Can call static method with null reference

[Steven Schveighoffer]

On Sun, 23 Jun 2013 06:09:19 -0400, Jonathan M Davis <jmdavisProg at gmx.com>  
wrote:

> On Sunday, June 23, 2013 12:02:42 Namespace wrote:

>> Also I don't know why I should call static methods from an
>> instance. What's the purpose?
>
> It's stupid and pointless as far as I can tell, but I believe that C++,  
> Java,
> C#, and D all do it, so as stupid as it is, it's a common stupidity. I
> certainly wish that we could change it, but I wouldn't expect Walter to  
> agree
> to the change, since it would break at least some existing code, and I  
> suspect
> that he doesn't consider the fact that you can call static functions on
> instances to be a problem. That's not the sort of thing that he generally
> seems to think is an issue. It's almost always stuff that causes actual  
> bugs
> that he agrees to change and not things that are aesthetically  
> displeasing or
> which could theoretically cause bugs.

I actually had a bug caused by this.

But the reason is simply duck typing.

For example:

class InfiniteRange
{
   ...
   static bool empty() { return false; }
}

My suggestion to fix this has always been: only allow static calls on  
instance variables via opt-in.  e.g.:

class InfiniteRange
{
    static bool empty() { return false; }
    alias InfiniteRange.empty this.empty; // just an example
}

This allows all the benefit, but none of the bug-prone problems.

-Steve