fix: recognise type from typehint and default value

arger/decorator.py

@@ -31,8 +31,8 @@ def _add_fn(self, fn) -> (str, Optional[Callable]):
             desc, args = opterate(fn)
 
             def add_args():  # lazy adding of arguments
-                for arg, kw in args:
-                    self.add_argument(*arg, **kw)
+                for flags, kw in args:
+                    self.add_argument(*flags, **kw)
 
             return desc, add_args
         return "", None

arger/parser/parser.py

@@ -1,5 +1,6 @@
 # most of this module is taken from https://github.com/dusty-phillips/opterator
 from enum import Enum
+from inspect import isclass
 from typing import Any, List, Set, Tuple
 
 from arger.parser.docstring import parse_docstring
@@ -92,15 +93,17 @@ def add_param(
         option_kwargs["dest"] = param
         names = get_arg_names(param, param_doc, option_generator)
 
-        if _type is UNDEFINED:
+        if _type is UNDEFINED and default is not None:
             _type = type(default)
 
     option_kwargs.update(
-        {"action": get_action(_type, default), "help": " ".join(param_doc),}
+        {"action": get_action(_type, default), "help": " ".join(param_doc)}
     )
 
-    if issubclass(_type, Enum):
+    if isclass(_type) and issubclass(_type, Enum):
         option_kwargs["choices"] = [e.value for e in _type]
+    elif (_type is not UNDEFINED) and _type != bool:
+        option_kwargs["type"] = _type
 
     return (names, option_kwargs)
 

tests/examples/1_single_function.md

@@ -2,7 +2,7 @@
 1. ran with both options
 ```shell script
 $ python 1_single_function.py 10 p2
-param1 (<class 'str'>): 10
+param1 (<class 'int'>): 10
 param2 (<class 'str'>): p2
 kw1 (<class 'NoneType'>): None
 kw2 (<class 'bool'>): False
@@ -42,13 +42,13 @@ pytest: error: the following arguments are required: param1, param2
 4. ran with invalid type
 ```shell script
 $ python 1_single_function.py p1 p2
-usage: pytest [-h] [-k KW1] [-w]  param1 param2
-pytest: error: unrecognized arguments: p1
+usage: pytest [-h] [-k KW1] [-w] param1 param2
+pytest: error: argument param1: invalid int value: 'p1'
 ```
 
 5. ran with one argument missing
 ```shell script
 $ python 1_single_function.py p1
 usage: pytest [-h] [-k KW1] [-w] param1 param2
-pytest: error: the following arguments are required: param2
+pytest: error: argument param1: invalid int value: 'p1'
 ```

tests/test_fn_parser.py

@@ -0,0 +1,35 @@
+from arger.parser import opterate
+
+from .utils import _reprint
+
+
+def main(param1: int, param2: str, kw1=None, kw2=False):
+    """Example function with types documented in the docstring.
+
+    :param param1: The first parameter.
+    :param param2: The second parameter.
+    """
+    _reprint(**locals())
+
+
+def test_opterate():
+    doc, args = opterate(func=main)
+    assert doc == "Example function with types documented in the docstring."
+    assert args == [
+        (['param1'], {'action': 'store', 'help': 'The first parameter.', 'type': int}),
+        (['param2'], {'action': 'store', 'help': 'The second parameter.', 'type': str}),
+        (
+            ['-k', '--kw1'],
+            {'action': 'store', 'default': None, 'dest': 'kw1', 'help': ''},
+        ),
+        (
+            ['-w', '--kw2'],
+            {
+                'action': 'store_true',
+                'default': False,
+                'dest': 'kw2',
+                'help': '',
+                "type": bool,
+            },
+        ),
+    ]