2

all.

I'd think that this could be answered easily, but it isn't. As long as I've been searching for an answer, I keep thinking that I'm overlooking something simple.

I have a python workspace with the following package structure:

    MyTestProject
        /src
           /TestProjectNamespace
              __init__.py
              Module_A.py
              Module_B.py

    SecondTestProject
        /src
           /SecondTestProjectNamespace
              __init__.py
              Module_1.py
              Module_2.py
              ...
              Module_10.py

Note that MyTestProjectNamespace has a reference to SecondTestProjectNamespace.

In MyTestProjectNamespace, I need to import everything in SecondTestProjectNamespace. I could import one module at a time with the following statement(s):

    from SecondTestProjectNamespace.Module_A import *
    from SecondTestProjectNamespace.Module_B import *

...but this isn't practical if the SecondTestProject has 50 modules in it.

Does Python support a way to import everything in a namespace / package? Any help would be appreciated.

Thanks in advance.

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  • 1
    Generally using import * is discouraged, since it clutters up the namespace. And if a project has 50 modules in it, and you want to import everything in all 50 of those modules, that's a lot of clutter... Commented Aug 31, 2012 at 18:49

4 Answers 4

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1

Yes, you can roll this using pkgutil.

Here's an example that lists all packages under twisted (except tests), and imports them:

# -*- Mode: Python -*-
# vi:si:et:sw=4:sts=4:ts=4

import pkgutil
import twisted

for importer, modname, ispkg in pkgutil.walk_packages(
    path=twisted.__path__,
    prefix=twisted.__name__+'.',
    onerror=lambda x: None):
        # skip tests
        if modname.find('test') > -1: 
            continue
        print(modname)
        # gloss over import errors
        try:
            __import__(modname)
        except:
            print 'Failed importing', modname
            pass

# show that we actually imported all these, by showing one subpackage is imported
print twisted.python

I have to agree with the other posters that star imports are a bad idea.

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1 Comment

Thanks, Thomas. Sorry it took me so long to get back to you. At the end of the day, I simply have to import each class from the modules I want to use. Init.py can help with that, as you spelled out. Thanks.
1

No. It is possible to set up SecondTestProject to automatically import everything in its submodules, by putting code in __init__.py to do the from ... import * you mention. It's also possible to automate this to some extent using the __import__ function and/or the imp module. But there is no quick and easy way to take a package that isn't set up this way and make it work this way.

It's probably not a good idea anyway. If you have 50 modules, importing everything from all of them into your global namespace is going to cause a proliferation of names, and very likely conflicts among those names.

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3 Comments

Thanks, Bren. Yes, I'm a python newbie. I'll spell this out further: Pretend that I have 50 modules in SecondTestProjectNamespace. Each module has a single class defined inside it, where Module_A.py has a class inside it named Module_A. I want to reference all of my modules from SecondTestNamespace in another module, so I can create new instances of them and manipulate them. I thought an import statement was the best way to do that. If there's a better way, please tell me.
@BobaFett: Why do you have only one class in each module? This is often a Java mindset that people erroneously apply to Python. In Python, it's perfectly fine to have lots of classes in the same module.
You can't make an instance of a module.
1

As other had put it - it might not be a good idea. But there are ways of keeping your namespaces and therefore avoiding naming conflicts - and having all the modules/sub-packages in a module available to the package user with a single import.

Let's suppose I have a package named "pack", within it a module named "a.py" defining some "b" variable. All I want to do is :

>>> import pack
>>> pack.a.b
1

One way of doing this is to put in pack/__init__.py a line that says import a - thus in your case you'd need fifty such lines, and keep them up to date.

Not that bad.

However, the documentation at http://docs.python.org/tutorial/modules.html#importing-from-a-package - says that if you have a string list named __all__ in your __init__.py file, all module/sub-package names in that list are imported when one does from pack import *

That alone would half-work - but would require users of your package to perform the not-recommended "from x import *" form.

But -- you can do the "... import *" inside __init__.py itself, after defining the __all__ variable - so all you have to do is to keep the __all__ up to date:

With the TestProjectNamespace/__init__.py being like this:

__all__ = ["Module_A", "Module_B", ...]
from TestProjectNamespace import *

your users would have TestProjectNamespace.Module_A (and others) available upon import of TestProjectNamespace.

And, of course - you could automate the creation of __all__ - it is just a variable, after all - but I would not recommend that.

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2 Comments

Thanks, Jsbueno. How would I make Module1, Module2, etc. available to TestProjectNamespace? Note that Module1, Module2, etc. are in the SecondTestProjectNamespace package, not TestProjectNamespace.
If you use the same technique on SecondTest..., from TestProject you can do import SecontTestProjectNameSpace and use ``SecondTestProjectNameSpace.Module_1` - or you can import * from SecondTest.. as well
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Does Python support a way to import everything in a namespace / package?

No. A package is not a super-module -- it's a collection of modules grouped together.

At least part of the reason is that it's not trivial to determine what 'everything' means inside a folder: there are problems like network drives, soft links, hard links, ...

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