nixpkgs/lib/customisation.nix
Graham Christensen 152c63c9ff
Convert libs to a fixed-point
This does break the API of being able to import any lib file and get
its libs, however I'm not sure people did this.

I made this while exploring being able to swap out docFn with a stub
in #2305, to avoid functor performance problems. I don't know if that
is going to move forward (or if it is a problem or not,) but after
doing all this work figured I'd put it up anyway :)

Two notable advantages to this approach:

1. when a lib inherits another lib's functions, it doesn't
   automatically get put in to the scope of lib
2. when a lib implements a new obscure functions, it doesn't
   automatically get put in to the scope of lib

Using the test script (later in this commit) I got the following diff
on the API:

  + diff master fixed-lib
  11764a11765,11766
  > .types.defaultFunctor
  > .types.defaultTypeMerge
  11774a11777,11778
  > .types.isOptionType
  > .types.isType
  11781a11786
  > .types.mkOptionType
  11788a11794
  > .types.setType
  11795a11802
  > .types.types

This means that this commit _adds_ to the API, however I can't find a
way to fix these last remaining discrepancies. At least none are
_removed_.

Test script (run with nix-repl in the PATH):

  #!/bin/sh

  set -eux

  repl() {
      suff=${1:-}
      echo "(import ./lib)$suff" \
          | nix-repl 2>&1
  }

  attrs_to_check() {
      repl "${1:-}" \
          | tr ';'  $'\n' \
          | grep "\.\.\." \
          | cut -d' ' -f2 \
          | sed -e "s/^/${1:-}./" \
          | sort
  }

  summ() {
      repl "${1:-}" \
          | tr ' ' $'\n' \
          | sort \
          | uniq
  }

  deep_summ() {
      suff="${1:-}"
      depth="${2:-4}"
      depth=$((depth - 1))
      summ "$suff"

      for attr in $(attrs_to_check "$suff" | grep -v "types.types"); do
          if [ $depth -eq 0 ]; then
              summ "$attr" | sed -e "s/^/$attr./"
          else
              deep_summ "$attr" "$depth" | sed -e "s/^/$attr./"
          fi
      done
  }

  (
      cd nixpkgs

      #git add .
      #git commit -m "Auto-commit, sorry" || true
      git checkout fixed-lib
      deep_summ > ../fixed-lib
      git checkout master
      deep_summ > ../master
  )

  if diff master fixed-lib; then
      echo "SHALLOW MATCH!"
  fi

  (
      cd nixpkgs
      git checkout fixed-lib
      repl .types
  )
2017-09-16 21:36:43 -04:00

206 lines
7.1 KiB
Nix

{ lib }:
let
inherit (builtins) 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 overridden
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 ~/.config/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
newDrv = derivation (drv.drvAttrs // (f drv));
in addPassthru newDrv (
{ meta = drv.meta or {};
passthru = if drv ? passthru then drv.passthru else {};
}
//
(drv.passthru or {})
//
(if (drv ? crossDrv && drv ? nativeDrv)
then {
crossDrv = overrideDerivation drv.crossDrv f;
nativeDrv = overrideDerivation drv.nativeDrv f;
}
else { }));
/* `makeOverridable` takes a function from attribute set to attribute set and
injects `override` attibute which can be used to override arguments of
the function.
nix-repl> x = {a, b}: { result = a + b; }
nix-repl> y = lib.makeOverridable x { a = 1; b = 2; }
nix-repl> y
{ override = «lambda»; overrideDerivation = «lambda»; result = 3; }
nix-repl> y.override { a = 10; }
{ override = «lambda»; overrideDerivation = «lambda»; result = 12; }
Please refer to "Nixpkgs Contributors Guide" section
"<pkg>.overrideDerivation" to learn about `overrideDerivation` and caveats
related to its use.
*/
makeOverridable = f: origArgs:
let
ff = f origArgs;
overrideWith = newArgs: origArgs // (if builtins.isFunction newArgs then newArgs origArgs else newArgs);
in
if builtins.isAttrs ff then (ff // {
override = newArgs: makeOverridable f (overrideWith newArgs);
overrideDerivation = fdrv:
makeOverridable (args: overrideDerivation (f args) fdrv) origArgs;
${if ff ? overrideAttrs then "overrideAttrs" else null} = fdrv:
makeOverridable (args: (f args).overrideAttrs fdrv) origArgs;
})
else if builtins.isFunction ff then {
override = newArgs: makeOverridable f (overrideWith newArgs);
__functor = self: ff;
overrideDerivation = throw "overrideDerivation not yet supported for functors";
}
else ff;
/* Call the package function in the file `fn' with the required
arguments automatically. The function is called with the
arguments `args', but any missing arguments are obtained from
`autoArgs'. This function is intended to be partially
parameterised, e.g.,
callPackage = callPackageWith pkgs;
pkgs = {
libfoo = callPackage ./foo.nix { };
libbar = callPackage ./bar.nix { };
};
If the `libbar' function expects an argument named `libfoo', it is
automatically passed as an argument. Overrides or missing
arguments can be supplied in `args', e.g.
libbar = callPackage ./bar.nix {
libfoo = null;
enableX11 = true;
};
*/
callPackageWith = autoArgs: fn: args:
let
f = if builtins.isFunction fn then fn else import fn;
auto = builtins.intersectAttrs (builtins.functionArgs f) autoArgs;
in makeOverridable f (auto // args);
/* Like callPackage, but for a function that returns an attribute
set of derivations. The override function is added to the
individual attributes. */
callPackagesWith = autoArgs: fn: args:
let
f = if builtins.isFunction fn then fn else import fn;
auto = builtins.intersectAttrs (builtins.functionArgs f) autoArgs;
origArgs = auto // args;
pkgs = f origArgs;
mkAttrOverridable = name: pkg: makeOverridable (newArgs: (f newArgs).${name}) origArgs;
in lib.mapAttrs mkAttrOverridable pkgs;
/* 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 (drv.${outputName}) outPath drvPath type outputName;
};
};
outputsList = map outputToAttrListElement outputs;
in commonAttrs // { outputUnspecified = true; };
/* Strip a derivation of all non-essential attributes, returning
only those needed by hydra-eval-jobs. Also strictly evaluate the
result to ensure that there are no thunks kept alive to prevent
garbage collection. */
hydraJob = drv:
let
outputs = drv.outputs or ["out"];
commonAttrs =
{ inherit (drv) name system meta; inherit outputs; }
// lib.optionalAttrs (drv._hydraAggregate or false) {
_hydraAggregate = true;
constituents = map hydraJob (lib.flatten drv.constituents);
}
// (lib.listToAttrs outputsList);
makeOutput = outputName:
let output = drv.${outputName}; in
{ name = outputName;
value = commonAttrs // {
outPath = output.outPath;
drvPath = output.drvPath;
type = "derivation";
inherit outputName;
};
};
outputsList = map makeOutput outputs;
drv' = (lib.head outputsList).value;
in lib.deepSeq drv' drv';
/* Make a set of packages with a common scope. All packages called
with the provided `callPackage' will be evaluated with the same
arguments. Any package in the set may depend on any other. The
`overrideScope' function allows subsequent modification of the package
set in a consistent way, i.e. all packages in the set will be
called with the overridden packages. The package sets may be
hierarchical: the packages in the set are called with the scope
provided by `newScope' and the set provides a `newScope' attribute
which can form the parent scope for later package sets. */
makeScope = newScope: f:
let self = f self // {
newScope = scope: newScope (self // scope);
callPackage = self.newScope {};
overrideScope = g:
makeScope newScope
(self_: let super = f self_; in super // g super self_);
packages = f;
};
in self;
}