game engine (as in rules not graphics)

Aaron Brady castironpi at
Sun Dec 28 01:21:33 CET 2008

On Dec 27, 3:02 pm, Martin <mar... at> wrote:
> Hello,
> I'd like to get in touch with game development a bit. I'm not talking
> about graphics but rather the game rules itself. Something like, is there even a
> general approach to that or should I just go sketch up my rules and
> try to implement them. Being totally new to this topic I don't quite
> now what to search for to get some decent results that let me make a
> mental link between game rules and what the best practices are to
> implement them in python (or any other programming language)
> thanks,
> martin

Not my expertise but here are my $0.02.  You are looking for ways to
represent rules: buying a house is legal in such and such situation,
and the formula for calculating its price is something.  You want
"predicates" such as InJail, OwnedBy, Costs.

Costs( New York Ave, 200 )
InJail( player2 )
OwnedBy( St. Charles Ave, player4 )
LegalMove( rolldie )
LegalMove( sellhouse )

There are rule-based languages out there, such as Prolog.  They are
equally expressive as Python (you can write a Turing machine in them),
but they are more convenient for representing rules in a prog.

Predicates are more or less equivalent to positive assertions about

NewYorkAve.cost= 200
player2.injail= True...
rolldie.islegal= True

Some predicates have to be calculated, rather than stored, but Python
descriptors go easy on you for that.  Someone else will have to tell
you how rule-based programming measures up against object-oriented
programming.  <passes mic.>

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