C# Dynamic Button Event Handler Mechanism

Question

I am creating buttons dynamically for a user-based app. Now I have to tell the new form what text to apply to the buttons via parameters to the form, the form then creates the buttons. Now I have an issue - the events for these buttons: What is the best mechanism to get the button click events through. I cannot access the form from the originating form, and I can only pass simple data types (and arrays).

My first thought is to use a code to reffer to the appropriate method in a static class - basically, pass an array of ints through with the names of the buttons and their onclick handler calls one method - handle(int code) -> where code is used in a giant switch statement to call the appropriate method.

But I doubt this is the best mechanism. I would prefer to create a listener of some sort that simply listens for button clicks, and should the click be unhandled, determine which button was clicked and manage it from there.

I have looked at the observer pattern and I am not entirely convinced this is the best one to follow. The problem is not that there is no solution, the problem is that I want the BEST solution.

This is in C# for monodroid - but the impact of this information should be minimal.

Thanks

Because of the way that creating Android forms works - it is not some object you simply create - it is an activity instance that must be started. There is no 'activity object' to access. — Quintin Balsdon, Jan 06 '12 at 12:47

score 1 · Answer 1 · answered Jan 05 '12 at 10:14

1

Not sure to fully understand what's actually your problem, but here's how you should deal with dynamic controls and event handlers:

Button myNewButton = new Button { Text = "MyCaption" };
myNewButton.Click += (sender, e) =>
    {
        ((Button)sender).Text = "New text here!";
        // Another logic could be put here
    };

answered Jan 05 '12 at 10:14

ken2k

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I can do this, but what I am doing is dynamic form generation. I am using an activity to inflate several versions of the same button (due to styling resctrictions) now the issue is that I have 3 or 4 activities which are loaded from the same code (re-usability). So the code is one class but made into many activities - each one with different buttons (all inflated dynamically). So now how do I create a management system for these buttons? – Quintin Balsdon Jan 05 '12 at 12:46

score 1 · Answer 2 · answered Jan 05 '12 at 10:23

1

If it was WPF i'd use Commanding but i don't know if it's available for monofroid. You may look at http://www.codeproject.com/KB/dotnet/EventBroker.aspx

answered Jan 05 '12 at 10:23

grzegorz_p

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score 0 · Accepted Answer · edited May 23 '17 at 12:24

Currently I have two options:

Use reflection - pass a method name to the button and that button can then invoke a method based on the string value passed. Then simply create a static class where all button methods are kept.
Use a switch statement - since I can have delegates that take parameters (one of them being a SENDER object) I can easily send the sender object to a method containing a switch statement which performs an action based on that object.

In my research I have determined that the former (reflection) is preferred, espcially since the number of buttons is rather large.

REFS:
http://embeddedgurus.com/stack-overflow/2010/04/efficient-c-tip-12-be-wary-of-switch-statements/
Large Switch statements: Bad OOP?
Method Factory - case vs. reflection

C# Dynamic Button Event Handler Mechanism

3 Answers3