When the Python iterator backing `PyIterator` has a `__length_hint__` special
method, we can use this as a lower bound for Rust's `Iterator::size_hint` to
e.g. support pre-allocation of collections.
This is implemented using `PyObject_LengthHint` which is not available in the
stable ABI and hence so is `Iterator::size_hint`. This should be fine since this
is an optimization in any case and the stable ABI is expected to have slightly
worse performance overall.
3203: support ordering magic methods for `#[pyclass]` r=adamreichold a=davidhewitt
Closes#2089
This adds `__lt__`, `__le__`, `__eq__`, `__ne__`, `__gt__`, and `__ge__` as per the Python implementations of what we call `__richcmp__`.
There's a UI test confirming that the user cannot implement split forms and `__richcmp__` simultaneously.
There's also a benchmark comparing implementing these split methods against using `__richcmp__`. I couldn't see a meaningful performance difference, so I'm tempted to deprecate `__richcmp__`, given that's not a magic method which exists in Python. Potentially we can provide options such as the opt-in `#[pyclass(eq, ord)]` to avoid boilerplate for people who don't want to implement six different methods.
Co-authored-by: David Hewitt <1939362+davidhewitt@users.noreply.github.com>
3029: use dynamic trampoline for all getters and setters r=adamreichold a=davidhewitt
This is an extension to the "trampoline" changes made in #2705 to re-use a single trampoline for all `#[getter]`s (and similar for all `#[setters]`). It works by setting the currently-unused `closure` member of the `ffi::PyGetSetDef` structure to point at a new `struct GetSetDefClosure` which contains function pointers to the `getter` / `setter` implementations.
A universal trampoline for all `getter`, for example, then works by reading the actual getter implementation out of the `GetSetDefClosure`.
Advantages of doing this:
- Very minimal simplification to the macro code / generated code size. It made a 4.4% reduction to `test_getter_setter` generated size, which is an exaggerated result as most code will probably have lots of bulk that isn't just the macro code.
Disadvantages:
- Additional level of complexity in the `getter` and `setter` trampolines and accompanying code.
- To keep the `GetSetDefClosure` objects alive, I've added them to the static `LazyTypeObject` inner.
- Very slight performance overhead at runtime (shouldn't be more than an additional pointer read). It's so slight I couldn't measure it.
Overall I'm happy to either merge or close this based on what reviewers think!
Co-authored-by: David Hewitt <1939362+davidhewitt@users.noreply.github.com>
