std::unique_ptr and custom allocator deleter

Question

I am trying to use std::unique_ptr with custom memory allocators. Basically, I have custom allocators that are subclasses of IAllocator,

Answer 1

Yes, there most certainly is a better way:
Use a maker-function.

template std::unique_ptr
my_maker(size_t count, A&& allocator) {
    return {somePtr(allocator.AllocArray(count), MyArrDeleter(allocator, count)};
}

auto p = my_maker(42, allocator);