c# - Python global variable referenced before assigned a value -
i started program in python, , love far. programmed in c# , java, causing problem. in c#, if have public variable, change in each method. sorry bad explanation, easier visualize code.
this code example of want happen in python in c# form. code not work because it's example.
class player { public var player; //create variable public var playerrectangle; public var playermovement; public player() { player = pygame.image.load("player.png"); //set variables value playerrectangle = player.get_rect(); playermovement = new int[0,0]; } public void update() { event in pygame.event.get(): if event.type == pygame.keydown , event.key == pygame.k_w: playermovement[1] = -2 //use variables value if event.type == pygame.keydown , event.key == pygame.k_s: playermovement[1] = 2 if event.type == pygame.keydown , event.key == pygame.k_a: playermovement[0] = -2 if event.type == pygame.keydown , event.key == pygame.k_d: playermovement[0] = 2 if event.type == pygame.keyup , event.key == pygame.k_w: playermovement[1] = 0 if event.type == pygame.keyup , event.key == pygame.k_s: playermovement[1] = 0 if event.type == pygame.keyup , event.key == pygame.k_a: playermovement[0] = 0 if event.type == pygame.keyup , event.key == pygame.k_d: playermovement[0] = 0 playerrectangle = playerrectangle.move(playermovement) } } the actual python code is:
import pygame class player: player = none #create variable playerrectangle = none playermovement = none def __init__(): global player player = pygame.image.load("player.png") #set variables value global playerrectangle playerrectangle = player.get_rect() global playermovement playermovement = [0,0] def update(): event in pygame.event.get(): if event.type == pygame.keydown , event.key == pygame.k_w: playermovement[1] = -2 #use variables !!error!! if event.type == pygame.keydown , event.key == pygame.k_s: playermovement[1] = 2 if event.type == pygame.keydown , event.key == pygame.k_a: playermovement[0] = -2 if event.type == pygame.keydown , event.key == pygame.k_d: playermovement[0] = 2 if event.type == pygame.keyup , event.key == pygame.k_w: playermovement[1] = 0 if event.type == pygame.keyup , event.key == pygame.k_s: playermovement[1] = 0 if event.type == pygame.keyup , event.key == pygame.k_a: playermovement[0] = 0 if event.type == pygame.keyup , event.key == pygame.k_d: playermovement[0] = 0 playerrectangle = playerrectangle.move(playermovement) def returntexture(): return player def returnrectangle(): return playerrectangle it says variable referenced before given value, gave value in constructor.
you have forgotten (or have not read) use of self in methods.
you need put self in method definitions , use self.<attribute> reference attributes on instance.
example:
class player(object): def __init__(self, name): self.name = name def update_name(self, name): self.name = name bob = player("bob") print bob.name # bob bob.update_name("bob jones") print bob.name # bob jones note: use of self in method definitions of classes in python convention only; can use whatever name , typically (by convention) use self.
see: classes
see also: what purpose of self?
side note: 1 of reasons (btw) in python more explicit how write code. see 2nd line of zen of python
the zen of python
beautiful better ugly. explicit better implicit. ...
update: it's worth nothing (please read documentation) there no notion of public vs. private members python's type system. define "private" members convention prefixed single underscore; e.g: def _foo(self): private/inernal method.
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