initial commit

argclass.py

@@ -0,0 +1,123 @@
+import typing
+from argparse import ArgumentParser
+from dataclasses import dataclass, field, MISSING
+
+
+def make_gnu_option(name):
+    return f'--{name.replace("_", "-")}'
+
+
+def decide_default(field_):
+    arg_cfg = {}
+    if field_.default != MISSING:
+        arg_cfg['default'] = field_.default
+    elif field_.default_factory != MISSING:
+        arg_cfg['default'] = field_.default_factory()
+    else:
+        arg_cfg['required'] = True
+    return arg_cfg
+
+
+def get_choices(field_):
+    arg_cfg = {}
+    try:
+        arg_cfg['choices'] = field_.metadata['choices']
+    except KeyError:
+        pass
+    return arg_cfg
+
+
+def compute_arg_names(name, field_):
+    names = [make_gnu_option(name)]  # long option
+    try:
+        names.append(f'-{field_.metadata["shortopt"]}')
+    except KeyError:
+        pass
+    return names
+
+
+def _prepare_bool(ap: ArgumentParser, name, field_):
+    arg_cfg = decide_default(field_)
+    required = 'required' in arg_cfg
+    bool_parser = ap.add_mutually_exclusive_group(required=required)
+    bool_parser.add_argument(make_gnu_option(name),
+                             action='store_true',
+                             dest=name)
+    bool_parser.add_argument(make_gnu_option(f'no_{name}'),
+                             action='store_false',
+                             dest=name)
+    if not required:
+        ap.set_defaults(**{name: arg_cfg['default']})
+
+
+def _prepare_list_cfg(name, field_):
+    arg_cfg = {
+        **decide_default(field_),
+        **get_choices(field_),
+    }
+    arg_cfg['type'] = typing.get_args(field_.type)[0]
+    if field_.metadata.get('allow_empty', False):
+        arg_cfg['nargs'] = '*'
+    else:
+        arg_cfg['nargs'] = '+'
+    return arg_cfg
+
+
+def _prepare_trivial_cfg(name, field_):
+    arg_cfg = {
+        **decide_default(field_),
+        **get_choices(field_),
+    }
+    arg_cfg['type'] = field_.type
+    return arg_cfg
+
+
+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)
+
+
+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)
+
+
+def prepare_field(ap, name, field_):
+    if field_.type is bool:
+        _prepare_bool(ap, name, field_)
+    elif typing.get_origin(field_.type) is list:
+        _prepare_list(ap, name, field_)
+    else:
+        _prepare_trivial(ap, name, field_)
+
+
+def argclass(cls):
+
+    class ArgClass(dataclass(cls)):
+
+        @classmethod
+        def parse_args(cls):
+            ap = ArgumentParser()
+            for name, field_ in cls.__dataclass_fields__.items():
+                prepare_field(ap, name, field_)
+            return ap.parse_args()
+
+    return ArgClass
+
+
+@argclass
+class A:
+    required_int_arg: int
+    required_bool_arg: bool
+    required_int_arg_with_choices: int = field(metadata={'choices': [3, 4, 5]})
+    arg_with_default: str = 'abc'
+    list_arg_with_default: list[int] = field(default_factory=lambda: [1, 2])
+    list_arg_with_default_mb_empty: list[int] = field(
+        default_factory=lambda: [], metadata={'allow_empty': True}
+    )
+
+
+if __name__ == '__main__':
+    print(A.parse_args())