add --prefix option for shell formatter; add docs for shell formatter

3 files changed, 36 insertions, 4 deletions

diff --git a/cliff/formatters/shell.py b/cliff/formatters/shell.py
index a490550..23f2368 100644
--- a/cliff/formatters/shell.py
+++ b/cliff/formatters/shell.py
@@ -19,6 +19,13 @@ class ShellFormatter(SingleFormatter):
             metavar='VARIABLE',
             help='specify the variable(s) to include, can be repeated',
             )
+        group.add_argument(
+            '--prefix',
+            action='store',
+            default='',
+            dest='prefix',
+            help='add a prefix to all variable names',
+            )
 
     def emit_one(self, column_names, data, stdout, parsed_args):
         variable_names = [c.lower().replace(' ', '_')
@@ -27,5 +34,5 @@ class ShellFormatter(SingleFormatter):
         desired_columns = parsed_args.variables
         for name, value in zip(variable_names, data):
             if name in desired_columns or not desired_columns:
-                stdout.write('%s="%s"\n' % (name, value))
+                stdout.write('%s%s="%s"\n' % (parsed_args.prefix, name, value))
         return
diff --git a/docs/source/history.rst b/docs/source/history.rst
index 5df2893..303b9cd 100644
--- a/docs/source/history.rst
+++ b/docs/source/history.rst
@@ -2,6 +2,10 @@
  Release History
 =================
 
+dev
+
+  - Add shell formatter for single objects.
+
 0.3
 
   - Add ShowOne base class for commands that show details about single
diff --git a/docs/source/show_commands.rst b/docs/source/show_commands.rst
index c3b8914..5ad72de 100644
--- a/docs/source/show_commands.rst
+++ b/docs/source/show_commands.rst
@@ -27,10 +27,10 @@ commands. :class:`ShowOne` adds a command line switch to let the user
 specify the formatter they want, so you don't have to do any extra
 work in your application.
 
-PrettyTable
------------
+table
+-----
 
-The ``PrettyTable`` formatter uses PrettyTable_ to produce output
+The ``table`` formatter uses PrettyTable_ to produce output
 formatted for human consumption.
 
 .. _PrettyTable: http://code.google.com/p/prettytable/
@@ -48,6 +48,27 @@ formatted for human consumption.
     | Modified Time | 1335569964.0 |
     +---------------+--------------+
 
+shell
+-----
+
+The ``shell`` formatter produces output that can be parsed directly by
+a typical UNIX shell as variable assignments. This avoids extra
+parsing overhead in shell scripts.
+
+::
+
+    (.venv)$ cliffdemo file -f shell setup.py
+    name="setup.py"
+    size="5916"
+    uid="527"
+    gid="501"
+    modified_time="1335655655.0"
+
+    (.venv)$ eval "$(cliffdemo file -f shell --prefix example_ setup.py)"
+    (.venv)$ echo $example_size
+    5916
+
+
 Creating Your Own Formatter
 ---------------------------