On Mon, Dec 1, 2008 at 11:45 AM, Sebastian Redl <sebastian.redl@getdesigned.at> wrote:
Zach Laine wrote:
On Mon, Dec 1, 2008 at 11:32 AM, Sebastian Redl <sebastian.redl@getdesigned.at> wrote:
Zach Laine wrote:
The docs include some example code on "using constrained objects in debug mode only", and make reference to using unconstrained<> to allow use of the .value() member function. Why not replace the .value() member function with a free function boost::constrained_value::value(), and then write something like this?
#ifndef NDEBUG typedef bounded_int<int, 0, 100>::type my_int; #else typedef int my_int; # if IM_FINE_WITH_MACROS # define value(x) x # else inline int value(int x) { return x; } # endif #endif
Then, as long as the user always writes "value(x)", letting ADL pick up the boost::constrained_value::value() free function, the macro/inline function above will silently kick in instead if defined. This gets rid of any requirements on the quality of the optimizer in order to get performance just like an int. Did you already try this and find it problematic?
Intuitively, I'd say this is problematic - the value(int) version wouldn't get picked up by ADL.
Why is ADL an issue when the parameter type is int? The value(int) overload is only declared when we don't care about ADL, since we're not using constrained_value types. Am I missing something?
The value overload for int would have to be in the global scope, or else it won't be found and you'll get compile errors.
Defining a function called "value" in the global scope sounds like a big no-no to me. Can you imagine a name more likely to collide with something else?
Quite true. But the code above is user-supplied, so the user can write their code so that such collisions do not occur, if they need identical behavior to int in NDEBUG mode, or the library author could change the spelling of value() to be something less likely to cause problems, or both. Zach