Hi Michael,
>> I want to build "cheetahTemplate" with both Python 2.5 and Python
>> 2.6. How is that supposed to be done? My impression is that the
>> recently added "override" feature is the way to go in that area.
>
> If I understand anything, override is exactly not the answer to your
> question (py 2.5+2.6).
Why not? Consider the following (fictional) package database:
{
python24 = import ../development/interpreters/python/2.4 { ... };
python25 = import ../development/interpreters/python/2.5 { ... };
python26 = import ../development/interpreters/python/2.6 { ... };
python = python24;
cheetahTemplate = import ../tools/text/cheetah-template { inherit python;
};
}
Building Cheetah with both python 2.5 and 2.6 means instantiating the
expression cheetahTemplate twice -- the 'python' attribute is overridden
with 'python25' and 'python26' respectively. On the command line, this
could be done quite easily, say:
nix-env --override python=python25,python26 -i -A cheetahTemplate
To me, this mechanism seems very powerful, because every single
attribute can be overridden by the user, just like that.
Anyway, I'm not a genuine Nix expert and it's likely that my notions are
naive or flat-out wrong. This problem fascinates me, however, and I
would be happy if someone has a better idea or can provide an insight as
for what's wrong with this one.
Take care,
Peter
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