fix: Resolve alt.binding signature/docstring issues

altair/vegalite/v5/api.py

@@ -105,6 +105,7 @@
         AnyMark,
         BindCheckbox,
         Binding,
+        BindInput,
         BindRadioSelect,
         BindRange,
         BinParams,
@@ -1751,10 +1752,49 @@ def selection_single(**kwargs: Any) -> Parameter:
     return _selection(type="point", **kwargs)
 
 
-@utils.use_signature(core.Binding)
-def binding(input: Any, **kwargs: Any) -> Binding:
-    """A generic binding."""
-    return core.Binding(input=input, **kwargs)
+def binding(
+    input: str,
+    *,
+    autocomplete: Optional[str] = Undefined,
+    debounce: Optional[float] = Undefined,
+    element: Optional[str] = Undefined,
+    name: Optional[str] = Undefined,
+    placeholder: Optional[str] = Undefined,
+) -> BindInput:
+    """
+    A generic binding.
+
+    Parameters
+    ----------
+    input : str
+        The type of input element to use. The valid values are ``"checkbox"``, ``"radio"``,
+        ``"range"``, ``"select"``, and any other legal `HTML form input type
+        <https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input>`__.
+    autocomplete : str
+        A hint for form autofill. See the `HTML autocomplete attribute
+        <https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/autocomplete>`__ for
+        additional information.
+    debounce : float
+        If defined, delays event handling until the specified milliseconds have elapsed
+        since the last event was fired.
+    element : str
+        An optional CSS selector string indicating the parent element to which the input
+        element should be added. By default, all input elements are added within the parent
+        container of the Vega view.
+    name : str
+        By default, the signal name is used to label input elements. This ``name`` property
+        can be used instead to specify a custom label for the bound signal.
+    placeholder : str
+        Text that appears in the form control when it has no value set.
+    """
+    return core.BindInput(
+        autocomplete=autocomplete,
+        debounce=debounce,
+        element=element,
+        input=input,
+        name=name,
+        placeholder=placeholder,
+    )
 
 
 @utils.use_signature(core.BindCheckbox)

tests/vegalite/v5/test_api.py

@@ -24,10 +24,13 @@
 from packaging.version import Version
 
 import altair as alt
+from altair.utils.core import use_signature
 from altair.utils.schemapi import Optional, SchemaValidationError, Undefined
 from tests import skip_requires_vl_convert, slow
 
 if TYPE_CHECKING:
+    from typing import Any
+
     from altair.vegalite.v5.api import _Conditional, _Conditions
     from altair.vegalite.v5.schema._typing import Map
 
@@ -1654,3 +1657,37 @@ def test_ibis_with_vegafusion(monkeypatch: pytest.MonkeyPatch):
         {"a": 2, "b": "2020-01-02T00:00:00.000"},
         {"a": 3, "b": "2020-01-03T00:00:00.000"},
     ]
+
+
+def test_binding() -> None:
+    @use_signature(alt.Binding)
+    def old_binding(input: Any, **kwargs: Any) -> alt.Binding:
+        """A generic binding."""
+        return alt.Binding(input=input, **kwargs)
+
+    # NOTE: `mypy` doesn't complain, but `pyright` does
+    old = old_binding(input="search", placeholder="Country", name="Search")  # pyright: ignore[reportCallIssue]
+    old_positional = old_binding("search", placeholder="Country", name="Search")
+
+    new = alt.binding(input="search", placeholder="Country", name="Search")
+    new_positional = alt.binding("search", placeholder="Country", name="Search")
+
+    assert (
+        old.to_dict()
+        == old_positional.to_dict()
+        == new.to_dict()
+        == new_positional.to_dict()
+    )
+    assert all(
+        isinstance(x, alt.Binding) for x in (old, old_positional, new, new_positional)
+    )
+
+    MISSING_INPUT = r"missing 1 required positional argument: 'input"
+
+    # NOTE: `mypy` doesn't complain, but `pyright` does (Again)
+    with pytest.raises(TypeError, match=MISSING_INPUT):
+        old_binding(placeholder="Country", name="Search")  # pyright: ignore[reportCallIssue]
+
+    # NOTE: Both type checkers can detect the issue on the new signature
+    with pytest.raises(TypeError, match=MISSING_INPUT):
+        alt.binding(placeholder="Country", name="Search")  # type: ignore[call-arg]