[MUD-Dev] i got's a question for yall on the best way to do something..

[Jim Clark]

You still want a state machine, but that horrible 1000 line switch is not
a good way to implement a state machine. The first step to make a decent
deterministic state machine would be to write down a list of states:

connect -> login -> new char -> new char passwd -> ect..
             |
             -----> old char -> get old char password -> playing
                                       |
                                       --> bad password

After you have a decent map of state transitions, you can get down
to the implementation. (It's been a few years since I did any large
state machines so bear with me)

First create a nice list of constants, one for each state.
const int STATE_CONNECT = 0;
const int STATE_LOGIN = 1;
const int STATE_OLD_CHAR = 2;
const int STATE_NEW_CHAR = 3;
ect..

const int MAX_STATE = 20; // Or whatever

Then make a large table which maps old state vs. next state.
With function pointers


const STATEHANDER STATE_TABLE[MAX_STATE][MAX_STATE] =
{
//         Next State (the one we are moving to)
//               Connect  Login   Old Char  NewChar
/* Connect  */ { NULL,    Login,  NULL,     NULL    },
/* Login    */ { NULL,    NULL,   OldChar,  NewChar },
/* Old Char */ { NULL,    NULL,   NULL,     NULL    },
/* New Char */ { NULL,    NULL,   NULL,     NULL    }
};

This table defines the links between states, as well as where to go next.
Some function such as this will handle that.

void HandleState( Ch* pCh, const String& strIn )
{
    // I can't rember if this is the right member function
    // syntax, and I'm to lazy to dig it up
    // And you should of course check for NULL's
    pCh->*( STATE_TABLE[pCh->m_nLastState][pCh->m_nCurrState] )( strIn );
}

And lastly an example of a STATEHANDLER, in psuado code

void Ch::Login( const String& strIn )
{
    if( strIn IS AN old player )


        m_nLastState = m_nCurrState;
        m_nCurrState = STATE_OLD_CHAR;
        Out( "some message about entering a password" );
    }
    else
    {
        m_nLastState = m_nCurrState;
        m_nCurrState = STATE_NEW_CHAR;
        Out( "some message about new characters and some instructions about
entering a new password" );
    }
}

-Jim

----- Original Message -----
From: <PartyG2816 at aol.com>
To: <mud-dev at kanga.nu>
Sent: Thursday, June 17, 1999 2:55 AM
Subject: [MUD-Dev] i got's a question for yall on the best way to do
something..


> Ok, any of yall familiar with the ROM code base? Tis a text based mud.
Well,
> they handle character creation via this big, ugly, confusing state
machine..
> Hard as hell to find stuff in, and just a bitch to look at.   Well, I've
> finally got around to starting my own mud in C++, tired of modifying ROM's
> and Oblivions yadda yadda, and gotten to the point where I need to figure
out
> a way to handle this.. The only way I know of doing it is via a big ugly
> state machine like ROM and most of the other's that I've seen use.. Mainly
> the Diku derivatives.  What are some other ways a person might go about
doing
> it? Any input would be greatly appreciated.. And if you need more info on
> what I'm talking about, just ask and I'll try to supply ;-)
>
> Thanx,
> JD





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