[Nix-dev] updates and nix-env -i vs nix-env -iA

[Florian Friesdorf]

Hi Peter,

On Fri, 21 Oct 2011 20:33:00 +0200, Peter Simons <simons at cryp.to> wrote:
> Hi Florian,
> 
>  > Could we, apart from having buildEnv, do something about nix-env
>  > remembering how things were installed?
>  >
>  > As far as I understand, "nix-env -u" does not care about attr-paths, but
>  > searches for updates based on attr-name.
>  >
>  > 1) nix-env -i python
>  > - attr-path: pkgs.pythonFull
>  >
>  > 2) nix-env -i python-2.7.1
>  > - attr-path: pkgs.python27 and pkgs.python
>  >
>  > 3) nix-env -iA pkgs.python27
>  > - attr-path: pkgs.python27
>  >
>  > "nix-env -u" could remember the attr-path and use that to search for
>  > updates.
> 
> it would be nice if nix-env could remember and re-use attribute names.
> The problem I see, though, is that attribute names change a lot over
> time. Granted, the name pythonFull is probably not going to change, but
> that is a special case. In general, how should nix-env respond when it
> detects that an attribute path has disappeared?

Store attribute path and name, use attribute path and fall back to
attribute name, if path does not exist?

Further, attributes could indicate that they used to have a different
attribute name:
name="new-python-x.y.z"
replaces="python"

and/or a special attribute could point to the new attribute:
pkgs.python = replacedBy <new.attribute>

regards
florian
-- 
Florian Friesdorf <flo at chaoflow.net>
  GPG FPR: 7A13 5EEE 1421 9FC2 108D  BAAF 38F8 99A3 0C45 F083
Jabber/XMPP: flo at chaoflow.net
IRC: chaoflow on freenode,ircnet,blafasel,OFTC
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 835 bytes
Desc: not available
Url : http://lists.science.uu.nl/pipermail/nix-dev/attachments/20111021/a13bcecd/attachment.bin