用Python的__import__函数如何等效于“从模块导入*”？

Question

Given a string with a module name, how do you import everything in the module as if you had called:

from module import *

ie given string S="module", how does one get the equivalent of the following:

__import__(S, fromlist="*")

This doesn't seem to perform as expected (as it doesn't import anything).

Answer 1

Please reconsider. The only thing worse than import * is magic import * .

If you really want to:

m = __import__ (S)
try:
    attrlist = m.__all__
except AttributeError:
    attrlist = dir (m)
for attr in attrlist:
    globals()[attr] = getattr (m, attr)

Answer 2

Here's my solution for dynamic naming of local settings files for Django. Note the addition below of a check to not include attributes containing '__' from the imported file. The __name__ global was being overwritten with the module name of the local settings file, which caused setup_environ() , used in manage.py, to have problems.

try:
    import socket
    HOSTNAME = socket.gethostname().replace('.','_')
    # See http://docs.python.org/library/functions.html#__import__
    m = __import__(name="settings_%s" % HOSTNAME, globals=globals(), locals=locals(), fromlist="*")
    try:
        attrlist = m.__all__
    except AttributeError:
        attrlist = dir(m)        
    for attr in [a for a in attrlist if '__' not in a]:
        globals()[attr] = getattr(m, attr)

except ImportError, e:
    sys.stderr.write('Unable to read settings_%s.py\n' % HOSTNAME)
    sys.exit(1)

Answer 3

It appears that you can also use dict.update() on module's dictionaries in your case:

config = [__import__(name) for name in names_list]

options = {}
for conf in config:
    options.update(conf.__dict__)

Update: I think there's a short "functional" version of it:

options = reduce(dict.update, map(__import__, names_list))

Answer 4

The underlying problem is that I am developing some Django, but on more than one host (with colleagues), all with different settings. I was hoping to do something like this in the project/settings.py file:

from platform import node

settings_files = { 'BMH.lan': 'settings_bmh.py", ... } 

__import__( settings_files[ node() ] )

It seemed a simple solution (thus elegant), but I would agree that it has a smell to it and the simplicity goes out the loop when you have to use logic like what John Millikin posted (thanks). Here's essentially the solution I went with:

from platform import node

from settings_global import *

n = node()

if n == 'BMH.lan':
  from settings_bmh import *
# add your own, here...
else:
  raise Exception("No host settings for '%s'. See settings.py." % node())

Which works fine for our purposes.

Answer 5

I didn't find a good way to do it so I took a simpler but ugly way from http://www.djangosnippets.org/snippets/600/

try:
    import socket
    hostname = socket.gethostname().replace('.','_')
    exec "from host_settings.%s import *" % hostname
except ImportError, e:
    raise e