[Python-ideas] Make `import a.b.c as m` is equivalent to `m = sys.modules['a.b.c']`

[Victor Varvariuc]

Thanks for the reply. CC'ing the mailing list.


> On 9 Apr 2017, at 10:05, Nick Coghlan <ncoghlan at gmail.com> wrote:
> 
> On 9 April 2017 at 16:13, Victor Varvariuc <victor.varvariuc at gmail.com> wrote:
>> I think there are can be several ways to achieve the result.
>> 
>> The question is if what I've presented is a valid concern. I think this would make the language more consistent and help reducing number of errors related to import without breaking old code.
>> 
>> May I create an issue in the bug tracker?
> 
> Aye, go ahead - I would previously have advised against it, but given
> at least one relatively low impact path to resolution, it's worth
> filing it as an enhancement request.
> 
> Cheers,
> Nick.
> 
> -- 
> Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia




> Begin forwarded message:
> 
> From: Nick Coghlan <ncoghlan at gmail.com>
> Subject: Re: [Python-ideas] Make `import a.b.c as m` is equivalent to `m = sys.modules['a.b.c']`
> Date: 9 April 2017 at 08:33:43 GMT+3
> To: Victor Varvariuc <victor.varvariuc at gmail.com>
> 
> On 8 April 2017 at 22:57, Victor Varvariuc <victor.varvariuc at gmail.com> wrote:
>> Thanks, Nick, for the thorough explanation.
>> 
>> changing those semantics isn't as
>> simple as just having the compiler reinterpret "import x.y.z as m" as
>> "from x.y import z as m"
>> 
>> 
>> I don't think this is a solution.
>> 
>> The solution, IMO, is to treat  `import x.y.z as m` as `m =
>> __import__('x.y.z')` (or similar, IIRC).
> 
> That's not quite how the `__import__` hook works: when the fromlist is
> empty, it returns the *base* module, not the most resolved one.
> 
>>>> __import__("unittest.mock")
>    <module 'unittest' from '/usr/lib64/python3.5/unittest/__init__.py'>
> 
> However, the idea does indicate a potential resolution, which would be
> to add a new IMPORT_ATTR opcode with roughly the following semantics:
> 
>    try:
>        _op_result = getattr(obj, ATTR)
>    except AttributeError:
>        _package_name = obj.__package__
>        if not _package_name:
>            raise
>        _op_result = sys.modules[_package_name + "." + ATTR]
> 
> And then have the import statement unconditionally emit IMPORT_ATTR
> instead of LOAD_ATTR for the "import x.* as y" case.
> 
> Cheers,
> Nick.
> 
> -- 
> Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia




-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20170409/5baa2f9b/attachment.html>