Implement help

src/argclass/__init__.py

@@ -38,6 +38,12 @@ def _get_choices(field_: Field, base_type):
     return {}
 
 
+def _get_help(field_: Field):
+    if HELP in field_.metadata:
+        return {"help": field_.metadata[HELP]}
+    return {}
+
+
 def _compute_arg_names(name, field_) -> list[str]:
     names = [_make_gnu_option(name)]  # long option
     if SHORTOPT in field_.metadata:
@@ -53,11 +59,25 @@ def _prepare_bool(ap: ArgumentParser, name, field_):
     defaults_cfg = _decide_default(field_)
     required = defaults_cfg.get("required", False)
     bool_parser = ap.add_mutually_exclusive_group(required=required)
+
+    if HELP in field_.metadata:
+        true_help = {"help": f"{field_.metadata[HELP]} (enable)"}
+        false_help = {"help": f"{field_.metadata[HELP]} (disable)"}
+    else:
+        true_help: dict[str, str] = {}
+        false_help: dict[str, str] = {}
+
     bool_parser.add_argument(
-        _make_gnu_option(name), action="store_true", dest=name
+        _make_gnu_option(name),
+        action="store_true",
+        dest=name,
+        **true_help,  # type: ignore
     )
     bool_parser.add_argument(
-        _make_gnu_option(f"no_{name}"), action="store_false", dest=name
+        _make_gnu_option(f"no_{name}"),
+        action="store_false",
+        dest=name,
+        **false_help,  # type: ignore
     )
     if not required:
         ap.set_defaults(**{name: defaults_cfg["default"]})
@@ -99,13 +119,13 @@ def _prepare_trivial_cfg(_, field_: Field):
 def _prepare_list(ap: ArgumentParser, name, field_):
     arg_cfg = _prepare_list_cfg(name, field_)
     arg_names = _compute_arg_names(name, field_)
-    ap.add_argument(*arg_names, **arg_cfg)
+    ap.add_argument(*arg_names, **arg_cfg, **_get_help(field_))
 
 
 def _prepare_trivial(ap: ArgumentParser, name, field_):
     arg_cfg = _prepare_trivial_cfg(name, field_)
     arg_names = _compute_arg_names(name, field_)
-    ap.add_argument(*arg_names, **arg_cfg)
+    ap.add_argument(*arg_names, **arg_cfg, **_get_help(field_))
 
 
 def _prepare_field(ap: ArgumentParser, name: str, field_: Field):
@@ -135,6 +155,7 @@ def argfield(
     shortopt: str | None = None,
     choices: list[typing.Any] | None = None,
     allow_empty: bool | None = None,
+    help: str | None = None,
     **kwargs,
 ):
     metadata = kwargs.pop("metadata", {})
@@ -148,4 +169,7 @@ def argfield(
     if allow_empty is not None:
         metadata[ALLOW_EMPTY] = allow_empty
 
+    if help is not None:
+        metadata[HELP] = help
+
     return field(**kwargs, metadata=metadata)