set up basic argparse functionality with sys, see #16

bin/okra

@@ -1,53 +1,18 @@
 #! /usr/bin/env python
 
-import argparse
+import sys
 import logging
 
+from okra.cli import print_help, parse_args
 from okra.logging_utils import enable_cloud_log
 
-logger = logging.getLogger(__name__)
-
-
-class _HelpAction(argparse._HelpAction):
-    """ Reference: https://stackoverflow.com/questions/20094215 """
-
-    def __call__(self, parser, namespace, values, option_string=None):
-        parser.print_help()
-
-        # retrieve subparsers from parser
-        subparsers_actions = [
-                action for action in parser._actions
-                if isinstance(action, argparse._SubParsersAction)]
-
-        # there will probably only be one subparser_action,
-        # but better safe than sorry
-
-        for subparsers_action in subparsers_actions:
-
-            # get all subparsers and print help
-
-            for choice, subparser in subparsers_action.choices.items():
 
-                print("Subparser '{}'".format(choice))
-                print(subparser.format_help())
-
-            parser.exit()
-
-
-parser = argparse.ArgumentParser(add_help=False)
-
-parser.add_argument('--help', action=_HelpAction, help='big help')
-parser.add_argument('task', action='store_true', help='name of task to perform (compute)')
-
-subparsers = parser.add_subparsers(help='run these tasks, pass the bong')
-task_parser = subparsers.add_parser("compute", help="compute the following")
+enable_cloud_log(level='INFO')
 
-task_parser.add_argument('-repo', help='git clone url to git repo')
+logger = logging.getLogger(__name__)
 
-# Configure logging
 
-enable_cloud_log(level='INFO')
+parse_args(sys.argv)
 
-parsed_args = parser.parse_args()
 
-print(parsed_args)
+print_help()

okra/cli.py

@@ -0,0 +1,43 @@
+""" Command Line Interface utilities for Okra """
+import sys
+
+CLI_HELP = """
+okra {task}
+
+    {task}
+        compute     Perform the 'compute' task.  
+
+    {compute}
+
+        repo        Check cache, clone repo if confirmed; create database and generate report.
+
+    Optional Args
+
+        -h --help   Print this help menu then exit.
+"""
+TASKS = ["compute"]
+
+def print_help(good=True):
+    print(CLI_HELP)
+    if good:
+        sys.exit(0)
+    sys.exit(2)
+
+def parse_args(args: list):
+    """ Parse sys.argv arguments. """
+
+    if len(args) < 2:
+        sys.stderr.write("\nERROR: 'okra {task}' missing from cli\n")
+        print_help()
+
+    if args[1] == "compute":
+        print("good one")
+
+    else:
+        sys.stderr.write("\nERROR: got {{task}}: {}, want one of {{task}}: {}\n".\
+                format(args[1], ",".join(TASKS)))
+
+
+
+    return True
+