- Very good, SergIo, I'm impressed. - 16 Updates
- Mutually exclusive execution for threads, OK with g++ but not MSVC - 6 Updates
- Usenet group for compiler development - 2 Updates
- Undefined Behaviour - 1 Update
| Jeff-Relf.Me @.: Apr 10 08:02PM -0700 |
| Melzzzzz <Melzzzzz@zzzzz.com>: Apr 11 03:09AM > I want to know how you came to that conclusion. > Was it this line: > PageUp ? ( --PP < BB ? PP = EE, iFolder = Cnt, rFolders = 0 : ( iFolder--, rFolders++ ) ) : PageDwn ? ( ++PP > EE ? PP = BB, rFolders = Cnt, iFolder = 0 : ( iFolder++, !--rFolders ) ) : 0 ; Garbage... -- press any key to continue or any other to quit... |
| Jeff-Relf.Me @.: Apr 10 09:47PM -0700 |
| Jeff-Relf.Me @.: Apr 10 10:10PM -0700 |
| SergIo <invalid@invalid.com>: Apr 11 12:51AM -0500 > Was it this line: > PageUp ? ( --PP < BB ? PP = EE, iFolder = Cnt, rFolders = 0 : ( iFolder--, rFolders++ ) ) : PageDwn ? ( ++PP > EE ? PP = BB, rFolders = Cnt, iFolder = 0 : ( iFolder++, !--rFolders ) ) : 0 ; > What languages have you programmed in ? early ones; CP/M DOS 1.25h, ever use PIP ? fortran, (8 byte precision, ugh, ugly) fortran 88, pascal (the $25 one) use linux mint now on several computers (formally windows) have two servers in garage, one is very linux low power you can install in a wall, the other is a full up Centos HP prolient G6 w 64Gbyte RAM, 4 xeon collecting dust-too loud if above 75F. even have raspberry pi 3 b+ is good, but you have to heat sink the processer. |
| Jeff-Relf.Me @.: Apr 10 11:23PM -0700 |
| David Brown <david.brown@hesbynett.no>: Apr 11 08:47AM +0200 > Was it this line: > PageUp ? ( --PP < BB ? PP = EE, iFolder = Cnt, rFolders = 0 : ( iFolder--, rFolders++ ) ) : PageDwn ? ( ++PP > EE ? PP = BB, rFolders = Cnt, iFolder = 0 : ( iFolder++, !--rFolders ) ) : 0 ; > What languages have you programmed in ? Hi, I don't know what newsgroups this thread started in or how it fits in those groups, but this is not a thread for comp.lang.c++. Please remove c.l.c++ from any other followups in this thread. If any of you want to discuss C++, then of course you are welcome here - but without cross-posts to such a selection of random other groups. |
| Pabst Blue Ribbon <pabst@blue.ribbon>: Apr 11 11:40AM > c.l.c++ from any other followups in this thread. > If any of you want to discuss C++, then of course you are welcome here - > but without cross-posts to such a selection of random other groups. That line of code above is C++. |
| chrisv <chrisv@nospam.invalid>: Apr 11 07:01AM -0500 Melzzzzz wrote: >> Was it this line: >> PageUp ? ( --PP < BB ? PP = EE, iFolder = Cnt, rFolders = 0 : ( iFolder--, rFolders++ ) ) : PageDwn ? ( ++PP > EE ? PP = BB, rFolders = Cnt, iFolder = 0 : ( iFolder++, !--rFolders ) ) : 0 ; > Garbage... I wonder if "Steve Carroll" would agree. He claims to be "unable to access" some things that I think should be obvious, even to non-programmers (note that he *has* done *some* programming, in his life). "Steve" would rather concede to being a fscking idiot, than admit that one of his shitty pals *lied* to attack me. -- "ALL non-idiots support the use of testing over compile-time warnings to determine if the code functions correctly. You're one of the few idiots who thinks otherwise." - Dumfsck, lying shamelessly |
| David Brown <david.brown@hesbynett.no>: Apr 11 02:31PM +0200 On 11/04/2019 13:40, Pabst Blue Ribbon wrote: >> If any of you want to discuss C++, then of course you are welcome here - >> but without cross-posts to such a selection of random other groups. > That line of code above is C++. That was not code, it was line noise that happened to be legal C++ syntax. The thread - at least the bit that has been cross-posted to c.l.c++ - has nothing to do with C++. I can't guess about the rest of the thread, or how it is conceivable for something to be relevant to physics, newsreader software and OS advocacy, but this out-of-context branch of a thread is not relevant to c.l.c++. If someone wants to discuss C++ code in the style of that jumble, that's fine - that could well be a thread in c.l.c++. But then it is not about physics or OS advocacy or newsreaders. My objection is to the cross-posting - a line like the one quoted does not make the thread suitable for cross-posting here any more than the fact we are writing in English means it should be cross-posted to alt.english.usage. |
| Jeff-Relf.Me @.: Apr 11 06:38AM -0700 |
| David Brown <david.brown@hesbynett.no>: Apr 11 04:10PM +0200 > It must be hard for you ( David Brown ) to laugh > with that stick so far up your ass. Do you hear that whooshing noise? It's the sound of my point flying /way/ over your head. No one cares what you think C++ is, or if you think it is the same think as C. If you want to write drivel instead of code, that's up to you. No one cares if you call it C++ or C. If you want to discuss C++ code, start a thread in c.l.c++. If you want to discuss C code, start a thread in c.l.c. Either would be great - we'd love to see the posts. But /please/ don't bring unrelated threads from unrelated newsgroups into groups that still have some semblance of topicality. There are no moderators here - this is a polite request. |
| SergIo <invalid@invalid.com>: Apr 11 09:20AM -0500 >>> What languages have you programmed in ? >> Early ones: CP/M DOS 1.25h. Ever use PIP ? > No, but PDP-11, on the Terak 8510 PC, was great. PDP-11s did an interface to one, they are boat ancors now! >> fortran, ( 8 byte precision, ugh, ugly ) fortran 88, > IBM ? did you wear a suit and tie ? na, collage most took fortran, remember in the 90's were IBM support still had to ware dark blue suits >> Pascal (the $25 one) > In college, Turbo Pascal/C, from Philippe Kahn ( a Paris immigrant ), > in Silicon Valley, was fantastic. that was amazing when it came out, really brought prices for SW down > Professionally, I used ETH Zurich's Modula-2 ( Niklaus Wirth ), 1981. > Microsoft and Apple "borrowed" a lot from those guys. > What country are you from ? various >> I have two Linux servers in my garage, > Collecting dust ? > You aren't running any servers ? running a small one, a $250 a local guy is selling, HW from china, he rolled a version of linux into it, looks like debian, the other is HP and is too loud, and has old Centos 6 on it but I saw on youtube where you can just replace the fans with quiet ones, but you have to take the lid off the unit for good. got it for $160 from a guy moving his surver farm to west coast |
| Jeff-Relf.Me @.: Apr 11 07:23AM -0700 |
| Jeff-Relf.Me @.: Apr 11 07:45AM -0700 |
| Melzzzzz <Melzzzzz@zzzzz.com>: Apr 11 02:59PM >> > PageUp ? ( --PP < BB ? PP = EE, iFolder = Cnt, rFolders = 0 : ( iFolder--, rFolders++ ) ) : PageDwn ? ( ++PP > EE ? PP = BB, rFolders = Cnt, iFolder = 0 : ( iFolder++, !--rFolders ) ) : 0 ; >> Garbage... > Not every hard-to-read document is garbage. This one is garbage... -- press any key to continue or any other to quit... |
| Sam <sam@email-scan.com>: Apr 10 07:40PM -0400 Alf P. Steinbach writes: >> different execution thread. As Mr. Spock would say: "highly illogical". > Thanks. I don't understand why the restriction, but given that it's there, > what can I do? Is this where condition variables are needed? Yes. A mutex, a condition variable, and a bool flag can be used to implement a logically-equivalent locking abstraction that can be unlocked by a different execution thread. The bool flag's initial value is false. Your thread-independent locking operation consists of locking the std::mutex, and waiting on the condition variable until the bool flag is false, then setting it to true, then unlocking the mutex. Your unlock operation consists of locking the std::mutex, setting the bool flag to false, notify_all() the condition variable, then unlocking the mutex. Your code is also quite vulnerable to undefined behavior due to the lifetime of its std::mutexes which are instantiated in automatic scope. If the std::mutex goes out of scope and gets destroyed while some other execution thread still attempts to screw around with it, more undefined behavior. I haven't analyzed whether the shown code guarantees that all references to the mutex are gone, before it gets destroyed. But it should not be necessary to rely on this rather fragile dependency. It's far more reliable to use smart pointers to dynamically-allocated objects with your mutex, condition variable, and the bool flag, and have a queue of smart pointers. Whichever thread ends up having the last smart pointer to the object go out of scope will destroy it, without worrying about making sure that it's the right thread. |
| Paavo Helde <myfirstname@osa.pri.ee>: Apr 11 09:50AM +0300 On 11.04.2019 1:28, Alf P. Steinbach wrote: >> As far as I can tell, the shown code ends up unlocking a mutex in a >> different execution thread. As Mr. Spock would say: "highly illogical". > Thanks. I don't understand why the restriction, A mutex is a very simple concept. You lock the mutex for doing some modifications on a shared data state which must appear as a single atomic operation to other threads. If the mutex is locked and unlocked in different threads, then the operation does not look very atomic to me any more. |
| Juha Nieminen <nospam@thanks.invalid>: Apr 11 10:02AM > $use_cppx( is_empty ); You understand that this is a C++ newsgroup, right? > auto main() -> int > { ... > return EXIT_FAILURE; > } All things considered, I think that's actually quite fitting. |
| Chris Vine <chris@cvine--nospam--.freeserve.co.uk>: Apr 11 12:40PM +0100 On Thu, 11 Apr 2019 09:50:11 +0300 > atomic operation to other threads. > If the mutex is locked and unlocked in different threads, then the > operation does not look very atomic to me any more. Semaphores with a maximum count of 1 can be used to provide mutual exclusion and synchronization, and so to that extent provide atomicity without having the ownership requirements of the (lighter overhead) mutex. These may be what Alf wants, but I haven't examined his code in detail. C++ does not have semaphores built in but they can be synthesized with a condition variable, mutex and flag. (However, both windows and POSIX have native semaphore objects.) As you and others have said, in C++ mutexes have ownerhip. Only the thread which currently holds the lock may unlock. |
| Paavo Helde <myfirstname@osa.pri.ee>: Apr 11 03:13PM +0300 On 11.04.2019 14:40, Chris Vine wrote: > detail. C++ does not have semaphores built in but they can be > synthesized with a condition variable, mutex and flag. (However, both > windows and POSIX have native semaphore objects.) C++ does not have semaphors because there is no need for them in multithreaded programming, one can synhronize access to any shared data state easily with a mutex and condvar. When using a semaphor the automatically shared data state would be just a single flag or a single counter, and then one would need to use more complicated logic and more error-prone code for sharing the rest of the data. |
| Chris Vine <chris@cvine--nospam--.freeserve.co.uk>: Apr 11 01:57PM +0100 On Thu, 11 Apr 2019 15:13:05 +0300 > a single flag or a single counter, and then one would need to use more > complicated logic and more error-prone code for sharing the rest of the > data. I am not sure I understand you. If using a semaphore, the shared state to which the semaphore is a gateway could be anything, depending on what the user is trying to implement. Perhaps you meant "if implementing a semaphore". If so, yes that is what I wrote ("... they can be synthesized with a condition variable, mutex and flag"). The main differences between a binary semaphore and a mutex is that a semaphore can be "unlocked" by any thread and is more heavy weight to implement. Non-binary semaphores are something else, where mutual exclusion is not the main objective. |
| Tim Rentsch <tr.17687@z991.linuxsc.com>: Apr 10 09:03PM -0700 > (my reputation becoming -1), and scolded for not just using an > array. I then asked on comp.lang.c++ and comp.lang.c++.moderated, > and it was answered by Bo Persson. An unfortunate aspect of stackoverflow is its catering to a culture of a continual popularity contest. I don't participate on stackoverflow, and experiences like this one are part of the reason why. |
| Melzzzzz <Melzzzzz@zzzzz.com>: Apr 11 04:07AM > culture of a continual popularity contest. I don't participate > on stackoverflow, and experiences like this one are part of the > reason why. I don't like stackoverflow at all... -- press any key to continue or any other to quit... |
| Tim Rentsch <tr.17687@z991.linuxsc.com>: Apr 10 08:52PM -0700 "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> writes: [...] > I'm sorry, I'm getting old, and today had my third kidney stone > trying to take me on. [...] I am truly sorry to hear you are going through this. I will hold off on responses in this thread for at least a few days to give that some time to resolve. I hope you feel better soon. |
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