Declaring Ref Variables Inside Function Calls

[Andrei Alexandrescu]

Bill Baxter wrote:
> On Wed, Apr 1, 2009 at 5:03 AM, Sergey Gromov <snake.scaly at gmail.com> wrote:
>> Tue, 31 Mar 2009 12:18:21 -0700, Andrei Alexandrescu wrote:
>>
>>> Jarrett Billingsley wrote:
>>>> On Tue, Mar 31, 2009 at 1:32 PM, Andrei Alexandrescu
>>>> <SeeWebsiteForEmail at erdani.org> wrote:
>>>>> Jarrett Billingsley wrote:
>>>>>> 2009/3/30 dsimcha <dsimcha at yahoo.com>:
>>>>>>> // How it works now:
>>>>>>> uint foo;
>>>>>>> string bar;
>>>>>>> unpack(foo, bar) = someFunction();
>>>>>>>
>>>>>>> // vs. how I want it to work:
>>>>>>> unpack(auto foo, auto bar) = someFunction();
>>>>>> Cute, but uh, I'd much rather see tuples just be returnable.
>>>>> They are.
>>>> template Tuple(T...)
>>>> {
>>>>      alias T Tuple;
>>>> }
>>>>
>>>> Tuple!(int, float) foo()
>>>> {
>>>>      return Tuple!(3, 4.5);
>>>> }
>>>>
>>>> foo.d(10): Error: functions cannot return a tuple
>>>>
>>>> Unless you're using some prerelease compiler, they are not.
>>> import std.typecons;
>>>
>>> Tuple!(int, float) foo()
>>> {
>>>      return tuple(2, 4.5);
>>> }
>>>
>>> The addition of the alias this feature and of constructor templates
>>> makes std.typecons.Tuple even better.
>>>
>>> Andrei
>> Unfair---std.typecons.Tuple is actually a struct!
>>
>> Well, basically struct is a run-time tuple, anyway.
>>
>> I think that all the buzz around "actual tuple support" boils down to
>> requests for syntax sugar for construction and decomposition of
>> anonymous structs.  While typecons.Tuple is sorta OK for construction,
>> things are still pretty ugly on the "decomposition" end.
> 
> For me the distinction is that I would only consider writing a
> function that returns something like "Tuple!(int, float)" as a last
> resort when no other design would work.  I would sooner use two out
> parameters.

Why? I use tuple returns all over.

> But in Python or ML, no question. I'd happily write a function that
> returns (2, 4.2) without giving it much thought.  Now perhaps cogent
> arguments like "blech" and "belch" can convince me that I should
> embrace the Tuple!(int,float) and use it everywhere, just like I'd use
> tuples in Python and ML, but so far I'm not convinced.
> 
> To me it seems to be in the same league as int[] vs std::vector<int>.
> int[] -- great I'll happily use that everywhere.  std::vector<int>
> kind of a pain, use begrudgingly as needed.

Well I think a language can only have so many built-in types. We can't 
go on forever.

Andrei