Something better than Switch Case

[Deresen]

Why would you like to throw away the switch case? This is a great way to code statemachines, for instance when you've got a status. Or you use if else, but is like the same as switch case. It really depends on what is it when you would like to get rid of the switch case. It depends on the situation. Show a situation and we'll give the solution.

[akidan]

Yes, it should work with enums. Again, though, it really depends a lot on what you're trying to do, so it's hard to recommend one approach over another... but here's a sample of some different techniques. Each have their strengths and weaknesses, depending on your situation. Assuming an enum like:

enum MyEnum { Foo, Bar, Baz }

switch way:

bool method(MyEnum val)
{
switch (val)
{
case MyEnum.Foo:
Console.WriteLine("Some");
Console.WriteLine("big");
Console.WriteLine("case");
Console.WriteLine("statement");
Console.WriteLine("that");
Console.WriteLine("Foo");
Console.WriteLine("does");
return true;
case MyEnum.Bar:
throw new Exception("Bar!");
case MyEnum.Baz:
Console.Beep();
Console.WriteLine("Beep.");
return false;
default:
throw new ArgumentOutOfRangeException("val");
}
}

Refactor to methods way:

bool method(MyEnum val)
{
switch (val)
{
case MyEnum.Foo:
return FooMethod();
case MyEnum.Bar:
return BarMethod();
case MyEnum.Baz:
return BazMethod();
default:
throw new ArgumentOutOfRangeException("val");
}
}

bool FooMethod()
{
Console.WriteLine("Some");
Console.WriteLine("big");
Console.WriteLine("case");
Console.WriteLine("statement");
Console.WriteLine("that");
Console.WriteLine("Foo");
Console.WriteLine("does");
return true;
}

bool BarMethod()
{
throw new Exception("Bar!");
}

bool BazMethod()
{
Console.Beep();
Console.WriteLine("Beep.");
return false;
}

Dictionary way (.Invoke() is just for clarity):

delegate bool BoolFunc();
readonly Dictionary<MyEnum, BoolFunc> methods;

MyClassConstructor()
{
methods = new Dictionary<MyEnum, BoolFunc>();
methods.Add(MyEnum.Foo, FooMethod);
methods.Add(MyEnum.Bar, BarMethod);
methods.Add(MyEnum.Baz, BazMethod);
}

bool method(MyEnum val)
{
BoolFunc funcToCall;

if (!methods.TryGetValue(val, out funcToCall))
	throw new ArgumentOutOfRangeException("val");

return funcToCall.Invoke();

}

bool FooMethod()
{
Console.WriteLine("Some");
Console.WriteLine("big");
Console.WriteLine("case");
Console.WriteLine("statement");
Console.WriteLine("that");
Console.WriteLine("Foo");
Console.WriteLine("does");
return true;
}

bool BarMethod()
{
throw new Exception("Bar!");
}

bool BazMethod()
{
Console.Beep();
Console.WriteLine("Beep.");
return false;
}

Subclass/override way (the enum actually goes away here):

b

[Pete OHanlon]

You could always use a Dictionary with an enumeration and a Action to use. For instance, you could have an enumeration that closed a window like this:

public enum Operation
{
Close,
Save,
}
public void Action(Operation action)
{
if (_dictionary.ContainsKey(action))
{
_dictionary[action]();
}
}
public void Register(Operation operation, Action action)
{
_dictionary.Add(operation, action);
}

Then, you can add your implementation like this:

Register(Operation.Close, delegate(){ this.Close(); });

As you can see, calling this method removes the need for a switch altogether.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

My blog | My articles | MoXAML PowerToys

[Pete OHanlon]

There's an even easier way. Take a look at my post below - it's as easy as this.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

My blog | My articles | MoXAML PowerToys

[akidan]

Thanks... I did write that way under Dictionary way already, though. :)

[led mike]

Pete O'Hanlon wrote:

As you can see, calling this method removes the need for a switch altogether.

Not if you have legacy code as the OP does. He still has to switch the code to the new method. ;P

[akidan]

Augh... that's terrible. :)

[Christian Graus]

The only place where there's a better solution, is where your switches indicate you should have a collection of classes, each representing a different case with the same overloaded method.

Christian Graus Driven to the arms of OSX by Vista.

[Muammar]

Wow, thanks akidan! I think I will go with the last one.

---

All generalizations are wrong, including this one! (\ /) (O.o) (><)

[Muammar]

Hi Pete, I like your solution, it looks short and effecient, however, there's still one big problem.. I cant understand it :-O See, I have this statement:

        foreach (DataGridViewColumn grdC in grd.Columns)
        {
            switch (grdC.HeaderText)
            {
                case "ID":
                    grdC.HeaderText = "id";
                    break;
                case "NAME":
                    grdC.HeaderText = "name";
                    break;
                ...
            }
        }

---

All generalizations are wrong, including this one!
(\ /)
(O.o)
(><)

[J4amieC]

your code is a WTF! All you're doing is lower-casing the header. This would suffice

foreach (DataGridViewColumn grdC in grd.Columns)
{
grdC.HeaderText = grdC.HeaderText.ToLower();
}

[Muammar]

J4amieC wrote:

your code is a WTF! All you're doing is lower-casing the header.

:laugh: :laugh: I'm sorry, I guess it was a bad example :-D, OF COURSE this's not what I'm doing, I'm just giving an example, obviously a bad one:) ok, let's give it a try again and try setting the text to whatever.. I'm sorry for the confusion mate:)

---

All generalizations are wrong, including this one! (\ /) (O.o) (><)

[akidan]

My pleasure! :) Happy I could help.