What's new in h5py 3.3
======================

New features
------------

* Compatibility with the upcoming HDF5 1.12.1 and possibly 1.14 (:pr:`1875`).
* H5T_BITFIELD types will now be cast to their ``numpy.uint`` equivalent by default
  (:issue:`1258`). This means that no knowledge of mixed type compound dataset
  schemas is required to read these types, and can simply be read as follows:

  .. code::

     arr = dset[:]

  Alternatively, 8-bit bitfields can still be cast to booleans explicitly:

  .. code::

     arr = dset.astype(numpy.bool_)[:]

* Key types are validated when accessing groups, to give more helpful errors
  when a group is indexed like a dataset (:pr:`1856`).
* A new :meth:`.Group.build_virtual_dataset` method acting as a context manager
  to assemble virtual datasets (:pr:`1905`).
* If the source and target of a virtual dataset mapping have different numbers
  of points, an error should now be thrown when you make the mapping in the
  :class:`VirtualLayout`, rather than later when writing this into the file.
  This should make it easier to find the source of such errors.

Deprecations
------------

* Linux wheels are now manylinux2010 rather than manylinux1
* The ``default_file_mode`` config option is deprecated, and setting it to
  values other than 'r' (for read-only mode) is no longer allowed. Pass the
  mode when creating a :class:`.File` object instead of setting a global
  default.

Bug fixes
---------

* Trying to open a file in append mode (``'a'``) should now give clearer
  error messages when the file exists but can't be opened (:pr:`1902`).
* Protect :func:`h5py.h5f.get_obj_ids` against garbage collection invalidating
  HDF5 IDs while it is retrieving them (:issue:`1852`).
* Make file closing more robust, including when closing files while the
  interpreter is shutting down, by using lower-level code to close HDF5 IDs
  of objects inside the file (:issue:`1495`).