我最近开始用python编程，到目前为止，我还是喜欢它。我以前用c＃和java编程，这可能是造成我问题的原因。在c＃中，如果您有一个公共变量，它将在每个方法中更改。抱歉，我们的解释不正确，但是使代码的可视化更加容易。
这段代码是我想在python中以c＃形式发生的示例。该代码实际上不起作用，因为它只是一个例子。
class Player
{
public var player; //create the variable
public var playerRectangle;
public var playerMovement;
public Player()
{
player = pygame.image.load("player.png"); //set the variables value
playerRectangle = player.get_rect();
playerMovement = new int[0,0];
}
public void Update()
{
for event in pygame.event.get():
if event.type == pygame.KEYDOWN and event.key == pygame.K_w:
playerMovement[1] = -2 //use the variables value
if event.type == pygame.KEYDOWN and event.key == pygame.K_s:
playerMovement[1] = 2
if event.type == pygame.KEYDOWN and event.key == pygame.K_a:
playerMovement[0] = -2
if event.type == pygame.KEYDOWN and event.key == pygame.K_d:
playerMovement[0] = 2
if event.type == pygame.KEYUP and event.key == pygame.K_w:
playerMovement[1] = 0
if event.type == pygame.KEYUP and event.key == pygame.K_s:
playerMovement[1] = 0
if event.type == pygame.KEYUP and event.key == pygame.K_a:
playerMovement[0] = 0
if event.type == pygame.KEYUP and event.key == pygame.K_d:
playerMovement[0] = 0
playerRectangle = playerRectangle.move(playerMovement)
}
}
实际的python代码是：
import pygame
class Player:
player = None #create the variable
playerRectangle = None
playerMovement = None
def __init__():
global player
player = pygame.image.load("player.png") #set the variables value
global playerRectangle
playerRectangle = player.get_rect()
global playerMovement
playerMovement = [0,0]
def update():
for event in pygame.event.get():
if event.type == pygame.KEYDOWN and event.key == pygame.K_w:
playerMovement[1] = -2 #use the variables !!ERROR!!
if event.type == pygame.KEYDOWN and event.key == pygame.K_s:
playerMovement[1] = 2
if event.type == pygame.KEYDOWN and event.key == pygame.K_a:
playerMovement[0] = -2
if event.type == pygame.KEYDOWN and event.key == pygame.K_d:
playerMovement[0] = 2
if event.type == pygame.KEYUP and event.key == pygame.K_w:
playerMovement[1] = 0
if event.type == pygame.KEYUP and event.key == pygame.K_s:
playerMovement[1] = 0
if event.type == pygame.KEYUP and event.key == pygame.K_a:
playerMovement[0] = 0
if event.type == pygame.KEYUP and event.key == pygame.K_d:
playerMovement[0] = 0
playerRectangle = playerRectangle.move(playerMovement)
def returnTexture():
return player
def returnRectangle():
return playerRectangle
它说在给变量赋值之前先对其进行引用，但是我在构造函数中给了它一个值。
最佳答案
您已经忘记（或尚未阅读）方法中对self的使用。
您需要在方法定义中放入self
并使用self.<attribute>引用实例上的属性。
例：
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
注意：在Python中，类的方法定义中使用
self仅是按照惯例。您可以使用任何喜欢的名称，但我们通常（按惯例）广泛使用self。参见：Classes
另请参见：What is the purpose of self?
旁注：造成这种情况（btw）的原因之一是，在Python中，我们希望对编写代码的方式更加明确。参见Zen of Python的第二行
Zen of Python
Beautiful is better than ugly.
Explicit is better than implicit.
...
更新：使用Python的类型系统没有公共或私有成员的概念也毫无意义（请阅读文档）。我们通常只用前缀下划线来定义“私有”成员。例如：
def _foo(self):作为私有/内部方法。关于c# - 在分配值之前引用的Python全局变量，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/30230120/