Update options.py

It is unclear in the documentation what tornado.options.parse_config_file does and how it works. I added a little text to the copy that should clarify its purpose.

diff --git a/tornado/options.py b/tornado/options.py
index bdb5baa0a9b04535d6a8f0f4ce9f67352bb5df5d..5477f833f433cf87f0964f5fc690b04453afa8b9 100644 (file)
--- a/tornado/options.py
+++ b/tornado/options.py
@@ -41,6 +41,13 @@ either::
     # or
     tornado.options.parse_config_file("/etc/server.conf")
 
+.. note:
+
+   When using tornado.options.parse_config_file(), the only options that are set
+   are ones that were previously defined either tornado.options.parse_command_line
+   or tornado.options.define. torndo.options.parse_config_file is used mainly as a 
+   means to offer overriding settings for different environments.
+
 Command line formats are what you would expect (``--myoption=myvalue``).
 Config files are just Python files. Global names become options, e.g.::