Typing

Per-interface static-typing for the mypy plugin

A backend interface may attach an InterfaceTyping subclass to its Interface.typing class variable to opt into:

• Mypy plugin constructor inference (so da.zeros((3, 3), dtype=np.uint8) refines to a literal-tuple shape and concrete dtype in the same way numpy constructors do).

• Mypy test file generation (the test generator uses the typing class to emit literal constructor expressions for each combinatorial test case).

class ConstructorSpec(fullname: str, shape_arg: int | str = 0, dtype_arg: str | None = 'dtype', mode: Literal['function', 'method'] = 'function')

How a single array-constructor call exposes shape and dtype.

fullname: str

Mypy-visible fully qualified name of the function or method, e.g. "dask.array.zeros" or "numpy._core.multiarray._ConstructorEmpty.__call__".

shape_arg: int | str = 0

Where the shape argument lives in the call. An int is a positional index; a str is a keyword name.

dtype_arg: str | None = 'dtype'

Keyword name for the dtype argument, if any

mode: Literal['function', 'method'] = 'function'

method if mypy sees this constructor as a method (get_method_hook), function for a free function or class instantiation (get_function_hook).

class InterfaceTyping

Optional static-typing companion class for an Interface, for use with the mypy plugin.

constructors: ClassVar[tuple[ConstructorSpec, ...]] = ()

Constructor calls whose return type the mypy plugin should refine.

classmethod emit_imports() → list[str]

Import lines required by emit_constructor_source().

Returned as a list of statement strings, e.g. ["import numpy as np", "import dask.array as da"].

classmethod emit_constructor_source(shape: tuple[int, ...], dtype: str) → str | None

Source-text for a constructor call producing the given array.

Returns a Python expression string (no trailing newline), e.g. "np.zeros((3, 3), dtype=np.uint8)".

Only needs to render one of the constructors that the interface supports - we assume if we detect one, they should all work the same way.