Question

You can do anonymous functions in C# like you can in JavaScript:

JavaScript:

var s = (function ()
{
    return "Hello World!";
}());

C#:

var s = new Func<String>(() =>
{
    return "Hello World!";
})();

… In JavaScript you can pass functions to be executed by other functions. On top of that; you can pass parameters to the function which gets executed:

var f = function (message) // function to be executed
{
    alert(message);
};

function execute(f) // function executing another function
{
    f("Hello World!"); // executing f; passing parameter ("message")
}

Is the above example possible in C#?

Update

Use-case: I am iterating over a bunch of database, logging specific entities. Instead of calling my second function (F()) inside Log() of Logger, I’d like to call F() outside the class.

… Something along the lines of:

public void F(String databaseName)
{
}

public class Logger
{
    public void Log(Function f)
    {
        var databaseName = "";

        f(databaseName);
    }
}

Answer 1

Absolutely – you just need to give the method an appropriate signature:

public void Execute(Action<string> action)
{
    action("Hello world");
}
...
Execute(x => Console.WriteLine(x));

Note that you do have to specify the particular delegate type in the parameter – you can’t just declare it as Delegate for example.

EDIT: Your database example is exactly the same as this – you want to pass in a string and not get any output, which is exactly what Action<string> does. Except if you’re trying to call an existing method (F() in your code) you don’t even need a lambda expression – you can use method group conversions instead:

public void F(String databaseName)
{
}

public class Logger
{
    public void Log(Action<string> f)
    {
        var databaseName = "";

        f(databaseName);
    }
}

// Call it like this:
Logger logger = new Logger(...);
logger.Log(F);