Python prints "function <name> at <address>" rather than function output

Question

Im studying pygame and trying to create a score function. But it doesn't work if I do same thing as the examples.
I did everything step by step third time however its doesnt work.
I need a text that shows me current spent time in game. Then I will turn it to score board.

My Function For Displaying Score:

def display_score():
    current_time = pygame.time.get_ticks()
    score_surf = myfont.render(f'{display_score}',False,(64,64,64))
    score_rect = score_surf.get_rect(center = (400, 50))
    screen.blit(score_surf,score_rect)

Create Font For Text:

myfont = pygame.font.Font('font/Pixeltype.ttf', 50)

All of Screen Displays: ( Spesificly section three #Functions Part )

    if game_active:
        # Layouts
        screen.blit(sky,(0,0))
        screen.blit(ground,(0,300))

        # Player
        screen.blit(player,player_rect)
        gravity += 1
        player_rect.y += gravity
        if player_rect.bottom >= 300: player_rect.bottom = 300

        # Functions
        display_score()

        # Snail
        screen.blit(snail,snail_rect)
        snail_rect.x -= 3
        if snail_rect.right <= 0: snail_rect.left = 800

        # collision
        if player_rect.colliderect(snail_rect):
            game_active = False
        
    else:
        screen.fill('Yellow')

Whats Wrong: : When I launched game, pygame displays text as "function display_score at 0x103e3ab90", when I try to print it terminal shows "None"

What am I missing?

Answer 1

There are two things wrong with your code:

1. In Python functions are first class objects, like numbers and strings, so in your code you are printing the function object, not the result of calling the function. In order to call the function you must put parenthesis after it, this example will clarify the problem:

>>> def func_hello(): print("hello")
... 
>>> func_hello
<function func_hello at 0x7f8ab8698700>
>>> func_hello()
hello

2. But if you add parenthesis here: score_surf = myfont.render(f'{display_score}',False,(64,64,64)) your function will become infinitely recursive. The fix is making a function compute_score that computes the score and calling it from display_score , and remembering the parenthesis.