Dictionary with delegate or switch?

Question

Hi,
I am writing a parser, which call some functions dependent on some value.

I can implement this logic with simple switch like this

switch(some_val)   
{   
    case 0:   
        func0();   
        break;   
    case 1:   
        func1();   
        break;   
}     

or with delegates and dictionary like this

delegate void some_delegate();   
Dictionary<int, some_delegate> some_dictionary = new Dictionary<int, some_delegate>();   
some_dictionary[0] = func0;   
some_dictionary[1] = func1;   

some_dictionary[some_value].Invoke();    

Are this two methods equal and which is preferred?
Thanks.

Answer 1

Both do the same (well you should check if the key appears in the dictonary).

It is just a matter of readability. What looks the best for your and more important, what do people reading your code would prefer.

(I think the dictionary)

Answer 2

In terms of access, they're identical: both just check if that specific value has a corresponding result. However, a Dictionary will throw an out-of-bounds exception if you try to access a non-existent key.

The choice should primarily be on re-usability. If you only need to make this branching logic at one point, then using a switch-case is probably makes more sense than storing a variable. If you need to access it repeatedly in separate points, then use the Dictionary to save yourself from just re-pasting the switch-statement repeatedly.

Answer 3

I strongly prefer the dictionary choice, because with an initializer, it can be a lot more compact and readable:

var actions = new Dictionary<int, Action>
{
  {1, () => Console.WriteLine("One!")},
  {2, () => Console.WriteLine("Two!")}
}

Also, you have some more flexibility; you can add conditions and actions programatically, which is often handy, depending on what you're doing.

Answer 4

switch statement seems to be more readable for a parser - you don't need dynamic capabilities provided by dictionary/delegate approach.

Answer 5

If the typical programmer on your team is anything like the ones I often deal with, you should go for the simplest option i.e. the switch. The delegates seem to me like a 'clever' solution that is not needed.