refactor argparse handling

freqtrade/main.py

@@ -2,6 +2,7 @@
 import copy
 import json
 import logging
+import sys
 import time
 import traceback
 from datetime import datetime
@@ -14,8 +15,9 @@ from jsonschema import validate
 
 from freqtrade import __version__, exchange, persistence
 from freqtrade.analyze import get_signal, SignalType
+from freqtrade.misc import CONF_SCHEMA, State, get_state, update_state, parse_args, throttle
 from freqtrade.misc import (
-    CONF_SCHEMA, State, get_state, update_state, build_arg_parser, throttle, FreqtradeException
+    FreqtradeException
 )
 from freqtrade.persistence import Trade
 from freqtrade.rpc import telegram
@@ -316,11 +318,8 @@ def main():
     :return: None
     """
     global _CONF
-    args = build_arg_parser().parse_args()
-
-    # Check if subcommand has been selected
-    if hasattr(args, 'func'):
-        args.func(args)
+    args = parse_args(sys.argv[1:])
+    if not args:
         exit(0)
 
     # Initialize logger

freqtrade/misc.py

@@ -3,7 +3,7 @@ import enum
 import logging
 import os
 import time
-from typing import Any, Callable
+from typing import Any, Callable, List
 
 from wrapt import synchronized
 
@@ -62,8 +62,11 @@ def throttle(func: Callable[..., Any], min_secs: float, *args, **kwargs) -> Any:
     return result
 
 
-def build_arg_parser() -> argparse.ArgumentParser:
-    """ Builds and returns an ArgumentParser instance """
+def parse_args(args: List[str]):
+    """
+    Parses given arguments and returns an argparse Namespace instance.
+    Returns None if a sub command has been selected and executed.
+    """
     parser = argparse.ArgumentParser(
         description='Simple High Frequency Trading Bot for crypto currencies'
     )
@@ -94,7 +97,14 @@ def build_arg_parser() -> argparse.ArgumentParser:
         action='store_true',
     )
     build_subcommands(parser)
-    return parser
+    parsed_args = parser.parse_args(args)
+
+    # No subcommand as been selected
+    if not hasattr(parsed_args, 'func'):
+        return parsed_args
+
+    parsed_args.func(parsed_args)
+    return None
 
 
 def build_subcommands(parser: argparse.ArgumentParser) -> None: