Cannot Create More than 1 Class Instance with Python

Question

# Creates a Dot Instance.
class Dot(object):
    velx=0
    vely=0
    def __init__(self, xloc=0, yloc=0,color=(0,7,0)):
        self.color=color
        self.xloc=xloc
        self.yloc=xloc

    def entity(self):
     for event in pygame.event.get():
        pygame.draw.rect(gameDisplay, (self.color), (self.xloc,self.yloc, 50, 50))
        pygame.display.update()


GameExit=False

# Main Function
def Main():
    global x,y,gameDisplay
    Red=Dot(50,50,color=(0,0,255))
    Blue=Dot(150,150,color=(255,0,0))
    Red.entity()
    Blue.entity()

    pygame.display.update()
    while not GameExit:
        if GameExit==False:
            pygame.QUIT

Main()

Im trying to create a second class instance that will display a Red Dot but it doesn't seem to be appearing. The first class instance works and it creates a Blue Dot on the Display. What is it that I am doing wrong?

As a better suggestion - follow python.org/dev/peps/pep-0008 — Błażej Michalik
– Błażej Michalik, Commented Nov 19, 2019 at 21:39
@BłażejMichalik no, you are correct, I just read it incorrectly, did not see the assignment statements, speaking of PEP8 formatting... — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Nov 19, 2019 at 21:46

Błażej Michalik · Accepted Answer · 2019-11-19 22:04:38Z

1

Try this:

def entity(self):
    pygame.draw.rect(gameDisplay, self.color, (self.xloc, self.yloc, 50, 50))
    pygame.display.update()

See it in online REPL with pyGame: https://repl.it/repls/ActiveMisguidedApplescript

The problem stems from implementation of .entity().

In your code:

for event in pygame.event.get():
    ...

You are essentially drawing stuff only if there's an event in the queue. So the call to Red.entity() exhausts this queue. The call to Blue.entity() doesn't even enter the aforementioned for loop, as there's nothing to iterate on at that particular moment - pygame.event.get() returns an empty list.

From pygame.event.get() docs:

This will get all the messages and remove them from the queue.

Also, your event loop looks wrong. It should be (in Main):

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            return

edited Nov 19, 2019 at 22:04

answered Nov 19, 2019 at 21:36

Błażej Michalik

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