The implementation is compiler dependant. Nevertheless, it would appear that the normal implementation is to create something which looks like a normal object with pointers back to the state it closes around. In theory it should be fast and light. The problem (as always with C++) is ensuring that the things to which the pointers point does not go away. Smart pointers help - but they are slow...
I think the most common use case for blocks in C++ are functional-ish STL algorithms, unlike C blocks, which were built for async operations. In that use case, they absolutely shine - since they don't outlive their parent scope, no memory management is necessary, they can be inlined and ideally add no overhead. I think this easily outweighs the cases where you need slow shared pointers.
Comments
The implementation is compiler dependant. Nevertheless, it would appear that the normal implementation is to create something which looks like a normal object with pointers back to the state it closes around. In theory it should be fast and light. The problem (as always with C++) is ensuring that the things to which the pointers point does not go away. Smart pointers help - but they are slow...
I think the most common use case for blocks in C++ are functional-ish STL algorithms, unlike C blocks, which were built for async operations. In that use case, they absolutely shine - since they don't outlive their parent scope, no memory management is necessary, they can be inlined and ideally add no overhead. I think this easily outweighs the cases where you need slow shared pointers.