Key value pairs in C# Params

Question

I\'m looking for a way to have a function such as:

myFunction({\"Key\", value}, {\"Key2\", value});

I\'m sure there\'s something with anonymous

Answer 1

Since C# 7.0, you can use value tuples. C# 7.0 not only introduces a new type but a simplified syntax for tuple types and for tuple values. A tuple type is simply written as a list of types surrounded by braces:

(string, int, double)

The corresponding elements are named Item1, Item2, Item2. You can also specify optional aliases. These aliases are only syntactic sugar (a trick of the C# compiler); the tuples are still based on the invariant (but generic) System.ValueTuple struct.

(string name, int count, double magnitude)

Tuple values have a similar syntax, except that you specify expressions instead of types

("test", 7, x + 5.91)

or with the aliases

(name: "test", count: 7, magnitude: x + 5.91)

Example with params array:

public static void MyFunction(params (string Key, object Value)[] pairs)
{
    foreach (var pair in pairs) {
        Console.WriteLine($"{pair.Key} = {pair.Value}");
    }
}

It is also possible to deconstruct a tuple like this

var (key, value) = pair;
Console.WriteLine($"{key} = {value}");

This extracts the items of the tuple in two separate variables key and value.

Now, you can call MyFunction with a varying number of arguments easily:

MyFunction(("a", 1), ("b", 2), ("c", 3));

It allows us to do things like

DrawLine((0, 0), (10, 0), (10, 10), (0, 10), (0, 0));

See: New Features in C# 7.0