Run a method before all methods of a class

Question

Is it possible to do that in C# 3 or 4? Maybe with some reflection?

class Magic
{

    [RunBeforeAll]
    public void BaseMethod()
    {
    }

    //runs Ba         


        

Answer 1

You can't do this automatically in C# - you should probably be looking at AOP, e.g. with PostSharp.

Answer 2

Just to make a thing clear why the following implementation won't work:

public class Magic{

private static Magic magic = new Magic();
public static Magic Instance{
  get
    {
   magic.BaseMethod();
    return magic;
    }
}

public void BaseMethod(){
}

//runs BaseMethod before being executed
public void Method1(){
}

//runs BaseMethod before being executed
public void Method2(){
}
}

in the case you just want to hold a Magic object, the method will be randomly called:

Magic m = Magic.Instance; //this will trigger unwanted call on BaseMethod

and also if one will want to call the BaseMethod, it will be called twice:

Magic.Instance.BaseMethod(); //two calls of the BaseMethod

which of course have a workaround, to return unwanted objects using get:

var unused = Magic.Instance;

Only to summarize: This is not possible (at least yet) in C#.

Answer 3

There is an alternate solution for this, make Magic a singleton and put your code on the getter of the static instance. That's what i did.

public class Magic{

private static Magic magic;
public static Magic Instance{
  get
    {
   BaseMethod();
    return magic;
    }
}

public void BaseMethod(){
}

//runs BaseMethod before being executed
public void Method1(){
}

//runs BaseMethod before being executed
public void Method2(){
}
}

Answer 4

Yes, you can! with a static constructor, it will run once before the class is referenced and you can do what you like in it.

Like this:

public class Magic{

static Magic()
{
    BaseMethod();
}

public void BaseMethod(){
}

//runs BaseMethod before being executed
public void Method1(){
}

//runs BaseMethod before being executed
public void Method2(){
}
}

Here's the Microsoft doc:

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/static-constructors

Answer 5

What you want can be done with AOP - some links to .NET C# AOP frameworks:

• http://www.postsharp.org/
• http://www.castleproject.org/dynamicproxy/index.html
• http://www.springframework.net/docs/1.2.0-M1/reference/html/aop.html

Answer 6

I've recently had cause to do this. I'll spare you the probably boring details of my use-case, except to state that I want the method DoThisFirst to run before the specific method I'm calling. Still learning C# so probably not the best way to do it...

using System;

namespace ConsoleApp1
{
    class Class1
    {
        public enum MethodToCall
        {
            Method2,
            Method3
        }

        public delegate void MyDelegate(int number = 0, bool doThis = false, double longitude = 32.11);

        public static void DoThisFirst(int number, bool doThis, double longitude)
        {
            Console.WriteLine("DoThisFirst has been called.");
        }

        public static void DoSomethingElse(int number, bool doThis, double longitude)
        {
            Console.WriteLine("DoSomethingElse has been called.");
        }

        public static void DoAnotherThing(int number, bool doThis, double longitude)
        {
            Console.WriteLine("DoAnotherThing has been called.");
        }

        public static void Main()
        {
            void Action(MethodToCall methodToCall)
            {
                MyDelegate myDel;

                myDel = new MyDelegate(DoThisFirst);

                switch (methodToCall)
                {
                    case MethodToCall.Method2:
                        myDel += DoSomethingElse;
                        break;
                    case MethodToCall.Method3:
                        myDel += DoAnotherThing;
                        break;
                }

                myDel.Invoke();
            }

            Action(MethodToCall.Method3);

            Console.ReadKey();
        }
    }
}