Exposing argparse ArgumentError and ArgumentTypeError, updating error types, and fixing UnionType import for Python < 3.10

Author: swansonk14

tap/__init__.py

@@ -1,4 +1,5 @@
+from argparse import ArgumentError, ArgumentTypeError
 from tap._version import __version__
 from tap.tap import Tap
 
-__all__ = ['Tap', '__version__']
+__all__ = ['ArgumentError', 'ArgumentTypeError', 'Tap', '__version__']

tap/tap.py

@@ -1,4 +1,4 @@
-from argparse import ArgumentParser
+from argparse import ArgumentParser, ArgumentTypeError
 from collections import OrderedDict
 from copy import deepcopy
 from functools import partial
@@ -8,7 +8,7 @@
 from shlex import quote, split
 import sys
 import time
-from types import MethodType, UnionType
+from types import MethodType
 from typing import Any, Callable, Dict, List, Optional, Sequence, Set, Tuple, TypeVar, Union, get_type_hints
 from typing_inspect import is_literal_type, get_args
 from warnings import warn
@@ -30,11 +30,14 @@
     enforce_reproducibility,
 )
 
+if sys.version_info >= (3, 10):
+    from types import UnionType
+
 
 # Constants
 EMPTY_TYPE = get_args(List)[0] if len(get_args(List)) > 0 else tuple()
 BOXED_COLLECTION_TYPES = {List, list, Set, set, Tuple, tuple}
-OPTIONAL_TYPES = {Optional, Union, UnionType}
+OPTIONAL_TYPES = {Optional, Union} | ({UnionType} if sys.version_info >= (3, 10) else set())
 BOXED_TYPES = BOXED_COLLECTION_TYPES | OPTIONAL_TYPES
 
 
@@ -202,8 +205,8 @@ def _add_argument(self, *name_or_flags, **kwargs) -> None:
 
                     # Don't allow Tuple[()]
                     if len(types) == 1 and types[0] == tuple():
-                        raise ValueError('Empty Tuples (i.e. Tuple[()]) are not a valid Tap type '
-                                         'because they have no arguments.')
+                        raise ArgumentTypeError('Empty Tuples (i.e. Tuple[()]) are not a valid Tap type '
+                                                'because they have no arguments.')
 
                     # Handle Tuple[type, ...]
                     if len(types) == 2 and types[1] == Ellipsis:

tap/utils.py

@@ -12,7 +12,6 @@
 import subprocess
 import sys
 import tokenize
-from types import UnionType
 from typing import (
     Any,
     Callable,
@@ -27,6 +26,8 @@
 from typing_extensions import Literal
 from typing_inspect import get_args, get_origin as typing_inspect_get_origin
 
+if sys.version_info >= (3, 10):
+    from types import UnionType
 
 NO_CHANGES_STATUS = """nothing to commit, working tree clean"""
 PRIMITIVES = (str, int, float, bool)
@@ -256,7 +257,7 @@ def get_literals(literal: Literal, variable: str) -> Tuple[Callable[[str], Any],
     literals = list(get_args(literal))
 
     if not all(isinstance(literal, PRIMITIVES) for literal in literals):
-        raise ValueError(
+        raise ArgumentTypeError(
             f'The type for variable "{variable}" contains a literal'
             f'of a non-primitive type e.g. (str, int, float, bool).\n'
             f'Currently only primitive-typed literals are supported.'
@@ -265,7 +266,7 @@ def get_literals(literal: Literal, variable: str) -> Tuple[Callable[[str], Any],
     str_to_literal = {str(literal): literal for literal in literals}
 
     if len(literals) != len(str_to_literal):
-        raise ValueError('All literals must have unique string representations')
+        raise ArgumentTypeError('All literals must have unique string representations')
 
     def var_type(arg: str) -> Any:
         return str_to_literal.get(arg, arg)
@@ -404,7 +405,7 @@ def as_python_object(dct: Any) -> Any:
             return UnpicklableObject()
 
         else:
-            raise ValueError(f'Special type "{_type}" not supported for JSON loading.')
+            raise ArgumentTypeError(f'Special type "{_type}" not supported for JSON loading.')
 
     return dct
 
@@ -482,7 +483,7 @@ def get_origin(tp: Any) -> Any:
     if origin is None:
         origin = tp
 
-    if isinstance(origin, UnionType):
+    if sys.version_info >= (3, 10) and isinstance(origin, UnionType):
         origin = UnionType
 
     return origin