Confused about GetCustomAttributes from FieldInfo

[CA]

I am learning about attributes and at this point, I am completely
confused.

I have posted some code below. I do not understand the following
points:

1) The TestAttribute does not appear for the StructureChanged field,
i.e. the GetCustomAttributes() method does not return any attributes
event though the field has been flagged.

2) If I remove the Bindings.NonPublic flag, the field StructureChanged
does not appear in the fields array.

I appreciate any help in clarifying my thoughts.

Regards

Chris
--------------------------------------------------
public void TestCode()
{
TesterObjectClass toc = new TesterObjectClass();
Type t = toc.GetType();
FieldInfo[] fields =
t.GetFields(BindingFlags.NonPublic|BindingFlags.Pu blic|BindingFlags.Instance|BindingFlags.DeclaredOn ly);
Type TestAttr = typeof(TestAttribute);
foreach (FieldInfo fi in fields)
{
object[] attr = fi.GetCustomAttributes(TestAttr, false);
// StructureChanged : attr.Length = 0; vIsBoolean : attr.Length = 1;
Console.WriteLine("Field Name: {0}, Length: {1}", fi.Name,
attr.Length);

}
}

[AttributeUsage(System.AttributeTargets.All,
AllowMultiple=false,
Inherited=false)]
public class TestAttribute : Attribute
{
}

public class TesterObjectClass
{

[TestAttribute] public event EventHandler StructureChanged;
[TestAttribute] public bool vIsBoolean;
public double vIsDouble;
}

[Mattias Sjögren]

Chris,

I am learning about attributes and at this point, I am completely
confused.
First you have to understand that the syntax

public event EventHandler StructureChanged;

is sort of a shortcut for the more explicit version

private EventHandler StructureChanged;
public event EventHandler StructureChanged
{
add { ... }
remove { ... }
}

So it compiles down to a private delegate field and add and remove
accessor methods for the event.

1) The TestAttribute does not appear for the StructureChanged field,
i.e. the GetCustomAttributes() method does not return any attributes
event though the field has been flagged.
The attribute is associated with the event by default. To put it on
the underlying field, you use

[field: TestAttribute] public event EventHandler StructureChanged;

2) If I remove the Bindings.NonPublic flag, the field StructureChanged
does not appear in the fields array.

Because the delegate field is private, only the event is public.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/
Please reply only to the newsgroup.

[CA]

Mattias,

That was a very elegant explanation. Thank you for clearing up my confusion.

Regards

Chris

Mattias Sjögren <ma********************@mvps.org> wrote in message news:<ej**************@TK2MSFTNGP12.phx.gbl>...

Chris,

I am learning about attributes and at this point, I am completely
confused.

First you have to understand that the syntax

public event EventHandler StructureChanged;

is sort of a shortcut for the more explicit version

private EventHandler StructureChanged;
public event EventHandler StructureChanged
{
add { ... }
remove { ... }
}

So it compiles down to a private delegate field and add and remove
accessor methods for the event.

1) The TestAttribute does not appear for the StructureChanged field,
i.e. the GetCustomAttributes() method does not return any attributes
event though the field has been flagged.

The attribute is associated with the event by default. To put it on
the underlying field, you use

[field: TestAttribute] public event EventHandler StructureChanged;

2) If I remove the Bindings.NonPublic flag, the field StructureChanged
does not appear in the fields array.

Because the delegate field is private, only the event is public.

Mattias