VS 2005 : why is the default for AutoEventWireup different for C# and VB.NET ?

[Juan T. Llibre]

OK, guys, usually I answer questions instead of asking them,
but this thing has me scratching my head.

Why is the default for AutoEventWireup different for C# and VB.NET ?

In VS 2005, if I create a new VB website using code-behind, the following Page directive is inserted
:

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>

If I create a new C# website using code-behind, the following Page directive is inserted :

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

Is there a reason for AutoEventWireup's default setting being "false" for VB.NET and "true" for C# ?

I asked this over at the MSDN forums, and PeteL told me this :

"The short answer to your question is that VB does this automatically, where as C# doesn't.

The easiest way to test this is to create a Page_Init method, and put a break point in it.

Then, try flipping the AutoEventWireup, in C# it will only fire when true,
but in VB it fires in either event. VB handles this for you."

My reply was :

"Your explanation tells me what happens, but I already knew that.

Why is there a difference in the way the 2 languages handle that ?

This is confusing to users.

I think this is the first instance I see of a glaringly different way
the 2 main VS.NET languages handle a .Net configuration.

Syntax differences I understand.

Why one .Net language would treat a .Net application's settings in a
different way than another .Net language is a bit more difficult to understand."

So, now I ask all of you :

Why is the default for AutoEventWireup different for C# and VB.NET ?
Why does C# need AutoEventWireup set to "true" while VB.NET can make do with "false" ?

There used to be ( pre v2 ) a difference in the way websites written in VS.NET
handled event wiring, because VS.NET handled the event wiring for you,
while hand-written code needed auto event wiring, but this is the first time
I see that two .Net languages need different settings to handle a .Net application.





Juan T. Llibre
ASP.NET MVP
============

 

[Karl Seguin]

I can give you one answer. Not sure if it's accurate, but it makes sense to
me.

It's easier in the VB.Net editor to override a class member. As you know,
VB.Net offers those 2 nice little dropdowns which let you pick the class and
member you which to implement/overwrite.

The C# IDE doesn't provide this fascility. Therefore, it might have been
decided that it'd be best to use the simpler AutoEventWireup for C#. Users
don't have access to the nice IDE feature, so let's make the name easier to
remember.

The one argument against my guess is that C# intellisense allows for easy
overriding, but it's still not as easyas the VB.Net one.

Karl

 

[Karl Seguin]

Oh ya, and I changed my c# templates to have it to false and override onInit
and onLoad

Karl

 

[Juan T. Llibre]

That's the most sensible thing to do, given the current state of things.

I wonder why the VS Dev Team decided on different defaults
for the two languages, given that it's a relatively simple thing to
fix so that the defaults are standardized across languages ?

i.e., if the default for c# were to be "false", it would be just as easy to flip it
back to "true", but at least there would be a standardized default for both languages.

I think I'll bug it and see if we can get a standardized default for both languages.




Juan T. Llibre
ASP.NET MVP
============

 

[Bruce Barker]

vb and c# have different syntax for linking event handlers.

in vb:

'* declare control
dim withevents mycontrol as new Control()

'* declare handler - the handles clause link the event to the contol
sub myHandler (sender as object, arg as System.EventArgs) handles
mycontrol.Click
end sub


in c#

// declare control

private Control mycontrol = new Control();

// declare function

void myHandler (object sender, System.EventArgs arg)
{
}

// auto wireup generate the following statement in the init code
// so that the onclick event calls the handler

mycontrol.Click += new System.EventHandler(myHandler);


in asp 1.1 because the vs ide generated the wireup code, so you always set
autowireup to false.


-- bruce (sqlwork.com)

 

[Juan T. Llibre]

Hi, Bruce.

You're exactly right, of course.

Let me add what Scott Guthrie said about this :
-----------------------------------------------
The VB language supports the "handles" statement -- which allows you to
wire-up the bindings to event handlers on the event handler methods themselves.

Although you can also explicitly wire-up event handlers using the server control
declaration (onclick="button1_click"), we've found that VB developers typically
expect/prefer using the Handles keyword instead.

C# as a language doesn't have a concept like the "handles" keyword.
Instead, you must explicitly wire-up event definitions.
-----------------------------------------------

So, the default setting of "false" for VB.NET seems to be
a question of choice while the setting of "true" is needed for C#.

i.e., VB developers can use either method but C# developers must explicitly wireup events.




Juan T. Llibre
ASP.NET MVP
============