Is it possible to disable events?

  • Thread starter Thread starter ORC
  • Start date Start date
O

ORC

Hi,

Is it possible to disable an event like e.g. disabling:
private void textBox1_TextChanged(object....) ?

Thanks,
Ole
 
Hi,

You can remove all event handlers and in this case, when the event is fired,
nothing will happen.
Why would you need to disable an event in the first place?
 
Ole,

Unless the class offers some sort of management for this, there is no
standard mechanism to do it.

Hope this helps.
 
Not possible. But, to achieve this effect, just don't hook any event
handlers to that event.


Hi,

Is it possible to disable an event like e.g. disabling:
private void textBox1_TextChanged(object....) ?

Thanks,
Ole
 
Thank you all for your input!
The reason for disabling events is that if e.g. all form controls are
initialized with a value from a database during load, it can be fatal if a
changed event fires and calculates new values from some of the controls that
hasn't yet finished updating - this is e.g. what I experied. However i found
something usefull, but it demands that one will have to do some work
himself:


EventHandler radioButtonEvent;
radioButtonEvent = new
System.EventHandler(this.radioButton1_CheckedChanged);

And now the event can be turned on and off at will like this:
enabling the event:
radioButton1.CheckedChanged += radioButtonEvent;
disabling the event:
radioButton1.CheckedChanged -= radioButtonEvent;

Thanks,
Ole


Dmitriy Lapshin said:
Hi,

You can remove all event handlers and in this case, when the event is fired,
nothing will happen.
Why would you need to disable an event in the first place?

--
Sincerely,
Dmitriy Lapshin [C# / .NET MVP]
Bring the power of unit testing to the VS .NET IDE today!
http://www.x-unity.net/teststudio.aspx

ORC said:
Hi,

Is it possible to disable an event like e.g. disabling:
private void textBox1_TextChanged(object....) ?

Thanks,
Ole
Click to expand...
Click to expand...
 
One thing you might want to try is the following:

You will find all the code to hook up the events in the generated code. You
can extract this code an put it into a subroutine that you can call in the
load after all the values required have been loaded.

One other thing is to set the controls to enabled = false. Then in the load
once the values are set enable all the controls. A disabled control will
not cause an event.

Lloyd Sheen

ORC said:
Thank you all for your input!
The reason for disabling events is that if e.g. all form controls are
initialized with a value from a database during load, it can be fatal if a
changed event fires and calculates new values from some of the controls
that
hasn't yet finished updating - this is e.g. what I experied. However i
found
something usefull, but it demands that one will have to do some work
himself:


EventHandler radioButtonEvent;
radioButtonEvent = new
System.EventHandler(this.radioButton1_CheckedChanged);

And now the event can be turned on and off at will like this:
enabling the event:
radioButton1.CheckedChanged += radioButtonEvent;
disabling the event:
radioButton1.CheckedChanged -= radioButtonEvent;

Thanks,
Ole


Dmitriy Lapshin said:
Hi,

You can remove all event handlers and in this case, when the event is fired,
nothing will happen.
Why would you need to disable an event in the first place?

--
Sincerely,
Dmitriy Lapshin [C# / .NET MVP]
Bring the power of unit testing to the VS .NET IDE today!
http://www.x-unity.net/teststudio.aspx

ORC said:
Hi,

Is it possible to disable an event like e.g. disabling:
private void textBox1_TextChanged(object....) ?

Thanks,
Ole
Click to expand...
Click to expand...
Click to expand...
 
A control that is disabled does indeed fire events! - the only solution is
to remove the eventhandler!

Thanks,
Ole

Lloyd Sheen said:
One thing you might want to try is the following:

You will find all the code to hook up the events in the generated code. You
can extract this code an put it into a subroutine that you can call in the
load after all the values required have been loaded.

One other thing is to set the controls to enabled = false. Then in the load
once the values are set enable all the controls. A disabled control will
not cause an event.

Lloyd Sheen

ORC said:
Thank you all for your input!
The reason for disabling events is that if e.g. all form controls are
initialized with a value from a database during load, it can be fatal if a
changed event fires and calculates new values from some of the controls
that
hasn't yet finished updating - this is e.g. what I experied. However i
found
something usefull, but it demands that one will have to do some work
himself:


EventHandler radioButtonEvent;
radioButtonEvent = new
System.EventHandler(this.radioButton1_CheckedChanged);

And now the event can be turned on and off at will like this:
enabling the event:
radioButton1.CheckedChanged += radioButtonEvent;
disabling the event:
radioButton1.CheckedChanged -= radioButtonEvent;

Thanks,
Ole


in message news:[email protected]...
Hi,

You can remove all event handlers and in this case, when the event is fired,
nothing will happen.
Why would you need to disable an event in the first place?

--
Sincerely,
Dmitriy Lapshin [C# / .NET MVP]
Bring the power of unit testing to the VS .NET IDE today!
http://www.x-unity.net/teststudio.aspx

Hi,

Is it possible to disable an event like e.g. disabling:
private void textBox1_TextChanged(object....) ?

Thanks,
Ole
Click to expand...
Click to expand...
Click to expand...
 
There is another solution that I use which, while it's less elegant,
is easy to understand, implement, and maintain, which makes it a
winner in my books.

Simply create a private bool flag in your form:

private bool populatingDisplay = false;

Then inside each event handler you say:

private void txtMyTextBox_TextChanged(object sender, System.EventArgs
e)
{
if (!this.populatingDisplay)
{
... react to event here ...
}
}

Now whenever you're mucking with the controls on the form and don't
want to react to the resulting events, just do this:

this.populatingDisplay = true;
.... do whatever you like with the controls on the form ...
this.populatingDisplay = false;

The events will still fire, but your bool flag will cause them all to
be ignored. (Yes, I hate bool flags, too, but this is one of those
cases in which all other solutions are uglier still.)
 
You're right - your solution is a lot easier to understand and maintain -
Thanks, I will use that instead!

Ole
 
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