Can I pass arbitrary number of named parameters to function in C#?

Question

Is there some kind of equivalent of Python's **kwargs in C#? I would like to be able to pass variable number of named arguments into functon, then get them as something Dictionary-like inside function and cycle over them.

Answer 1

There is nothing in C# available to let you pass in arbitrary named parameters like this.

You can get close by adding a Dictionary<string, object> parameter, which lets you do something similar but requiring a constructor, the "parameter names" to be strings and some extra braces:

static void Method(int normalParam, Dictionary<string, object> kwargs = null)
{
   ...
}

Method(5, new Dictionary<String, object>{{ "One", 1 }, { "Two", 2 }});

You can get closer by using the ObjectToDictionaryRegistry here, which lets you pass in an anonymous object which doesn't require you to name a dictionary type, pass the parameter names as strings or add quite so many braces:

static void Method(int normalParam, object kwargs = null)
{
    Dictionary<string, object> args = ObjectToDictionaryRegistry(kwargs);
    ...
}

Method(5, new { One = 1, Two = 2 });

However, this involves dynamic code generation so will cost you in terms of performance.

In terms of syntax, I doubt you'll ever be able to get rid of the `new { ... }' wrapper this requires.