Difference between revisions of "Writing Modules In Python"

Revision as of 14:34, 7 February 2005

Basic python module

I have tried to comment what is going on in the source. This module demonstrates callbacks, commands and using interfaces.

# demo asss python module
# dec 28 2004 smong

# nearly always use this
from asss import *


# get some interfaces
# see chat.h for where I_CHAT comes from, see other .h files for more (fx:
#  game.h)
chat = get_interface(I_CHAT)


# a callback
# this function is called when a player enters/leaves, see core.h for PA_???
#  constants
def paction(p, action, arena):
    # start indenting
    if action == PA_ENTERARENA:
        # see chat.h for the names of more functions like SendMessage
        chat.SendMessage(p, "hello " + p.name)

# tell asss to call 'paction' when CB_PLAYERACTION is signalled
# see .h files for CB_??? names
cb1 = reg_callback(CB_PLAYERACTION, paction)


# a command
# see cmdman.h for what each parameter does
def c_moo(cmd, params, p, targ):
# help text (?help moo)
    """\
Module: <py> demo
Targets: none
a sample command.
"""
    chat.SendMessage(p, "moo cows")

# tell asss to call 'c_moo' when a player types ?moo
# note: add cmd_moo to conf/groupdef.dir/default so players have permission to
#  use this command.
cmd1 = add_command("moo", c_moo)

# setting chat (or other interfaces), cb* or cmd* to None is equivalent to
#  unregistering that item.

Save this in bin/demo.py. Then ingame make sure pymod is loaded by using ?lsmod and ?insmod. Then add this module with the following command: ?insmod <py> demo. Re-entering the arena and typing ?moo should do some stuff.

Code snippets

The bread and butter of most custom modules.

Callbacks

from asss import *

chat = get_interface(I_CHAT)

def goal(arena, p, bid, x, y):
    chat.SendArenaMessage(arena, "goal.")

cb1 = reg_callback(CB_GOAL, goal) 

Commands

Useful for controlling events, fx: ?elim start. In this case the command is ?t1.

from asss import *

chat = get_interface(I_CHAT)

def c_mycmd(cmd, params, p, targ):
    """\
some help text
"""
    chat.SendMessage(p, "moo.")

cmd1 = add_command("t1", c_mycmd)
#where the "t1" is located would be the name of the command, ex: ?t1

You can parse integers from the params using the following code:

try:
    val = int(params)
except ValueError:
    # here the conversion of params from a string to an int failed.
    # change the next line to 'pass' to silently ignore the conversion error,
    # 'return' to exit the function, or 'val = 0' to set a default value to val.
    chat.SendMessage(p, "Integer parameter required.")

Per-player/arena data

Use this to store game state, player score, etc.

def shipchange(p, newship, newfreq):
    # prefix mymod_ an abbreviation of your module name to the variable
    #  so that it doesn't clash with other modules. per arena data works
    #  in exactly the same way.
    p.mymod_lastship = p.ship

cb1 = reg_callback(CB_SHIPCHANGE, shipchange)

Attach/Detach

Attaching and detaching is similar to load/unload in a C module except it is arena specific. So you can use it to initialise per-arena data.

def mm_attach(arena):
    # do stuff with arena
def mm_detach(arena):
    # undo stuff

Looping over all players

This example counts the number of players in an arena.

def count_players(arena):
    # a list must be used as all other variables are immutable to
    #  nested functions.
    players = [0]
    def cb_count(p):
        if p.arena == arena:
            players[0] = players[0] + 1
    for_each_player(cb_count)
    return players[0]

Timers

Good for checking if a game is over yet. A reference to the timer is returned and must be retained (you can use per-arena data to store it). Losing the reference will cancel the timer.

initial is the time in 1/100th's of a second before the nested function timer() will be called, you can cancel the timer before it is called. interval is the time gap, again in 1/100th's of a second between all future calls of timer(). So make_hello_timer(100, 200, arena) will make it send the arena message "hello" every 2 seconds starting from 1 second after make_hello_timer() was called.

The parameter arena is needed in this case because SendArenaMessage() requires an arena parameter.

def make_hello_timer(initial, interval, arena):
    def timer():
        # announce
        chat.SendArenaMessage(arena, "hello")
        # non-repeating timer. return 1 for it to be called after the next interval
        return 0
    return set_timer(timer, initial, interval)

def somefunc(arena):
    # create a hello timer that will execute after 1 second, and then every
    #  2 seconds until cancelled. timers can cancel themselves, see above.
    myref = make_hello_timer(100, 200, arena)

    # cancel the timer by losing the reference to it
    myref = None

Regions

This is untested but it should go something like this:

mapdata = get_interface(I_MAPDATA)

# regionname is a string, x and y are map tile coords.
def region_contains(arena, regionname, x, y):
    success = 0

    rgn = mapdata.FindRegionByName(arena, regionname)

    if rgn != None and mapdata.Contains(rgn, x, y):
        success = 1

    return success

It is a good idea to cache rgn within per-arena data so you don't add unecessary load to the server looking it up everytime.

Trouble shooting

Look at the asss console for execution errors (at the time of writing not all errors are relayed to logged in staff), and if that doesn't help, add some chat.SendArenaMessage(ALLARENAS, "i'm at line ...") type messages to locate the buggy piece of code.