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nixpkgs/pkgs/lib/customisation.nix
Shea Levy 98860f429d Add the addPassthru library function
With multiple outputs, adding attributes to a derivation without
changing the {drv,out}Path is no longer as trivial as simply using the
`//' operator, as we usually want to add the attribute to _each_ output,
and even if we only care about one that one output can be reached via
multiple paths.

For stdenv.mkDerivation, we already had code in place to add passthru
and meta attributes to derivations. This commit simply factors part of
that code out into a lib function addPassthru, which takes a derivation
and an attribute set and appends the attribute set to each output of the
derivation.

Signed-off-by: Shea Levy <shea@shealevy.com>
2013-03-24 08:29:10 -04:00

120 lines
4.4 KiB
Nix

let lib = import ./default.nix;
inherit (builtins) getAttr attrNames isFunction;
in
rec {
/* `overrideDerivation drv f' takes a derivation (i.e., the result
of a call to the builtin function `derivation') and returns a new
derivation in which the attributes of the original are overriden
according to the function `f'. The function `f' is called with
the original derivation attributes.
`overrideDerivation' allows certain "ad-hoc" customisation
scenarios (e.g. in ~/.nixpkgs/config.nix). For instance, if you
want to "patch" the derivation returned by a package function in
Nixpkgs to build another version than what the function itself
provides, you can do something like this:
mySed = overrideDerivation pkgs.gnused (oldAttrs: {
name = "sed-4.2.2-pre";
src = fetchurl {
url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2;
sha256 = "11nq06d131y4wmf3drm0yk502d2xc6n5qy82cg88rb9nqd2lj41k";
};
patches = [];
});
For another application, see build-support/vm, where this
function is used to build arbitrary derivations inside a QEMU
virtual machine. */
overrideDerivation = drv: f:
let
# Filter out special attributes.
drop = [ "meta" "passthru" "outPath" "drvPath" "crossDrv" "nativeDrv" "type" "override" "deepOverride" "origArgs" "drvAttrs" "outputName" "all" "out" ]
# also drop functions such as .merge .override etc
++ lib.filter (n: isFunction (getAttr n drv)) (attrNames drv);
attrs = removeAttrs drv drop;
newDrv = derivation (attrs // (f drv));
in newDrv //
{ meta = if drv ? meta then drv.meta else {};
passthru = if drv ? passthru then drv.passthru else {};
}
//
(if (drv ? crossDrv && drv ? nativeDrv)
then {
crossDrv = overrideDerivation drv.crossDrv f;
nativeDrv = overrideDerivation drv.nativeDrv f;
}
else { });
# usage: (you can use override multiple times)
# let d = makeOverridable stdenv.mkDerivation { name = ..; buildInputs; }
# noBuildInputs = d.override { buildInputs = []; }
# additionalBuildInputs = d.override ( args : args // { buildInputs = args.buildInputs ++ [ additional ]; } )
makeOverridable = f: origArgs:
let
ff = f origArgs;
in
if builtins.isAttrs ff then (ff //
{ override = newArgs:
makeOverridable f (origArgs // (if builtins.isFunction newArgs then newArgs origArgs else newArgs));
deepOverride = newArgs:
makeOverridable f (lib.overrideExisting (lib.mapAttrs (deepOverrider newArgs) origArgs) newArgs);
})
else ff;
deepOverrider = newArgs: name: x: if builtins.isAttrs x then (
if x ? deepOverride then (x.deepOverride newArgs) else
if x ? override then (x.override newArgs) else
x) else x;
/* Call the package function in the file `fn' with the required
arguments automatically. The function is called with the
arguments `args', but any missing arguments are obtained from
`autoArgs'. This function is intended to be partially
parameterised, e.g.,
callPackage = callPackageWith pkgs;
pkgs = {
libfoo = callPackage ./foo.nix { };
libbar = callPackage ./bar.nix { };
};
If the `libbar' function expects an argument named `libfoo', it is
automatically passed as an argument. Overrides or missing
arguments can be supplied in `args', e.g.
libbar = callPackage ./bar.nix {
libfoo = null;
enableX11 = true;
};
*/
callPackageWith = autoArgs: fn: args:
let f = if builtins.isFunction fn then fn else import fn; in
makeOverridable f ((builtins.intersectAttrs (builtins.functionArgs f) autoArgs) // args);
/* Add attributes to each output of a derivation without changing the derivation itself */
addPassthru = drv: passthru:
let
outputs = drv.outputs or [ "out" ];
commonAttrs = drv // (builtins.listToAttrs outputsList) //
({ all = map (x: x.value) outputsList; }) // passthru;
outputToAttrListElement = outputName:
{ name = outputName;
value = commonAttrs // {
inherit (builtins.getAttr outputName drv) outPath drvPath type outputName;
};
};
outputsList = map outputToAttrListElement outputs;
in builtins.getAttr drv.outputName commonAttrs;
}