Automatic import PEP

[Georg Brandl]

Dan Bishop wrote:
> On Sep 22, 10:09 pm, Connelly Barnes <connellybar... at yahoo.com> wrote:
>> Hi,
>>
>> I wrote the 'autoimp' module [1], which allows you to import lazy modules:
>>
>> from autoimp import *     (Import lazy wrapper objects around all modules; "lazy
>>                            modules" will turn into normal modules when an attribute
>>                            is first accessed with getattr()).
>> from autoimp import A, B  (Import specific lazy module wrapper objects).
>>
>> The main point of autoimp is to make usage of the interactive Python prompt
>> more productive by including "from autoimp import *" in the PYTHONSTARTUP file.
> 
> And it does.  Gets rid of "oops, I forgot to import that module"
> moments without cluttering my $PYTHONSTARTUP file with imports.  +1.
> 
> My only complaint is that it breaks globals().

And startup takes quite long the first time, because a list of all available
modules must be gathered.

To work around that, one can either use a special importing "lib" object,
defined like that:

class _lib:
     def __getattr__(self, name):
         return __import__(name)
lib = _lib()


or modify the globals() to automatically look up modules on KeyError, like this
(put into PYTHONSTARTUP file):


import sys, code

class LazyImpDict(dict):
     def __getitem__(self, name):
         try:
             return dict.__getitem__(self, name)
         except KeyError:
             exc = sys.exc_info()
             try:
                 return __import__(name)
             except ImportError:
                 raise exc[0], exc[1], exc[2]

d = LazyImpDict()
code.interact(banner='', local=d)
sys.exit()


Of course, this is not perfect as it may break quite a lot of things,
I haven't tested it thoroughly.

Georg