document setuptools monkeypatching and DETERMINISTIC_BUILD=1

1 files changed, 6 insertions, 3 deletions

diff --git a/pkgs/development/python-modules/generic/default.nix b/pkgs/development/python-modules/generic/default.nix
index fc91fcd3d8a8..c2a389a78be1 100644
--- a/pkgs/development/python-modules/generic/default.nix
+++ b/pkgs/development/python-modules/generic/default.nix
@@ -54,14 +54,17 @@ python.stdenv.mkDerivation (attrs // {
   configurePhase = attrs.configurePhase or ''
     runHook preConfigure
 
-    # TODO: document
+    # patch python interpreter to write null timestamps when compiling python files
+    # with following var we tell python to activate the patch so that python doesn't
+    # try to update them when we freeze timestamps in nix store
     export DETERMINISTIC_BUILD=1
 
-    # we need to prepend following line to monkeypatch distutils commands
+    # prepend following line to import setuptools before distutils
+    # this way we make sure setuptools monkeypatches distutils commands
+    # this way setuptools provides extra helpers such as "python setup.py test"
     sed -i '0,/import distutils/s//import setuptools;import distutils/' setup.py
     sed -i '0,/from distutils/s//import setuptools;from distutils/' setup.py
 
-
     runHook postConfigure
   '';