Vladimir Prus wrote:
> Hi,
> just now I've nearly comitted the following addition to one of BGL
> headers:
>
> + struct null_property_copier {
> + template<class V1, class V2>
> + void operator()(const V1&, const V2&) const {}
> + };
> +
>
> What stopped me is that is not BGL specific at all. Is there some
> class in Boost which can be used insteead?
If you have a do-nothing nullary function:
struct do_nothing
{
typedef void result_type;
void operator()() const {}
};
you can build the other variations with bind(do_nothing()).
[...]
> And another question. Do we have a functional object which always
> returns true, and can be called with two arguments of any types?
If you have identity:
template<class T> struct identity
{
typedef T result_type;
T operator()(T const & t) { return t; }
};
you can use bind(identity<bool>(), false). With Lambda I think that you can
just use constant(false) in both cases.
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