[issue9141] Allow objects to decide if they can be collected by GC

Martin v. Löwis mar...@v.loewis.de added the comment: I'm still unclear about the rationale for this change. krisvale says in the patch and in msg109099 that this is to determine whether an object can be collected at this time. Is the intended usage that the result value may change over the

[issue14478] Decimal hashing very slow, could be cached

Antoine Pitrou pit...@free.fr added the comment: I recommend that __hash__ should use functools.lru_cache for caching. Why would you do such a thing? A hash value is a single 64-bit slot, no need to add the memory consumption of a whole dictionary and the runtime cost of a LRU eviction

[issue14478] Decimal hashing very slow, could be cached

Changes by Antoine Pitrou pit...@free.fr: -- stage: - needs patch versions: +Python 3.3 -Python 3.2 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14478 ___

[issue14310] Socket duplication for windows

Antoine Pitrou pit...@free.fr added the comment: Any other comments? No, the patch looks ok now. Please watch the buildbots after you commit. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14310

[issue9141] Allow objects to decide if they can be collected by GC

Kristján Valur Jónsson krist...@ccpgames.com added the comment: Jim: The edge case of collecting an object that is alone in a cycle is something that isn't handled. I'm also not sure that it is worth doing or even safe or possible. but that is beside the point and not the topic of this

[issue9141] Allow objects to decide if they can be collected by GC

Kristján Valur Jónsson krist...@ccpgames.com added the comment: Btw. tangentially related to this discussion, issue 10576 aims to make the situation with uncollectable objects a little more bearable. An application can listen for garbage collection, visit gc.garbage and deal with its

[issue4892] Sending Connection-objects over multiprocessing connections fails

Antoine Pitrou pit...@free.fr added the comment: err, is it possible to edit out those file paths? I don't know how to do that. If you want I can remove the message altogether. But I don't see anything confidential or exploitable in your message. -- nosy: +pitrou

[issue4892] Sending Connection-objects over multiprocessing connections fails

Changes by Antoine Pitrou pit...@free.fr: -- assignee: jnoller - nosy: +sbt versions: +Python 3.3 -Python 3.2 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4892 ___

[issue7978] SocketServer doesn't handle syscall interruption

Antoine Pitrou pit...@free.fr added the comment: Jerzy's latest patch looks ok to me. This is a slight behaviour change so I'm not sure it should go in 3.2/2.7. -- stage: - patch review versions: +Python 3.3 -Python 2.7, Python 3.1 ___ Python

[issue14520] Buggy Decimal.__sizeof__

New submission from Antoine Pitrou pit...@free.fr: I'm not sure __sizeof__ is implemented correctly: from decimal import Decimal import sys d = Decimal(123456789123456798123456789123456798123456789123456798) d Decimal('123456789123456798123456789123456798123456789123456798')

[issue14425] Improve handling of 'timeout' parameter default in urllib.urlopen

Senthil Kumaran sent...@uthcode.com added the comment: Hi David, I am sorry, I did not notice your second comment in this bug and later when you closed this, noticed the bug report. Yes, the default=None but actually pointing to a sentinel value is an odd duck and I believe the explanation

[issue14310] Socket duplication for windows

Roundup Robot devn...@psf.upfronthosting.co.za added the comment: New changeset 51b4bddd0e92 by Kristján Valur Jónsson in branch 'default': Issue #14310: inter-process socket duplication for windows http://hg.python.org/cpython/rev/51b4bddd0e92 -- nosy: +python-dev

[issue14310] Socket duplication for windows

Changes by Kristján Valur Jónsson krist...@ccpgames.com: -- resolution: - fixed status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14310 ___

[issue14520] Buggy Decimal.__sizeof__

Stefan Krah stefan-use...@bytereef.org added the comment: It isn't implemented at all. The Python version also always returns 96, irrespective of the coefficient length. Well, arguably the coefficient is a separate object in the Python version: 96 sys.getsizeof(d._int) 212 For the C version

[issue14520] Buggy Decimal.__sizeof__

Stefan Krah stefan-use...@bytereef.org added the comment: In full: d = Decimal(1) sys.getsizeof(d) 96

[issue14478] Decimal hashing very slow, could be cached

Serhiy Storchaka storch...@gmail.com added the comment: I recommend that __hash__ should use functools.lru_cache for caching. Why would you do such a thing? A hash value is a single 64-bit slot, no need to add the memory consumption of a whole dictionary and the runtime cost of a LRU

[issue14478] Decimal hashing very slow, could be cached

Antoine Pitrou pit...@free.fr added the comment: I recommend that __hash__ should use functools.lru_cache for caching. Why would you do such a thing? A hash value is a single 64-bit slot, no need to add the memory consumption of a whole dictionary and the runtime cost of a LRU

[issue10576] Add a progress callback to gcmodule

Kristján Valur Jónsson krist...@ccpgames.com added the comment: Here is an updated patch, taking Jim's and Antoine's comments into account. Jim, I´d like to comment that I think the reason __del__ objects are uncollectable is more subtle than there being no defined order of calling the

[issue10576] Add a progress callback to gcmodule

Antoine Pitrou pit...@free.fr added the comment: Uploaded another review. I also notice you didn't really address my point, since self.visit is still initialized too early. IMO it should be initialized after the first gc.collect() at the beginning of each test (not in setUp()). --

[issue3561] Windows installer should add Python and Scripts directories to the PATH environment variable

Brian Curtin br...@python.org added the comment: Attached is issue3561.diff which adds a path option, off by default, as a feature to be installed. I've tested installation and un-installation with the feature both installed and not installed and it seems to work fine for me.

[issue4892] Sending Connection-objects over multiprocessing connections fails

sbt shibt...@gmail.com added the comment: Jimbofbx wrote: def main(): from multiprocessing import Pipe, reduction i, o = Pipe() print(i); reduced = reduction.reduce_connection(i) print(reduced); newi = reduced[0](*reduced[1]) print(newi); newi.send(hi)

[issue13621] Unicode performance regression in python3.3 vs python3.2

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13621 ___ ___ Python-bugs-list

[issue13031] small speed-up for tarfile.py when unzipping tarballs

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13031 ___ ___ Python-bugs-list

[issue4892] Sending Connection-objects over multiprocessing connections fails

Antoine Pitrou pit...@free.fr added the comment: Having said all that I agree multiprocessing.reduction should be fixed. Maybe an enable_pickling_support() function could be added to register the necessary things with copyreg. Why not simply use ForkingPickler? --

[issue10408] Denser dicts and linear probing

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10408 ___ ___ Python-bugs-list

[issue14478] Decimal hashing very slow, could be cached

Changes by Raymond Hettinger raymond.hettin...@gmail.com: -- keywords: +patch Added file: http://bugs.python.org/file25152/decimal_hash.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14478

[issue14511] _static/opensearch.xml for Python 3.2 docs directs searches to 3.3 docs

Roundup Robot devn...@psf.upfronthosting.co.za added the comment: New changeset 7f123dec2731 by Georg Brandl in branch '3.2': Closes #14511: fix wrong opensearch link for 3.2 docs. http://hg.python.org/cpython/rev/7f123dec2731 New changeset 57a8a8f5e0bc by Georg Brandl in branch 'default':

[issue4892] Sending Connection-objects over multiprocessing connections fails

sbt shibt...@gmail.com added the comment: ForkingPickler is only used when creating a child process. The multiprocessing.reduction module is only really intended for sending stuff to *pre-existing* processes. As things stand, after importing multiprocessing.reduction you can do something

[issue13126] find() slower than rfind()

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13126 ___ ___ Python-bugs-list

[issue12805] Optimizations for bytes.join() et. al

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue12805 ___ ___ Python-bugs-list

[issue4892] Sending Connection-objects over multiprocessing connections fails

Antoine Pitrou pit...@free.fr added the comment: ForkingPickler is only used when creating a child process. The multiprocessing.reduction module is only really intended for sending stuff to *pre-existing* processes. But ForkingPickler could be used in multiprocessing.connection, couldn't

[issue14478] Decimal hashing very slow, could be cached

Antoine Pitrou pit...@free.fr added the comment: Le samedi 07 avril 2012 à 17:22 +, Raymond Hettinger a écrit : -- keywords: +patch Added file: http://bugs.python.org/file25152/decimal_hash.diff I think patching the C version of Decimal would be more useful :) --

[issue2377] Replace __import__ w/ importlib.__import__

Brett Cannon br...@python.org added the comment: On Fri, Apr 6, 2012 at 16:05, Antoine Pitrou rep...@bugs.python.org wrote: Antoine Pitrou pit...@free.fr added the comment: OK, -v/PYTHONVERBOSE is as done as it is going to be by me. Next up is (attempting) Windows registry stuff. After

[issue4892] Sending Connection-objects over multiprocessing connections fails

James Hutchison jamesghutchi...@gmail.com added the comment: @pitrou You can just delete my original post. I'll repost an edited version here for reference original post with paths removed: This is an issue for me (Python 3.2). I have a custom pool that sends arguments for a function call

[issue4892] Sending Connection-objects over multiprocessing connections fails

Changes by Antoine Pitrou pit...@free.fr: -- Removed message: http://bugs.python.org/msg157702 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4892 ___

[issue12986] Using getrandbits() in uuid.uuid4() is faster and more readable

Serhiy Storchaka storch...@gmail.com added the comment: uuids = set() for u in [uuid.uuid4() for i in range(1000)]: uuids.add(u) uuids = {uuid.uuid4() for i in range(1000)} However, I'm not sure of the legitimacy of replacement suitable for cryptographic

[issue11981] dupe self.fp.tell() in zipfile.ZipFile.writestr

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue11981 ___ ___ Python-bugs-list

[issue10376] ZipFile unzip is unbuffered

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10376 ___ ___ Python-bugs-list

[issue4892] Sending Connection-objects over multiprocessing connections fails

sbt shibt...@gmail.com added the comment: But ForkingPickler could be used in multiprocessing.connection, couldn't it? I suppose so. Note that the way a connection handle is transferred between existing processes is unnecessarily inefficient on Windows. A background server thread (one per

[issue14521] math.copysign(1., float('nan')) returns -1.

New submission from mattip matti.pi...@gmail.com: Python 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] on win32 Type help, copyright, credits or license for more information. import math math.copysign(1., float('inf')) 1.0 math.copysign(1., float('-inf')) -1.0

[issue6972] zipfile.ZipFile overwrites files outside destination path

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6972 ___ ___ Python-bugs-list

[issue2824] zipfile to handle duplicate files in archive

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue2824 ___ ___ Python-bugs-list

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

New submission from sbt shibt...@gmail.com: In multiprocessing.connection on Windows, socket handles are indirectly duplicated using DuplicateHandle() instead the WSADuplicateSocket(). According to Microsoft's documentation this is not supported. This is easily avoided by using

[issue14521] math.copysign(1., float('nan')) returns -1.

Martin v. Löwis mar...@v.loewis.de added the comment: This is a near duplicate of issue7281. Most likely, copysign is behaving correctly, and it's already the float conversion that errs. For struct.pack('d', float('nan')), I get '\x00\x00\x00\x00\x00\x00\xf8\xff'; for -nan, I get

[issue4892] Sending Connection-objects over multiprocessing connections fails

sbt shibt...@gmail.com added the comment: There is a simpler way to do this on Windows. The sending process duplicates the handle, and the receiving process duplicates that second handle using DuplicateHandle() and the DUPLICATE_CLOSE_SOURCE flag. That way no server thread is necessary

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

Martin v. Löwis mar...@v.loewis.de added the comment: What is the bug that this fixes? Can you provide a test case? -- nosy: +loewis ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14522 ___

[issue6839] zipfile can't extract file

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6839 ___ ___ Python-bugs-list

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

Changes by sbt shibt...@gmail.com: Removed file: http://bugs.python.org/file25153/mp_socket_dup.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14522 ___

[issue4844] ZipFile doesn't range check in _EndRecData()

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4844 ___ ___ Python-bugs-list

[issue10905] zipfile: fix arcname with leading '///' or '..'

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10905 ___ ___ Python-bugs-list

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

sbt shibt...@gmail.com added the comment: What is the bug that this fixes? Can you provide a test case? The bug is using an API in a way that the documentation says is wrong/unreliable. There does not seem to be a classification for that. I have never seen a problem caused by using

[issue10614] ZipFile: add a filename_encoding argument

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10614 ___ ___ Python-bugs-list

[issue10972] zipfile: add unicode option to the force the filename encoding to UTF-8

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue10972 ___ ___ Python-bugs-list

[issue11980] zipfile.ZipFile.write should accept fp as argument

Changes by Serhiy Storchaka storch...@gmail.com: -- nosy: +storchaka ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue11980 ___ ___ Python-bugs-list

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

sbt shibt...@gmail.com added the comment: Actually Issue 9753 was causing failures in test_socket.BasicTCPTest and test_socket.BasicTCPTest2 on at least one Windows XP machine. -- ___ Python tracker rep...@bugs.python.org

[issue4892] Sending Connection-objects over multiprocessing connections fails

James Hutchison jamesghutchi...@gmail.com added the comment: Shouldn't reduce_pipe_connection just be an alias for reduce_connection in unix so that using reduce_pipe_connection would work for both win and unix? My understanding after looking at the code is that reduce_pipe_connection isn't

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

Antoine Pitrou pit...@free.fr added the comment: Is there a reason the patch changes close() to win32.CloseHandle()? -- components: +Library (Lib) nosy: +pitrou stage: - patch review type: - behavior versions: +Python 3.2, Python 3.3 ___ Python

[issue12986] Using getrandbits() in uuid.uuid4() is faster and more readable

Antoine Pitrou pit...@free.fr added the comment: However, I'm not sure of the legitimacy of replacement suitable for cryptographic use `os.urandom` on fast pseudo-random `random.getrandbits`. Especially for applications that need to generate a lot of uuids. Agreed. urandom() is supposed to

[issue14310] Socket duplication for windows

Antoine Pitrou pit...@free.fr added the comment: Re-opening. There is now a buildbot failure: == ERROR: testTypes (test.test_socket.TestSocketSharing) --

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

sbt shibt...@gmail.com added the comment: Is there a reason the patch changes close() to win32.CloseHandle()? This is a Windows only code path so close() is just an alias for win32.CloseHandle(). It allow removal of the lines # Late import because of circular import from

[issue14310] Socket duplication for windows

Roundup Robot devn...@psf.upfronthosting.co.za added the comment: New changeset 9b858096044e by Kristján Valur Jónsson in branch 'default': Issue #14310: Catch testing errors when trying to create unsupported socket http://hg.python.org/cpython/rev/9b858096044e --

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

Roundup Robot devn...@psf.upfronthosting.co.za added the comment: New changeset f8a92fd084c2 by Antoine Pitrou in branch 'default': Issue #14522: Avoid duplicating socket handles in multiprocessing.connection. http://hg.python.org/cpython/rev/f8a92fd084c2 -- nosy: +python-dev

[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

Antoine Pitrou pit...@free.fr added the comment: Patch committed, thank you! -- resolution: - fixed stage: patch review - committed/rejected status: open - closed versions: -Python 3.2 ___ Python tracker rep...@bugs.python.org

[issue6972] zipfile.ZipFile overwrites files outside destination path

Changes by Antoine Pitrou pit...@free.fr: -- priority: normal - high stage: - needs patch versions: +Python 3.3 -Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6972 ___

[issue14521] math.copysign(1., float('nan')) returns -1.

mattip matti.pi...@gmail.com added the comment: It appears that microsoft decided NAN will be represented by '\x00\x00\x00\x00\x00\x00\xf8\xff', which has the sign bit set. Compiling this c code with visual 9.0 gives the correct answers for the first value, and a mess for the second:

[issue14087] multiprocessing.Condition.wait_for missing

sbt shibt...@gmail.com added the comment: New patch skips tests if ctypes not available. -- Added file: http://bugs.python.org/file25155/cond_wait_for.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14087

[issue6972] zipfile.ZipFile overwrites files outside destination path

Thomas W. Barr t...@rice.edu added the comment: I'll update my patch to work on the current 3.x head later tonight. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6972 ___

[issue14523] IDLE's subprocess startup error

New submission from Arcangeltj arcange...@gmail.com: IDLE's subprocess didn't make connection. Either IDLE can't start a subprocess or personal firewall software is blocking the connection. What or why is this happening? Is there something that can fix this issue? -- components: IDLE

[issue14521] math.copysign(1., float('nan')) returns -1.

mattip matti.pi...@gmail.com added the comment: Sorry for the garbage c code, the comment however is correct: Py_NAN is created with the sign bit set (on windows), and then _copysign on windows uses the sign bit to determine the output, which results in the wrong answer. --

[issue14222] Use time.steady() to implement timeout

Raymond Hettinger raymond.hettin...@gmail.com added the comment: [Victor] The duration of a timeout of N seconds should be N seconds even if the system clock is updated (e.g. a daylight saving time (DST) change). IIRC, time.time() is not a local time and it is unaffected by a DST change.

[issue14222] Use time.steady() to implement timeout

Raymond Hettinger raymond.hettin...@gmail.com added the comment: I'm closing this one. The not subject to adjustment property is more desirable than not. The undefined reference point property isn't harmful in this context (the start time isn't exposed). I'll follow the python-dev thread

[issue14524] Python-2.7.3rc2/Modules/_ctypes/libffi/src/dlmalloc.c won't compile on ia64-hp-hpux11.31 without -DHAVE_USR_INCLUDE_MALLOC_H

New submission from Paul A. p...@freeshell.org: Shouldn't configure be able to arrive at that without me adding manually? Anyway, after the build finishes thing soon come crashing down; my stack trace is at the end... running build_scripts creating build/scripts-2.7 copying and adjusting

[issue14524] Python-2.7.3rc2/Modules/_ctypes/libffi/src/dlmalloc.c won't compile on ia64-hp-hpux11.31 without -DHAVE_USR_INCLUDE_MALLOC_H

Changes by Paul A. p...@freeshell.org: -- type: - crash ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14524 ___ ___ Python-bugs-list mailing list

[issue14525] ia64-hp-hpux11.31 won't compile Python-2.6.8rc2 without -D_TERMIOS_INCLUDED

New submission from Paul A. p...@freeshell.org: I can't help thinking that configure should be able to figure out the need for this -- Modules/termios.c won't compile without adding -D_TERMIOS_INCLUDED by hand. This is far from new, all 2.5+ versions I've tried to compile are like that on

[issue14524] Python-2.7.3rc2/Modules/_ctypes/libffi/src/dlmalloc.c won't compile on ia64-hp-hpux11.31 without -DHAVE_USR_INCLUDE_MALLOC_H

R. David Murray rdmur...@bitdance.com added the comment: Is this a bug report about configure, or a bug report about a crash during compilation after you've adjusted the configure parameters? It seems like you are reporting two different things here. For the configure issue, would you care

[issue14526] Python-2.6.8rc2 test never finishes ia64-hp-hpux11.31

New submission from Paul A. p...@freeshell.org: Perhaps I'm not interpreting something happening earlier, but `make test' here only seems to run a short time but doesn't actually finish. It appears not to be using any cpu, or waiting for input, so I'm not sure what's happening. ...

[issue14525] ia64-hp-hpux11.31 won't compile Python-2.6.8rc2 without -D_TERMIOS_INCLUDED

R. David Murray rdmur...@bitdance.com added the comment: Can you suggest a patch? As I said on the other issue I don't believe any core developers have access to hpux. -- nosy: +r.david.murray ___ Python tracker rep...@bugs.python.org

[issue14526] Python-2.6.8rc2 test never finishes ia64-hp-hpux11.31

R. David Murray rdmur...@bitdance.com added the comment: To quote Martin from an older issue: Python on HP-UX has never really worked well, but it has worked in some fashion for a long time. IA64 probably introduces a whole slew of new issues. If you can work through them and suggest

[issue14526] Python-2.6.8rc2 test never finishes ia64-hp-hpux11.31

R. David Murray rdmur...@bitdance.com added the comment: Oh, and python2.6 is in security-fix only mode, so any fixes would only go into go into 2.7 and later. Have you gotten as far as trying to reproduce this on 2.7? -- ___ Python tracker

[issue14526] Python-2.6.8rc2 test never finishes ia64-hp-hpux11.31

R. David Murray rdmur...@bitdance.com added the comment: Oh, wait, I see you are testing the security RC. Is this a new problem, or does it also occur with the previous released version of 2.6? -- ___ Python tracker rep...@bugs.python.org

[issue14527] How to link with an external libffi?

New submission from Paul A. p...@freeshell.org: I trying to build python using an external libffi package I have installed -- is there some trick in directing --with-system-ffi to the path where it's located. I don't see clues in config.log or anywhere to help. -- messages: 157776

[issue14527] How to link with an external libffi?

Ross Lagerwall rosslagerw...@gmail.com added the comment: If it is in a non-standard location, try setting the environment variables: LDFLAGS linker flags, e.g. -Llib dir if you have libraries in a nonstandard directory lib dir CPPFLAGS(Objective) C/C++ preprocessor flags, e.g.