CODEWITHSUNDEEP
pythondynamicimportextension-methods
Stamoulohta
Stamoulohta

Reputation: 659

python list all imported modules imported via *, the pythonic way

Say I have a package "colorExtentions" and in my __init__.py I have __all__=["red", "blue"]. This package should be able to be extended automatically by adding modules to the directory and to the __all__ list. Is the following acceptable or is there another "best practice" for such kind of things? 

import colorExtentions
from colorExtentions import *

for moduleName in colorExtentions.__all__:
    colors.append(moduleName)
promptUserToChoose(colors)

Upvotes: 0

Views: 247

Answers (2)

Gareth Latty
Gareth Latty

Reputation: 88997

Presuming that each colour is a class, I would argue the nicer solution would be to ensure all of your colours subclass from a single class (which is good design anyway):

class Color:
    ...

Then, when you want a list of all colours, you can simply import any modules that will contain the classes, and do:

from colorExtentions import *

colors = Color.__subclasses__()

This way you end up with a list of each Color subclass.

Note in 2.x, you will need new-style classes (inheriting from object) to have the __subclasses__() method available.

Upvotes: 3

Dawid
Dawid

Reputation: 4062

Importing all names from modules are discouraged in the official Python documentation. See:

http://docs.python.org/2/howto/doanddont.html#from-module-import

Quote:

When It Is Just Fine

There are situations in which from module import * is just fine:

  • The interactive prompt. For example, from math import * makes Python an amazing scientific calculator.
  • When extending a module in C with a > module in Python.
  • When the module advertises itself as from import * safe.

If you insist of using __all__ - use some other name, like color_list, and extend that variable dynamically. Then import that variable:

import colorExtentions
from colorExtentions import color_list

colors.extends(color_list)

Upvotes: 0

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