On 21 April 2013 11:36, Zach the Mystic <reachzach@gggggmail.com> wrote:

On Sunday, 21 April 2013 at 00:51:31 UTC, Manu wrote:

That's not what scope does. Scope promises that the variables will not
escape the scope. And as such, just happens to make passing a temporary by
ref safe.
It does not implement r-value ref's. It simply allows refs to temporaries
to be considered a safe operation.

It's a two-fer! (2 for 1 deal)

This DIP is actually likely to solve an important source of problems,
consider:

void func(const ref matrix m);

func(x.getMatrix()); // compile error!

// fu*^&%$ing hell! you piece of &%^#≈¿$!
// ...

matrix temp = x.getMatrix();
func(temp); // no more compile error! (but equally unsafe/dangerous)

It's hard to fully understand this example without getMatrix() defined, and why func() is unsafe (does it escape the reference?). Help!

definition:

matrix getMatrix(T x); // this is all you know

That's the point of the example. You _don't know_ if func() is unsafe, does it escape the reference? But you need to pass a temp anyway, you have no bearing on whether you should just hack it to work, or reconsider the problem.

And when 99 times out of 100, the correct answer is 'hack it to work', you're basically asking for a spectacular bug in that other 1% of cases.

<Side rant>
In my experience showing D to new people, this is the #1 complaint. It's
the first one that comes up, every time (which really doesn't help with
first impressions), and I'm fairly sure every single person I've introduced
to D has complained about this.
It's kind of embarrassing when I'm saying that D is really cool, and then I
have to start making excuses and apologising for this, and assure them that
it's a known issue, and it'll be fixed one day.

Yikes.