How to call an appropriate method by string value from collection?

Question

I have a collection of strings. For example,

string[] coll={"1", "2", "3" ..."100"..."150"...}

and I have respective methods for the string collection such as

void Method1, void Method2, void Method100

I select appropriate method like that:

string selector=string.Empty;
switch(selector)
 { case "1": 
            MethodOne();
            break;
    ........
    case "150":
            Method150();
            break;
  }

The above code is really bored and I will have more string elements in the string collection {"150" ... "250"...}. How to make like that:

 string sel=col[55];
 if(sel!=null)
        // call here the respective         method(method55)

I do not want to use switch operator cause it gives rise to surplus of code.

Something like this? http://stackoverflow.com/questions/540066/calling-a-function-from-a-string-in-c-sharp — Sossenbinder, Aug 20 '15 at 09:01
@Eser I've given points to the answers. Your answer were earlier and the first. It is fair. — StepUp, Aug 20 '15 at 10:27

score 2 · Answer 1 · answered Aug 20 '15 at 09:24

Solution 1:

Use a delegate mapping. This is the faster solution.

private static Dictionary<string, Action> mapping =
    new Dictionary<string, Action>
    {
        { "1", MethodOne },
        // ...
        { "150", Method150 }
    };

public void Invoker(string selector)
{
    Action method;
    if (mapping.TryGetValue(selector, out method)
    {
        method.Invoke();
        return;
    }

    // TODO: method not found
}

Solution 2:

Use reflection. This is slower and is appropriate only if your methods have strict naming (eg. 1=MethodOne 150=Method150 will not work).

public void Invoker(string selector)
{
    MethodInfo method = this.GetType().GetMethod("Method" + selector);
    if (method != null)
    {
        method.Invoke(this, null);
        return;
    }

    // TODO: method not found
}

You can also combine the two solutions: have a dictionary of delegates and fill it using reflection. That gives you the efficiency of solution 1, while not repeating code like solution 2. — svick, Aug 23 '15 at 11:39

score 1 · Answer 2 · answered Aug 20 '15 at 09:16

1

You can use dynamic invocation

 var methodName = "Method" + selector;
 var method = this.GetType().GetMethod(methodName);
 if (method == null)
 {
    // show error
 }
 else
    method.Invoke(this, null);

answered Aug 20 '15 at 09:16

Richard Schneider

34,944
9
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score 1 · Accepted Answer · answered Aug 20 '15 at 10:50

1

You can declare a dictionary with your keys and actions like

Dictionary<string, Action> actions = new Dictionary<string, Action>()
{
    { "1", MethodOne },
    { "2", ()=>Console.WriteLine("test") },
    ............
};

and invoke it as

actions["1"]();

PS: Presuming method void MethodOne(){ } is declared somewhere.

answered Aug 20 '15 at 10:50

Eser

12,346
1
22
32

Maybe you know how to call "void MethodOne(int x)"? Method with parameter – StepUp Aug 20 '15 at 13:16
1

@StepUp `()=>MethodOne(i)` ? Maybe declaring `Dictionary>` and then `actions["1"](i)`. Depends on your case... – Eser Aug 20 '15 at 13:23

How to call an appropriate method by string value from collection?

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