Re: [boost] [proto] transforms && rvalue refs

Subject: Re: [boost] [proto] transforms && rvalue refs
From: troy d. straszheim (troy_at_[hidden])
Date: 2009-03-30 14:45:52

Joel Falcou wrote:
> troy d. straszheim a écrit :
>>
>> That's the point...   you can't do that here.   The elements behind A 
>> B and C are on the other end of a very slow bus.
> That wasn't clear, sorry.  What kind of slow bus ?
> 

A bus that has an CUDA-capable video card on the other end.  Transforms 
fire CUDA kernels that do the math.

Before I started playing with a c++0x capable compiler, I dealt with by 
putting 'rvalueness' into the type system.  This works with proto 
expression templates:

template <typename T, typename IsRValue = mpl::false_>
class array
: public Expression<bp::terminal<array_impl<T, IsRValue> > >
{ // ...

transforms return array_impl<T, mpl::true_>, and later transforms can 
tell that their arguments are reusable.  It works fine, though it is 
arguably ugly, and as eric points out, this isn't what expression 
templates are 'for'.

Anyhow, the other day I decided to see if I could make those extra 
template parameters go away via rvalue refs </chase_own_tail>

-t