> Well, your explanation doesn't really tell why do I call .deinit() on a structure before alllocator() call and calling all the rest important stuff on a struc

> Well, your explanation doesn't really tell why do I call .deinit() on a structure before alllocator() call and calling all the rest important stuff on a structure after such call. That's because the Allocator interface doesn't define that an allocator must be deinitable (see in the link above the fn pointers held by the vtable field). So just like you have to call flush() on a BufferedWriter implementation (because the Writer interface doesn't define that writers must be flushable), you have to call deinit on the implementation and not through the interface. Fun fact, not all allocators are deinitable. For example std.heap.c_allocator is an interface to libc's malloc, and that allocator, while usable from Zig, doesn't have a concept of deiniting. Similarly, std.heap.page_allocator (mmap /virtualalloc) doesn't have any deinit because it's stateless (i.e. the kernel holds the state).