Attributes in base and derived classes

[Edward Diener]

If I set an attribute on some part of a class, such as a property or event,
does that attribute also apply to the same property or event of a derived
class ?

If the above is true, can I change the attribute of a property or event from
something in a base class to something different in a derived class ?

[Mattias Sjögren]

Re: Attributes in base and derived classes

Edward,
[color=blue]
>If I set an attribute on some part of a class, such as a property or event,
>does that attribute also apply to the same property or event of a derived
>class ?[/color]

It depends on how you look up the attribute, the GetCustomAttrib ute
reflection methods usually have a boolean parameter to indicate
whether you want to search base class members for attributes as well.

It also depends on the AttributeUsage. Inherited setting of the
attribute class.



Mattias

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Mattias Sjögren [MVP] mattias @ mvps.org
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[Edward Diener]

Re: Attributes in base and derived classes

Mattias Sjögren wrote:[color=blue]
> Edward,
>[color=green]
>> If I set an attribute on some part of a class, such as a property or
>> event, does that attribute also apply to the same property or event
>> of a derived class ?[/color]
>
> It depends on how you look up the attribute, the GetCustomAttrib ute
> reflection methods usually have a boolean parameter to indicate
> whether you want to search base class members for attributes as well.[/color]

In that case I would have to know how the attribute is being used by
whomever is using it.
[color=blue]
>
> It also depends on the AttributeUsage. Inherited setting of the
> attribute class.[/color]

Amazingly enough one topic in the MSDN documentation says that the default
value for the Inherited value of AttributeUsageA ttribute class is true ( in
the actual .NET framework reference for the class ), while another topic
says that the default value for the Inherited value of the
AttributeUsageA ttribute class is false ( C# Programmer's Reference, C#
Attributes ). I tend to believe the former is true, as it is more natural to
believe that if one sets an attribute on an element in a base class, the
same attribute should be applied to the inherited element of the derived
class.

This whole question came about because I wished to be able to change a
property or event in a base class from being browsable to being not
browsable in a derived class. The BrowsableAttrib ute normally defaults to
true. I was wondering how I can set it to false for a derived class,
especially as I can't just redeclare a given property or event. Is there a
way to apply an attribute to an element of a base class which has been
automatically derived in a derived class ?