disable all member function calls for rvalues?

[Steven Schveighoffer]

On Tue, 22 Dec 2009 08:41:11 -0500, Steven Schveighoffer  
<schveiguy at yahoo.com> wrote:

> On Tue, 22 Dec 2009 08:30:33 -0500, Andrei Alexandrescu  
> <SeeWebsiteForEmail at erdani.org> wrote:
>
>> Kagamin wrote:
>>> Andrei Alexandrescu Wrote:
>>>
>>>>> I think, possible solution is to disallow assign operations on the  
>>>>> return value: =, +=, *=, ~=, ++ etc, but read operations should be  
>>>>> allowed and functions should be callable by their symbolical names.
>>>> Won't help. Consider:
>>>>
>>>> a.b.c.d.e.f = g;
>>>>
>>>> If anywhere on the path an rvalue is created, the code is useless  
>>>> busywork.
>>>  In contrast with the original example this is not a bug.
>>
>> I think it is to the extent (a) it does nothing (b) the syntactic  
>> equivalent code involving fields does something. It's an egregious  
>> breakage of consistency because properties were meant to be  
>> generalizations of fields in the first place.
>
> What if a.b returns a Rebindable!(const(T)) rvalue, and the rest are  
> lvalues?

I just realized in my efforts to use a real phobos-supported wrapper type,  
I doomed my own argument :)

The point is, wrapper types shouldn't have second-class citizenship as  
rvalues to pointers and references.  There's got to be a way to identify  
types as being lvalues even though the compiler doesn't see it that way.   
If you can accomplish that, then I have no problem disallowing setting  
members of true rvalues.

-Steve