[Nix-dev] Querying package options via nix expressions

[Michael Raitza]

Hi,

as far as I know (and the manual states), there is no way to query
package options with nix. I realise that nix expressions defining
packages are mere functions on a set of attributes. And the user is
intrested in the attributes' names for tweaking a package, e.g. emacs,
to be built without X support.

Wouldn't an easy solution be to register the path of the nix file
defining the package in the derivation that is built via callPackage and
friends? This way one could easily achieve two things:
1) Import the path to query its argument names with
   builtins.functionArgs, 
2) Find the file defining the package in question to look, how it is
   built and must be manipulated to ones needs.

As a side note: Maybe a convention like 'optX' or 'withY', 'withoutZ'
would help to distinguish option arguments from buildInputs.

Is this or something similar done already?

Regards,

Michael