Version 0.9 (April 25th, 2023)

This release adds numerous major features and indicates the end of HPy’s alhpa phase. We’ve migrated several key packages to HPy (for a list, see our website and we are now confident that HPy is mature enough for being used as serious extension API. We also plan that the next major release will be 1.0.

Major new features

Support subclasses of built-in types

It is now possible to create pure HPy types that inherit from built-in types like type or float. This was already possible before but in a very limited way, i.e., by setting HPyType_Spec.basicsize to 0. In this case, the type implicitly inherited the basic size of the supertype but that also means that you cannot have a custom C struct. It is now possible inherit from a built-in type AND have a custom C struct. For further reference, see HPyType_Spec.builtin_shape and HPyType_BuiltinShape.

Support for metaclasses

HPy now supports creating types with metaclasses. This can be done by passing type specification parameter with kind HPyType_SpecParam_Metaclass when calling HPyType_FromSpec().

HPy Hybrid ABI

In addition to CPython ABI and HPy Universal ABI, we now introduced the Hybrid ABI. The major difference is that whenever you use a legacy API like HPy_AsPyObject() or HPy_FromPyObject(), the prdouced binary will then be specific to one interpreter. This was necessary to ensure that universal binaries are really portable and can be used on any HPy-capable interpreter.

Trace Mode

Similar to the Debug Mode, HPy now provides the Trace Mode that can be enabled at runtime and helps analyzing API usage and identifying performance issues.

Multi-phase Module Initialization

HPy now support multi-phase module initialization which is an important feature in particular needed for two important use cases: (1) module state support (which is planned to be introduced in the next major release), and (2) subinterpreters. We decided to drop support for single-phase module initialization since this makes the API cleaner and easier to use.

HPy Calling Protocol

This was a big missing piece and is now eventually available. It enables slot HPy_tp_call, which can now be used in the HPy type specification. We decided to use a calling convention similar to CPython’s vectorcall calling convention. This is: the arguments are passed in a C array and the keyword argument names are provided as a Python tuple. Before this release, the only way to create a callable type was to set the special method __call__. However, this has several disadvantages. In particlar, poor performance on CPython (and maybe other implementations) and it was not possible to have specialized call function implementations per object (see HPy_SetCallFunction())

Added APIs

Deleting attributes and items

HPy_DelAttr(), HPy_DelAttr_s(), HPy_DelItem(), HPy_DelItem_i(), HPy_DelItem_s()

Capsule API

HPyCapsule_New(), HPyCapsule_IsValid(), HPyCapsule_Get(), HPyCapsule_Set()

Eval API

HPy_Compile_s() and HPy_EvalCode()

Formatting helpers

HPyUnicode_FromFormat() and HPyErr_Format()

Contextvar API

HPyContextVar_New(), HPyContextVar_Get(), HPyContextVar_Set()

Unicode API

HPyUnicode_FromEncodedObject() and HPyUnicode_Substring()

Dict API

HPyDict_Keys() and HPyDict_Copy()

Type API

HPyType_GetName() and HPyType_IsSubtype()

Slice API

HPySlice_Unpack() and HPySlice_AdjustIndices()

Structseq API

HPyStructSequence_NewType(), HPyStructSequence_New()

Call API

HPy_Call(), HPy_CallMethod(), HPy_CallMethodTupleDict(), HPy_CallMethodTupleDict_s()

HPy call protocol


Debug mode

  • Detect closing and returning (without dup) of context handles

  • Detect invalid usage of stored HPyContext * pointer

  • Detect invalid usage of tuple and list builders

  • Added Windows support for checking invalid use of raw data pointers (e.g HPyUnicode_AsUTF8AndSize) after handle was closed.

  • Added support for backtrace on MacOS


Incompatible changes to version 0.0.4

  • Simplified HPyDef_* macros

  • Changed macro HPy_MODINIT because of multi-phase module init support.

  • Replace environment variable HPY_DEBUG by HPY (see Debug Mode or Trace Mode).

  • Changed signature of HPyFunc_VARARGS and HPyFunc_ KEYWORDS to align with HPy’s call protocol calling convention.

Supported Python versions

  • Added Python 3.11 support

  • Preliminary Python 3.12 support

  • Dropped Python 3.6 support (since EOL)

  • Dropped Python 3.7 support (since EOL by June 2023)


  • Ensure deterministic auto-generation

  • Ensure ABI backwards compatibility

    • Explicitly define slot within HPyContext of function pointers and handles

    • Compile HPy ABI version into binary and verify at load time

  • Added proper support for object members HPyMember_OBJECT

  • Changed HPyBytes_AsString() and HPyBytes_AS_STRING() to return const char *

  • Use fixed-width integers in context functions

Version 0.0.4 (May 25th, 2022)

New Features/API:

  • HPy headers are C++ compliant

  • Python 3.10 support

  • HPyField: References to Python objects that can be stored in raw native memory owned by Python objects.

    • New API functions: HPyField_Load, HPyField_Store

  • HPyGlobal: References to Python objects that can be stored into a C global variable.

    • New API functions: HPyGlobal_Load, HPyGlobal_Store

    • Note: HPyGlobal does not allow to share Python objects between (sub)interpreters

  • GIL support - New API functions: HPy_ReenterPythonExecution, HPy_LeavePythonExecution

  • Value building support (HPy_BuildValue)

  • New type slots

    • HPy_mp_ass_subscript, HPy_mp_length, HPy_mp_subscript

    • HPy_tp_finalize

  • Other new API functions

    • HPyErr_SetFromErrnoWithFilename, HPyErr_SetFromErrnoWithFilenameObjects

    • HPyErr_ExceptionMatches

    • HPyErr_WarnEx

    • HPyErr_WriteUnraisable

    • HPy_Contains

    • HPyLong_AsVoidPtr

    • HPyLong_AsDouble

    • HPyUnicode_AsASCIIString, HPyUnicode_DecodeASCII

    • HPyUnicode_AsLatin1String, HPyUnicode_DecodeLatin1

    • HPyUnicode_DecodeFSDefault, HPyUnicode_DecodeFSDefaultAndSize

    • HPyUnicode_ReadChar

Debug mode:

  • Support activation of debug mode via environment variable HPY_DEBUG

  • Support capturing stack traces of handle allocations

  • Check for invalid use of raw data pointers (e.g HPyUnicode_AsUTF8AndSize) after handle was closed.

  • Detect invalid handles returned from extension functions

  • Detect incorrect closing of handles passed as arguments

Misc Changes:

  • Removed unnecessary prefix "m_" from fields of HPyModuleDef (incompatible change)

  • For HPy implementors: new pytest mark for HPy tests assuming synchronous GC

Version 0.0.3 (September 22nd, 2021)

This release adds various new API functions (see below) and extends the debug mode with the ability to track closed handles. The default ABI mode now is ‘universal’ for non-CPython implementations. Also, the type definition of HPyContext was changed and it’s no longer a pointer type. The name of the HPy dev package was changed to ‘hpy’ (formerly: ‘hpy.devel’). Macro HPy_CAST was replaced by HPy_AsStruct.

New features:

  • Added helper HPyHelpers_AddType for creating new types

  • Support format specifier ‘s’ in HPyArg_Parse

  • Added API functions: HPy_Is, HPy_AsStructLegacy (for legacy types), HPyBytes_FromStringAndSize, HPyErr_NewException, HPyErr_NewExceptionWithDoc, HPyUnicode_AsUTF8AndSize, HPyUnicode_DecodeFSDefault, HPyImport_ImportModule

  • Debug mode: Implemented tracking of closed handles

  • Debug mode: Add hook for invalid handle access

Bug fixes:

  • Distinguish between pure and legacy types

  • Fix Sphinx doc errors