D's greatest mistakes

[Fawzi Mohamed]

On 30-nov-10, at 22:24, Steven Schveighoffer wrote:

> On Tue, 30 Nov 2010 15:47:22 -0500, Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org 
> > wrote:
>
>> On 11/30/10 12:38 PM, Steven Schveighoffer wrote:
>
>>> No, that's not what I'm saying. Creating a language-based tail-const
>>> solution *unifies* all references, including any smart references  
>>> you
>>> can create. I can say tail-const anything and it always means the  
>>> same
>>> thing. It's another tool to allow creating of smart references.  
>>> Without
>>> this, we have to special case tail-const in all smart reference  
>>> types.
>>> If anything Rebindable is a special case smart reference, it only
>>> addresses class tail-const. The language solution addresses general
>>> tail-const. E.g. how does Rebindable address tail-const ranges?
>>>
>>> I see it 100% opposite from what you are saying, a library solution
>>> looks to me like "look! we don't have to change the language to add
>>> language features, all you need is this template that adds 10k of  
>>> bloat
>>> to your exe! And why do you need to pass them as parameters, just  
>>> create
>>> a new local variable? And why do you need it to work with *all*
>>> reference types, there's other syntax for that!" All for the sake  
>>> of not
>>> changing the language, which I think is the more direct and complete
>>> solution. I don't really understand the resistance.
>>
>> Understanding the "resistance" is very simple. Right now a lot of  
>> current readers cheerily ignore this thread. Also a lot of  
>> potential users couldn't care any less. Once the feature will be in  
>> the language, it will affect them all.
>
> It affects them all as much as Rebindable affects them all.  Either  
> way, it's something new they have to learn, whether it's a language  
> feature or a library feature.  This argument makes no sense.
>
> Another way to look at it -- whichever solution is used is really  
> going to affect only library writers, not library users.  Whether  
> the user writes:
>
> @tail const(C);
>
> or
>
> Rebindable!(const(C))
>
> or something else is really irrelevant to them, what's relevant is  
> what hoops do I as a library writer have to jump through to get this  
> damned thing to work seamlessly.

I mostly agree with Steve (I just made it though the thread), I also  
find tail const very useful.
In fact I independently wrote a related post about tail const (but  
with a different syntax).
The fact that tail const can be reasonably extended to any type, and  
still guarantees purity shows its usefulness.
mostly it can be seen as a shortcut to declare a special kind of  
constness, only for classes one can express something with tail const  
that cannot be  directly expressed with const()

>