@property needed or not needed?

[Jonathan M Davis]

On Sunday, December 02, 2012 01:16:40 Andrej Mitrovic wrote:
> On 11/20/12, Jonathan M Davis <jmdavisProg at gmx.com> wrote:
> > I suspect that the
> > best that we can hope for at this point is for lax property enforcement -
> > that is that it's enforced that @property functions are used as properties
> > but there is no enforcement that non- at property functions be called with
> > parens.
> Here's a good reason why the latter isn't the best idea:
> http://d.puremagic.com/issues/show_bug.cgi?id=2159
> 
> The reporter made the mistake of issuing a function call instead of
> taking an address of a function, which in turn invoked a different
> function overload with the temporary result.

I'd _love_ to make it illegal to call non-property functions without parens, 
and there are definitely folks around here who agree with me, including some on 
the Phobos dev team (e.g. Steven has always agreed with me when this has come 
up), but there are enough folks around here here who like to call functions 
without parens - especially with UFCS and templated functions like map or 
filter - that I don't think that that's going to fly at this point. Maybe if 
Andrei agreed it could happen, but he's hated the idea of @property 
practically from the get-go, and when you combine that with the facts that 
strengthening @property enforcement as originally intended would break a lot 
of code at this point and that Walter absolutely hates breaking people's code 
for pratically any reason whatsoever, I expect that Walter would be against it 
too. And with both of them against it, it just wouldn't happen.

The workaround for the bug in question is to not overload functions that take 
function pointers with an overload that takes something other than a function 
pointer or delegate. Even that's not perfect, because a function could return 
a function pointer or delegate, but at this point, I just don't see Andrei and 
Walter agreeing to the level of property enforcement required to stop it, even 
if they had agreed to it in the past. UFCS seems to be the feature that puts 
the nail in the coffin of that idea, because people don't want to do stuff like 
range.filter!(a => a.func() < 2)() but would rather do range.filter!(a => 
a.func() < 2).

- Jonathan M Davis