Obsolete attribute in a derived class

[Steve James]

I am trying to mark an override method in a derived class as obsolete using
the ObsoleteAttribu te. The compiler, however is not picking up this
attribute and is not generating a warning or an error.

Sample code is below:

If I put the attribute on the static method DoSomething() in the main class,
a warning/error is generated by the compiler.

If I put the attribute on the virtual instance method DoSomething() of
Class2, a warning/error is generated.

If I put the attribute on the override instance method DoSomething() of
Class3 ( which is derived from Class2), no warning or error is generated by
the compiler.

Is this a bug, or is there some good reason for this? It certainly isn't
documented. Any ideas?
using System;
namespace ConsoleApplicat ion
{

class Class1
{
[STAThread]
static void Main(string[] args)
{
Class2 o = new Class2();
o.DoSomething() ;

o = new Class3();
o.DoSomething() ;

DoSomething();

Console.ReadLin e();
}

[Obsolete("Funct ion 'DoSomething()' is obsolete.", true )]
static void DoSomething()
{
Console.WriteLi ne( "I've done something.");
}
}

public class Class2
{
public Class2() {}

public virtual void DoSomething()
{
Console.WriteLi ne("Class2.DoSo mething()");
}
}

public class Class3 : Class2
{
public Class3(){}

[Obsolete("Use somethiing else instead.", true)]
public override void DoSomething()
{
Console.WriteLi ne("Class3.DoSo mething()");
}
}

}

Thanks,

Steve

[Philip Rieck]

If you look into the il generated, you'll notice the line :
callvirt instance void
ConsoleApplicat ion1.ConsoleApp lication.Class2 ::DoSomething()
For both calls to o.DoSomething() .
Even if you turn it into
Class3 o = new Class3();
o.DoSomething() ;

the il still reads the same. Because Class2.DoSometh ing is virtual, the
instance call to Classxxx.DoSome thing() will always be a callvirt to
Class2.DoSometh ing, as long as Classxxx has Class2 as an ancestor. (unless
you declare DoSomething with "new")

This is why the obsolete isn't being applied -- class3.DoSometh ing() is not
actually called directly.


"Steve James" <st***********@ ntlworld.com> wrote in message
news:Rb******** *****@newsfep3-gui.server.ntli .net...

I am trying to mark an override method in a derived class as obsolete using the ObsoleteAttribu te. The compiler, however is not picking up this
attribute and is not generating a warning or an error.

Sample code is below:

If I put the attribute on the static method DoSomething() in the main class, a warning/error is generated by the compiler.

If I put the attribute on the virtual instance method DoSomething() of
Class2, a warning/error is generated.

If I put the attribute on the override instance method DoSomething() of
Class3 ( which is derived from Class2), no warning or error is generated by the compiler.

Is this a bug, or is there some good reason for this? It certainly isn't
documented. Any ideas?
using System;
namespace ConsoleApplicat ion
{

class Class1
{
[STAThread]
static void Main(string[] args)
{
Class2 o = new Class2();
o.DoSomething() ;

o = new Class3();
o.DoSomething() ;

DoSomething();

Console.ReadLin e();
}

[Obsolete("Funct ion 'DoSomething()' is obsolete.", true )]
static void DoSomething()
{
Console.WriteLi ne( "I've done something.");
}
}

public class Class2
{
public Class2() {}

public virtual void DoSomething()
{
Console.WriteLi ne("Class2.DoSo mething()");
}
}

public class Class3 : Class2
{
public Class3(){}

[Obsolete("Use somethiing else instead.", true)]
public override void DoSomething()
{
Console.WriteLi ne("Class3.DoSo mething()");
}
}

}

Thanks,

Steve

[Steve James]

I suppose, when you think about it, why would a warning or error be raised
at compile-time, on a method call bound at run-time?

Thanks, Philip. I'll look at the IL next time.

Steve

"Philip Rieck" <st***@mckraken .com> wrote in message
news:ep******** ******@tk2msftn gp13.phx.gbl...

If you look into the il generated, you'll notice the line :
callvirt instance void
ConsoleApplicat ion1.ConsoleApp lication.Class2 ::DoSomething()
For both calls to o.DoSomething() .
Even if you turn it into
Class3 o = new Class3();
o.DoSomething() ;

the il still reads the same. Because Class2.DoSometh ing is virtual, the
instance call to Classxxx.DoSome thing() will always be a callvirt to
Class2.DoSometh ing, as long as Classxxx has Class2 as an ancestor. (unless
you declare DoSomething with "new")

This is why the obsolete isn't being applied -- class3.DoSometh ing() is not actually called directly.


"Steve James" <st***********@ ntlworld.com> wrote in message
news:Rb******** *****@newsfep3-gui.server.ntli .net...

I am trying to mark an override method in a derived class as obsolete

using

the ObsoleteAttribu te. The compiler, however is not picking up this
attribute and is not generating a warning or an error.

Sample code is below:

If I put the attribute on the static method DoSomething() in the main

class,

a warning/error is generated by the compiler.

If I put the attribute on the virtual instance method DoSomething() of
Class2, a warning/error is generated.

If I put the attribute on the override instance method DoSomething() of
Class3 ( which is derived from Class2), no warning or error is generated

by

the compiler.

Is this a bug, or is there some good reason for this? It certainly isn't
documented. Any ideas?
using System;
namespace ConsoleApplicat ion
{

class Class1
{
[STAThread]
static void Main(string[] args)
{
Class2 o = new Class2();
o.DoSomething() ;

o = new Class3();
o.DoSomething() ;

DoSomething();

Console.ReadLin e();
}

[Obsolete("Funct ion 'DoSomething()' is obsolete.", true )]
static void DoSomething()
{
Console.WriteLi ne( "I've done something.");
}
}

public class Class2
{
public Class2() {}

public virtual void DoSomething()
{
Console.WriteLi ne("Class2.DoSo mething()");
}
}

public class Class3 : Class2
{
public Class3(){}

[Obsolete("Use somethiing else instead.", true)]
public override void DoSomething()
{
Console.WriteLi ne("Class3.DoSo mething()");
}
}

}

Thanks,

Steve