[Boost-users] Re: Lambda question

From: David Abrahams (dave_at_[hidden])
Date: 2004-03-30 19:34:24

Anders Sundman <d00-asu_at_[hidden]> writes:

> Hi all!
>
> I'm using the lambda library to compute the sum of squared
> differences, but I have encountered a puzzling problem. I would
> really appreciate if someone could explain it to me.
>
> This doesn't compile:
>
> std::inner_product(i1, i1+x, i2, 0.0,
> 		   (_1 + _2), (_1*_1)(_1 - _2));
>
> however, this does:
>
> std::inner_product(i1, i1+x, i2, 0.0,
> 		   std::plus<double>(), (_1*_1)(_1 - _2));
                                ^^^^^^^^       ^

Doesn't seem right.  Do you really mean to invoke the function call
operator on the result of _1*_1  ??

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com