Iterating over containers of immutable objects

[Steven Schveighoffer]

On Tue, 29 Jun 2010 19:08:13 -0400, Justin Johansson <no at spam.com> wrote:

> Steven Schveighoffer wrote:
>> On Tue, 29 Jun 2010 18:42:18 -0400, Justin Johansson <no at spam.com>  
>> wrote:
>>
>>> Steven Schveighoffer wrote:
>>
>>> There is another solution which requires introducing an extra virtual
>>> method (and associated cost thereof) namely "hasNext" to the iterator
>>> interface.  This allows pulling a single item (if it exists) out of
>>> the iterator on demand.
>>  Duh... I just thought of this too:
>>  while(auto bar = iter.next())	// line 37
>> {
>>   ...
>> }
>
> Sorry that does not compile, dunno if it should I'm using
> the latest D2.
>
> test.d(37): expression expected, not 'auto'
> test.d(37): found 'bar' when expecting ')'
> test.d(37): found '=' instead of statement
> test.d(41): unrecognized declaration


Hm... a common idiom to deal with whether an object casts to a type is  
this:

if(auto c = cast(C)obj)
{
    // use c
}

I wonder why while doesn't work...

Walter?

-Steve