Cleaned up context defaults and documented them.

2 files changed, 44 insertions, 7 deletions

diff --git a/click/core.py b/click/core.py
index 9e59b41..b168e52 100644
--- a/click/core.py
+++ b/click/core.py
@@ -156,6 +156,10 @@ class Context(object):
         #: the user object stored.
         self.obj = obj
         #: A dictionary (-like object) with defaults for parameters.
+        if default_map is None \
+           and parent is not None \
+           and parent.default_map is not None:
+            default_map = parent.default_map.get(info_name)
         self.default_map = default_map
 
         if terminal_width is None and parent is not None:
@@ -392,16 +396,9 @@ class BaseCommand(object):
         :param extra: extra keyword arguments forwarded to the context
                       constructor.
         """
-        if 'default_map' not in extra:
-            default_map = None
-            if parent is not None and parent.default_map is not None:
-                default_map = parent.default_map.get(info_name)
-            extra['default_map'] = default_map
-
         for key, value in iteritems(self.context_defaults or {}):
             if key not in extra:
                 extra[key] = value
-
         ctx = Context(self, info_name=info_name, parent=parent, **extra)
         self.parse_args(ctx, args)
         return ctx
diff --git a/docs/commands.rst b/docs/commands.rst
index 6cad462..620f56f 100644
--- a/docs/commands.rst
+++ b/docs/commands.rst
@@ -293,6 +293,8 @@ Example usage:
             }
         })
 
+And in action:
+
 .. click:run::
 
     invoke(cli, prog_name='cli', args=['runserver'], default_map={
@@ -300,3 +302,41 @@ Example usage:
             'port': 5000
         }
     })
+
+Context Defaults
+----------------
+
+.. versionadded:: 2.0
+
+Starting with click 2.0 you can override defaults for contexts not just
+when calling your script, but also in the decorator that declares a
+command.  For instance given the previous example which defines a custom
+``default_map`` this can also be accomplished in the decorator now.
+
+This example does the same as the previous example:
+
+.. click:example::
+
+    import click
+
+    CONTEXT_DEFAULTS = dict(
+        default_map={'runserver': {'port': 5000}}
+    )
+
+    @click.group(context_defaults=CONTEXT_DEFAULTS)
+    def cli():
+        pass
+
+    @cli.command()
+    @click.option('--port', default=8000)
+    def runserver(port):
+        click.echo('Serving on http://127.0.0.1:%d/' % port)
+
+    if __name__ == '__main__':
+        cli()
+
+And again the example in action:
+
+.. click:run::
+
+    invoke(cli, prog_name='cli', args=['runserver'])