Merge pull request #10 from patch/types

Fixed a bug with default collection type hints

README.md

@@ -366,7 +366,7 @@ The `pyrallis.field` behaves like the regular `dataclasses.field` with an additi
 
 
 # TODOs:
-- [ ] Fix error with default Dict and List
+- [x] Fix error with default Dict and List
 >         Underlying error: No decoding function for type ~KT, consider using pyrallis.decode.register
 - [x] Refine the `--help` command
 > For example the `options` argument is confusing there

pyrallis/parsers/decoding.py

@@ -18,7 +18,8 @@
     is_union,
     is_enum,
     ParsingError,
-    format_error
+    format_error,
+    has_generic_arg
 )
 
 logger = getLogger(__name__)
@@ -130,30 +131,31 @@ def get_decoding_fn(t: Type[T]) -> Callable[[Any], T]:
     elif is_dict(t):
         logger.debug(f"Decoding a Dict field: {t}")
         args = get_type_arguments(t)
-        if len(args) != 2:
+        if args is None or len(args) != 2 or has_generic_arg(args):
             args = (Any, Any)
         return decode_dict(*args)
 
     elif is_set(t):
         logger.debug(f"Decoding a Set field: {t}")
         args = get_type_arguments(t)
-        if len(args) != 1:
+        if args is None or len(args) != 1 or has_generic_arg(args):
             args = (Any,)
         return decode_set(args[0])
 
     elif is_tuple(t):
         logger.debug(f"Decoding a Tuple field: {t}")
         args = get_type_arguments(t)
+        if args is None:
+            args = []
         return decode_tuple(*args)
 
     elif is_list(t):  # NOTE: Looks like can't be written with a dictionary
         logger.debug(f"Decoding a List field: {t}")
         args = get_type_arguments(t)
-        if not args:
+        if args is None or len(args) != 1 or has_generic_arg(args):
             # Using a `List` or `list` annotation, so we don't know what do decode the
             # items into!
             args = (Any,)
-        assert len(args) == 1
         decode_fn = decode_list(args[0])
 
         return decode_fn

pyrallis/utils.py

@@ -588,6 +588,20 @@ def format_error(e: Exception):
         return f'Exception: {e}'
 
 
+def is_generic_arg(arg):
+    try:
+        return arg.__name__ in ['KT', 'VT', 'T']
+    except Exception:
+        return False
+
+
+def has_generic_arg(args):
+    for arg in args:
+        if is_generic_arg(arg):
+            return True
+    return False
+
+
 CONFIG_ARG = 'config_path'
 
 if __name__ == "__main__":

tests/test_lists.py

@@ -1,8 +1,6 @@
 from dataclasses import dataclass, field
 from typing import *
-
 import pytest
-
 from .testutils import *
 
 
@@ -80,3 +78,29 @@ class SomeClass(TestSetup):
         arguments = "--a " + format_list_using_brackets(value)
         result = SomeClass.setup(arguments)
         assert result == SomeClass(a=value)
+
+
+@parametrize(
+    "item_type, type_hint, value, arg",
+    [
+        (list, List, [1, 2, 3], '[1, 2, 3]'),
+        (set, Set, {1, 2, 3}, '[1, 2, 3]'),
+        (tuple, Tuple, (1, 2, 3), '[1, 2, 3]'),
+        (dict, Dict, {1: 2}, '{1: 2}')
+    ],
+)
+def test_collection_no_type(item_type, type_hint, value, arg):
+    @dataclass
+    class ContainerHint(TestSetup):
+        a: type_hint
+
+    c = ContainerHint.setup(f"--a '{arg}'")
+    assert c.a == value
+
+    @dataclass
+    class ContainerType(TestSetup):
+        a: item_type
+
+    c = ContainerType.setup(f"--a '{arg}'")
+    assert c.a == value
+