Python按文件夹模块导入

Question

I have a directory structure:

example.py
templates/
    __init__.py
    a.py
    b.py

a.py and b.py have only one class, named the same as the file (because they are cheetah templates). For purely style reasons, I want to be able to import and use these classes in example.py like so:

import templates

t = templates.a()

Right now I do that by having this in the template folder's __init__.py :

__all__ = ["a", "b"]
from . import *

However, this seems pretty poor (and maybe superfluous), and doesn't even do what I want, as I have to use the classes like this:

t = templates.a.a()

Thoughts?

Answer 1

To avoid repeating from <whatever> import * 25 times, you need a loop, such as:

import sys

def _allimports(modnames)
  thismod = sys.modules[__name__]

  for modname in modnames:
    submodname = '%s.%s' % (thismod, modname)
    __import__(submodname)
    submod = sys.modules[submodname]
    thismod.__dict__.update(submod.__dict__)

_allimports('a b c d e'.split())  # or whatever

I'm putting the meaningful code in a function because (a) it's always best [[for performance and to avoid polluting the module's namespace]], (b) in this particular case it also avoids accidents (eg, some submodule might define a name thismod or modnames ... so it's important to keep those names that we're using in the loop local to the function, not module globals, so they can't be accidentally trampled;-).

If you want to enforce the fact that a module named modname only has one class (or other global) with the same name, change the last statement of the loop to:

    setattr(thismod, modname, getattr(submod, modname))

Answer 2

In your __init__.py :

from a import *
from b import *

Now all of a 's contents will be in templates , as will all of b 's contents.

Answer 3

I didn't even know you could have from . import * from . import * . My python interpreter complains about such statements. Still, to your problem, you could do:

# __init__.py
from . import a, b
a = a.a
b = a.b

you can now use

# example.py
import templates
t = templates.a()

other solution:

# __init__.py
from a import *
from b import *