Hy,
I understand that attribute programming is used to add metadata to the code,
but since they are implemented with a class and we can extend that class, we
should be able to do any normal class thing with attributes like:

-Have methods
-Use any kind of code in the constructor and the methods (ex. Use a
MessageBox)

But the run time will not execute a MessageBox in the constructor?? why?
Where is it defiened that and attribute can only have fields (properties)
and that the constructor is used only to init these
fields....???

James

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An attribute can have any kind of constructor you like, and can have
any methods you like. However, when you *specify* an attribute for a
field/type/method etc, you're limited as to which types can be passed
in the constructor.

See section 22.3 of partition 2 of the ECMA CLI spec (ECMA 335) for
more details.

--
Jon Skeet - <skeet@pobox.com>
http://www.pobox.com/~skeet/

Hi James,

Attributes can have methods and use any kind of code in the constructor.

This compiles/runs just fine on my machine.

using System;

public class MyAttribute : Attribute
{
public MyAttribute()
{
System.Windows.Forms.MessageBox.Show("MyAttribute Constructor");
}
public void Hello()
{
System.Windows.Forms.MessageBox.Show("Hello from MyAttribute");
}
}

[MyAttribute()]
class AttributeTest
{
static void Main()
{
Type type = typeof(AttributeTest);

// check if attribute exists
if(type.IsDefined(typeof(MyAttribute), true))
{
// create an instance of the attribute
MyAttribute tmp =
type.GetCustomAttributes(false)[0] as MyAttribute;

// call method on attribute
tmp.Hello();
}
}
}


/Mikael

"James Lapalme" <james.lapalme@videotron.ca> skrev i meddelandet
news:%23WJiobCRDHA.3700@tk2msftngp13.phx.gbl...
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