I run upgrade after installing all recommended updates from update manager, and I got dialog:

Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade:
E:Unable to correct problems, you have held broken packages.

 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug using the command 'ubuntu-bug update-manager' in a terminal.


So I reported bug.

I also tried

umpirsky@umpirsky:~$ sudo apt-get update
...
Fetched 16.6 kB in 1min 22s (200 B/s)
Reading package lists... Done
W: GPG error: http://archive.canonical.com oneiric Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key &lt;email address hidden&gt;


Any workaround for this?


What is the easiest way to resolve apt-get BADSIG GPG errors?
First and second solution didn't work, last one returned cd: /var/cache/apt-cacher-ng: No such file or directory. Still getting GPG error.



Question: Equivalent of Java 1.6 @Override for interfaces in C#
Answer: As stated, you cannot get that kind of control from an interface alone in C#. You could get it from an abstract class however. For the purpose of completeness, here is what you could do:

public interface IA
{
    void Foo();
    //void Bar(); - removed
}

public abstract class A : IA
{
    virtual void Foo()
    { }

    // Removed method
    //virtual void Bar()
    //{ }
}

public class B : A
{
    public override void Foo()
    { }

    //throws an error like the one you were receiving regarding no method to override.
    public override void Bar()
    { }
}