From ca41e642fba9af41b3ba0ed971361a127e50240a Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 9 Jun 2018 13:47:49 +0530
Subject: [PATCH] Nicer error message when no kitten name is specified

---
 __main__.py       | 7 ++++++-
 kittens/runner.py | 8 ++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/__main__.py b/__main__.py
index c54ee3847..1ad027db5 100644
--- a/__main__.py
+++ b/__main__.py
@@ -33,7 +33,12 @@ def launch(args):
 
 
 def run_kitten(args):
-    kitten = args[1]
+    try:
+        kitten = args[1]
+    except IndexError:
+        from kittens.runner import list_kittens
+        list_kittens()
+        raise SystemExit(1)
     sys.argv = args[1:]
     from kittens.runner import run_kitten
     run_kitten(kitten)
diff --git a/kittens/runner.py b/kittens/runner.py
index c540a756d..d507cc299 100644
--- a/kittens/runner.py
+++ b/kittens/runner.py
@@ -101,6 +101,14 @@ def all_kitten_names():
     return ans
 
 
+def list_kittens():
+    print('You must specify the name of a kitten to run')
+    print('Choose from:')
+    print()
+    for kitten in all_kitten_names():
+        print(kitten)
+
+
 def get_kitten_cli_docs(kitten):
     sys.cli_docs = {}
     run_kitten(kitten, run_name='__doc__')