Prettify argparse

hpvm/tools/py-approxhpvm/main.py.in

@@ -179,19 +179,19 @@ def parse_args():
 
     # Relaying arguments for clang++ (source -> bitcode stage)
     parser.add_argument(
-        "-I", "--include", type=Path, action="append",
+        "-I", "--include", type=Path, action="append", metavar="dir",
         help="[clang emit-llvm] Add directory to include search path"
     )
     parser.add_argument(
-        "-D", type=str, action="append",
+        "-D", type=str, action="append", metavar="<macro>=<value>",
         help="[clang emit-llvm] Define macro"
     )
     parser.add_argument(
-        "-f", type=str, action="append",
+        "-f", type=str, action="append", metavar="flag",
         help="[clang emit-llvm] clang++ flags (such as -ffastmath)"
     )
     parser.add_argument(
-        "-O", type=str, default="0",
+        "-O", type=str, default="0", metavar="level",
         help="[clang emit-llvm] Optimization level"
     )
     parser.add_argument(
@@ -201,10 +201,12 @@ def parse_args():
 
     # Relaying arguments for clang++ (linking stage)
     parser.add_argument(
-        "-L", type=Path, action="append", help="[clang linker] Add directory to library search path"
+        "-L", type=Path, action="append", metavar="dir",
+        help="[clang linker] Add directory to library search path"
     )
     parser.add_argument(
-        "-l", type=str, action="append", help="[clang linker] Link library (such as -lpthread)"
+        "-l", type=str, action="append", metavar="name",
+        help="[clang linker] Link library (such as -lpthread)"
     )
 
     args = parser.parse_args()