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  • Is it possible to read to a Paradox 7.x .db file in a .Net app?

    - by Pedro
    I'm trying to read a Paradox 7.x .db file in a .Net 3.5 app and I'm not being successful on that. First of all, when I'm registering the odbc, as a user or system dsn, the Microsoft Paradox ODBC Driver only display versions up to 5.x, so it looks like that it does not support Paradox version 7.x. At connectionsstrings.com I've found the connection string that is supposed to work with Paradox 7.x: Provider=MSDASQL;Persist Security Info=False;Mode=Read; Extended Properties='DSN=Paradox;DBQ=C:\mydbfolder; DefaultDir=C:\mydbfolder;DriverId=538;FIL=Paradox 7.X;MaxBufferSize=2048; PageTimeout=600;';Initial Catalog=C:\mydbfolder But when I try to test the connection using a Data Adapter I get the following exception: "ERROR [IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified" I have specified the ODBC as a user DSN and as a System DSN as well but kept receiving the same error. Any clues on what should I do? Thanks, Pedro

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  • How can I easily make a java application invisible to the user?

    - by Pedro Bellora
    Hello! I have developed a Java aplication that is currently being run by double-clicking on a ".bat" file that does something like "java -jar proy.jar". This application just listens on a port and writes to a database, so it does not have any user interface (such as a window). I need this application to run as in background mode, or as it where a service, but I don't really anything more than that. It's enough if the application is run in a way that is not noticeable by the user, so that the user is not bothered and so the application can not be mistakenly closed. By the way, this will be run on an specific computer so it's okay if I have to do any manual configuration ir order to make this work. Also, I need this application to run on startup. Any help/tips regarding this? In advance, thank you very much for your help! Regards, Pedro

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  • iPhone - finding items in current entity that share related item

    - by Pedro
    G'day Folks My core data driven app has an Events entity, essentially a list of times & venues, with a related Acts entity, the names & bios of the acts appearing at those events. I have a table view that shows the event time & venue (as a table section with 1 row), the act name & act bio that works nicely. If that act is appearing at more than one event I'd like to include another table section that lists those events. I think could get that with event.act.events except that it would include the event I'm currently displaying. Can anyone suggest how to get the data I want & exclude the current record? Cheers & TIA, Pedro :) PS... I have not quite 18 hours until the promised time for a prototype of my app to be available for some testers to download.

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  • I'm trying to install VMWare tools on Ubuntu 12.04.2 LTS and I seem to have a problem with Kernel headers

    - by Pedro Irusta
    I have Ubuntu 12.04.2 LTS installed on a VMware machine on Windows 7 host. I seem to have a problem with Kernel headers when trying to install them I did: sudo apt-get install gcc make build-essential linux-headers-$(uname -r) Reading package lists... Done Building dependency tree Reading state information... Done gcc is already the newest version. build-essential is already the newest version. linux-headers-3.5.0-28-generic is already the newest version. make is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 100 not upgraded. However, when installing VMware tools I get the following error: make[1]: Entering directory `/usr/src/linux-headers-3.5.0-28-generic' CC [M] /tmp/vmware-root/modules/vmhgfs-only/backdoor.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/backdoorGcc32.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/bdhandler.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/cpName.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/cpNameLinux.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/cpNameLite.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/dentry.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/dir.o CC [M] /tmp/vmware-root/modules/vmhgfs-only/file.o /tmp/vmware-root/modules/vmhgfs-only/file.c:122:4: warning: initialization from incompatible pointer type [enabled by default] /tmp/vmware-root/modules/vmhgfs-only/file.c:122:4: warning: (near initialization for ‘HgfsFileFileOperations.fsync’) [enabled by default] CC [M] /tmp/vmware-root/modules/vmhgfs-only/filesystem.o /tmp/vmware-root/modules/vmhgfs-only/filesystem.c:48:28: fatal error: linux/smp_lock.h: No such file or directory compilation terminated. make[2]: *** [/tmp/vmware-root/modules/vmhgfs-only/filesystem.o] Error 1 make[1]: *** [_module_/tmp/vmware-root/modules/vmhgfs-only] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-28-generic' make: *** [vmhgfs.ko] Error 2 make: Leaving directory `/tmp/vmware-root/modules/vmhgfs-only' Any help appreciated!

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  • No audio with headphones, but audio works with integrated speakers

    - by Pedro
    My speakers work correctly, but when I plug in my headphones, they don't work. I am running Ubuntu 10.04. My audio card is Realtek ALC259 My laptop model is a HP G62t a10em In another thread someone fixed a similar issue (headphones work, speakers not) folowing this: sudo vi /etc/modprobe.d/alsa-base.conf (or some other editor instead of Vi) Append the following at the end of the file: alias snd-card-0 snd-hda-intel options snd-hda-intel model=auto Reboot but it doesnt work for me. Before making and changes to alsa, this was the output: alsamixer gives me this: Things I did: followed this HowTo but now no hardware seems to be present (before, there were 2 items listed): Now, alsamixer gives me this: alsamixer: relocation error: alsamixer: symbol snd_mixer_get_hctl, version ALSA_0.9 not defined in file libasound.so.2 with link time reference I guess there was and error in the alsa-driver install so I began reinstalling it. cd alsa-driver* //this works fine// sudo ./configure --with-cards=hda-intel --with-kernel=/usr/src/linux-headers-$(uname -r) //this works fine// sudo make //this doesn't work. see ouput error below// sudo make install Final lines of sudo make: hpetimer.c: In function ‘snd_hpet_open’: hpetimer.c:41: warning: implicit declaration of function ‘hpet_register’ hpetimer.c:44: warning: implicit declaration of function ‘hpet_control’ hpetimer.c:44: error: expected expression before ‘unsigned’ hpetimer.c: In function ‘snd_hpet_close’: hpetimer.c:51: warning: implicit declaration of function ‘hpet_unregister’ hpetimer.c:52: error: invalid use of undefined type ‘struct hpet_task’ hpetimer.c: In function ‘hpetimer_init’: hpetimer.c:88: error: ‘EINVAL’ undeclared (first use in this function) hpetimer.c:99: error: invalid use of undefined type ‘struct hpet_task’ hpetimer.c:100: error: invalid use of undefined type ‘struct hpet_task’ hpetimer.c: At top level: hpetimer.c:121: warning: excess elements in struct initializer hpetimer.c:121: warning: (near initialization for ‘__param_frequency’) hpetimer.c:121: warning: excess elements in struct initializer hpetimer.c:121: warning: (near initialization for ‘__param_frequency’) hpetimer.c:121: warning: excess elements in struct initializer hpetimer.c:121: warning: (near initialization for ‘__param_frequency’) hpetimer.c:121: warning: excess elements in struct initializer hpetimer.c:121: warning: (near initialization for ‘__param_frequency’) hpetimer.c:121: error: extra brace group at end of initializer hpetimer.c:121: error: (near initialization for ‘__param_frequency’) hpetimer.c:121: warning: excess elements in struct initializer hpetimer.c:121: warning: (near initialization for ‘__param_frequency’) make[1]: *** [hpetimer.o] Error 1 make[1]: Leaving directory `/usr/src/alsa/alsa-driver-1.0.9/acore' make: *** [compile] Error 1 And then sudo make install gives me: rm -f /lib/modules/0.0.0/misc/snd*.*o /lib/modules/0.0.0/misc/persist.o /lib/modules/0.0.0/misc/isapnp.o make[1]: Entering directory `/usr/src/alsa/alsa-driver-1.0.9/acore' mkdir -p /lib/modules/0.0.0/misc cp snd-hpet.o snd-page-alloc.o snd-pcm.o snd-timer.o snd.o /lib/modules/0.0.0/misc cp: cannot stat `snd-hpet.o': No such file or directory cp: cannot stat `snd-page-alloc.o': No such file or directory cp: cannot stat `snd-pcm.o': No such file or directory cp: cannot stat `snd-timer.o': No such file or directory cp: cannot stat `snd.o': No such file or directory make[1]: *** [_modinst__] Error 1 make[1]: Leaving directory `/usr/src/alsa/alsa-driver-1.0.9/acore' make: *** [install-modules] Error 1 [SOLUTION] After screwing it all up, someone mentioned why not trying using the packages in Synaptic - so I did. I have reinstalled the following packages and rebooter: -alsa-hda-realtek-ignore-sku-dkms -alsa-modules-2.6.32-25-generic -alsa-source -alsa-utils -linux-backports-modules-alsa-lucid-generic -linux-backports-modules-alsa-lucid-generic-pae -linux-sound-base -(i think i listed them all) After rebooting, the audio worked, both in speakers and headphones. I have no idea which is the package that made my audio work, but it certainly was one of them. [/SOLUTION]

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  • Cannot reinstall Unity - Broken dependencies

    - by Pedro Sardinha U94410
    I've lost my Unity after sudo apt-get autoremove --purge unity-webapp and cleaned the system with Ubuntu Tweak. I try to install it, but I always get a warning of broken dependencies... I've added the Unity Team PPA, dist-upgrade, among other efforts. (same with Unity 2D) When I try to install ubuntu-desktop I get this: E: Unable to correct problems, you have held packages (hold) spoiled. Please help me! [Ubuntu 12.10]

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  • DPMS, keep screen off when lid shut

    - by Evan Teran
    I have a laptop running linux. In my xorg configuration, I have DPMS setup so that the screen automatically turns off during several events. In addition to that I have to the following script tied to ACPI lid open/close events: #!/bin/sh for i in $(pidof X); do CMD=$(ps --no-heading $i) XAUTH="$(echo $CMD | sed -n 's/.*-auth \(.*\)/\1/p')" DISPLAY="$(echo $CMD | sed -n 's/.* \(:[0-9]\) .*/\1/p')" # turn the display off or back on export XAUTHORITY=$XAUTH /usr/bin/xset -display $DISPLAY dpms force $1 done Basically, this script takes one parameter ("on" or "off") then iterates through all of my running X sessions and either turns on or turns off the monitor. Here's my issue. When I close the lid of the laptop, the screen goes off as expected, but if a mouse event occurs (like if something bumps into the table...) then the screen turns back on even though it is closed (I can see the light through the side of the laptop). Is there a way to prevent the screen from turning on during a mouse event if the lid is closed?

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  • Is there any practical use for the empty type in Common Lisp?

    - by Pedro Rodrigues
    The Common Lisp spec states that nil is the name of the empty type, but I've never found any situation in Common Lisp where I felt like the empty type was useful/necessary. Is it there just for completeness sake (and removing it wouldn't cause any harm to anyone)? Or is there really some practical use for the empty type in Common Lisp? If yes, then I would prefer an answer with code example. For example, in Haskell the empty type can be used when binding foreign data structures, to make sure that no one tries to create values of that type without using the data structure's foreign interface (although in this case, the type is not really empty).

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  • How can I set a second screen (DISPLAY=:0.1) as the default gnome display?

    - by Pedro Silva
    Due to various reasons, I have my main monitor set as the secondary display in xorg.conf. I would like to have gnome initialize metacity, gnome-panel as running primarily on :0.1, instead of :0.0. Is this possible at all? To clarify, this is a laptop with its LCD turned off. My main monitor is connected to the VGA out and is driven by the nouveau driver for NVIDIA; a secondary monitor is on a displaylink usb-vga donverter. The seconday monitor is set in xorg.conf as the primary display (no way around it). I can do things like DISPLAY=:0.1 gnome-terminal to run applications on the main monitor. My question is whether it is possible to do this (GNOME-) system-wide.

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  • How is intermediate data organized in MapReduce?

    - by Pedro Cattori
    From what I understand, each mapper outputs an intermediate file. The intermediate data (data contained in each intermediate file) is then sorted by key. Then, a reducer is assigned a key by the master. The reducer reads from the intermediate file containing the key and then calls reduce using the data it has read. But in detail, how is the intermediate data organized? Can a data corresponding to a key be held in multiple intermediate files? What happens when there is too much data corresponding to one key to be held by a single file? In short, how do intermediate partitions differ from intermediate files and how are these differences dealt with in the implementation?

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  • window decoration command change

    - by Pedro
    I'm quite new to Ubuntu, and I don't know how to fix this: I have been experiencing the problem with window decorations that go away. I have been told that I could correct that with compiz fusion icon, just restarting the graphics whenever it happened. This solution only fixed the problem for like 30 seconds. Then I found out that the command inside the window decorator had changed, so I only had to reset it to default (/usr/bin/compiz-decorator). The only problem is that it keeps changing the command by itself once or twice a day. I can live with that, but I would like to find a more permanent solution, if there is one. I am running Ubuntu 11.10

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  • Wireless network unstable and often WPA2 protected networks just don't work

    - by Pedro
    I have an issue with my wireless network,so that the connection is working for only a few minutes, after which my browser no longer is able to load pages, even if the wireless is still active/connected. Furthermore, most of the time WPA2-personal protected networks don't work, (yesterday was the first time it worked - for a few minutes). By "don't work" I mean that it seems to successfully connect, but the browser can't load pages. I am running Ubuntu 10.10 32bit, and my wireless card is a RaLink rt3090. No changes have been done to any settings since Ubuntu was installed - networking began working on its own after the installation - but as described in first paragraph not very well.

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  • 2D Physics in a networked game (iOS)?

    - by Pedro
    I am researching the possibilities for a new iOS game. It's going to be a run-n-gun type platformer, and I'm looking into the possibility of co-op multiplayer. The game itself wouldn't be very physics intensive, there will most likely be 20-30 physics bodies at any given time. For the multiplayer, I think I would have one player "hosting" and up to 3 other connecting via the Internet. Here's my first question, are there any 2D physics engines that work over a network(preferably open source)? My second question, Does anyone have any thoughts on using a non-networked engine (like Box2D or Chipmunk) and adding the networking component? Since there would not be very much information sent, do you think it would cause a lot of lag?

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  • Sync ERROR!! LOST MY WORK!

    - by Pedro Pisandelli
    Sorry my English... hope you understand me... I had a document. Edited it yesterday. But today, when i open it, it was desync. It show an one month earlier version!! I LOST A LOT OF WORK!! And i can't recover my right version of the document! I have a paid plan for Ubuntu One, but this made me very angry. And i don't see a way to recover and don't see a way to talk to somebody! There's no recovery mode like Dropbox... Man, i'm really ANGRY!! REALLY! I'll not recomend Ubuntu One services anymore! I don't know what to do... I lost my work and now i'm one month late! Thanks!!!

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  • Storing a Hex Grid

    - by Pedro Caetano
    I've been creating a small hex grid framework for Unity3D and have come to the following dilema. This is my coordinate system (taken from here) Link because I'm a new user It all works pretty nicely except for the fact I have no idea how to store it. I originally intended to store this in a 2D array and use images to generate my maps. One problem was that it had negative values (this was easily fixed by offsetting the coordinates a bit). However, due to this coordinate system, such an image or bitmap would have to be diamond shaped - and since these structures are square shaped, this would cause a lot of headaches even if I hack something together. Is there anything I'm missing that could fix this? I recall seeing a forum post regarding this in the unity forums but I can no longer find the link. Is writing a set of coordinate translators the best solution here? If you guys think it would be helpful, I can post code and images of my problem.

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  • Can we have some "coming soon" text in our app? Will Apple reject it? [closed]

    - by Pedro
    We're getting ready to push our app live. There's some functionality that's not ready yet; it's accessory, not crucial to the user, but it does provide some interesting context. If I have a button with the name of the feature (e.g., "Panoramic Views") and a "COMING SOON" label stuck over it, will Apple reject the submission? What if instead of a button it's just a text label somewhere announcing "Panoramic Views coming soon!"? I've seen some material online saying that "coming soon" is a no-no but all I could find in Apple's guidelines themselves was 2.9, "Apps that are "beta", "demo", "trial", or "test" versions will be rejected". Which is certainly not the case! Thanks in advance, any help greatly appreciated.

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  • Editing 8bpp indexed Bitmaps

    - by Pedro Sá
    hi, i'm trying to edit the pixels of a 8bpp. Since this PixelFormat is indexed i'm aware that it uses a Color Table to map the pixel values. Even though I can edit the bitmap by converting it to 24bpp, 8bpp editing is much faster (13ms vs 3ms). But, changing each value when accessing the 8bpp bitmap results in some random rgb colors even though the PixelFormat remains 8bpp. I'm currently developing in c# and the algorithm is as follows: (C#) 1- Load original Bitmap at 8bpp 2- Create Empty temp Bitmap with 8bpp with the same size as the original 3-LockBits of both bitmaps and, using P/Invoke, calling c++ method where I pass the Scan0 of each BitmapData object. (I used a c++ method as it offers better performance when iterating through the Bitmap's pixels) (C++) 4- Create a int[256] palette according to some parameters and edit the temp bitmap bytes by passing the original's pixel values through the palette. (C#) 5- UnlockBits. My question is how can I edit the pixel values without having the strange rgb colors, or even better, edit the 8bpp bitmap's Color Table? Regards, Pedro

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  • Is this a bug in plist or Xcode?

    - by Pedro
    G'day All If you create a date item in the plist editor of Xcode or Apple's standalone plist editor you get something of the form <date>2010-05-29T10:30:00Z</date> which is a nice well formed ISO date at UTC (indicated by the "Z"). Because I'm in timezone UTC +10 when that's read into my app & then displayed I get 8:30 PM out, still good. However if that is a time in my timezone it should be <date>2010-05-29T10:30:00+10</date> (replacing "Z" with my timezone offset). All of my attempts at reading such dates into my iPhone app have had the plist rejected as if it is malformed & editing a plist with such a date in Apple's editors changed the "+10" to "Z" without adjusting the time. Do others think I'm correct in thinking this is a bug in either plist or Xcode? My feeling is that the implementation of ISO date & time in plist is incomplete. Cheers, Pedro :)

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  • How do I resize table view after resizing it's footer?

    - by Pedro
    I have a UITableView with header & footer added with code following the pattern shown in Apple's recipes example so the code for the footer is... if (tableFooterView == nil) { [[NSBundle mainBundle] loadNibNamed:@"DetailFooterView" owner:self options:nil]; self.tableView.tableFooterView = tableFooterView; } The footer NIB contains nothing more than a UITextView & I set text & resize with... CGSize size = [footerText sizeWithFont:[footerTextView font] constrainedToSize:CGSizeMake(304.0, 500.0)]; CGRect frame = CGRectMake(8.0, 0.0, size.width, size.height + 24.0); footerTextView.frame = frame; footerTextView.text = footerText; [tableFooterView sizeToFit]; That all works however I can't get the UITableView to resize around the resized footer. If I set the original size of the footer for any possible text I have a big whitespace in most cases. If I set it smaller then I can push the view up to see the whole text but it bounces back on release. I've tried [[self view] sizeToFit]; but that doesn't work. Can anyone fill me in? Cheers & TIA, Pedro :)

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  • Required Skill Sets Of A Software Architect

    The question has been asked as to what is the required skill sets of a software architect. The answer to this is that it truly depends. When I state that it depend, it depends on the organization, industry, and skill sets available on the open market and internally within a company. With open ended skill sets even Napoleon Dynamite could be an architect. Napoleon Dynamite’s Skills Pedro: Have you asked anybody yet? Napoleon Dynamite: No, but who would? I don't even have any good skills. Pedro: What do you mean? Napoleon Dynamite: You know, like nunchuck skills, bow hunting skills, computer hacking skills... Girls only want boyfriends who have great skills. Pedro: Aren't you pretty good at drawing, like animals and warriors and stuff? This example might be a little off base but it does illustrate a point. What are the real required skills of a software architect? In my opinion, an architect needs to demonstrate the knowledge of the following three main skill set categories so that they are successful. General Skill Sets of an Architect Basic Engineering Skills Organizational  Skills Interpersonal Skills Basic Engineering Skills are a very large part of what a software architect deal with on a daily bases when designing or updating systems. Think about it, how good would a lead mechanic be if they did not know how to fix or repair cars? They would not be, and that is my point that architects need to have at least some basic skills regarding engineering. The skills listed below are generic in nature because they change from job to job, so in this discussion I am trying to focus more on generalities so that anyone can apply this information to their individual situation. Common Basic Engineering Skills Data Modeling Code Creation Configuration Testing Deployment/Publishing System and Environment Knowledge Organizational Skills If an Architect works for or with an origination then they will need strong organization skills to survive. An architect is no use to a project if the project is missed managed. Additionally, budgets and timelines can really affect a company and their products when established deadlines are repeated not meet. By not meeting these timelines a company is forced to cancel the project and waste all the money and time spent or spend more money until it is completed, if it is ever completed. Common Organizational Skills Project Management Estimation (Cost and Time) Creation and Maintenance of Accepted Standards Interpersonal Skills For me personally Interpersonal skill ranks above the other types of skill sets because an architect can quickly pick up the other two skill sets by communicating with other team/project members so that they are quickly up to speed on a project. Additionally, in order for an architect to manage a project or even derive rough estimates they will more than likely have to consult with others actually working on the code (Programmers/Software Engineers) to get there estimates since they will be the ones actually working on the changes to be implemented. Common Interpersonal Skills Good Communicator Focus on projects success over personal Honors roles within a team Reference: Taylor, R. N., Medvidovic, N., & Dashofy, E. M. (2009). Software architecture: Foundations, theory, and practice Hoboken, NJ: John Wiley & Sons

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  • Ways std::stringstream can set fail/bad bit?

    - by Evan Teran
    A common piece of code I use for simple string splitting looks like this: inline std::vector<std::string> split(const std::string &s, char delim) { std::vector<std::string> elems; std::stringstream ss(s); std::string item; while(std::getline(ss, item, delim)) { elems.push_back(item); } return elems; } Someone mentioned that this will silently "swallow" errors occurring in std::getline. And of course I agree that's the case. But it occurred to me, what could possibly go wrong here in practice that I would need to worry about. basically it all boils down to this: inline std::vector<std::string> split(const std::string &s, char delim) { std::vector<std::string> elems; std::stringstream ss(s); std::string item; while(std::getline(ss, item, delim)) { elems.push_back(item); } if(ss.fail()) { // *** How did we get here!? *** } return elems; } A stringstream is backed by a string, so we don't have to worry about any of the issues associated with reading from a file. There is no type conversion going on here since getline simply reads until it sees a newline or EOF. So we can't get any of the errors that something like boost::lexical_cast has to worry about. I simply can't think of something besides failing to allocate enough memory that could go wrong, but that'll just throw a std::bad_alloc well before the std::getline even takes place. What am I missing?

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  • who free's setvbuf buffer?

    - by Evan Teran
    So I've been digging into how the stdio portion of libc is implemented and I've come across another question. Looking at man setvbuf I see the following: When the first I/O operation occurs on a file, malloc(3) is called, and a buffer is obtained. This makes sense, your program should have a malloc in it for I/O unless you actually use it. My gut reaction to this is that libc will clean up its own mess here. Which I can only assume it does because valgrind reports no memory leaks (they could of course do something dirty and not allocate it via malloc directly... but we'll assume that it literally uses malloc for now). But, you can specify your own buffer too... int main() { char *p = malloc(100); setvbuf(stdio, p, _IOFBF, 100); puts("hello world"); } Oh no, memory leak! valgrind confirms it. So it seems that whenever stdio allocates a buffer on its own, it will get deleted automatically (at the latest on program exit, but perhaps on stream close). But if you specify the buffer explicitly, then you must clean it up yourself. There is a catch though. The man page also says this: You must make sure that the space that buf points to still exists by the time stream is closed, which also happens at program termination. For example, the following is invalid: Now this is getting interesting for the standard streams. How would one properly clean up a manually allocated buffer for them, since they are closed in program termination? I could imagine a "clean this up when I close flag" inside the file struct, but it get hairy because if I read this right doing something like this: setvbuf(stdio, 0, _IOFBF, 100); printf("hello "); setvbuf(stdio, 0, _IOLBF, 100); printf("world\n"); would cause 2 allocations by the standard library because of this sentence: If the argument buf is NULL, only the mode is affected; a new buffer will be allocated on the next read or write operation.

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  • What is the general feeling about reflection extensions in std::type_info?

    - by Evan Teran
    I've noticed that reflection is one feature that developers from other languages find very lacking in c++. For certain applications I can really see why! It is so much easier to write things like an IDE's auto-complete if you had reflection. And certainly serialization APIs would be a world easier if we had it. On the other side, one of the main tenets of c++ is don't pay for what you don't use. Which makes complete sense. That's something I love about c++. But it occurred to me there could be a compromise. Why don't compilers add extensions to the std::type_info structure? There would be no runtime overhead. The binary could end up being larger, but this could be a simple compiler switch to enable/disable and to be honest, if you are really concerned about the space savings, you'll likely disable exceptions and RTTI anyway. Some people cite issues with templates, but the compiler happily generates std::type_info structures for template types already. I can imagine a g++ switch like -fenable-typeinfo-reflection which could become very popular (and mainstream libs like boost/Qt/etc could easily have a check to generate code which uses it if there, in which case the end user would benefit with no more cost than flipping a switch). I don't find this unreasonable since large portable libraries like this already depend on compiler extensions. So why isn't this more common? I imagine that I'm missing something, what are the technical issues with this?

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  • QValidator for hex input

    - by Evan Teran
    I have a Qt widget which should only accept a hex string as input. It is very simple to restrict the input characters to [0-9A-Fa-f], but I would like to have it display with a delimiter between "bytes" so for example if the delimiter is a space, and the user types 0011223344 I would like the line edit to display 00 11 22 33 44 Now if the user presses the backspace key 3 times, then I want it to display 00 11 22 3. I almost have what i want, so far there is only one subtle bug involving using the delete key to remove a delimiter. Does anyone have a better way to implement this validator? Here's my code so far: class HexStringValidator : public QValidator { public: HexStringValidator(QObject * parent) : QValidator(parent) {} public: virtual void fixup(QString &input) const { QString temp; int index = 0; // every 2 digits insert a space if they didn't explicitly type one Q_FOREACH(QChar ch, input) { if(std::isxdigit(ch.toAscii())) { if(index != 0 && (index & 1) == 0) { temp += ' '; } temp += ch.toUpper(); ++index; } } input = temp; } virtual State validate(QString &input, int &pos) const { if(!input.isEmpty()) { // TODO: can we detect if the char which was JUST deleted // (if any was deleted) was a space? and special case this? // as to not have the bug in this case? const int char_pos = pos - input.left(pos).count(' '); int chars = 0; fixup(input); pos = 0; while(chars != char_pos) { if(input[pos] != ' ') { ++chars; } ++pos; } // favor the right side of a space if(input[pos] == ' ') { ++pos; } } return QValidator::Acceptable; } }; For now this code is functional enough, but I'd love to have it work 100% as expected. Obviously the ideal would be the just separate the display of the hex string from the actual characters stored in the QLineEdit's internal buffer but I have no idea where to start with that and I imagine is a non-trivial undertaking. In essence, I would like to have a Validator which conforms to this regex: "[0-9A-Fa-f]( [0-9A-Fa-f])*" but I don't want the user to ever have to type a space as delimiter. Likewise, when editing what they types, the spaces should be managed implicitly.

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  • Potential g++ template bug?

    - by Evan Teran
    I've encountered some code which I think should compile, but doesn't. So I'm hoping some of the local standards experts here at SO can help :-). I basically have some code which resembles this: #include <iostream> template <class T = int> class A { public: class U { }; public: U f() const { return U(); } }; // test either the work around or the code I want... #ifndef USE_FIX template <class T> bool operator==(const typename A<T>::U &x, int y) { return true; } #else typedef A<int> AI; bool operator==(const AI::U &x, int y) { return true; } #endif int main() { A<int> a; std::cout << (a.f() == 1) << std::endl; } So, to describe what is going on here. I have a class template (A) which has an internal class (U) and at least one member function which can return an instance of that internal class (f()). Then I am attempting to create an operator== function which compares this internal type to some other type (in this case an int, but it doesn't seem to matter). When USE_FIX is not defined I get the following error: test.cc: In function 'int main()': test.cc:27:25: error: no match for 'operator==' in 'a.A<T>::f [with T = int]() == 1' Which seems odd, because I am clearly (I think) defining a templated operator== which should cover this, in fact if I just do a little of the work for the compiler (enable USE_FIX), then I no longer get an error. Unfortunately, the "fix" doesn't work generically, only for a specific instantiation of the template. Is this supposed to work as I expected? Or is this simply not allowed? BTW: if it matters I am using gcc 4.5.2.

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