Why exceptions for error handling is so important

[Tobias Pankrath via Digitalmars-d]

On Monday, 12 January 2015 at 19:30:10 UTC, Russel Winder via 
Digitalmars-d wrote:
>
> On Mon, 2015-01-12 at 10:43 -0800, H. S. Teoh via Digitalmars-d 
> wrote:
>> 
> […]
>> And what exactly should operator[] return if a key wasn't 
>> found?
>> 
> […]
>
> Go has an interesting solution, key lookup in a map return a 
> pair
> (result, ok), if lookup succeeded then result is the associated 
> value,
> if ok is false then result is undefined. I quite like this.

That's basically the same as a pointer to the value. If the 
pointer is null, dereferencing it is undefined.