Add interface class member to Benchmark class

src/nnbench/types.py

@@ -1,6 +1,7 @@
 """Useful type interfaces to override/subclass in benchmarking workflows."""
 from __future__ import annotations
 
+import inspect
 import os
 from dataclasses import dataclass, field
 from typing import Any, Callable, Generic, TypedDict, TypeVar
@@ -98,4 +99,22 @@ def __post_init__(self):
             name = self.fn.__name__
 
             super().__setattr__("name", name)
-        # TODO: Parse interface using `inspect`, attach to the class
+            super().__setattr__("interface", Interface.from_callable(self.fn))
+
+
+@dataclass(frozen=True)
+class Interface:
+    varnames: tuple[str, ...]
+    vartypes: tuple[type, ...]
+    varitems: tuple[tuple[str, inspect.Parameter], ...]
+    defaults: dict[str, Any]
+
+    @classmethod
+    def from_callable(cls, fn: Callable) -> Interface:
+        sig = inspect.signature(fn)
+        return cls(
+            tuple(sig.parameters.keys()),
+            tuple(p.annotation for p in sig.parameters.values()),
+            tuple(sig.parameters.items()),
+            {n: p.default for n, p in sig.parameters.items()},
+        )

tests/test_benchmark_cls.py

@@ -0,0 +1,32 @@
+import inspect
+
+from nnbench import types
+
+
+def test_interface_with_no_arguments():
+    def empty_function() -> None:
+        pass
+
+    interface = types.Interface.from_callable(empty_function)
+    assert interface.varnames == ()
+    assert interface.vartypes == ()
+    assert interface.varitems == ()
+    assert interface.defaults == {}
+
+
+def test_interface_with_multiple_arguments():
+    def complex_function(a: int, b, c: str = "hello", d: float = 10.0) -> None:  # type:ignore
+        pass
+
+    interface = types.Interface.from_callable(complex_function)
+    assert interface.varnames == ("a", "b", "c", "d")
+    assert interface.vartypes == (
+        int,
+        inspect._empty,
+        str,
+        float,
+    )
+
+    varitems = [(param.name, param.annotation) for name, param in interface.varitems]
+    assert varitems == [("a", int), ("b", inspect._empty), ("c", str), ("d", float)]
+    assert interface.defaults == {"a": inspect._empty, "b": inspect._empty, "c": "hello", "d": 10.0}