Bartosz Milewski seems to like D more than C++ now :)

[H. S. Teoh]

On Fri, Sep 20, 2013 at 05:42:03PM +0200, Joseph Rushton Wakeling wrote:
> On 20/09/13 17:22, H. S. Teoh wrote:
> >Which makes it even more confusing, since newbies would probably
> >equate arrays (the container) with ranges from their frequent use in
> >range examples.
> 
> Yes, it's completely non-obvious.  I think the first time I realized
> the range/container distinction was when I tried experimentally
> replacing some built-in arrays with std.container.Array and
> discovered that I couldn't use them in a foreach loop.

Sad to say, I encountered a good number of Phobos bugs caused by the
conflation between built-in arrays and ranges. Code would inadvertently
assume array behaviour on ranges, and break when you pass in a non-array
range. Some of these have been fixed; I'm pretty sure there are still
more lurking around.


> >Perhaps it's more useful to think of T[] not as an array per se, but
> >as a *slice* of the underlying array data which is managed by
> >druntime. I think I'm OK with saying that arrays (i.e. the underlying
> >data) are containers, while slices (what we think of today as
> >"arrays") are ranges.
> 
> It's not a bad description, but I'm not sure that takes into account
> the const(T[]) case.

Actually, it helps you understand the const(T[]) case. To iterate over a
const array, you need a range over it (i.e., a slice); and indeed,
writing arr[] on an array of type const(T[]) gives you a tail-const
slice of type const(T)[], which *is* an iterable range.

The confusion really just stems from the conflation between T[] and a
range over T[] in the non-const case.


T

-- 
People tell me I'm stubborn, but I refuse to accept it!