Fix state indexing (#16)

pynecone/utils.py

@@ -46,6 +46,9 @@ join = os.linesep.join
 # Console for pretty printing.
 console = Console()
 
+# Union of generic types.
+GenericType = Union[Type, _GenericAlias]
+
 
 def get_args(alias: _GenericAlias) -> Tuple[Type, ...]:
     """Get the arguments of a type alias.
@@ -59,7 +62,59 @@ def get_args(alias: _GenericAlias) -> Tuple[Type, ...]:
     return alias.__args__
 
 
-def get_base_class(cls: Type) -> Type:
+def is_generic_alias(cls: GenericType) -> bool:
+    """Check whether the class is a generic alias.
+
+    Args:
+        cls: The class to check.
+
+    Returns:
+        Whether the class is a generic alias.
+    """
+    # For older versions of Python.
+    if isinstance(cls, _GenericAlias):
+        return True
+
+    try:
+        from typing import _SpecialGenericAlias  # type: ignore
+
+        if isinstance(cls, _SpecialGenericAlias):
+            return True
+    except ImportError:
+        pass
+
+    # For newer versions of Python.
+    try:
+        from types import GenericAlias  # type: ignore
+
+        return isinstance(cls, GenericAlias)
+    except ImportError:
+        return False
+
+
+def is_union(cls: GenericType) -> bool:
+    """Check if a class is a Union.
+
+    Args:
+        cls: The class to check.
+
+    Returns:
+        Whether the class is a Union.
+    """
+    try:
+        from typing import _UnionGenericAlias  # type: ignore
+
+        return isinstance(cls, _UnionGenericAlias)
+    except ImportError:
+        pass
+
+    if is_generic_alias(cls):
+        return cls.__origin__ == Union
+
+    return False
+
+
+def get_base_class(cls: GenericType) -> Type:
     """Get the base class of a class.
 
     Args:
@@ -68,37 +123,16 @@ def get_base_class(cls: Type) -> Type:
     Returns:
         The base class of the class.
     """
-    # For newer versions of Python.
+    if is_union(cls):
-    try:
+        return tuple(get_base_class(arg) for arg in get_args(cls))
-        from types import GenericAlias  # type: ignore
 
-        if isinstance(cls, GenericAlias):
+    if is_generic_alias(cls):
-            return get_base_class(cls.__origin__)
-    except:
-        pass
-
-    # Check Union types first.
-    try:
-        from typing import _UnionGenericAlias  # type: ignore
-
-        if isinstance(cls, _UnionGenericAlias):
-            return tuple(get_base_class(arg) for arg in get_args(cls))
-    except:
-        pass
-
-    # Check other generic aliases.
-    if isinstance(cls, _GenericAlias):
-        if cls.__origin__ == Union:
-            return tuple(get_base_class(arg) for arg in get_args(cls))
         return get_base_class(cls.__origin__)
 
-    # This is the base class.
     return cls
 
 
-def _issubclass(
+def _issubclass(cls: GenericType, cls_check: GenericType) -> bool:
-    cls: Union[Type, _GenericAlias], cls_check: Union[Type, _GenericAlias]
-) -> bool:
     """Check if a class is a subclass of another class.
 
     Args:
@@ -118,7 +152,7 @@ def _issubclass(
     return cls_check_base == Any or issubclass(cls_base, cls_check_base)
 
 
-def _isinstance(obj: Any, cls: Union[Type, _GenericAlias]) -> bool:
+def _isinstance(obj: Any, cls: GenericType) -> bool:
     """Check if an object is an instance of a class.
 
     Args:

pynecone/var.py

@@ -149,14 +149,14 @@ class Var(ABC):
             assert isinstance(
                 i, utils.get_args(Union[int, Var])
             ), "Index must be an integer."
-            if isinstance(self.type_, _GenericAlias):
+            if utils.is_generic_alias(self.type_):
                 type_ = utils.get_args(self.type_)[0]
             else:
                 type_ = Any
         elif utils._issubclass(self.type_, Dict) or utils.is_dataframe(self.type_):
             if isinstance(i, str):
                 i = utils.wrap(i, '"')
-            if isinstance(self.type_, _GenericAlias):
+            if utils.is_generic_alias(self.type_):
                 type_ = utils.get_args(self.type_)[1]
             else:
                 type_ = Any

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "pynecone-io"
-version = "0.1.3"
+version = "0.1.6"
 description = ""
 authors = [
     "Nikhil Rao <nikhil@pynecone.io>",

tests/test_utils.py

@@ -1,3 +1,5 @@
+import typing
+
 import pytest
 
 from pynecone import utils
@@ -181,3 +183,24 @@ def test_merge_imports():
     assert set(d.keys()) == {"react", "react-dom"}
     assert set(d["react"]) == {"Component"}
     assert set(d["react-dom"]) == {"render"}
+
+
+@pytest.mark.parametrize(
+    "cls,expected",
+    [
+        (str, False),
+        (int, False),
+        (float, False),
+        (bool, False),
+        (typing.List, True),
+        (typing.List[int], True),
+    ],
+)
+def test_is_generic_alias(cls: type, expected: bool):
+    """Test checking if a class is a GenericAlias.
+
+    Args:
+        cls: The class to check.
+        expected: Whether the class is a GenericAlias.
+    """
+    assert utils.is_generic_alias(cls) == expected