Thanks for stepping in Wallace. So the constructor does get called, and
my last comment was inaccurate. It's not the instance that's serialized.
Thanks,
Fred
> Girish,
>
> As you discovered, the attribute declaration does not cause the
> constructor
> to execute. You would need to call GetCustomAttribute on each member in
> order for the constructor of the corresponding attribute to be called.
>
> According to Essential .NET,
>
> "Custom attributes are stored as passive BLOBs in the
> CLR metadata. These BLOBs represent serialized
> constructor calls to the attribute type... Calling
> GetCustomAttributes causes the serialized attribute
> constructors to execute as the attribute objects are
> instantiated from the metadata prior to your code seeing
> them."
>
> Stepping through the attached code illustrates this.
>
> Wally
>
> using System;
> using System.Reflection;
>
> class MyAttribute : Attribute
> {
> static int counter = 0;
> public MyAttribute()
> {
> Console.WriteLine("In constructor of attribute #{0}.",
> ++MyAttribute.counter);
> }
> }
>
> [MyAttribute]
> class MyClass : Object
> {
> [MyAttribute]
> public int i;
>
> [MyAttribute]
> public int j;
> }
>
> class MyApp
> {
> static void Main()
> {
> Type myType = typeof(MyClass);
> MyClass myClass = new MyClass();
> MemberInfo[] memberInfos = myType.GetMembers();
> foreach(MemberInfo mi in memberInfos)
> {
> // Custom attribute constructor called
> // in the following method
> mi.GetCustomAttributes(false);
> }
> }
> }
>
> -----Original Message-----
> From: Unmoderated discussion of advanced .NET topics.
> [mailto:[EMAIL PROTECTED] On Behalf Of Girish Jain
> Sent: Tuesday, January 18, 2005 7:19 AM
> To: ADVANCED-DOTNET@DISCUSS.DEVELOP.COM
> Subject: [ADVANCED-DOTNET] When does the attribute contructor gets
> executed??
>
> Hi All,
>
> I have written a custom attribute and applied it to the public
> fields/properties of a class. This attribute actually maintains certain
> data
> per **Type**.
>
> In the constructor of this attribute class I am adding data to a static
> HashTable object, declared in the attribute class (Certainly, after
> checking
> that it does not already exist for the given Type)
>
> For example :
>
> public class A
> {
> [MyCustom("some data...")]
> public int i;
>
> [MyCustom("some data...")]
> public string Name
> {
> get { return this._ColName; }
> set { this._ColName = value; }
> }
> }
>
> I expect the attribute constructor to have already executed by the time I
> create the first instance of the class A. But it is not happening.
>
>
> Can anybody tell me when does the constructor for the attribute gets
> executed?
>
> Thanks in advance
>
> Regards,
> Girish Jain
>
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