Re: Should range foreach be iterating over an implicit copy?

[Steven Schveighoffer]

On Wed, 16 May 2012 17:37:14 -0400, Nick Sabalausky  
<seewebsitetocontac...@semitwist.com> wrote:

A small debate has broken out over on D.learn (
http://forum.dlang.org/thread/jovicg$jta$1...@digitalmars.com#post-jovicg:24jta:241:40digitalmars.com  
)
that I thought I should move here.
Basically, the issue is this: Currently, when you have a struct-based  
range,
foreach will iterate over a *copy* of it:

    Range r;
    auto save = r;
    foreach(e; r)
        assert(r == save);
    assert(r == save);

One side of the argument is that this behavior is correct and expected  
since
structs are value types, and iterating shouldn't consume the range.

My argument is this:

First of all, foreach is conceptually a flow-control statement, not a
function. So I'd intuitively expect:

    Range r;
    foreach(e; r) {...}

To work like this:

    Range r;
    for(; !r.empty; r.popFront)
    {
        auto e = r.front;
        ...
    }

Hm... proposal:

foreach(e; ref r)
{
}

equates to your desired code.  Would this help?

-Steve