Python: Cannot import native functions to the Kernel that have more than one parameter.

[alexchaomander]

Describe the bug
Right now, when you try to import a native function to the Semantic Kernel that has more than one parameter, you run into this issue

  File "/Users/jtohahn/Desktop/GPT/semantic-kernel/python/commodore/commodore.py", line 29, in <module>
    kernel.import_skill(FileIOSkill(), "file")
  File "/Users/jtohahn/Desktop/GPT/semantic-kernel/.venv/lib/python3.10/site-packages/semantic_kernel/kernel.py", line 223, in import_skill
    SKFunction.from_native_method(candidate, skill_name, self.logger)
  File "/Users/jtohahn/Desktop/GPT/semantic-kernel/.venv/lib/python3.10/site-packages/semantic_kernel/orchestration/sk_function.py", line 80, in from_native_method
    delegate_type=DelegateInference.infer_delegate_type(method),
  File "/Users/jtohahn/Desktop/GPT/semantic-kernel/.venv/lib/python3.10/site-packages/semantic_kernel/orchestration/delegate_inference.py", line 243, in infer_delegate_type
    if wrapped(function_signature, awaitable):
TypeError: DelegateInference.infer_unknown() takes 1 positional argument but 2 were given

To Reproduce
Example function:

@sk_function(description="List the contents of a directory", name="listDirectory")
    async def list_directory(
        self, input_dir: str, depth: int = 0, parent_idx: str = ""
    ) -> str:
        """
        List the contents of a directory

        Example:
            {{file.listDirectory $path }}
        Args:
            input_dir -- The path to the directory to list

        Returns:
            A representation of the directory structure
        """

        assert os.path.exists(input_dir), f"Directory {input_dir} does not exist"

        tree_str = ""
        if not os.path.isdir(input_dir):
            raise ValueError(f"{input_dir} is not a directory")

        for idx, entry in enumerate(os.listdir(input_dir)):
            path = os.path.join(input_dir, entry)
            current_idx = f"{parent_idx}.{idx}" if parent_idx else f"{idx}"
            if os.path.isfile(path):
                tree_str += f"F{current_idx}:{entry}|"
            elif os.path.isdir(path):
                tree_str += f"D{current_idx}:{entry}|"
                tree_str += self.list_directory(path, depth + 1, current_idx)

        return tree_str[:-1]

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. Windows]
• IDE: [e.g. Visual Studio, VS Code]
• NuGet Package Version [e.g. 0.1.0]

Additional context
Add any other context about the problem here.

[joowon-dm-snu]

@alexchaomander

I met that issue last night too! If I understand semantic-kernel correctly, the list_directory not working is by design.
you can find its design here semantic-kernel/python/semantic_kernel/orchestration/delegate_inference.py

There can be at most two parameters, and only str or SKContext can be used as NativeFunction's parameter and there are a limited number of possible combinations.
list_directory requires 3 paramters (str, str, str), which is why the error occurs.

Anyway I opened the PR separately because I thought it was an inappropriate warning.

I think it would be more usable NativeFunction if I could put in multiple parameters like you wrote :)

[alexchaomander]

This might be helpful and if so should be communicated more clearly:

[microsoftShannon]

@dluc We should look to have better error messaging in Python. Can we add this to the backlog.