How to import large number of global variables without listing each one? (Python)

DEFINE1 = 1
DEFINE2 = 2
DEFINE3 = 3
...
DEFINE10 = 10

Let's say one file has 10 global constants that I want to import into another file.

Instead of doing the following, is there a开发者_StackOverflow中文版ny simpler way to import all the global constants without doing something like: from file_one.py import *. I don't want it to import the entire file, just the global variables.

from file_one.py import DEFINE1, DEFINE2, DEFINE3, ..............

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First of all, I think it's perfectly okay to create a lot of constants like you're doing and put them all in a constants.py file and then do a from constants import * - I do this myself all the time. So long as all of my constants are defined in that file, I know exactly where to look when I need to figure out where SOME_CONSTANT came from.

But I'll assume for the moment that you have a module with a lot of constants and they all consist of upper-case letters, numbers, and underscores. At that point you can do something very hackish like

import re, file_one
for name,val in file_one.__dict__.items():
    if re.match("[A-Z0-9_]+", name):
        globals()[name] = val

I would strongly advise against this sort of hackery, but this would make it possible to automatically import the constants you define without having to list them individually.

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Assuming that all upper-case names are global constants:

import file_one
g = globals()
for key in dir(file_one):
    if key.isupper():
        g[key] = getattr(file_one, key)

Or shorter:

import file_one
globals().update((key, getattr(file_one, key)) for key in dir(file_one)
                                               if key.isupper())

Having said that: Don't do it. Explicit is better than implicit. You should put these constants in a separate module and import them in both modules using from constants import *.

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Couldn't you just have a file with the constants, and call:

from file_constants import *

..?

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I would suggest having an object that stores your constants. For example, something like this:

# file_one.py
class _COLORS:
    BLUE = 0
    RED = 1
    GREEN = 2
COLORS = _COLORS()

Then you can reference it like this:

# file_two.py
from file_one import COLORS
print COLORS.BLUE #prints 0

---

You could do this:

class _Constants(object): pass

constants = _Constants()
constants.DEFINE1 = 1
constants.DEFINE2 = 2
...

Then to import these, do (leave off the '.py' from the import):

from file_one import constants

This also allows you to group your constants into meaningful subsets too:

colors = _Constants()
colors.RED = (255,0,0)
colors.GREEN = (0,255,0)
colors.BLACK = (0,0,0)
colors.WHITE = (255,255,255)

linetypes = _Constants()
linetypes.SOLID = 0
linetypes.DOTTED = 1
linetypes.DASHED = 2

And just import colors or linetypes. This will give your constants something of a namespace within your module, so that you can limit your imports, and avoid some name clashing.