New linked list

[Sean Kelly]

Walter Bright wrote:
> Sean Kelly wrote:
>> Very cool.  One thing... does this work:
>>
>>     foreach( Person p; per.each )
>>     {
>>         if( p.age > 50 )
>>             p.listRemove();
>>     }
>>
>> ie. can you remove elements within a foreach?
> 
> It's undefined behavior. foreach is entitled to assume that the 
> aggregate is a loop invariant, although the contents of the aggregate's 
> elements can change. This precludes things like resizing an array inside 
> a foreach, etc.

Even for a class that defines an opApply?  What about an alternate syntax:

     foreach( Person p; personList )
     {
         if( p.age > 50 )
             personList.remove( p );
     }

Assuming the list code supports this operation (say the 'next' pointer 
isn't set to null when p is removed, and thus the iteration should 
continue without any problems), is the behavior still undefined?  If so, 
I assume it would be okay to store a list of 'removed' items until the 
iteration ends and them remove them all at once?


Sean