[Python-Dev] 3.2.1 encoding surprise

[Glenn Linderman]

On 7/20/2011 5:34 PM, Mark Hammond wrote:
> On 21/07/2011 10:13 AM, Glenn Linderman wrote:
>> On 7/20/2011 2:43 PM, Glenn Linderman wrote:
>>>> It's not py's job to walk the path: the shell does that when you 
>>>> just type
>>>> "foo". It locates foo.py, and then invokes py because of file 
>>>> association - py
>>>> then checks the file for a shebang to decide which Python to 
>>>> dispatch it to.
>>>
>>> Certainly when the launcher is invoked via an association, this would
>>> be the case.  However, when the launcher is invoked via the command
>>> line, then the unqualified name is passed through.  To be useful from
>>> the command line, the launcher should walk the PATH to find the .py 
>>> file.
>>
>> The Windows SearchPath API
>> <http://msdn.microsoft.com/en-us/library/aa365527%28v=VS.85%29.aspx>
>> makes it a pretty easy job to walk the PATH.  Would even allow low cost
>> additional feature of searching for both   foo and foo.py  at the 
>> same time.
>
> But that would also require us to parse the command-line, understand 
> which options require 2 args and which just require 1 (making it 
> fragile in the face of later versions introducing new options), then 
> re-stitching a modified command-line back together for the child 
> process.  IMO that is all out of scope.

Yes it would be more work.

>
> Are you maybe forgetting about the PATHEXT functionality?  If you 
> include .py in your PATHEXT and file associations are set so .py files 
> are handled by the launcher, you should be able to directly execute 
> just 'foo' and have the command processor search the PATH for a foo.py 
> and invoke it via the launcher.

Not at all.  I was just testing the use of the launcher from the command 
line, and seeing the cumbersomeness of using it as a prefix to a command 
that would work on its own, but fails when launched by the launcher from 
the command line.  And the SearchPath API has a limited form of PATHEXT 
support built in, which is what I was trying to point out above.  Yes, 
the use of the launcher via file associations can be friendly because it 
leverages Windows features, but its use from the command line presently 
seems rather unfriendly, because it leverages Windows misfeatures.
>
>
> Mark 

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