From 8dadb44196a07f6b4ab42b16fdb64f2fcc3fc94c Mon Sep 17 00:00:00 2001
From: Frederik Rietdijk <fridh@fridh.nl>
Date: Fri, 28 Oct 2016 13:31:07 +0200
Subject: [PATCH] pythonPackages: use fixed-point combinator

Use a fixed-point combinator for the Python package set to allow easier overriding of its contents.
Earlier implementations were proposed in #16784 and #17428. This commit is by comparison much smaller
and changes only what is needed.
---
 pkgs/top-level/all-packages.nix    |  7 -------
 pkgs/top-level/python-packages.nix | 14 ++++++++++++--
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 34d24a89ff7e..e0b0656a59e7 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -9897,37 +9897,30 @@ in
   # regardless.
   python26Packages = callPackage ./python-packages.nix {
     python = python26;
-    self = python26Packages;
   };
 
   python27Packages = lib.hiPrioSet (recurseIntoAttrs (callPackage ./python-packages.nix {
     python = python27;
-    self = python27Packages;
   }));
 
   python33Packages = callPackage ./python-packages.nix {
     python = python33;
-    self = python33Packages;
   };
 
   python34Packages = callPackage ./python-packages.nix {
     python = python34;
-    self = python34Packages;
   };
 
   python35Packages = recurseIntoAttrs (callPackage ./python-packages.nix {
     python = python35;
-    self = python35Packages;
   });
 
   python36Packages = (callPackage ./python-packages.nix {
     python = python36;
-    self = python36Packages;
   });
 
   pypyPackages = callPackage ./python-packages.nix {
     python = pypy;
-    self = pypyPackages;
   };
 
   ### DEVELOPMENT / R MODULES
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index fc5972bfbf0f..ca2e88da94e4 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -1,7 +1,14 @@
-{ pkgs, stdenv, python, self }:
+{ pkgs
+, stdenv
+, python
+, overrides ? (self: super: {})
+}:
 
 with pkgs.lib;
 
+let
+  packages = ( self:
+
 let
   pythonAtLeast = versionAtLeast python.pythonVersion;
   pythonOlder = versionOlder python.pythonVersion;
@@ -31323,4 +31330,7 @@ in {
   zeitgeist = if isPy3k then throw "zeitgeist not supported for interpreter ${python.executable}" else
     (pkgs.zeitgeist.override{python2Packages=self;}).py;
 
-}
+
+});
+
+in fix' (extends overrides packages)