Instance of a class not being destroyed with del

Question

I'm trying to delete an object (in this case, and instance of a Fruit class) when it intersects with the head of my snake. The problem is that when it detects a fruit object, del doesn't appear to do anything. I don't know if I'm not implementing the delete function correctly, or it may be something to do with how I am feeding the objects to the function.

Here's part of the main.py script that deals the game functionality:

    # Main loop
    while running:
        # event handling, gets all event from the event queue
        for event in pygame.event.get():
            # only do something if the event is of type QUIT
            if event.type == pygame.QUIT:
                # change the value to False, to exit the main loop
                running = False

        # Modify game fruit properties
        if fruit_tick < 50:
            fruit_tick += 1
        else:
            game.spawn_fruit()
            fruit_tick = 0

        # Modify game player properties
        if not game.player_python:
            game.spawn_player()
        else:
            game.player_python.move()
            game.player_python.detect_object(game.get_objects())

        # Modify display properties
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        game.draw_shapes()
        pygame.display.flip()

Here's the function that is being executed when the head is at the same position of a Fruit object:

    # Detect object
    def detect_object(self, objects):
        for obj in objects:
            if obj.pivot == self.location:
                if isinstance(obj, Fruit):
                    self.grow(obj.get_growth())
                    del obj

If I add a print() statement under if isinstance(obj, Fruit):, it executes no problem. The problem is that del obj does nothing.

It deletes the `obj` variable. It doesn't invalidate any other references to the same object. — khelwood, Jan 29 '21 at 01:39
Furthermore, `del` is almost never the right solution for anything, unless your problem is that you're specifically trying to free up RAM because you're using huge amounts of it on objects you no longer want. — Kirk Strauser, Jan 29 '21 at 01:40
Have a look at [What does “del” do exactly?](https://stackoverflow.com/q/21053380/3890632) — khelwood, Jan 29 '21 at 01:42
u should keep the iterator variable intact, dont delete it anyway — Dee, Jan 29 '21 at 01:45

score 1 · Accepted Answer · answered Jan 29 '21 at 01:53

Don't delete iterator variable or items in a list while looping over it as that's a bad practice, whatever, try another way. Maybe some objects can be deleted this way:

# Detect object
def detect_object(self, objects):
    del_indices = []

    for i in len(objects):
        obj = objects[i]

        if obj.pivot == self.location:
            if isinstance(obj, Fruit):
                self.grow(obj.get_growth())
                # del obj
                del_indices.append(i)

    # Remove some objects
    new_objects = []

    for i in len(objects):
        if not i in del_indices:
            new_objects.append(objects[i])

    objects = new_objects
    # return objects

I definitely get the idea. I decided to pop the fruit object from the list rather than calling del. — Python_plusSharp, Jan 29 '21 at 03:01

Instance of a class not being destroyed with del

1 Answers1