dropping parentheses on template instantiation

[KennyTM~]

KennyTM~ wrote:
> Ary Borenszweig wrote:
>> Andrei Alexandrescu escribió:
>>> Denis Koroskin wrote:
>>>> On Sun, 05 Oct 2008 22:18:26 +0400, Andrei Alexandrescu 
>>>> <SeeWebsiteForEmail at erdani.org> wrote:
>>>>
>>>>> I just realized something different. After making an informal 
>>>>> review of some code, I saw that a large percentage of template 
>>>>> instantiations only need ONE argument.
>>>>>
>>>>> This makes me think, with the old "!" notation, parentheses could 
>>>>> be dropped entirely without prejudice:
>>>>>
>>>>> auto covariance = Matrix!real(n, n);
>>>>> auto normalized = SparseVector!double(n);
>>>>>
>>>>> and so on.
>>>>>
>>>>> To the unbridled joy of the enemies of the Sad Pirate, the dot 
>>>>> won't work for template instantiation because without the 
>>>>> parentheses it DOES engender ambiguity.
>>>>>
>>>>> Now say we take the following route:
>>>>>
>>>>> 1) We find something different from shouting
>>>>>
>>>>> 2) We drop the parentheses for 1 argument
>>>>>
>>>>> That sounds like a possible winner. In this case the "#" becomes 
>>>>> considerably more attractive, in fact very attractive exactly 
>>>>> because it looks unlike any letter:
>>>>>
>>>>> auto covariance = Matrix#real(n, n);
>>>>> auto normalized = SparseVector#double(n);
>>>>>
>>>>> Ideas?
>>>>>
>>>>>
>>>>> Andrei
>>>>>
>>>>> P.S. The Sad Pirate is the emoticon
>>>>>
>>>>> .(
>>>>>
>>>>> It doesn't have an eye and is sad, too.
>>>>
>>>> Just to clarify things: Do you propose moving the first template 
>>>> argument outside of the parentheses *or* ditching them iff there is 
>>>> only one parameter? I mean, what does the original code look like, 
>>>> because there is ambiguaty in your statement (to me):
>>>
>>> Ditch parens if there's only one argument. In that case the extra 
>>> character becomes an enabling asset, not a liability.
>>>
>>>> const int n = 42;
>>>> auto covariance = Matrix!(real, n, n); <-> auto covariance = 
>>>> Matrix#real(n,n);
>>>>
>>>> *or*
>>>>
>>>> auto covariance = Matrix!(real)(n, n); <-> auto covariance = 
>>>> Matrix#real(n,n);
>>>
>>> The latter.
>>>
>>>> Other than that Vector at real or Vector#real both sound good!
>>>
>>> I agree. In fact "Vector at real" sounds like a good way of talking 
>>> about templates instead of "Vector instantiated with real". One 
>>> reason for which I think "this" is a poor choice (as opposed to e.g. 
>>> "self") is that it's very hard to talk about it.
>>
>> I like Vector at real. Also: HashMap@(Key, Value) looks nice to me. The 
>> only thing is that in spanish keboards, I have to do alt-gr + Q to get 
>> one @ :-P
> 
> It seems that
> 
> Stack!int
> Stack at int
> Stack#int
> 
> are the only choices we're left with. All others are either binary 
> operators, delimiters or some kind of parenthesis. But frankly speaking 
> all of these characters are not very pretty :/

And I think # will cause problem if a name a class "line":

   Stack#line // #line integer ["filespec"]\n expected

(http://www.digitalmars.com/d/2.0/lex.html#specialtokenseq)