Refactor to avoid using a default value in argparse

See discussion here: #15 (comment)
And here #21

Author: DanielNoord

.github/CONTRIBUTING.md

@@ -9,9 +9,9 @@ Use `pre-commit install` to install the pre-commit hook for the repository.
 - Implement a Formatter by inheriting from `pydocstringformatter.formatting.Formatter`
 - Add your new formatter to `pydocstringformatter.formatting.FORMATTERS`
 - Write a clear docstring because this will be user-facing: it's what will be seen in
-  the help message for the formatters command line option.
+  the help message for the formatter's command line option.
 - Choose a proper name because this will be user-facing: the name will be used to turn
-  the checker on and off via the command line or config files.
+  the formatter on and off via the command line or config files.
 
 ### Testing
 

pydocstringformatter/run.py

@@ -9,21 +9,20 @@
 from typing import List, Union
 
 from pydocstringformatter import __version__, formatting, utils
-from pydocstringformatter.formatting import FORMATTERS
 
 
 class _Run:
     """Main class that represent a run of the program."""
 
     def __init__(self, argv: Union[List[str], None]) -> None:
         self.arg_parser = utils._register_arguments(__version__)
-        utils._register_arguments_formatters(self.arg_parser, FORMATTERS)
+        utils._register_arguments_formatters(self.arg_parser, formatting.FORMATTERS)
         self.config = argparse.Namespace()
 
         if argv := argv or sys.argv[1:]:
-            utils._parse_toml_file(self.arg_parser, self.config)
-            utils._parse_command_line_arguments(self.arg_parser, argv, self.config)
-
+            utils._parse_options(
+                self.arg_parser, self.config, argv, formatting.FORMATTERS
+            )
             self._check_files(self.config.files)
         else:
             self.arg_parser.print_help()

pydocstringformatter/utils/__init__.py

@@ -1,6 +1,5 @@
 from pydocstringformatter.utils.argument_parsing import (
-    _parse_command_line_arguments,
-    _parse_toml_file,
+    _parse_options,
     _register_arguments,
     _register_arguments_formatters,
 )
@@ -18,12 +17,11 @@
     "_find_python_files",
     "_generate_diff",
     "_is_docstring",
-    "_parse_command_line_arguments",
-    "_parse_toml_file",
     "ParsingError",
     "PydocstringFormatterError",
     "_register_arguments",
     "_register_arguments_formatters",
     "TomlParsingError",
+    "_parse_options",
     "_print_to_console",
 ]

pydocstringformatter/utils/argument_parsing.py

@@ -51,7 +51,6 @@ def _register_arguments_formatters(
             f"--{name}",
             action="store_true",
             dest=name,
-            default=not formatter.optional,
             help=f"A{help_text} : {formatter.__doc__}",
         )
         parser.add_argument(
@@ -100,3 +99,37 @@ def _parse_toml_file(
             arguments += _parse_toml_option(key, value)
 
         parser.parse_args(arguments, namespace)
+
+
+def _load_formatters_default_option(
+    parser: argparse.ArgumentParser,
+    namespace: argparse.Namespace,
+    formatters: List[Formatter],
+) -> None:
+    """Load the list of formatters based on their 'optional' attribute."""
+    arguments: List[str] = []
+    for formatter in formatters:
+        if formatter.optional:
+            arguments.append(f"--no-{formatter.name}")
+        elif not formatter.optional:
+            arguments.append(f"--{formatter.name}")
+
+    parser.parse_known_args(arguments, namespace)
+
+
+def _parse_options(
+    parser: argparse.ArgumentParser,
+    namespace: argparse.Namespace,
+    argv: List[str],
+    formatters: List[Formatter],
+) -> None:
+    """Load all default option values.
+
+    The order of parsing is:
+    1. default values, 2. configuration files, 3. command line arguments.
+    """
+    _load_formatters_default_option(parser, namespace, formatters)
+
+    _parse_toml_file(parser, namespace)
+
+    _parse_command_line_arguments(parser, argv, namespace)