C# Passing Function as Argument
There are a couple generic types in .Net (v2 and later) that make passing functions around as delegates very easy.
For functions with return types, there is Func<> and for functions without return types there is Action<>.
Both Func and Action can be declared to take from 0 to 4 parameters. For example, Func < double, int > takes one double as a parameter and returns an int. Action < double, double, double > takes three doubles as parameters and returns nothing (void).
So you can declare your Diff function to take a Func:
public double Diff(double x, Func<double, double> f) {
double h = 0.0000001;
return (f(x + h) - f(x)) / h;
}
And then you call it as so, simply giving it the name of the function that fits the signature of your Func or Action:
double result = Diff(myValue, Function);
You can even write the function in-line with lambda syntax:
double result = Diff(myValue, d => Math.Sqrt(d * 3.14));
Using the Func as mentioned above works but there are also delegates that do the same task and also define intent within the naming:
public delegate double MyFunction(double x);
public double Diff(double x, MyFunction f)
{
double h = 0.0000001;
return (f(x + h) - f(x)) / h;
}
public double MyFunctionMethod(double x)
{
// Can add more complicated logic here
return x + 10;
}
public void Client()
{
double result = Diff(1.234, x => x * 456.1234);
double secondResult = Diff(2.345, MyFunctionMethod);
}
public static T Runner<T>(Func<T> funcToRun)
{
//Do stuff before running function as normal
return funcToRun();
}
Usage:
var ReturnValue = Runner(() => GetUser(99));