How to fix a "NameError: name 'color' is not defined"?

Question

here is my code :

size = (1280, 850)
Win = pygame.display.set_mode(size)
class Particle:
    color = (255, 255, 0)
    ID = 0

    def __init__(self, rect):
        Particle.ID += 1
        self.color = (color)
        self.ID = Particle.ID
        self.rect = rect

    def move(self, x, y):
        self.rect.move(x, y)

    def draw(self):
        pygame.draw.rect(Win, self.color, self.rect)

    def collide(self, rect1):
        return self.rect.colliderect(rect1)

When I run my project, I have : "self.color = (color) NameError: name 'color' is not defined" but color is defined...It is at the beginning of my class "Particle"...

Thank you to help me !

Answer 1

The fact you defined color in the class's namespace (making it a class attribute) doesn't make it available in methods bodies. Names in a method (actually a function) body are resolved at function execution time, not at function definition time, and at this point the color varibale defined in the class body has already be turned into a class attributes - they are not part of the function's non-local namespace.

Now the "proper" solution depends on what you want to achieve.

If all of your particle instance should share the same "color" value, just keep the class attribute and remove the instance one in your initializer - class attributes can be accessed directly from the instances, so self.color will automagically resolve to type(self).color. Note that this won't prevent you to assign per-instance color values - the class attribute is only accessed thru the instance if the instance has no attribute by that name, so setting your_particle.color = something_else (or self.color = ... - just the same) later in your code will still create an instance attribute and shadow the class-level one - but this is usually considered bad practice as it doesn't make the intent clear.

If you want per-instance colors, the best solution is to get rid of the class level attribute and only set the color in the initializer ie

class Particle:

    # better to make this an implementation attribute
    _ID = 0

    @classmethod
    def _next_id(cls):
        cls._ID += 1
        return cls._ID

    def __init__(self, rect):
        self.ID = self._next_id()
        self.color = (255, 0, 0)

or (if you want to be able to specify the color at instantiation time):

    def __init__(self, rect, color=(255, 0, 0)):
        self.ID = self._next_id()
        self.color = color

Answer 2

Technically spoken: You dont need the instance attributes, color and ID are already available:

class Particle:
    color = (255, 255, 0)
    ID = 0

    def __init__(self, rect):
        Particle.ID += 1
        self.rect = rect

        print(self.ID)
        print(self.color)

p = Particle(None)

Output:

1
(255, 255, 0)

Note: In case you really need color and ID as instance variables, use a another name:

class Particle:
    color = (255, 255, 0)
    ID = 0
    def __init__(self, rect):
        Particle.ID += 1
        self.rect = rect
        self.pcolor = self.color
        self.pID = self.ID

Answer 3

Remove the line self.color = (color) in order to make your code working.

Answer 4

You don't have variable color in your __init__(), so it's senseless to assign class variable to instance variable - it will have it by default. But you can do something like

MyParticle = Particle(some_rect)
MyParticle.color = (255, 0, 255)

Answer 5

A couple comments. Since you define color as a class variable, you probably don't want to reassign it as an instance variable. Just use it directly with Particle.color (see draw below). If you want to keep track of IDs you can just use id(object). You can use your existing strategy for ID as a count though.

class Particle:
    color = (255, 255, 0)

    def __init__(self, rect):
        self.rect = rect

    def move(self, x, y):
        self.rect.move(x, y)

    def draw(self):
        print(Particle.color, self.rect) # pygame.draw.rect

p = Particle("Rectangle dimensions")                                   
id(p)                                                                  
> 4559902608

p2 = Particle("Rectangle dimensions")
id(p2)
> 4559964496

Answer 6

I cannot comment yet.

Try this:

self.color = (color) -> self.color = color

Edit: Let me correct, I do not have the full context of your implementation of the class. You have to initialize the class as an object because the funciton draw cals the color in the self container. Hence you have to create the object, then call the draw function from the object. Thus Particle.draw() will not work because the classes initializer is not called.

Thus:

particle = Particle()
particle.draw()