Python Custom Class __init__ not initializing class instance variables

Question

Custom Python class __init__ function not properly generating variables or calling functions.

I have the following code which I wish to use to store and manipulate information about a mesh face. I'm running into issues where the __init__ function does not seem to do anything.

class Face():
    """A class to store and manipulate information about a face"""
    def __int__(self):
        self.face_id = 0
        self.vertices=[0,1,2]
        self.color=[255,255,255]
        self.bright=False
        self.transparency=0
        self.light_sprite=False
        self.normal_location=[0,0,0]
        self.normal_vector=[0,0,0]
        self.double_sided=False        
        
        print(self.light_sprite)
        
    def set_srf_normal(self, data):
        """Set the normal information of the face from a SRF format"""
        self.normal_location = [float(i) for i in data[:3]]
        self.normal_vector = [float(i) for i in data[3:]]
        
        # Determine if face is double-sided if the normal vector is zero for all elements.
        double_sided = True
        for i in self.normal_vector:
            if i != 0:
                double_sided = False
                break
        self.double_sided = double_sided        
        
    def set_srf_color(self, data):
        """Set the face color from a SRF format input"""
        self.color = [int(i) for i in data]
        
        # Valid colors component values are 0-255. 
        for idx, color in enumerate(self.color):
            if color > 255:
                self.color[idx] = 255
            elif color < 0:
                self.color[idx] = 0
                
    def print_properties(self):
        print(self.face_id, self.vertices, self.color, self.normal_location, self.normal_vector, 
              self.color, self.light_sprite, self.transparency, self.bright, self.double_sided)


face = Face()
print(face.face_id)

When I run this code, I expect 2 print outputs. One from the print(self.light_sprite) in the __init__ and one from the final line print(face.face_id).

>>> False
>>> 0

However instead I get the following error:

Traceback (most recent call last):
  File "/Users/Documents/testing.py", line 46, in <module>
    print(face.face_id)
AttributeError: 'Face' object has no attribute 'face_id'

Now when I replace the last two lines with these lines, suddenly face.face_id exists and is printable.

face = Face()
face.face_id = 0
print(face.face_id)

>>> 0

If I call one of the class functions, the class variables that are updated by the functions now suddenly exist.

face = Face()
print(face.color)

Traceback (most recent call last):
  File "/Users/Documents/testing.py", line 46, in <module>
    print(face.color)
AttributeError: 'Face' object has no attribute 'color'

face = Face()
face.set_srf_color([0,255,0])
print(face.color)
print(face.face_id)

>>> [0, 255, 0]
>>> Traceback (most recent call last):
  File "/Users/Documents/testing.py", line 48, in <module>
    print(face.face_id)
AttributeError: 'Face' object has no attribute 'face_id'

I feel like there is something basic that I'm missing, but I cannot see it. I would appreciate anyone who can help straighten me out as to why:

1. The __init__ function is not running and calling the print command
2. The __init__ function is not initializing variables in the class instance
3. Why setting variables or calling functions to update variables suddenly makes them available in the class instance.

Answer 1

Your class has a typo. You have written __int__ instead of __init__ at your third line.

__int__ is a separate built-in method for converting the class itself into the integer type.

For example:

class Face:
    # some init method
    def __init__(self, value):
        self.value = value

    def __int__(self):
        return int(self.value) + 1

f = Face("1")
print(int(f) + 1)

will print out

3