[Server] Implement variadic parameter handling in ReferenceHandler

[monayemislam]

• Add support for variadic parameters (...) in prepareArguments method
• Collect all numeric-indexed arguments starting from parameter position
• Add proper error handling for variadic parameter processing
• Remove TODO comment and complete the implementation
• Maintain backward compatibility with existing parameter handling

Fixes the TODO item in ReferenceHandler.php line 88 and enables proper handling of functions with variadic parameters in MCP tools and resources.

[chr-hertel]

Hey @monayemislam, good catch that todo comment - thanks for picking up on that!

I made some smaller comments, but can you share how you tested this?

[chr-hertel]

i think this is clear with the next line of code already and we can remove this comment

Suggested change

// Handle variadic parameters

[chr-hertel]

this reads like array_slice could be of help 👍

[chr-hertel]

this is basically the same like in line 112-118 - does it make sense to shift the throw RegistryException into the castArgumentType method instead and skip the try-catch in both cases?

or somehow merge this block into lower if-else part as well?

[chr-hertel]

Hi @monayemislam, do you want to continue here?

[soyuka]

Suggested change

	if ($parameter->isVariadic()) {
	// For variadic parameters, collect all remaining arguments
	$variadicArgs = [];
	foreach ($arguments as $key => $value) {
	if (is_numeric($key) && $key >= $paramPosition) {
	try {
	$variadicArgs[] = $this->castArgumentType($value, $parameter);
	} catch (InvalidArgumentException $e) {
	throw RegistryException::invalidParams($e->getMessage(), $e);
	} catch (\Throwable $e) {
	throw RegistryException::internalError("Error processing variadic parameter `{$paramName}`: {$e->getMessage()}", $e);
	}
	}
	}
	$finalArgs[$paramPosition] = $variadicArgs;
	continue;
	}
	if ($parameter->isVariadic()) {
	return $arguments;
	}

This is sufficient for a use case where the handler has ...$arguments:

                $definition['handler'] = fn (...$arguments) => ($this->operationHandler)($mcpName, $arguments);

Could you enlighten me with your use case where you gather the type of the variadic argument? What's the use case?

[chr-hertel]

Closing here for now - please feel free to reopen and continue the work if it still matters to you.