a more consistent const syntax

[Paul Collier]

Rioshin an'Harthen wrote:
> "Chris Nicholson-Sauls" <ibisbasenji at gmail.com> kirjoitti viestissä 
> news:f951kq$2fss$1 at digitalmars.com...
>> Daniel919 wrote:
>>> 3. const P func(P p) { ... }
>>> reads like: func returns a const(P)
>>
>> Which is, indeed, a problem -- in that I agree.
> 
> I agree, as well. It reads like returning a const P.
> 
>>> const / invariant alone (without brackets) is an attribute and has no 
>>> other meaning
>>> further proposal: returned types in a bracket at the end:
>>> 3. const func (P p) (P) { ... }
>>> //templated syntax: const func!(T) (T p) (T) { ... }
>>
>> Uhm.  Ew.  No, seriously, I just could not possibly handle that; I 
>> would keep thinking I saw templates where there aren't any.  Worse 
>> yet, for a long time I'll see the '!(' and keep wondering how I could 
>> be instantiating a template in that position, when its really a 
>> template declaration.  T'is a naughty naughty thing to mix the two -- 
>> would give both the compiler and the user headaches.  IMHO, its the 
>> 'const'/'invariant' keyword on methods that needs to move -- not sure 
>> where it should go, though.  What looks best down here?  ;)  (First 
>> listing is the current state, for reference.)
>>
>> const P       vunc       (P p)       { ... }
>>       P const func       (P p)       { ... }
>>       P const:func       (P p)       { ... }
>>       P const(func)      (P p)       { ... }
>>       P       func const (P p)       { ... }
>>       P       func:const (P p)       { ... }
>>       P       func       (P p) const { ... }
> 
> Definitely the last one. It's immediately familiar to anyone with a C++ 
> background, which I guess most of those coming to D has, and which I 
> think are the people Walter is especially targetting. It also has the 
> added bonus of not complicating method declaration grammar too much.
> 
> Same list, this time a const func returning a const return value:
> 
> const const(P) func (P p)
> const(P) const func (P p)
> const(P) const(func) (P p)
> const(P) func const (P p)
> const(P) func:const (P p)
> const(P) func (P p) const
> 
> I definitely prefer the last one as the cleanest of these.

Just chiming in on a slightly different note... the line that stuck out 
in both examples for me was actually the const(func) line. That seems 
really intuitive and consistent with the const syntax elsewhere.

I do find the const-on-the-end readable too, but really mostly because 
of familiarity with C++ ;)