Open Stack

Here is one that is more complete:

https://gist.github.com/harlowja/e22e8c0771b336ca392f

Using a really simple requirement set that will not work:

$ cat test.txt
taskflow
networkx<1.5

Running the above gist on that (and waiting for a while; since it does 
do a lot of backtracking and trying of different versions....) the 
program will eventually break with something like the following:

http://paste.ubuntu.com/9907530/

The above can likely be optimized more (to avoid diving into 
requirements that have already failed being selected) but it does seem 
to work as a satisfiability solver that will recursively check 
requirements deeply and try as many solutions as possible (with 
backtracking when a requirement is selected that doesn't work).

-Josh

Joshua Harlow wrote:
> Seems like a simple fix?
>
> https://github.com/pypa/pip/blob/1.5.6/pip/req.py#L1536
>
> Make a new session somewhere in that gist/code and profit?
>
> Kevin L. Mitchell wrote:
>> On Wed, 2015-01-21 at 18:48 -0800, Joshua Harlow wrote:
>>> Another thing that I just started whipping together:
>>>
>>> https://gist.github.com/harlowja/5e39ec5ca9e3f0d9a21f
>>
>> One problem, though, is that parse_requirements() now requires the
>> session keyword argument. In version 6.0.6, parse_requirements() begins
>> with:
>>
>> def parse_requirements(filename, finder=None, comes_from=None,
>> options=None,
>> session=None):
>> if session is None:
>> raise TypeError(
>> "parse_requirements() missing 1 required keyword argument: "
>> "'session'"
>> )