Known limitations of the current implementation:
- documentation changes are incomplete
- there's a reference leak I haven't tracked down yet
The leak is most visible by running:
./python -m test -R3:3 test_importlib
However, you can also see it by running:
./python -X showrefcount
Importing the array or _testmultiphase modules, and
then deleting them from both sys.modules and the local
namespace shows significant increases in the total
number of active references each cycle. By contrast,
with _testcapi (which continues to use single-phase
initialisation) the global refcounts stabilise after
a couple of cycles.
The concept of .pyo files no longer exists. Now .pyc files have an
optional `opt-` tag which specifies if any extra optimizations beyond
the peepholer were applied.
PyObject_Calloc(), _PyObject_GC_Calloc(). bytes(int) and bytearray(int) are now
using ``calloc()`` instead of ``malloc()`` for large objects which is faster
and use less memory (until the bytearray buffer is filled with data).
__file__.
This causes _frozen_importlib to no longer have __file__ set as well
as any frozen module imported using imp.init_frozen() (which is
deprecated).
now register both filenames in the exception on failure.
This required adding new C API functions allowing OSError exceptions
to reference two filenames instead of one.
* You may now specify an expression as the default value for a
parameter! Example: "sys.maxsize - 1". This support is
intentionally quite limited; you may only use values that
can be represented as static C values.
* Removed "doc_default", simplified support for "c_default"
and "py_default". (I'm not sure we still even need
"py_default", but I'm leaving it in for now in case a
use presents itself.)
* Parameter lines support a trailing '\\' as a line
continuation character, allowing you to break up long lines.
* The argument parsing code generated when supporting optional
groups now uses PyTuple_GET_SIZE instead of PyTuple_GetSize,
leading to a 850% speedup in parsing. (Just kidding, this
is an unmeasurable difference.)
* A bugfix for the recent regression where the generated
prototype from pydoc for builtins would be littered with
unreadable "=<object ...>"" default values for parameters
that had no default value.
* Converted some asserts into proper failure messages.
* Many doc improvements and fixes.
- don't call PyErr_NoMemory with interpreter is not initialised
- note that it's OK to call _PyMem_RawStrDup here
- don't include this in the limited API
- capitalise "IO"
- be explicit that a non-zero return indicates an error
- include versionadded marker in docs
This new pre-initialization API allows embedding
applications like Blender to force a particular
encoding and error handler for the standard IO streams.
Also refactors Modules/_testembed.c to let us start
testing multiple embedding scenarios.
(Initial patch by Bastien Montagne)
The GIL must be held to call PyMem_Malloc(), whereas PyOS_Readline() releases
the GIL to read input.
The result of the C callback PyOS_ReadlineFunctionPointer must now be a string
allocated by PyMem_RawMalloc() or PyMem_RawRealloc() (or NULL if an error
occurred), instead of a string allocated by PyMem_Malloc() or PyMem_Realloc().
Fixing this issue was required to setup a hook on PyMem_Malloc(), for example
using the tracemalloc module.
PyOS_Readline() copies the result of PyOS_ReadlineFunctionPointer() into a new
buffer allocated by PyMem_Malloc(). So the public API of PyOS_Readline() does
not change.
_PyMem_RawMalloc/Realloc/Free, instead of _PyMem_Malloc/Realloc/Free. So it
becomes possible to use the fast pymalloc allocator for the PYMEM_DOMAIN_MEM
domain (PyMem_Malloc/Realloc/Free functions).
-I
Run Python in isolated mode. This also implies -E and -s. In isolated mode
sys.path contains neither the script’s directory nor the user’s
site-packages directory. All PYTHON* environment variables are ignored,
too. Further restrictions may be imposed to prevent the user from
injecting malicious code.
Add new enum:
* PyMemAllocatorDomain
Add new structures:
* PyMemAllocator
* PyObjectArenaAllocator
Add new functions:
* PyMem_RawMalloc(), PyMem_RawRealloc(), PyMem_RawFree()
* PyMem_GetAllocator(), PyMem_SetAllocator()
* PyObject_GetArenaAllocator(), PyObject_SetArenaAllocator()
* PyMem_SetupDebugHooks()
Changes:
* PyMem_Malloc()/PyObject_Realloc() now always call malloc()/realloc(), instead
of calling PyObject_Malloc()/PyObject_Realloc() in debug mode.
* PyObject_Malloc()/PyObject_Realloc() now falls back to
PyMem_Malloc()/PyMem_Realloc() for allocations larger than 512 bytes.
* Redesign debug checks on memory block allocators as hooks, instead of using C
macros
* Add a new PyMemAllocators structure
* New functions:
- PyMem_RawMalloc(), PyMem_RawRealloc(), PyMem_RawFree(): GIL-free memory
allocator functions
- PyMem_GetRawAllocators(), PyMem_SetRawAllocators()
- PyMem_GetAllocators(), PyMem_SetAllocators()
- PyMem_SetupDebugHooks()
- _PyObject_GetArenaAllocators(), _PyObject_SetArenaAllocators()
* Add unit test for PyMem_Malloc(0) and PyObject_Malloc(0)
* Add unit test for new get/set allocators functions
* PyObject_Malloc() now falls back on PyMem_Malloc() instead of malloc() if
size is bigger than SMALL_REQUEST_THRESHOLD, and PyObject_Realloc() falls
back on PyMem_Realloc() instead of realloc()
* PyMem_Malloc() and PyMem_Realloc() now always call malloc() and realloc(),
instead of calling PyObject_Malloc() and PyObject_Realloc() in debug mode
Forgot to raise ModuleNotFoundError when None is found in sys.modules.
This led to introducing the C function PyErr_SetImportErrorSubclass()
to make setting ModuleNotFoundError easier.
Also updated the reference docs to mention ModuleNotFoundError
appropriately. Updated the docs for ModuleNotFoundError to mention the
None in sys.modules case.
Lastly, it was noticed that PyErr_SetImportError() was not setting an
exception when returning None in one case. That issue is now fixed.
ImportError.
The exception is raised by import when a module could not be found.
Technically this is defined as no viable loader could be found for the
specified module. This includes ``from ... import`` statements so that
the module usage is consistent for all situations where import
couldn't find what was requested.
This should allow for the common idiom of::
try:
import something
except ImportError:
pass
to be updated to using ModuleNotFoundError and not accidentally mask
ImportError messages that should propagate (e.g. issues with a
loader).
This work was driven by the fact that the ``from ... import``
statement needed to be able to tell the difference between an
ImportError that simply couldn't find a module (and thus silence the
exception so that ceval can raise it) and an ImportError that
represented an actual problem.
attributes to None.
The long-term goal is for people to be able to rely on these
attributes existing and checking for None to see if they have been
set. Since import itself sets these attributes when a loader does not
the only instances when the attributes are None are from someone
overloading __import__() and not using a loader or someone creating a
module from scratch.
This patch also unifies module initialization. Before you could have
different attributes with default values depending on how the module
object was created. Now the only way to not get the same default set
of attributes is to circumvent initialization by calling
ModuleType.__new__() directly.
PyErr_SetFromWindowsErrWithFilenameObject, and
PyErr_SetExcFromWindowsErrWithFilenameObject.
Note that PyErr_SetExcFromWindowsErrWithFilenameObjectAndSomeOtherParametersSoThatTheNameGetsSoLongThatNobodyIsEverGonnaUseThisStrangeFunctionForAnything is still undocumented.
Serhiy Storchaka
Yury Selivanov
Nick Coghlan
R David Murray
Larry Hastings
Gregory P. Smith
Brett Cannon
Victor Stinner
Berker Peksag
Stefan Krah
Georg Brandl
Benjamin Peterson
Antoine Pitrou
Andrew Svetlov
Jesus Cea
Zachary Ware
Eric Snow
Éric Araujo
Martin v. Löwis
Raymond Hettinger
Christian Heimes
Eli Bendersky
Andrew Kuchling
Ezio Melotti
Kristján Valur Jónsson