py: verify overload signatures at runtime

Signed-off-by: Isabella Basso do Amaral <idoamara@redhat.com>

clients/python/src/model_registry/_utils.py

@@ -0,0 +1,109 @@
+from __future__ import annotations
+
+import functools
+import inspect
+from collections.abc import Sequence
+from typing import Any, Callable, TypeVar
+
+CallableT = TypeVar("CallableT", bound=Callable[..., Any])
+
+
+# copied from https://github.com/Rapptz/RoboDanny
+def human_join(seq: Sequence[str], *, delim: str = ", ", final: str = "or") -> str:
+    size = len(seq)
+    if size == 0:
+        return ""
+
+    if size == 1:
+        return seq[0]
+
+    if size == 2:
+        return f"{seq[0]} {final} {seq[1]}"
+
+    return delim.join(seq[:-1]) + f" {final} {seq[-1]}"
+
+
+def quote(string: str) -> str:
+    """Add single quotation marks around the given string. Does *not* do any escaping."""
+    return f"'{string}'"
+
+
+# copied from https://github.com/openai/openai-python
+def required_args(*variants: Sequence[str]) -> Callable[[CallableT], CallableT]:  # noqa: C901
+    """Decorator to enforce a given set of arguments or variants of arguments are passed to the decorated function.
+
+    Useful for enforcing runtime validation of overloaded functions.
+
+    Example usage:
+    ```py
+    @overload
+    def foo(*, a: str) -> str:
+        ...
+
+
+    @overload
+    def foo(*, b: bool) -> str:
+        ...
+
+
+    # This enforces the same constraints that a static type checker would
+    # i.e. that either a or b must be passed to the function
+    @required_args(["a"], ["b"])
+    def foo(*, a: str | None = None, b: bool | None = None) -> str:
+        ...
+    ```
+    """
+
+    def inner(func: CallableT) -> CallableT:  # noqa: C901
+        params = inspect.signature(func).parameters
+        positional = [
+            name
+            for name, param in params.items()
+            if param.kind
+            in {
+                param.POSITIONAL_ONLY,
+                param.POSITIONAL_OR_KEYWORD,
+            }
+        ]
+
+        @functools.wraps(func)
+        def wrapper(*args: object, **kwargs: object) -> object:
+            given_params: set[str] = set()
+            for i, _ in enumerate(args):
+                try:
+                    given_params.add(positional[i])
+                except IndexError:
+                    msg = f"{func.__name__}() takes {len(positional)} argument(s) but {len(args)} were given"
+                    raise TypeError(msg) from None
+
+            for key in kwargs:
+                given_params.add(key)
+
+            for variant in variants:
+                matches = all(param in given_params for param in variant)
+                if matches:
+                    break
+            else:  # no break
+                if len(variants) > 1:
+                    variations = human_join(
+                        [
+                            "("
+                            + human_join([quote(arg) for arg in variant], final="and")
+                            + ")"
+                            for variant in variants
+                        ]
+                    )
+                    msg = f"Missing required arguments; Expected either {variations} arguments to be given"
+                else:
+                    # TODO: this error message is not deterministic
+                    missing = list(set(variants[0]) - given_params)
+                    if len(missing) > 1:
+                        msg = f"Missing required arguments: {human_join([quote(arg) for arg in missing])}"
+                    else:
+                        msg = f"Missing required argument: {quote(missing[0])}"
+                raise TypeError(msg)
+            return func(*args, **kwargs)
+
+        return wrapper  # type: ignore
+
+    return inner

clients/python/src/model_registry/utils.py

@@ -6,6 +6,7 @@
 
 from typing_extensions import overload
 
+from ._utils import required_args
 from .exceptions import MissingMetadata
 
 
@@ -32,6 +33,17 @@ def s3_uri_from(
 ) -> str: ...
 
 
+@required_args(
+    (),
+    (  # pre-configured env
+        "bucket",
+    ),
+    (  # custom env or non-default bucket
+        "bucket",
+        "endpoint",
+        "region",
+    ),
+)
 def s3_uri_from(
     path: str,
     bucket: str | None = None,
@@ -62,7 +74,7 @@ def s3_uri_from(
             msg = "Custom environment requires all arguments"
             raise MissingMetadata(msg)
         bucket = default_bucket
-    elif (not default_bucket or default_bucket != bucket) and not (endpoint and region):
+    elif (not default_bucket or default_bucket != bucket) and not endpoint:
         msg = (
             "bucket_endpoint and bucket_region must be provided for non-default bucket"
         )