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Merge pull request #8490 from lethalman/overridepkgs

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Add pkgs.overridePackages
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lethalman 2015-06-26 17:14:22 +02:00
parent dd73d2af87 7f5f9072ad
commit 5754fd9e02
3 changed files with 77 additions and 2 deletions
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57
doc/functions.xml Normal file
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@ -0,0 +1,57 @@
<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xml:id="chap-functions">
<title>Functions reference</title>
<para>
The nixpkgs repository has several utility functions to manipulate Nix expressions.
</para>
<section xml:id="sec-pkgs-overridePackages">
<title>pkgs.overridePackages</title>
<para>
This function inside the nixpkgs expression (<varname>pkgs</varname>)
can be used to override the set of packages itself.
</para>
<para>
Warning: this function is expensive and must not be used from within
the nixpkgs repository.
</para>
<para>
Example usage:
<programlisting>let
pkgs = import &lt;nixpkgs&gt; {};
newpkgs = pkgs.overridePackages (self: super: {
foo = super.foo.override { ... };
};
in ...</programlisting>
</para>
<para>
The resulting <varname>newpkgs</varname> will have the new <varname>foo</varname>
expression, and all other expressions depending on <varname>foo</varname> will also
use the new <varname>foo</varname> expression.
</para>
<para>
The behavior of this function is similar to <link
linkend="sec-modify-via-packageOverrides">config.packageOverrides</link>.
</para>
<para>
The <varname>self</varname> parameter refers to the final package set with the
applied overrides. Using this parameter may lead to infinite recursion if not
used consciously.
</para>
<para>
The <varname>super</varname> parameter refers to the old package set.
It's equivalent to <varname>pkgs</varname> in the above example.
</para>
</section>
</chapter>

1
doc/manual.xml
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@ -13,6 +13,7 @@
<xi:include href="quick-start.xml" />
<xi:include href="stdenv.xml" />
<xi:include href="packageconfig.xml" />
<xi:include href="functions.xml" />
<xi:include href="meta.xml" />
<xi:include href="language-support.xml" />
<xi:include href="package-notes.xml" />

21
pkgs/top-level/all-packages.nix
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@ -100,6 +100,8 @@ let
# ... pkgs.foo ...").
pkgs = applyGlobalOverrides (config.packageOverrides or (pkgs: {}));
mkOverrides = pkgsOrig: overrides: overrides //
(lib.optionalAttrs (pkgsOrig.stdenv ? overrides && crossSystem == null) (pkgsOrig.stdenv.overrides pkgsOrig));
# Return the complete set of packages, after applying the overrides
# returned by the `overrider' function (see above). Warning: this
@ -110,8 +112,7 @@ let
# in the case of cross-building, or otherwise the basic
# overrided packages will not be built with the crossStdenv
# adapter.
overrides = overrider pkgsOrig //
(lib.optionalAttrs (pkgsOrig.stdenv ? overrides && crossSystem == null) (pkgsOrig.stdenv.overrides pkgsOrig));
overrides = mkOverrides pkgsOrig (overrider pkgsOrig);
# The un-overriden packages, passed to `overrider'.
pkgsOrig = pkgsFun pkgs {};
@ -142,6 +143,22 @@ let
newScope = extra: lib.callPackageWith (defaultScope // extra);
# Easily override this package set.
# Warning: this function is very expensive and must not be used
# from within the nixpkgs repository.
#
# Example:
# pkgs.overridePackages (self: super: {
# foo = super.foo.override { ... };
# }
#
# The result is `pkgs' where all the derivations depending on `foo'
# will use the new version.
overridePackages = f:
let
newpkgs = pkgsFun newpkgs overrides;
overrides = mkOverrides pkgs (f newpkgs pkgs);
in newpkgs;
# Override system. This is useful to build i686 packages on x86_64-linux.
forceSystem = system: kernel: (import ./all-packages.nix) {