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39 lines
1.8 KiB
ReStructuredText
39 lines
1.8 KiB
ReStructuredText
.. highlightlang:: c
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.. _stable:
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**********************************
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Stable Appliction Binary Interface
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**********************************
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Traditionally, the C API of Python will change with every release.
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Most changes will be source-compatible, typically by only adding API,
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rather than changing existing API or removing API (although some
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interfaces do get removed after being deprecated first).
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Unfortunately, the API compatibility does not extend to binary
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compatibility (the ABI). The reason is primarily the evolution of
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struct definitions, where addition of a new field, or changing
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the type of a field, might not break the API, but can break the ABI.
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As a consequence, extension modules need to be recompiled for
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every Python release (although an exception is possible on Unix
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when none of the affected interfaces are used). In addition, on
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Windows, extension modules link with a specific pythonXY.dll and
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need to be recompiled to link with a newer one.
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Since Python 3.2, a subset of the API has been declared to guarantee
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a stable ABI. Extension modules wishing to use this API need to define
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Py_LIMITED_API. A number of interpreter details then become hidden
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from the extension module; in return, a module is built that works
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on any 3.x version (x>=2) without recompilation. In some cases, the
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stable ABI needs to be extended with new functions. Extensions modules
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wishing to use these new APIs need to set Py_LIMITED_API to the
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PY_VERSION_HEX value of the minimum Python version they want to
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support (e.g. 0x03030000 for Python 3.3). Such modules will work
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on all subsequent Python releases, but fail to load (because of
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missing symbols) on the older releases.
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As of Python 3.2, the set of functions available to the limited API
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is documented in PEP 384.
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.. XXX copy exact list here? Into each functions definition?
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