On Tue, Jul 22, 2008 at 12:01 AM, Robert Jones <robertgbjones@gmail.com> wrote: [snip]
Obviously the intent is to enquire if all members of a range satisfy the predicate.
Now, as is, this doesn't compile, because it needs ptr_fun() on the predicate, but then a couple of things come up.
- ptr_fun( ) requires that it's argument is a pointer-to-function - I'd like my all_if( ) to permit functions or functors, including lambda functors
How can this be done? Is it impossible to dress-up a standard algorithm in this way?
You can add an additional level of indirection which has different implementations in cases where: 1. You have a function object derived from std::unary_function. 2. You have a function pointer passed as an argument. 3. You have a lambda/bind expression. You'd have to do something like this: template <class InputIterator, class Predicate> inline bool all_if(InputIterator first, InputIterator last, Predicate predicate) { // defer implementation typedef dispatch_on<Predicate>::type predicate_tag; return all_if_impl(first, last, predicate, predicate_tag()); } template <class InputIterator, class Predicate> inline bool all_if_impl(InputIterator first, InputIterator last, Predicate predicate, unary_function_tag); template <class InputIterator, class Predicate> inline bool all_if_impl(InputIterator first, InputIterator last, Predicate predicate, lambda_expression_tag); ... HTH -- Dean Michael C. Berris Software Engineer, Friendster, Inc.