create custom functions for objects

Game Engine Game Engine Support and Discussion
1

Hey all…
I have a question that recently came up!

Is it possible to create my own functions and use them through the object. Here is an example:

i have 2 scripts:

func.py


import bge

def func():
    print(obj.name)

script.py


import bge
from func import func

def main(c):
    obj = c.owner
    
    if 'init' not in obj:
        obj['init'] = True
        obj.func = func

    obj.func()

Is something in this direction possible. This would be really awesome to extend the gameobject!! Or do I have to modify the bge code itself to create such type of functions?

2

functions can be added as methods to an existing instance object, python permits this so yes it is possible. here is an example

assuming you have already an instance obj called obj and it has a method called func1 you can call it like this

obj.func1()

so far so good

if you define a function called func2 like

def func2(): print("hello I am the second method")

in order to attach to the object all you have to do is this

objc.func2 = func2

observe the lack of parantheses
after this assignment you can call the method normally as expected

obj.func2()

the reason this can happen is that functions are objects so in this case you created a reference back to your function definition in the object. In short an object inside another object , isnt it fun ? :smiley:

you can use this to even rename existing methods though the method still can be called by the original names you can add a secondary name that makes more sense to you

for example lets say you dont like func1 as name you can do this


obj.first_function = obj.func1
obj.first_function()
3

@kilon
thanks for your answer!
that’s what I tried. Note, that obj is my KX_GameObject.

import bge

def func():
    print("Hello World!")


c = bge.logic.getCurrentController()


obj = c.owner
obj.func = func


obj.func()

Unfortunately I get this error message. Do I miss something?


File "Text", line 9, in <module>
AttributeError: 'KX_GameObject' object has no attribute 'func'
4

Ok… I got it working!!!
I needed to create a custom KX_GameObject class before, that inherited from the main KX_GameObject class. And then I could put my own functions into that class!!
Great!

Thanks kilon!!

Thats what it looks like now:

mainscript.py

import bgefrom myObject import myObject


def main(c):
    
    obj = myObject(c.owner)
    
    def func():
        print('Hallo Welt')
        
    obj.test = func
    
    obj.test()   
    obj.localLinearVelocity.x = 10

myObject.py

import bge



class myObject(bge.types.KX_GameObject):
    def __init__(self, obj):
        pass
        
    def update(self):
        print("Hallo Welt!")
5

you dont need the function-assignment, as long as you use your object-functions

6

what do you mean exactly?
I don’t want to use object-functions, thats why I want to create custom functions and put them into my objects… :slight_smile:

7

You may experience some problems because blender has the nasty habit of making some data ready only , so i am not sure the type of reaction that you going to have if you do this. And this is why i don’t find The blender Python API, at all pythonic. But generally is a good idea to create your own objects and classes and clean up all that mess.

And to be clear on this and use the correct terminology. Functions tied to an instance object are called “instance methods”,functions tied to a a class are called “class methods”. Variables inside an object are called attributes and so on.