Importing by file name

[Chris Angelico]

On Sun, Nov 24, 2013 at 7:00 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> The importer mechanism as far as I know only accepts module names, not
> filesystem paths; I believe this is by design.  You could imitate it by
> doing something like this:
>
> import imp
> import sys
>
> mod = imp.new_module('spam')
> exec(open('/path/to/spam.py').read(), mod.__dict__)
> sys.modules['spam'] = mod

That's a bit better than just working with a bare dictionary as I did,
but it's still getting a bit heavy-handed with the details. How is
__main__ imported? Presumably that one, at least, can be loaded from a
specific file. Or is that pure magic?

> Is 'spam' really the appropriate name for this module?  What if there is
> already a different module with the name 'spam'?  Presumably if the module
> is named 'spam' then it should be importable as 'spam', but then why the
> need for the path-based import?  Alternatively, you might name the module
> something like "</path/to/spam.py>", which surely won't collide with
> anything imported by the normal mechanism, but then what if the spam module
> is also imported by normal means?  You would end up with two copies of the
> same module with different names.

The same problem already exists with __main__ - I was hoping to
replicate that, not necessarily to solve all its problems :) I'm okay
with using a fixed name (either "__main__" or something that doesn't
collide with that), for the purposes of experimentation.

I know the recent Pythons give a lot of import power to the script.
But maybe I'm just asking too much, and some of this stuff really is
magical and implemented in C?

ChrisA