sorting hidden data.

[Steven Schveighoffer]

On Wed, 29 Sep 2010 12:26:39 -0400, Andrei Alexandrescu  
<SeeWebsiteForEmail at erdani.org> wrote:

> On 9/29/10 6:22 PDT, Steven Schveighoffer wrote:
>> std.algorithm.sort seems to require lvalue access to elements of a
>> range, presumably so it can call swap on two elements during sorting. So
>> while a range can technically allow changing of data, it cannot be
>> passed to swap.
>>
>> e.g.
>>
>> struct myrange
>> {
>> @property T front() {...}
>> @property T front(T t) {...}
>> void popFront() {...}
>> @property bool empty() {...}
>> myrange opSlice(size_t low, size_t hi) {...}
>> @property size_t length() {...}
>> }
>
> Good news - you should be able to use sort on sealed ranges if they  
> define moveFront, moveBack, and moveAt. Look e.g. at Zip, it's also  
> sealed yet you can sort Zips no problem.
>
> This is a relatively new addition.

I'm not liking this...

How many more boiler-plate functions will we be forced to add in order to  
support standard ranges?  save() was bad enough, this is three more, when  
the functionality *already exists*.

Can't sort just use:

x = r1.front;
r1.front = r2.front;
r2.front = x;

???

-Steve