Add generative config example

2 files changed, 23 insertions, 2 deletions

diff --git a/doc/config.txt b/doc/config.txt
index d743e1b..b5a717f 100644
--- a/doc/config.txt
+++ b/doc/config.txt
@@ -261,7 +261,7 @@ Complete list of settings that you can put into ``testenv*`` sections:
     Do not install the current package. This can be used when you need the
     virtualenv management but do not want to install the current package
     into that environment.
-    
+
     **default**: ``False``
 
 
@@ -449,6 +449,8 @@ This uses two new facilities of tox-1.8:
 Let's go through this step by step.
 
 
+.. _generative-envlist:
+
 Generative envlist
 +++++++++++++++++++++++
 
@@ -482,6 +484,8 @@ You can still list environments explicitly along with generated ones::
         flake
 
 
+.. _factors:
+
 Factors and factor-conditional settings
 ++++++++++++++++++++++++++++++++++++++++
 
diff --git a/doc/example/basic.txt b/doc/example/basic.txt
index 916990e..e0dbece 100644
--- a/doc/example/basic.txt
+++ b/doc/example/basic.txt
@@ -74,7 +74,7 @@ depending on requirements.txt
 (experimental) If you have a ``requirements.txt`` file
 you can add it to your ``deps`` variable like this::
 
-    deps = -rrequirements.txt 
+    deps = -rrequirements.txt
 
 All installation commands are executed using ``{toxinidir}``
 (the directory where ``tox.ini`` resides) as the current
@@ -260,3 +260,20 @@ In some cases, you may want to ignore a command exit code. For example::
 
 By using the ``-`` prefix, similar to a ``make`` recipe line, you can ignore
 the exit code for that command.
+
+Compressing dependency matrix
+-----------------------------
+
+If you have a large matrix of dependencies, python versions and/or environments you can
+use :ref:`generative-envlist` and :ref:`conditional settings <factors>` to express that in a concise form::
+
+    [tox]
+    envlist = py{26,27,33}-django{15,16}-{sqlite,mysql}
+
+    [testenv]
+    deps =
+        django15: Django>=1.5,<1.6
+        django16: Django>=1.6,<1.7
+        py33-mysql: PyMySQL     ; use if both py33 and mysql are in an env name
+        py26,py27: urllib3      ; use if any of py26 or py27 are in an env name
+        py{26,27}-sqlite: mock  ; mocking sqlite in python 2.x