Paolo Crosetto wrote:
Dear all,
I am writing an application in Python for an experiment in Experimental
Economics.
For those who do not know what this is: experimental economics uses
controlled, computerised lab experiments with real subjects, putting the
subject in a game mimicking the situation of interest and collecting
behavioural data about choices made.
Hence, experiments involve the use of a multi-client architecture with one
server, and are sort of online games, with actions taken by clients and
computation, data collection, etc... handled by servers.
I chose to use Python because I needed something flexible, powerful and easy -
I am a beginner programmer.
My game is a sort of scrabble, with palyers buying letters and producing words
or extending existing words. I use a pipe to ispell -a for spellcheck, XMLRPC
for the server-client infrastructure, and have developed all the rules of the
game as server functions, called by a client. States of players and of words
created are stored in instances of two basic classes, Player and Word, on the
server side.
The problem I now face is to organise turns. Players, as in Scrabble, will
play in turns. So far I have developed the server and ONE client, and cannot
get my head round to - nor find many examples of - how to simply develop a
turn-based interaction.
I basically need the server to freeze in writing all the clients while client
i is playing, then when i is over passing the turn to i+1; clients are still
accessible by the server at any time (the payoff of a player changes even as
she is not playing, by royalties collected from other players extending her
words).
In another thread (about a battleship game) I found two possible leads to a
solution:
1. using 'select'.
2. using threads.
But in both cases I could not find any clear documentation on how to do this.
The 'select' road was said to be the easiest, but I found no further hints.
Does anyone have any hints?
As I understand your description, the server and each client will be a
separate process on a separate machine (once deployed), so threads do
not seem applicable. (For development, you can use separate processes on
one machine communicating through sockets just as if they were on
multiple machines.) As I understand select, it is for select *any*
available client input, not just one in particular. I believe the
standard solution is to define a 'turn token' and write the clients so
that they only do 'turn' activities when and only when they have that
token. I presume you do not need to worry about players trying to cheat
by rewriting the client.
tjr
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