diff -r afe119a3619f -r 3d3887a7ee1d Lib/dis.py
--- a/Lib/dis.py	Sun Jul 21 16:25:30 2013 +0200
+++ b/Lib/dis.py	Wed Jul 24 00:30:33 2013 +0100
@@ -433,25 +433,14 @@

 def _test():
     """Simple test program to disassemble a file."""
-    if sys.argv[1:]:
-        if sys.argv[2:]:
-            sys.stderr.write("usage: python dis.py [-|file]\n")
-            sys.exit(2)
-        fn = sys.argv[1]
-        if not fn or fn == "-":
-            fn = None
-    else:
-        fn = None
-    if fn is None:
-        f = sys.stdin
-    else:
-        f = open(fn)
-    source = f.read()
-    if fn is not None:
-        f.close()
-    else:
-        fn = "<stdin>"
-    code = compile(source, fn, "exec")
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('infile', type=argparse.FileType(), nargs='?', default='-')
+    args = parser.parse_args()
+    with args.infile as infile:
+        source = infile.read()
+    code = compile(source, args.infile.name, "exec")
     dis(code)

 if __name__ == "__main__":