1]=="quit"){app.quit();}
}
but it will take a long time to re write everything. is there any way to make this easier?
0
C++ turning "APP.QUIT()" (a string) into actual code
Started by bennettbugs, Feb 17 2012 05:19 PM
13 replies to this topic
Ad:
#2 Senior Moderators - Reputation: 2448
Posted 17 February 2012 - 05:28 PM
You want a parser. Or tie in a simple scripting language like lua.
In time the project grows, the ignorance of its devs it shows, with many a convoluted function, it plunges into deep compunction, the price of failure is high, Washu's mirth is nigh.
ScapeCode - Blog | SlimDX
ScapeCode - Blog | SlimDX
#5 Members - Reputation: 1199
Posted 17 February 2012 - 08:06 PM
You could also look at using a map using the command string as the key and a function pointer as the value, it should be enough if you don't have all that many commands to deal with and you don't need to pass parameters to them (If you need to pass parameters to functions them it gets messy really fast), for a large number of commands or more complex commands then something like lua is definitly the way to go. (its extremely easy to execute lua scripts in C or C++ and also quite easy to expose C functions to lua, exposing full C++ classes to lua is a bit more work but there are third party libraries(luabind, tolua for example) that help with that.
I don't suffer from insanity, I'm enjoying every minute of it.
The voices in my head may not be real, but they have some good ideas!
The voices in my head may not be real, but they have some good ideas!
#6 Members - Reputation: 1170
Posted 18 February 2012 - 12:45 AM
Assuming C++:
If your actions need parameters, you might pass those via a stack, once parsed out of the command string, and each action's invoke() method would attempt to pop them as needed before use (with appropriate checking for underflow).
I'd also agree that Lua is a good idea in principle, but it might actually be more work to do it that way, especially to someone that's relatively new to C++. On the other hand, using a proper scripting language opens up your code to all kinds of other possibilities...
struct action : uncopyable
{
action() { }
virtual ~action() { }
virtual void invoke() = 0;
};
struct quit_action : action
{
quit_action(Application &app) : app(app) { }
virtual void invoke() { app.quit(); }
Application &app;
};
// ...
std::map<std::string, shared_ptr<action> > actions;
actions["quit"].reset(new quit_action(the_app));
// ...
bool do_action(const std::string &name)
{
std::map<std::string, shared_ptr<action> >::iterator f = actions.find(name);
if (f != actions.end())
{
(*f)->invoke();
return true;
}
return false;
}
If your actions need parameters, you might pass those via a stack, once parsed out of the command string, and each action's invoke() method would attempt to pop them as needed before use (with appropriate checking for underflow).
I'd also agree that Lua is a good idea in principle, but it might actually be more work to do it that way, especially to someone that's relatively new to C++. On the other hand, using a proper scripting language opens up your code to all kinds of other possibilities...
#7 Members - Reputation: 1216
Posted 18 February 2012 - 02:40 AM
Well, this'll be complete overkill for your game, but if you really wanted a nice, extendable solution, Thrift is a good option, as it helps manage serializing data (i.e. you give it a data structure and it constructs a compact message representing that data which you can pass through the network) and RPC (Remote Procedure Call, which is exactly what you're asking about now).
[edit]
Google's protocol buffers (protobuf) apparently does RPC too.
[edit]
Google's protocol buffers (protobuf) apparently does RPC too.
[ Realistic Rendering ] [ School + Dublin = Boom ] [ I've been ninja'd 70 times ] [ f.k.a. MikeTacular ] [ My Blog ]
#9 Members - Reputation: 1216
Posted 18 February 2012 - 03:02 PM
IceBreaker23, on 18 February 2012 - 11:29 AM, said:
You could use reflection. It turns strings into real code in runtime. Don´t know how to do this in c++. Java has its own class for this.
[ Realistic Rendering ] [ School + Dublin = Boom ] [ I've been ninja'd 70 times ] [ f.k.a. MikeTacular ] [ My Blog ]
#10 Members - Reputation: 110
Posted 20 February 2012 - 08:56 AM
Cornstalks, on 18 February 2012 - 03:02 PM, said:
IceBreaker23, on 18 February 2012 - 11:29 AM, said:
You could use reflection. It turns strings into real code in runtime. Don´t know how to do this in c++. Java has its own class for this.
Didnt knew that
Is there no way to do this?Oh, i forgot java/c# gets interpreted and c++ is an executeable.
#11 Members - Reputation: 2303
Posted 20 February 2012 - 09:18 AM
IceBreaker23, on 20 February 2012 - 08:56 AM, said:
Oh, i forgot java/c# gets interpreted and c++ is an executeable.
On Android, Java is statically compiled, exactly the same way as C++.
On most modern x86 CPUs even native code is "interpreted", at very least the instructions that CPU executes are defined via microcode rather than being implemented directly.
Quote
Didnt knew that Is there no way to do this?
Is there no way to do this?Of course there is, it's just a bit of work. Structure data must either be manually defined or somehow generated by compiler or some other tool.
C++ doesn't offer reflection out-of-box due to optimization. A compiler is free to remove anything it deems redundant, including structures and functions. Full reflection would require preserving even unused parts. Templates in particular cause unacceptable overhead without such optimization.
#12 Members - Reputation: 110
Posted 21 February 2012 - 02:21 PM
Antheus, on 20 February 2012 - 09:18 AM, said:
IceBreaker23, on 20 February 2012 - 08:56 AM, said:
Oh, i forgot java/c# gets interpreted and c++ is an executeable.
On Android, Java is statically compiled, exactly the same way as C++.
On most modern x86 CPUs even native code is "interpreted", at very least the instructions that CPU executes are defined via microcode rather than being implemented directly.
Quote
Didnt knew that Is there no way to do this?
Is there no way to do this?Of course there is, it's just a bit of work. Structure data must either be manually defined or somehow generated by compiler or some other tool.
C++ doesn't offer reflection out-of-box due to optimization. A compiler is free to remove anything it deems redundant, including structures and functions. Full reflection would require preserving even unused parts. Templates in particular cause unacceptable overhead without such optimization.
Really usefull knowledge
Thank you.
#13 Members - Reputation: 697
Posted 21 February 2012 - 02:30 PM
Antheus, on 20 February 2012 - 09:18 AM, said:
On Android, Java is statically compiled, exactly the same way as C++.
#14 Members - Reputation: 2303
Posted 21 February 2012 - 05:18 PM
Martins Mozeiko, on 21 February 2012 - 02:30 PM, said:
Antheus, on 20 February 2012 - 09:18 AM, said:
On Android, Java is statically compiled, exactly the same way as C++.
