Call an method that is an eventhandler

[jac]

Hae,

I have a windows form with a ComboBox an other things.
On that combobox I have an eventhandler on de selectedindexch anged.

But somewhere in my code want to do excecute the same code that is writen
in the eventhandler.
Is it posible to call that eventhandler from the code (not from a real
selectedindexch anged on the form). So, I don't have to call that code twice.
tkx
jac

[Brendan Grant]

Just to make sure I understand you... somewhere in your code you’ve got
something to the effect of:

this.comboBox1. SelectedIndexCh anged += new
System.EventHan dler(this.combo Box1_SelectedIn dexChanged);

setting up an EventHandler for when SelectedIndexCh anged is fired... and you
are curious if you can call your equivalent of comboBox1_Selec tedIndexChanged
on your own? Absolutely!

Two things to take note of... first up, the first argument passed into an
event handler is a reference to the sender... if you are not using this
reference you can simply pass in null, otherwise be sure to pass in a
reference to the ComboBox in question.

Second... EventArgs. Some handlers use them, some don’t, if yours doesn’t
you can pass in null or EventArgs.Empty .

Brendan
"jac" wrote:

Hae,

I have a windows form with a ComboBox an other things.
On that combobox I have an eventhandler on de selectedindexch anged.

But somewhere in my code want to do excecute the same code that is writen
in the eventhandler.
Is it posible to call that eventhandler from the code (not from a real
selectedindexch anged on the form). So, I don't have to call that code twice.
tkx
jac

[Nicholas Paldino [.NET/C# MVP]]

jac,

You could just call the event handler like a normal function.

Or are you saying you want to call all the event handlers attached to
that control? If that is the case, you can't do it, as only objects can
fire their own events.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"jac" <ja*@discussion s.microsoft.com > wrote in message
news:84******** *************** ***********@mic rosoft.com...

Hae,

I have a windows form with a ComboBox an other things.
On that combobox I have an eventhandler on de selectedindexch anged.

But somewhere in my code want to do excecute the same code that is writen
in the eventhandler.
Is it posible to call that eventhandler from the code (not from a real
selectedindexch anged on the form). So, I don't have to call that code
twice.
tkx
jac

[Kai Brinkmann [MSFT]]

Yes, it's possible as long as you provide the expected parameters (usually
sender and EventArgs). However, it would be cleaner to put the relevant code
in a separate method and call that method from within the event handler
rather than putting the code in the event handler itself. That way, you
could simply call that method from anywhere in your code.
--
Kai Brinkmann [MSFT]

Please do not send e-mail directly to this alias. This alias is for
newsgroup purposes only.
This posting is provided "AS IS" with no warranties, and confers no rights.

"jac" <ja*@discussion s.microsoft.com > wrote in message
news:84******** *************** ***********@mic rosoft.com...

Hae,

I have a windows form with a ComboBox an other things.
On that combobox I have an eventhandler on de selectedindexch anged.

But somewhere in my code want to do excecute the same code that is writen
in the eventhandler.
Is it posible to call that eventhandler from the code (not from a real
selectedindexch anged on the form). So, I don't have to call that code
twice.
tkx
jac

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

Yes you can, just call combo_selectedi ndexchanged ( null, null );
cheers,
--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation
"jac" <ja*@discussion s.microsoft.com > wrote in message
news:84******** *************** ***********@mic rosoft.com...

Hae,

I have a windows form with a ComboBox an other things.
On that combobox I have an eventhandler on de selectedindexch anged.

But somewhere in my code want to do excecute the same code that is writen
in the eventhandler.
Is it posible to call that eventhandler from the code (not from a real
selectedindexch anged on the form). So, I don't have to call that code
twice.
tkx
jac

[Kevin Spencer]

Generally speaking, and for good design, you should not call an Event
Handler directly. Instead, create a method that the Event Handler can call,
as well as any other method that needs it.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
Ambiguity has a certain quality to it.

"jac" <ja*@discussion s.microsoft.com > wrote in message
news:84******** *************** ***********@mic rosoft.com...

Hae,

I have a windows form with a ComboBox an other things.
On that combobox I have an eventhandler on de selectedindexch anged.

But somewhere in my code want to do excecute the same code that is writen
in the eventhandler.
Is it posible to call that eventhandler from the code (not from a real
selectedindexch anged on the form). So, I don't have to call that code
twice.
tkx
jac

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,
Why it's not?
An "event handler" is just a method as any other, in the same way that you
can have the same method hooked to more than one controls you can call it
yourself,
IMO that is the reason why the sender parameter is there in the first
place, so the method can have a reference to who called it.

Having another method that both the event handler and your code call to
perform the work do have sense IF the logic is different in any case,
otherwise I can't see how it makes it clearer.You are only removing the
parameters and you end with two methods:

void control_handle( ... )
{
do_the_real_wor k();
}

void do_the_real_wor k(){}
IMO that is not clearer at all.
Now, in 2.0 with anonymous methods it's a complete different history, you
can declare the control_handle as a anonymous method and the code will be
clear indeed.
What you folks think about the above?
Do you write two methods like the above?
Cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

"Kevin Spencer" <ke***@DIESPAMM ERSDIEtakempis. com> wrote in message
news:Oc******** ******@tk2msftn gp13.phx.gbl...

Generally speaking, and for good design, you should not call an Event
Handler directly. Instead, create a method that the Event Handler can
call, as well as any other method that needs it.

--
HTH,

Kevin Spencer
Microsoft MVP
.Net Developer
Ambiguity has a certain quality to it.

"jac" <ja*@discussion s.microsoft.com > wrote in message
news:84******** *************** ***********@mic rosoft.com...

Hae,

I have a windows form with a ComboBox an other things.
On that combobox I have an eventhandler on de selectedindexch anged.

But somewhere in my code want to do excecute the same code that is
writen
in the eventhandler.
Is it posible to call that eventhandler from the code (not from a real
selectedindexch anged on the form). So, I don't have to call that code
twice.
tkx
jac

[Scott Roberts]

"Ignacio Machin ( .NET/ C# MVP )" <ignacio.mach in AT dot.state.fl.us > wrote
in message news:%2******** **********@TK2M SFTNGP14.phx.gb l...

IMO that is the reason why the sender parameter is there in the first
place, so the method can have a reference to who called it.
The "sender" parameter is there so you know which *component* fired the
event. This is so that multiple *components* can share a single event
handler.
Having another method that both the event handler and your code call to
perform the work do have sense IF the logic is different in any case,
otherwise I can't see how it makes it clearer.You are only removing the
parameters and you end with two methods:

void control_handle( ... )
{
do_the_real_wor k();
}

void do_the_real_wor k(){}
IMO that is not clearer at all.
IMO, you should never code "real work" in an event handler - period. All
"real work" belongs in a method that is not inside the GUI in the first
place.
What you folks think about the above?
Do you write two methods like the above?

Yes. Two methods.

[Jon Skeet [C# MVP]]

Scott Roberts wrote:

<snip>

IMO, you should never code "real work" in an event handler - period. All
"real work" belongs in a method that is not inside the GUI in the first
place.

You're making three assumptions which may be invalid:

1) That the event being handled is a GUI event
2) That the real work is not GUI work (if it's GUI work, it's
reasonable for it to be done in the GUI code)
3) That the event handler is defined in GUI code (it may not be,
even if it happens to be hooked up to a GUI event)

Jon

[Scott Roberts]

"Jon Skeet [C# MVP]" <sk***@pobox.co m> wrote in message
news:11******** **************@ g14g2000cwa.goo glegroups.com.. .

Scott Roberts wrote:

<snip>

IMO, you should never code "real work" in an event handler - period. All
"real work" belongs in a method that is not inside the GUI in the first
place.

You're making three assumptions which may be invalid:

1) That the event being handled is a GUI event
2) That the real work is not GUI work (if it's GUI work, it's
reasonable for it to be done in the GUI code)
3) That the event handler is defined in GUI code (it may not be,
even if it happens to be hooked up to a GUI event)

The original post was related to combox events. In general, you are correct.