On 6/11/2010 1:24 PM, Giovanni Piero Deretta wrote:
On Fri, Jun 11, 2010 at 6:03 PM, Eric Niebler <eric@boostpro.com> wrote:
Well, there's a hitch.
ref[ bigobj += _1 ]
Users might reasonably expect this to not make a copy of bigobj, and the way to avoid it is not obvious:
ref[ ref(bigobj) += _1 ]
Clearly the user has already stated their intention to capture bigobj by reference and shouldn't have to say it again.
I think default capture modes may be unworkable if we want the default mode to be by-value.
unless you forbid 'naked' lambdas:
int x = 0; auto f0 = lambda [ x += _1 ]; // capture x by val auto f1 = lambda_r [ x += _1 ]; // capture x by ref auto f2 = x += _1 ; // just a proto expression tree, not a lambda
f0(1); //ok f2(1); //ok f3(1); // no operator()
The lambda syntax becomes more heavy weight, but lambdas do stand up more in code. You would have to protect nested lambdas anyway ...
That's true, and I /personally/ wouldn't be opposed to that; I just don't have a strong preference. This should be Joel's call. -- Eric Niebler BoostPro Computing http://www.boostpro.com