Alias this with array can only be used once

[Ali Çehreli]

On 02/22/2012 03:16 PM, Blake Anderton wrote:

 > With an array the above tests work (I assume because each
 > operation is implicitly a new slice?).

It works because the slice itself is copied to count() and count() 
consumes that copy internally.

Now I see the issue here: Why does 'alias this' disable the parameter 
copying behavior? Why is the member slice not being copied?

This must be clarified. Is this a bug? A hole in the spec?

 > I found I can fix the above example by aliasing a function that returns
 > a slice of the member array instead of aliasing the field itself,

That function is called save() on ForwardRange ranges and does exactly that.

 > but
 > that may still be too close a relationship of the container/range. My
 > instinct (which could be completely wrong) is that it's fine since the
 > container is taking responsibility for creating valid ranges, it is just
 > doing so implicitly.
 >
 > User code having to explicitly take ranges (either through opSlice or a
 > property/method) isn't a terrible thing, but it would be convenient to
 > not have to take that extra step.

You have to decide whether this is a container or a range. If it's a 
range, the users should be able to freely consume it from the top and 
save copies of it by save() when they need to. I recommend defining the 
range functions directly on this type in that case.

Ali