Add best::box and rename best::object_ptr to best::ptr; add best::vptr and best::vbox
#26
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mcy
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Feb 21, 2025
This is an attempt to redo the vtable work in #26 that I wound up rolling back. In the new approach, we have: - `best::dyn<Interface>` is a special type for putting in a `best::ptr` and friends, which emulates Rust's `dyn Trait`. - `best::interface` defines what can go in a `best::dyn`, which is essentially a type that provides a `best::vtable` plus an untyped pointer. It is expected, but not required, that this type provide helper functions that emulate calling virtual functions. The `BEST_INTERFACE` macro makes it "easy" to define these. - I tried very hard to avoid the macro, but I gave up. - To support `BEST_INTERFACE`, I've added `macro.h` which contains all of the usual very evil macro-writing-macros. - To support generating vtable entries, `best::fnref` now exposes `best::fnref::fnptr`, which makes it easy to convert between the member function signature (which lacks a `this` pointer) and the equivalent with a `void* this` argument. - `best::dynptr` and `best::dynbox` are convenience aliases for working with dyns. - `best::box` now supports `best::try_copy`, which is needed because `best::interfaces` cannot guarantee copying at the moment.
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This patch adds a bunch of pointer-related stuff. In summary:
best::box<T>,best::box<T[]>, andbest::vbox<T>are nicerstd::unique_ptrreplacements.best::ptr<T>got a facelift: the copying/moving functions have been updated to be the canonical generic memcpy entrypoitns.best::vptr<T>andbest::vtableare necessary to implement virtual pointers that use thebest::mallocallocator. Unlike C++ virtual pointers, they carry sufficient information for making it possible to (fallibly) copy abest::vbox<T>and to stride abest::vptr<T>. Although NYI, this makesbest::vbox<T[]>a posibility.bytes.his gone: its functionality now lives inbest::ptrandbest::span.best::span<T>now lives underbest/memory.best::vec<T>andbest::box<T[]>are inter-convertible.best::mallocnow uses allocator cookies in debug mode to ensure sized delete is used correctly.Although not tested yet, all of the above has custom allocator support. I need to implement
best::arenaor similar and add tests forbest::box<T, best::arena&>and friends.