[Python-Dev] Re: [Pythonmac-SIG] The versioning question...

["Martin v. Löwis"]

Chris Barker wrote:
> This really doesn't work well for complex packages. I was quite involved 
> with the debate about versioning for wxPython (and helped drive it 
> happening) and that was what I originally proposed. The problem is that 
> you have a whole pile of modules and libs and user code that all imports 
> the package. There are a LOT of "import wx" lines in the wxPython 
> library, and a whole bunch more in a sizable wxPython app. As you 
> upgrade, every one of those would have to be changed to
> 
> import wx_x_y_z as wx

Not at all. Import wx_x_y_z could do

sys.modules["wx"] = wx_x_y_z

and then all references to

import wx

would automatically resolve to the version that was imported first
(or last, depending on your implementation strategy).

> This was not considered a reasonable solution. Among other things, it's 
> really nice to be able to make a small change in just one file, and be 
> able to test your app against a new version.

Even if the package is not prepared to register itself under a different
name also, this one file could modify sys.modules. Or you can have a 
wx.py that reads

from wx_x_y_z import *

Then, wx.py would be that single file.

> The versioning system that wxPython now has is quite nice, and seems to 
> fit most people's needs well. 

Very good! Then I don't see a need to change anything in Python.

> This is quite true, and why I haven't bothered with a PEP, but maybe 
> I've got the thinking backwards, we need the PEP to get the "important" 
> people thinking about it.

I don't think a PEP is needed - Python already appears to have
everything you need to come up with your own versioning rules.

Regards,
Martin