316 lines
11 KiB
Nix
316 lines
11 KiB
Nix
{ lib }:
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let
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inherit (builtins) attrNames isFunction;
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in
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rec {
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/* `overrideDerivation drv f' takes a derivation (i.e., the result
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of a call to the builtin function `derivation') and returns a new
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derivation in which the attributes of the original are overridden
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according to the function `f'. The function `f' is called with
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the original derivation attributes.
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`overrideDerivation' allows certain "ad-hoc" customisation
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scenarios (e.g. in ~/.config/nixpkgs/config.nix). For instance,
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if you want to "patch" the derivation returned by a package
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function in Nixpkgs to build another version than what the
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function itself provides, you can do something like this:
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mySed = overrideDerivation pkgs.gnused (oldAttrs: {
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name = "sed-4.2.2-pre";
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src = fetchurl {
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url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2;
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sha256 = "11nq06d131y4wmf3drm0yk502d2xc6n5qy82cg88rb9nqd2lj41k";
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};
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patches = [];
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});
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For another application, see build-support/vm, where this
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function is used to build arbitrary derivations inside a QEMU
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virtual machine.
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*/
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overrideDerivation = drv: f:
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let
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newDrv = derivation (drv.drvAttrs // (f drv));
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in addPassthru newDrv (
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{ meta = drv.meta or {};
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passthru = if drv ? passthru then drv.passthru else {};
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}
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//
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(drv.passthru or {})
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//
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(if (drv ? crossDrv && drv ? nativeDrv)
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then {
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crossDrv = overrideDerivation drv.crossDrv f;
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nativeDrv = overrideDerivation drv.nativeDrv f;
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}
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else { }));
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# A more powerful version of `makeOverridable` with features similar
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# to `makeExtensibleWithInterface`.
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makeOverridableWithInterface = interface: f: origArgs: let
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addOverrideFuncs = {val, args, ...}: overridePackage:
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(lib.optionalAttrs (builtins.isAttrs val) (val // {
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extend = f: overridePackage (_: self: super: {
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val = super.val // f self.val super.val;
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});
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overrideDerivation = newArgs: overridePackage (_: self: super: {
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val = lib.overrideDerivation super.val newArgs;
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});
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${if val ? overrideAttrs then "overrideAttrs" else null} = fdrv:
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overridePackage (_: self: super: {
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val = super.val.overrideAttrs fdrv;
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});
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})) // (lib.optionalAttrs (builtins.isFunction val) {
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__functor = _: val;
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extend = throw "extend not yet supported for functors";
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overrideDerivation = throw "overrideDerivation not yet supported for functors";
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}) // {
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inherit overridePackage;
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override = newArgs: overridePackage (_: self: super: {
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args = super.args //
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(if builtins.isFunction newArgs then newArgs super.args else newArgs);
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});
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};
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in lib.fixedPoints.makeExtensibleWithInterface (x: o: interface (addOverrideFuncs x o) o) (output: self: {
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args = origArgs;
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val = f output self.args self.val;
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});
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/* `makeOverridable` takes a function from attribute set to
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attribute set and injects 4 attributes which can be used to
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override arguments and return values of the function.
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1. `override` allows you to change what arguments were passed to
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the function and acquire the new result.
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nix-repl> x = {a, b}: { result = a + b; }
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nix-repl> y = lib.makeOverridable x { a = 1; b = 2; }
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nix-repl> y
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{ override = «lambda»; overrideDerivation = «lambda»; result = 3; }
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nix-repl> y.override { a = 10; }
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{ override = «lambda»; overrideDerivation = «lambda»; result = 12; }
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2. `extend` changes the results of the function, giving you a
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view of the original result and a view of the eventual final
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result. It is meant to do the same thing as
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`makeExtensible`. That is, it lets you add to or change the
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return value, such that previous extensions are consistent with
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the final view, rather than being based on outdated
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values. "Outdated" values come from the `super` argument, which
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must be used when you are attempting to modify and old value. And
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the final values come from the `self` argument, which recursively
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refers to what all extensions combined return.
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nix-repl> obj = makeOverridable (args: { }) { }
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nix-repl> obj = obj.extend (self: super: { foo = "foo"; })
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nix-repl> obj.foo
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"foo"
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nix-repl> obj = obj.extend (self: super: { foo = super.foo + " + "; bar = "bar"; foobar = self.foo + self.bar; })
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nix-repl> obj
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{ bar = "bar"; foo = "foo + "; foobar = "foo + bar"; ... } # Excess omitted
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3. `overrideDerivation`: Please refer to "Nixpkgs Contributors
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Guide" section "<pkg>.overrideDerivation" to learn about
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`overrideDerivation` and caveats related to its use.
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4. `overridePackage` is by far the most powerful of the four, as
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it exposes a deeper structure. It provides `self` and `super`
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views of both the arguments and return value of the function,
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allowing you to change both in one override; you can even have
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overrides for one based on overrides for the other. It also
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provides the `output` view, which is the view of `self` after
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passing it through the `makeOverridable` interface and adding all
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the `overrideX` functions. `output` is necessary when your
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overrides depend on the overridable structure of `output`.
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nix-repl> obj = makeOverridable ({a, b}: {inherit a b;}) {a = 1; b = 3;}
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nix-repl> obj = obj.overridePackage (output: self: super: { args = super.args // {b = self.val.a;}; })
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nix-repl> obj.b
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1
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nix-repl> obj = obj.overridePackage (output: self: super: { val = super.val // {a = self.args.a + 10;}; })
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nix-repl> obj.b
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11
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*/
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makeOverridable = fn: makeOverridableWithInterface (x: _: x) (_: args: _: fn args);
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callPackageCommon = functionArgs: scope: f: args:
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let
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intersect = builtins.intersectAttrs functionArgs;
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interface = val: overridePackage: val // {
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overrideScope = newScope: overridePackage (_: self: super: {
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scope = super.scope.extend newScope;
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});
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};
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in (makeOverridableWithInterface interface f (intersect scope // args))
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.overridePackage (output: self: super: {
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inherit scope;
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# Don't use super.args because that contains the original scope.
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args = intersect self.scope // args;
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});
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/* Call the package function in the file `fn' with the required
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arguments automatically. The function is called with the
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arguments `args', but any missing arguments are obtained from
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`autoArgs'. This function is intended to be partially
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parameterised, e.g.,
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callPackage = callPackageWith pkgs;
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pkgs = {
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libfoo = callPackage ./foo.nix { };
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libbar = callPackage ./bar.nix { };
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};
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If the `libbar' function expects an argument named `libfoo', it is
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automatically passed as an argument. Overrides or missing
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arguments can be supplied in `args', e.g.
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libbar = callPackage ./bar.nix {
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libfoo = null;
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enableX11 = true;
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};
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On top of the additions from `makeOverridable`, an `overrideScope`
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function is also added to the result. It is similar to `override`,
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except that it provides `self` and `super` views to the
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scope. This can't be done in `makeOverridable` because the scope
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is filtered to just the arguments needed by the function before
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entering `makeOverridable`. It is useful to have a view of the
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scope before restriction; for example, to change versions for a
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particular dependency.
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foo.overrideScope (self: super: {
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llvm = self.llvm_37;
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})
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`llvm_37` would not exist in the scope after restriction.
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*/
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callPackageWith = autoArgs: fn: args:
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let f = if builtins.isFunction fn then fn else import fn;
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in callPackageCommon (builtins.functionArgs f) autoArgs (output: x: _: f x) args;
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# Like `callPackageWith`, but provides the function with a `self`
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# view of the output, which has the override functions
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# injected. `fn` is called with the new output whenever an override
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# or extension is added.
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callPackageWithOutputWith = autoArgs: fn: args:
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let f = if builtins.isFunction fn then fn else import fn;
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in callPackageCommon (builtins.functionArgs f) autoArgs (output: args: _: f args output ) args;
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/* Like callPackage, but for a function that returns an attribute
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set of derivations. The override function is added to the
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individual attributes. */
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callPackagesWith = autoArgs: fn: args:
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let
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f = if builtins.isFunction fn then fn else import fn;
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auto = builtins.intersectAttrs (builtins.functionArgs f) autoArgs;
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origArgs = auto // args;
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pkgs = f origArgs;
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mkAttrOverridable = name: pkg: makeOverridable (newArgs: (f newArgs).${name}) origArgs;
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in lib.mapAttrs mkAttrOverridable pkgs;
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/* Add attributes to each output of a derivation without changing
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the derivation itself. */
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addPassthru = drv: passthru:
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let
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outputs = drv.outputs or [ "out" ];
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commonAttrs = drv // (builtins.listToAttrs outputsList) //
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({ all = map (x: x.value) outputsList; }) // passthru;
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outputToAttrListElement = outputName:
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{ name = outputName;
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value = commonAttrs // {
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inherit (drv.${outputName}) outPath drvPath type outputName;
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};
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};
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outputsList = map outputToAttrListElement outputs;
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in commonAttrs // { outputUnspecified = true; };
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/* Strip a derivation of all non-essential attributes, returning
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only those needed by hydra-eval-jobs. Also strictly evaluate the
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result to ensure that there are no thunks kept alive to prevent
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garbage collection. */
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hydraJob = drv:
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let
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outputs = drv.outputs or ["out"];
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commonAttrs =
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{ inherit (drv) name system meta; inherit outputs; }
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// lib.optionalAttrs (drv._hydraAggregate or false) {
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_hydraAggregate = true;
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constituents = map hydraJob (lib.flatten drv.constituents);
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}
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// (lib.listToAttrs outputsList);
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makeOutput = outputName:
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let output = drv.${outputName}; in
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{ name = outputName;
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value = commonAttrs // {
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outPath = output.outPath;
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drvPath = output.drvPath;
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type = "derivation";
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inherit outputName;
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};
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};
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outputsList = map makeOutput outputs;
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drv' = (lib.head outputsList).value;
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in lib.deepSeq drv' drv';
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/* Make a set of packages with a common scope. All packages called
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with the provided `callPackage' will be evaluated with the same
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arguments. Any package in the set may depend on any other. The
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`overrideScope' function allows subsequent modification of the package
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set in a consistent way, i.e. all packages in the set will be
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called with the overridden packages. The package sets may be
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hierarchical: the packages in the set are called with the scope
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provided by `newScope' and the set provides a `newScope' attribute
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which can form the parent scope for later package sets. */
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makeScope = newScope: f:
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let self = f self // {
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newScope = scope: newScope (self // scope);
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callPackage = self.newScope {};
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overrideScope = g:
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makeScope newScope
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(self_: let super = f self_; in super // g super self_);
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packages = f;
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};
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in self;
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}
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