Storing a list of methods in C#

Question

I have a list of method that I would like to call in a specific order. Therefore I would want to store them either in an ordered list or in a table with a specified index. This way the list would be the only thing to change the day we want to change the call order.

I found this article explaining how to do it using an array and delegates. But I read in the comments and some other places that it could also be done using a Dictionary and or LinQ. Any advices ?

score 40 · Accepted Answer · answered Sep 22 '10 at 09:35

40

You can define Action objects, which are parameterless delegates that return void. Each action is a pointer to a method.

// Declare the list
List<Action> actions = new List<Action>();

// Add two delegates to the list that point to 'SomeMethod' and 'SomeMethod2'
actions.Add( ()=> SomeClass.SomeMethod(param1) );
actions.Add( ()=> OtherClass.SomeMethod2() );

// Later on, you can walk through these pointers
foreach(var action in actions)
    // And execute the method
    action.Invoke();

answered Sep 22 '10 at 09:35

Jan Jongboom

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15

You can omit Invoke() btw, just call action() – testalino Sep 22 '10 at 09:37
2

Everything is ok but Queue is much more suitable for the OP's task rather than List, imo. Isn't it? – abatishchev Sep 22 '10 at 09:49
4

Don't think so. It's just a static list, no need for queue'ing or dequeue'ing tasks, as they won't change dynamically. He might want to re-run the batch a couple of times etc. – Jan Jongboom Sep 22 '10 at 10:12

score 8 · Answer 2 · answered Sep 22 '10 at 09:39

8

How about a Queue<Action> ?

var queue = new Queue<Action>();

queue.Enqueue(() => foo());
queue.Enqueue(() => bar());

while(queue.Count != 0)
{
    Action action = queue.Dequeue();
    action();
}

answered Sep 22 '10 at 09:39

abatishchev

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TalentTuner · Answer 3 · 2010-09-22T09:50:06.613

4

Why don't you consider using a Queue it's FIFO , store delegates in Queue and when you call Dequeue it will call your methods in a specified manner.

What about using Multicast Delegate , it stores delegates in a LinkList, so when you call Invoke() , it will be called in a specified manner.

edited Sep 22 '10 at 09:50

answered Sep 22 '10 at 09:36

TalentTuner

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score 0 · Answer 4 · answered Sep 22 '10 at 09:36

0

I would advise to look at Command pattern. Hope it 's what you lookng for.

answered Sep 22 '10 at 09:36

Arseny

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score 0 · Answer 5 · answered Sep 22 '10 at 09:42

You could use List<> which would fit your need pretty well:

delegate void MyFunction(...);
List<MyFunction> delegateList;

If your delegate returns void, you can use event. Multiple delegates can be added to a single event invocation list and will be called in the order they were added.

delegate void MyEvent(...);
event MyEventEventHandler MyEvent;

Dictionary order is undefined and it's meant to make a lookup.

Storing a list of methods in C#

5 Answers5

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