convention that allows safe access to errno)
This code does not yet work on OS X (__thread storage specifier not
available), so i needs a configure check plus a more portable
solution.
errno (and LastError, on Windows).
ctypes maintains a module-global, but thread-local, variable that
contains an error number; called 'ctypes_errno' for this discussion.
This variable is a private copy of the systems 'errno' value; the copy
is swapped with the 'errno' variable on several occasions.
Foreign functions created with CDLL(..., use_errno=True), when called,
swap the values just before the actual function call, and swapped
again immediately afterwards. The 'use_errno' parameter defaults to
False, in this case 'ctypes_errno' is not touched.
The values are also swapped immeditately before and after ctypes
callback functions are called, if the callbacks are constructed using
the new optional use_errno parameter set to True: CFUNCTYPE(..., use_errno=TRUE)
or WINFUNCTYPE(..., use_errno=True).
Two new ctypes functions are provided to access the 'ctypes_errno'
value from Python:
- ctypes.set_errno(value) sets ctypes_errno to 'value', the previous
ctypes_errno value is returned.
- ctypes.get_errno() returns the current ctypes_errno value.
---
On Windows, the same scheme is implemented for the error value which
is managed by the GetLastError() and SetLastError() windows api calls.
The ctypes functions are 'ctypes.set_last_error(value)' and
'ctypes.get_last_error()', the CDLL and WinDLL optional parameter is
named 'use_last_error', defaults to False.
---
On Windows, TlsSetValue and TlsGetValue calls are used to provide
thread local storage for the variables; ctypes compiled with __GNUC__
uses __thread variables.
* Expand comments.
* Swap variable names in the sum_exact code so that x and y
are consistently chosen as the larger and smaller magnitude
values respectively.
all the upper level libraries that use it, including urllib2.
Added and fixed some tests, and changed docs correspondingly.
Thanks to John J Lee for the patch and the pusing, :)
Alexandre Vassalotti
Thomas Heller
Georg Brandl
Martin v. Löwis
Benjamin Peterson
Walter Dörwald
Gregory P. Smith
Robert Schuppenies
Gerhard Häring
Mark Summerfield
Mark Hammond
Raymond Hettinger
Marc-André Lemburg
Eric Smith
Mark Dickinson
Brett Cannon
Facundo Batista