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Reputation: 10030

how to set global const variables in python

I am building a solution with various classes and functions all of which need access to some global consants to be able to work appropriately. As there is no const in python, what would you consider best practice to set a kind of global consants.

global const g = 9.8

So I am looking for a kind of the above

edit: How about:

class Const():
    @staticmethod
    def gravity():
        return 9.8

print 'gravity: ', Const.gravity()

?

Upvotes: 8

Views: 33050

Answers (2)

chhantyal
chhantyal

Reputation: 12242

General convention is to define variables with capital and underscores and not change it. Like,

GRAVITY = 9.8

However, it is possible to create constants in Python using namedtuple

import collections

Const = collections.namedtuple('Const', 'gravity pi')
const = Const(9.8, 3.14)

print(const.gravity) # => 9.8
# try to change, it gives error
const.gravity = 9.0 # => AttributeError: can't set attribute

For namedtuple, refer to docs here

Upvotes: 11

John La Rooy
John La Rooy

Reputation: 304117

You cannot define constants in Python. If you find some sort of hack to do it, you would just confuse everyone.

To do that sort of thing, usually you should just have a module - globals.py for example that you import everywhere that you need it

Upvotes: 13

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