Android Question What is the default scope of a Sub?

[Joacim]

I'm fairly new to B4A, or rather I've returned to it after being away from it for a few years. I was wondering what the default scope is for a Sub if you haven't specified it to be private or public? I'm also wondering how event handlers are really wired up? I can easily wire up events in the Designer but how would I do that if I wanted, for example, the TextChanged event for several EditText views to point to the same event handler?

 

[KMatle]

It's quite simple. The code behind (here the EditText) just calls a sub when "something" happens. Here it is a change of the text. The eventname is just added. At the end it's just a sub's name.

When you have several ET's the same sub can be called (same event name). Here you can use "sender" to get the object which has called the sub ("the event").

Subs can be private (internal only for the Editttext) or public to get/set something. If you create a library, you use subs which are privat and others which are accessable.

 

[Joacim]

Thanks for the reply but I think you misunderstood my question. I do understand what events are, I was wondering how you wire them up, in the designer I can simply just pick the events I want to handle, but I can't make two EditText views call the same sub for the same event using it, so how do I do it?

I also wanted to know what the default scope of a sub is when you haven't specified the private or public modifier. Personally I don't like code that doesn't explicitly mention what scope they have, so I want to add the correct modifier myself, but I don't know what the default is.

 

[Erel]

but I can't make two EditText views call the same sub for the same event using it, so how do I do it?

Why not? Just set the event name to be the same. Later use Sender to distinguish between them.

The default scope is public, though there is a small difference in the way the warnings engine treats "unscoped subs". Good practice is to add Public to public subs.

 

[Joacim]

What I mean is that I can't do it from the designer, so how do I do it from code? Since the designer doesn't specify scope for event handlers, and the default scope is public does that mean that event handler has to be public?

 

[Erel]

There is nothing special with the code generated from the designer. You can add Private or Public to the subs. Events can be private.

 

[Joacim]

Thanks for the reply Erel, now about the event handlers, is there a way to specify the same event handler for multiple views using the designer or do I have to manually wire that up, in which case how do I do that? I'm sure I'm missing something very simple here.

 

[Erel]

Of course. Select the views and set the event name parameter.

 

[klaus]

Set a different Event name.

And if you duplicate the view, the event name is maintained.

You may have a look at the SecondProgram project in the B4X Getting started booklet.

 

[Joacim]

Aha, I misunderstood you earlier. So by just setting that property to the same string for more than one view, they will share the events, that's great. So if I understand this correctly the event handlers will magically have the Sender parameter even though the Sub doesn't specify that?

 

[klaus]

So by just setting that property to the same string for more than one view, they will share the events,

Yes.

In the Event Sub

Sub btnEvent_Click
    Private btnSender As Button
   
    btnSender = Sender

 

[Joacim]

Thanks, Klaus and Erel.