Prevent instantiation of jaxtyping annotations.

patrick-kidger · Feb 15, 2025 · 759b50d · 759b50d
1 parent d3c6b0f
commit 759b50d
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diff --git a/jaxtyping/_array_types.py b/jaxtyping/_array_types.py
@@ -375,6 +375,12 @@ class for `Float32[Array, "foo"]`.
     dims: tuple[_AbstractDimOrVariadicDim, ...]
     index_variadic: Optional[int]
 
+    def __new__(cls, *args, **kwargs):
+        raise RuntimeError(
+            "jaxtyping annotations cannot be instantiated -- they should be used for "
+            "type hints only."
+        )
+
 
 _not_made = object()
 

diff --git a/test/test_array.py b/test/test_array.py
@@ -853,3 +853,8 @@ def f(x: Float[array_type, "foo bar"]):
     # Not an array
     with pytest.raises(ParamError):
         f(1)
+
+
+def test_non_instantiation():
+    with pytest.raises(RuntimeError, match="cannot be instantiated"):
+        Float[Array, ""]()  # pyright: ignore[reportCallIssue]