[Nix-dev] variable scope / recursion

[Lluís Batlle i Rossell]

On Fri, Jul 06, 2012 at 02:25:25PM +0200, Mathijs Kwik wrote:
> On Fri, Jul 6, 2012 at 2:12 PM, Marc Weber <marco-oweber at gmx.de> wrote:
> > Excerpts from Mathijs Kwik's message of Fri Jul 06 11:53:28 +0200 2012:
> >>   packageOverrides = pkgs:
> >>     { foo = "string";
> >>       bar = pkgs.foo + " concatenation";
> >>     };
> >
> > solution a) use rec:
> >
> >
> > (rec {
> >   foo = ...
> >   bar = foo
> >   ;
> > })
> 
> 
> I'l make myself more clear... the example was simplified.
> I want to do something like callPackage.
> 
> packageOverrides = pkgs:
> { myPackage1 = import ./my-package1 { inherit pkgs; };
>   myPackage2 = import ./my-package2 { inherit pkgs; };
> }
> 
> the expressions for myPackage1 and 2 need a "pkgs" argument which is
> the full packages-tree, so the original one _and_ my extensions. So
> myPackage2 wants to depend on myPackage1 and (for example) stdenv. Now
> I can of course pass myPackage1 as explicit argument to myPackage2,
> but I prefer to have a unified pkgs set.
> 
> so I can't use your solution.

I have a maybe similar use case. I use usernixos, and in usernixos I need to
pass pkgs, and I have some ovverrides I want to be used in it. I have some of my
overrides in a file apart (and my public old svn's configuration directory), and
I use them this way in my ~/nixpkgs/config.nix. That's not as nice as having all
recursively nice applied, of course.

let
  mypkgs = import ./myconfigs/nixpkgs-overrides.nix;
in
{
    usernixos = {pkgs, config, ...}: {
      mercurialwsgi.all = {
        destination = "/home/viric/public_html/wsgi-bin/hgweb.wsgi";
        hgwebConfig = ''
          [web]
          motd = "Hello"
          style = gitweb

          [collections]
          /home/viric/hg = /home/viric/hg
        '';
      };
      .....
    }

    packageOverrides = pkgs : with pkgs;
    (mypkgs pkgs) // rec {
      usernixos = import ./usernixos { pkgs = pkgs // (mypkgs pkgs); };

      # This will not be available to usernixos, but 'mypkgs' yes.
      btarEnv = pkgs.myEnvFun {
        name = "btar";
        buildInputs = [ stdenv librsync ];
      };
      .....
    };
}


(For my usernixos:
https://viric.name/cgi-bin/usernixos/timeline )

Regards,
Lluís.