How can I pass a function as a parameter?

Question

I want to know if is there any way to pass a function to another function to handle its try/catch. I am working on an existing codebase that does not have any Exception handling.

Answer 1

NOTE: This answer addresses the text of the question rather than the title, as the problem does not seem to do with passing functions as parameters.

It is a little difficult to know exactly what you are trying to do, but you can certainly invoke public methods within your own try…catch block.

public void ExistingMethod()
{
    // bad code
    // bad code
    throw new NullReferenceException("The previous developers are always the problem.");
}

…

public void MyMethod(ComponentFromOldCode component)
{
    try
    {
        component.ExistingMethod();
    }
    catch (NullReferenceException nre)
    {
        // do something
    }
    catch (Exception ex)
    {
        // do something
    }
}

What you cannot do* is add error handling to existing calls to that function.

You may instead be able to add some high-level error handling that will at least give you an opportunity to log the exceptions and show a more graceful failure experience to your users.

*not reasonably

Answer 2

look into Delegates - http://msdn.microsoft.com/en-us/library/ms173171(v=vs.80).aspx

Answer 3

Look into Actions. They will allow you to pass an anonymous method as a parameter.

However, I don't think this is going to help you with your problem. You're probably going to want to refactor the codebase to have proper exception handling.

Answer 4

You can use Lambda Expression

class Program
{
private static int Sum(int a, int b)
{
    return a + b;
}

private static int Multiply(int a, int b)
{
    return a * b;
}


private static int GetResult(Func<int, int, int> solver, int a, int b)
{
    try {
      return solver(a, b);
    } catch {
    }
    return 0; // your default return
}

static void Main(string[] args)
{
    var a = 2;
    var b = 3;

    var sum = GetResult(Sum, a, b);
    var multiply = GetResult(Multiply, a, b);
}

More information at

Lambda Expressions (C# Programming Guide)

http://msdn.microsoft.com/en-us/library/bb397687.aspx

Func Delegate

http://msdn.microsoft.com/en-us/library/bb549151.aspx