Passing Variables to Class Attributes












0















I've two files, one of which is a python (2.7) file with a class defined. I know how to create instances and the differences between class attributes and instance attributes. I know that upon creation of any instance, you pass variables based on what's defined in the constructor. But I'd like to pass a variable from the other file into my python file as a class attribute, not an instance attribute. Is this possible?



File #1 (Python 2.7):



class Controller:

"""
counter is my desired class attribute. But here, python
tells me GRID is not defined.
"""
counter = (GRID ** 2) # Gives a NameError.

def __init__(self, WIDTH, HEIGHT, GRID):
"""I'd like GRID to be a variable that's read from another file."""
self.WIDTH = WIDTH
self.HEIGHT = HEIGHT
self.GRID = GRID


File #2 ("Master" file to hold all constants and magic numbers):



WIDTH = 500
HEIGHT = 500
GRID = 4
controller = Controller(WIDTH, HEIGHT, GRID) # New Controller object.


When I try to define counter as a formula based on variable GRID, I get a NameError: GRID is not defined. Is there a way that I can define a class attribute -- counter in this case -- in terms of a variable?



Obviously I could just write counter = 4 ** 2, but I'd like to keep all constants and magic numbers in a single file, so I can update them only in one file as necessary.










share|improve this question























  • It makes no sense to take GRID as parameter, when at the same time it’s supposed to be a predefined constant. Define counter to be an INSTANCE variable instead and be happy.

    – deets
    Nov 22 '18 at 23:17











  • You just need an import statement to use a constant in another module

    – Robin Zigmond
    Nov 22 '18 at 23:22











  • @deets Well I've other files (.py modules) that need to read the same exact counter -- like a global variable, so if I put counter as an instance attribute, how can other modules read/write the same counter? Wouldn't there be separate counter instances in every module, every time I create a Controller object in my other modules?

    – WaterGuy
    Nov 22 '18 at 23:48













  • Then pass the one object around.

    – deets
    Nov 23 '18 at 0:06
















0















I've two files, one of which is a python (2.7) file with a class defined. I know how to create instances and the differences between class attributes and instance attributes. I know that upon creation of any instance, you pass variables based on what's defined in the constructor. But I'd like to pass a variable from the other file into my python file as a class attribute, not an instance attribute. Is this possible?



File #1 (Python 2.7):



class Controller:

"""
counter is my desired class attribute. But here, python
tells me GRID is not defined.
"""
counter = (GRID ** 2) # Gives a NameError.

def __init__(self, WIDTH, HEIGHT, GRID):
"""I'd like GRID to be a variable that's read from another file."""
self.WIDTH = WIDTH
self.HEIGHT = HEIGHT
self.GRID = GRID


File #2 ("Master" file to hold all constants and magic numbers):



WIDTH = 500
HEIGHT = 500
GRID = 4
controller = Controller(WIDTH, HEIGHT, GRID) # New Controller object.


When I try to define counter as a formula based on variable GRID, I get a NameError: GRID is not defined. Is there a way that I can define a class attribute -- counter in this case -- in terms of a variable?



Obviously I could just write counter = 4 ** 2, but I'd like to keep all constants and magic numbers in a single file, so I can update them only in one file as necessary.










share|improve this question























  • It makes no sense to take GRID as parameter, when at the same time it’s supposed to be a predefined constant. Define counter to be an INSTANCE variable instead and be happy.

    – deets
    Nov 22 '18 at 23:17











  • You just need an import statement to use a constant in another module

    – Robin Zigmond
    Nov 22 '18 at 23:22











  • @deets Well I've other files (.py modules) that need to read the same exact counter -- like a global variable, so if I put counter as an instance attribute, how can other modules read/write the same counter? Wouldn't there be separate counter instances in every module, every time I create a Controller object in my other modules?

    – WaterGuy
    Nov 22 '18 at 23:48













  • Then pass the one object around.

    – deets
    Nov 23 '18 at 0:06














0












0








0








I've two files, one of which is a python (2.7) file with a class defined. I know how to create instances and the differences between class attributes and instance attributes. I know that upon creation of any instance, you pass variables based on what's defined in the constructor. But I'd like to pass a variable from the other file into my python file as a class attribute, not an instance attribute. Is this possible?



File #1 (Python 2.7):



class Controller:

"""
counter is my desired class attribute. But here, python
tells me GRID is not defined.
"""
counter = (GRID ** 2) # Gives a NameError.

def __init__(self, WIDTH, HEIGHT, GRID):
"""I'd like GRID to be a variable that's read from another file."""
self.WIDTH = WIDTH
self.HEIGHT = HEIGHT
self.GRID = GRID


File #2 ("Master" file to hold all constants and magic numbers):



WIDTH = 500
HEIGHT = 500
GRID = 4
controller = Controller(WIDTH, HEIGHT, GRID) # New Controller object.


When I try to define counter as a formula based on variable GRID, I get a NameError: GRID is not defined. Is there a way that I can define a class attribute -- counter in this case -- in terms of a variable?



Obviously I could just write counter = 4 ** 2, but I'd like to keep all constants and magic numbers in a single file, so I can update them only in one file as necessary.










share|improve this question














I've two files, one of which is a python (2.7) file with a class defined. I know how to create instances and the differences between class attributes and instance attributes. I know that upon creation of any instance, you pass variables based on what's defined in the constructor. But I'd like to pass a variable from the other file into my python file as a class attribute, not an instance attribute. Is this possible?



File #1 (Python 2.7):



class Controller:

"""
counter is my desired class attribute. But here, python
tells me GRID is not defined.
"""
counter = (GRID ** 2) # Gives a NameError.

def __init__(self, WIDTH, HEIGHT, GRID):
"""I'd like GRID to be a variable that's read from another file."""
self.WIDTH = WIDTH
self.HEIGHT = HEIGHT
self.GRID = GRID


File #2 ("Master" file to hold all constants and magic numbers):



WIDTH = 500
HEIGHT = 500
GRID = 4
controller = Controller(WIDTH, HEIGHT, GRID) # New Controller object.


When I try to define counter as a formula based on variable GRID, I get a NameError: GRID is not defined. Is there a way that I can define a class attribute -- counter in this case -- in terms of a variable?



Obviously I could just write counter = 4 ** 2, but I'd like to keep all constants and magic numbers in a single file, so I can update them only in one file as necessary.







python class






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 22 '18 at 23:10









WaterGuyWaterGuy

426




426













  • It makes no sense to take GRID as parameter, when at the same time it’s supposed to be a predefined constant. Define counter to be an INSTANCE variable instead and be happy.

    – deets
    Nov 22 '18 at 23:17











  • You just need an import statement to use a constant in another module

    – Robin Zigmond
    Nov 22 '18 at 23:22











  • @deets Well I've other files (.py modules) that need to read the same exact counter -- like a global variable, so if I put counter as an instance attribute, how can other modules read/write the same counter? Wouldn't there be separate counter instances in every module, every time I create a Controller object in my other modules?

    – WaterGuy
    Nov 22 '18 at 23:48













  • Then pass the one object around.

    – deets
    Nov 23 '18 at 0:06



















  • It makes no sense to take GRID as parameter, when at the same time it’s supposed to be a predefined constant. Define counter to be an INSTANCE variable instead and be happy.

    – deets
    Nov 22 '18 at 23:17











  • You just need an import statement to use a constant in another module

    – Robin Zigmond
    Nov 22 '18 at 23:22











  • @deets Well I've other files (.py modules) that need to read the same exact counter -- like a global variable, so if I put counter as an instance attribute, how can other modules read/write the same counter? Wouldn't there be separate counter instances in every module, every time I create a Controller object in my other modules?

    – WaterGuy
    Nov 22 '18 at 23:48













  • Then pass the one object around.

    – deets
    Nov 23 '18 at 0:06

















It makes no sense to take GRID as parameter, when at the same time it’s supposed to be a predefined constant. Define counter to be an INSTANCE variable instead and be happy.

– deets
Nov 22 '18 at 23:17





It makes no sense to take GRID as parameter, when at the same time it’s supposed to be a predefined constant. Define counter to be an INSTANCE variable instead and be happy.

– deets
Nov 22 '18 at 23:17













You just need an import statement to use a constant in another module

– Robin Zigmond
Nov 22 '18 at 23:22





You just need an import statement to use a constant in another module

– Robin Zigmond
Nov 22 '18 at 23:22













@deets Well I've other files (.py modules) that need to read the same exact counter -- like a global variable, so if I put counter as an instance attribute, how can other modules read/write the same counter? Wouldn't there be separate counter instances in every module, every time I create a Controller object in my other modules?

– WaterGuy
Nov 22 '18 at 23:48







@deets Well I've other files (.py modules) that need to read the same exact counter -- like a global variable, so if I put counter as an instance attribute, how can other modules read/write the same counter? Wouldn't there be separate counter instances in every module, every time I create a Controller object in my other modules?

– WaterGuy
Nov 22 '18 at 23:48















Then pass the one object around.

– deets
Nov 23 '18 at 0:06





Then pass the one object around.

– deets
Nov 23 '18 at 0:06












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