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  • Is learning how to use C (or C++) a requirement in order to be a good (excellent) programmer?

    - by blueberryfields
    When I first started to learn how to program, real programmers could write assembly in their sleep. Any serious schooling in computer science would include a hefty bit of training and practice in programming using assembly. That has since changed, to the point where I see Computer Science degrees with assembly, if included at all, is relegated to one assignment, and one chapter, for a total of two weeks' work out of 4 years' schooling. C/C++ programming seems to have followed a similar path. I'm no longer surprised to interview university graduates who have not spent more than two weeks programming in C++, and have only read of C in a book somewhere. While the most serious CS degrees still seem to include significant time learning and using one or both of the languages, the trend is clearly towards less enforced C/C++ in school. It's clearly possible to make a career producing good work without ever reading or writing a single line of C or C++ code. Given all of that, is learning the two languages worth the effort? Are they at all required to excel? (beyond the obvious, non-language specific advice, such as "a good selection of languages is probably important for a comprehensive education", and "it's probably a good idea to keep trying out and learning new languages throughout a programmers' career, just to stretch the gray cells")

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  • How can I make multiple displays work on my Asus UX32VD?

    - by oKtosiTe
    Original title: Why do I have two trash icons in the Unity Launcher? Whether I run Ubuntu as a live-USB or install it, I always have two trash bins on the Unity Launcher. Both work, and both open the same location. This seems a bit redundant; what could be done about it? Update: Turning auto-hide on made it obvious that I have multiple Launchers showing. With auto-hide off, they simply overlap, making it look like there's a double trash icon, but with auto-hide enabled, I can display one Launcher (and therefore one trash icon) at a time. Still, two are running simultaneously. Second update: This problem appears to be caused by the way Ubuntu handles multiple displays on my Asus UX32VD Ultrabook. Somehow, the laptop display cannot be used while my external display is connected. It is shown in the Displays list, but remains black no matter how I configure it. The external display runs at 1920x1200, the laptop monitor should run at 1920x1080. It therefore becomes obvious that the Launcher that's supposed to run on the laptop display, is actually displayed on the external monitor. Using nomodeset as a kernel parameter as indicated here makes the laptop display inaccessible altogether, detecting the external monitor as the laptop display and making resolutions other than 1920x1200 inaccessible. That is not an option.

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  • Dell Upgrade to 12.04 LTS No wifi, graphic card driver and bluetooth Problem?

    - by Mattlinux1
    (Dell inspiron m5040 Upgrade to 12.04 LTS from 11.10 wifi wont work and has two bluetooth icons?) Old title of post! No Wifi/Bluetooth Problem. "Both Fixed", see below comments for bluetooth fix and see bottom answer for wifi fix. My online upgrade of 12.04 LTS, was installed to my laptop the Dell inspiron m5040, when it was done i found that my wifi did not even get picked up anymore and i now have two bluetooth icons at the top?? So what i have been doing for now is at the boot screen. I hit the use previous linux version, this works fine but also has the two bluetooth at the top. Is very thankful for any answers for this fix, Thank You. Ok bluetooth problem solved by – fossfreedom answer by deleting the other bluetooth program running in software center. Now the other problem is Wifi: just have to restart system as it works in previous linux version boot opt, but on the first boot screen opt run ubuntu it will not pick up wifi drivers. Broadcom 802.11 Linux STA wireless driverfor use with Broadcom's BCM4311-, BCM4312-, BCM4313-, BCM4321-,BCM4322-, BCM43224-, and BCM43225-, BCM43227- and BCM43228-basedhardware. And 3D-accelerated proprietary graphics driver for ATI cards. This driver is required to fully utilise the 3D potential of some ATI graphics cards, as well as provide 2D acceleration of newer cards. will not instill is there anyway for me to make a copy of the drivers via usb HDD and then put them on new upgraded version.

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  • Object construction design

    - by James
    I recently started to use c# to interface with a database, and there was one part of the process that appeared odd to me. When creating a SqlCommand, the method I was lead to took the form: SqlCommand myCommand = new SqlCommand("Command String", myConnection); Coming from a Java background, I was expecting something more similar to SqlCommand myCommand = myConnection.createCommand("Command String"); I am asking, in terms of design, what is the difference between the two? The phrase "single responsibility" has been used to suggest that a connection should not be responsible for creating SqlCommands, but I would also say that, in my mind, the difference between the two is partly a mental one of the difference between a connection executing a command and a command acting on a connection, the latter of which seems less like what I have been lead to believe OOP should be. There is also a part of me wondering if the two should be completely separate, and should only come together in some sort of connection.execute(command) method. Can anyone help clear up these differences? Are any of these methods "more correct" than the others from an OO point of view? (P.S. the fact that c# is used is completely irrelevant. It just highlighted to me that different approaches were used)

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  • Implementing the NetBeans Project API on Maven in IntelliJ IDEA

    - by Geertjan
    James McGivern, one of the speakers I met at JAX London, is creating media software on the NetBeans Platform. However, he's using Maven and IntelliJ IDEA and one of the features he needs is project support, i.e., the project infrastructure that's part of NetBeans IDE. The two documents that describe the NetBeans Project API are these: http://platform.netbeans.org/tutorials/nbm-projecttype.html http://netbeans.dzone.com/how-create-maven-nb-project-type By combining the above two, you'll understand how to create a project infrastructure on top of the NetBeans Platform with Maven. However, an additional step of complexity is added when IntelliJ IDEA is included into the mix and therefore I created the following screencast which, in 15 minutes, puts all the pieces together. Be aware that I'm probably not using IntelliJ IDEA and Maven as optimally as I could and I'm publishing this at least partly so that the errors of my ways can be pointed out to me. But, first and foremost, this is especially for you James:  Note: Intentionally no sound, only callouts explaining what I'm doing. You'll probably need to pause the movie here and there to absorb the text; for details on the text, see the two links referred to above.

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  • How to improve my backup strategy (rsync)?

    - by GUI Junkie
    I've seen the QAs about backup solutions, but I'm asking anyway. One because it's a personal situation I haven't solved yet, and two, because the answer can be useful for others. My situation is rather simple. I have two computers with two users and one external hard-drive. I want to sync/backup a shared directory. Currently I use rsync with the -azvu options to sync to the external drive. My problem is the round-trip. All deleted files are restored! Using rsync I'm doing Computer A --> External disk --> Computer A Computer B --> External disk --> Computer B (I should probably do External disk -- Computer A as a last step) I've seen 'bup' mentioned and other QA talk about dropbox + rsync... Another option is maybe to delete files from rsync? Can my running backup strategy be improved in some other way?

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  • If you develop on multiple operating systems, is it better to have multiple computers + displays?

    - by dan
    I develop for iOS and Linux. My preferred OS is Ubuntu. Now my software shop (me and a partner) is developing for Windows too. Now the question is, is it more efficient to have multiple workstations, one for each target OS? Efficiency and productivity is a higher priority than saving money. I have a 3.4Ghz i7 desktop workstation running Ubuntu and virtualized Windows with two displays, and I'm putting together an even more powerful i7 Hackintosh with 16GB RAM (to replace my weak 2.2Ghz i5 Macbook Pro). My specific dilemma is whether I should sell the first computer and triple boot on the second one, or buy two more displays and run both desktop systems simultaneously. Would appreciate answers from developers who write software for multiple OSes. Running guest OSes in VirtualBox on one system not ideal, because in my experience performance is seriously degraded under virtualization. So the choice is between dual/triple booting on one system vs having two systems, one for OSX+iOS/Windows (dual boot) and the other for Ubuntu (which I prefer to use as my main OS). For much of our work, I write a server-side application in Linux and a client for iOS (or for Windows or OS X) simultaneously.

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  • Virtual Pageview Goal Funnel Not Tracking Correctly

    - by cphill
    I have an AJAX form that has three stages: 1. The landing page where a user fills out a form and selects between three question sets and clicks begin assessment 2. The assessment page, where users fill out questions relating to the question set that they selected on the landing page. 3.The results page, which shows whether they are at High Risk or Low Risk. Since this is an AJAX form that does not open a new page for each step of the process, I implemented a virtual pageview that would fire on the pageload of each step of the form process. The following is my virtual pageview setup for each stage: /form/begin-assessment /form/assessment/* (* = Three different virtual pageviews depending on the users selection of the three sets of questions: /one, /two, /three) 3./form/finished-assessment I have set up three separate goals to track user progress through each step of the form assessment. Here is my Goal setup: Goal Description: -Goal Type: Destination Goal Details: -Destination: /form/finished-assessment -Funnel: On Step 1: /form/begin-assessment (Required: Yes) Step 2: /form/assessment/one (Step 2: replace /one with /two or /three and you have my two other goals setup) Now my goals are recording the correct data in the first step and show the completions in the destination, but the second step does not show any drop offs. They show the same data as the destination. Any ideas of how I set up the goals wrong?

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  • Handling Types for Real and Complex Matrices in a BLAS Wrapper

    - by mga
    I come from a C background and I'm now learning OOP with C++. As an exercise (so please don't just say "this already exists"), I want to implement a wrapper for BLAS that will let the user write matrix algebra in an intuitive way (e.g. similar to MATLAB) e.g.: A = B*C*D.Inverse() + E.Transpose(); My problem is how to go about dealing with real (R) and complex (C) matrices, because of C++'s "curse" of letting you do the same thing in N different ways. I do have a clear idea of what it should look like to the user: s/he should be able to define the two separately, but operations would return a type depending on the types of the operands (R*R = R, C*C = C, R*C = C*R = C). Additionally R can be cast into C and vice versa (just by setting the imaginary parts to 0). I have considered the following options: As a real number is a special case of a complex number, inherit CMatrix from RMatrix. I quickly dismissed this as the two would have to return different types for the same getter function. Inherit RMatrix and CMatrix from Matrix. However, I can't really think of any common code that would go into Matrix (because of the different return types). Templates. Declare Matrix<T> and declare the getter function as T Get(int i, int j), and operator functions as Matrix *(Matrix RHS). Then specialize Matrix<double> and Matrix<complex>, and overload the functions. Then I couldn't really see what I would gain with templates, so why not just define RMatrix and CMatrix separately from each other, and then overload functions as necessary? Although this last option makes sense to me, there's an annoying voice inside my head saying this is not elegant, because the two are clearly related. Perhaps I'm missing an appropriate design pattern? So I guess what I'm looking for is either absolution for doing this, or advice on how to do better.

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  • Java enum pairs / "subenum" or what exactly?

    - by vemalsar
    I have an RPG-style Item class and I stored the type of the item in enum (itemType.sword). I want to store subtype too (itemSubtype.long), but I want to express the relation between two data type (sword can be long, short etc. but shield can't be long or short, only round, tower etc). I know this is wrong source code but similar what I want: enum type { sword; } //not valid code! enum swordSubtype extends type.sword { short, long } Question: How can I define this connection between two data type (or more exactly: two value of the data types), what is the most simple and standard way? Array-like data with all valid (itemType,itemSubtype) enum pairs or (itemType,itemSubtype[]) so more subtype for one type, it would be the best. OK but how can I construct this simplest way? Special enum with "subenum" set or second level enum or anything else if it does exists 2 dimensional "canBePairs" array, itemType and itemSubtype dimensions with all type and subtype and boolean elements, "true" means itemType (first dimension) and itemSubtype (second dimension) are okay, "false" means not okay Other better idea Thank you very much!

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  • Which approach is the most maintainable?

    - by 2rs2ts
    When creating a product which will inherently suffer from regression due to OS updates, which of these is the preferable approach when trying to reduce maintenance cost and the likelihood of needing refactoring, when considering the task of interpreting system state and settings for a lay user? Delegate the responsibility of interpreting the results of inspecting the system to the modules which perform these tasks, or, Separate the concerns of interpretation and inspection into two modules? The first obviously creates a blob in which a lot of code would be verbose, redundant, and hard to grok; the second creates a strong coupling in which the interpretation module essentially has to know what it expects from inspection routines and will have to adapt to changes to the OS just as much as the inspection will. I would normally choose the second option for the separation of concerns, foreseeing the possibility that inspection routines could be re-used, but a developer updating the product to deal with a new OS feature or something would have to not only write an inspection routine but also write an interpretation routine and link the two correctly - and it gets worse for a developer who has to change which inspection routines are used to get a certain system setting, or worse yet, has to fix an inspection routine which broke after an OS patch. I wonder, is it better to have to patch one package a lot or two packages, each somewhat less so?

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  • Views : ViewControllers, many to one, or one to one?

    - by conor
    I have developed an Android application where, typically, each view (layout.xml) displayed on the screen has it's own corresponding fragment (for the purpose of this question I may refer to this as a ViewController). These views and Fragments/ViewControllers are appropriately named to reflect what they display. So this has the effect of allowing the programmer to easily pinpoint the files associated with what they see on any given screen. The above refers to the one to one part of my question. Please note that with the above there are a few exceptions where very similar is displayed on two views so the ViewController is used for two views. (Using a simple switch (type) to determine what layout.xml file to load) On the flip side. I am currently working on the iOS version of the same app, which I didn't develop. It seems that they are adopting more of a one-to-many (ViewController:View) approach. There appears to be one ViewController that handles the display logic for many different types of views. In the ViewController are an assortment of boolean flags and arrays of data (to be displayed) that are used to determine what view to load and how to display it. This seems very cumbersome to me and coupled with no comments/ambiguous variable names I am finding it very difficult to implement changes into the project. What do you guys think of the two approaches? Which one would you prefer? I'm really considering putting in some extra time at work to refactor the iOS into a more 1:1 oriented approach. My reasoning for 1:1 over M:1 is that of modularity and legibility. After all, don't some people measure the quality of code based on how easy it is for another developer to pick up the reigns or how easy it is to pull a piece of code and use it somewhere else?

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  • Oracle OpenWorld Highlights

    - by Doug Reid
    We are in the final days of Oracle OpenWorld 2012 and the data integration team have been hard at work giving sessions, meeting customers, demonstrating product and conducting hands-on labs.    It has been a great conference, but the best part is meeting our customers and learning about all the great implementations of our products.  Wednesday was the last day that the exhibition hall was open and attendees were getting in their final opportunities to see our products and meet with the product management team.   Two hours before the close of the hall, people lined up to learn about GoldenGate 11gR2, Monitor, Adapters, Veridata, and all the different use cases.    Here's a picture of Sjaak Vossepoel, who is our DIS Sales Consulting Manager for EMEA speaking to a potential customer on the options of using Oracle GoldenGate for heterogenous data replication.  Over the last two days, the GoldenGate team ran two labs; Introduction to Oracle GoldenGate Veridata and Deep Dive into Oracle GoldenGate.   Both of the labs were completely booked out and unfortunately we had to turn away people.   BUT,  all of our labs were recorded recently so if you were not able to get into the lab or did not have enough time to complete your labs, visit youtube.com/oraclegoldengate to see a  complete recording of the labs we used at OpenWorld plus more.  Here are a couple pictures from the Deep Dive into Oracle GoldenGate lead by Chis Lawless from the Product Management team.   Thanks to the GoldenGate Hands-on Lab team for putting on a great session!!! We will post more information about where you can find additional details on OpenWorld as they become public.   

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  • Good design for class with similar constructors

    - by RustyTheBoyRobot
    I was reading this question and thought that good points were made, but most of the solutions involved renaming one of the methods. I am refactoring some poorly written code and I've run into this situation: public class Entity { public Entity(String uniqueIdentifier, boolean isSerialNumber) { if (isSerialNumber) { this.serialNumber = uniqueIdentifier; //Lookup other data } else { this.primaryKey = uniqueIdentifier; // Lookup other data with different query } } } The obvious design flaw is that someone needed two different ways to create the object, but couldn't overload the constructor since both identifiers were of the same type (String). Thus they added a flag to differentiate. So, my question is this: when this situation arises, what are good designs for differentiating between these two ways of instantiating an object? My First Thoughts You could create two different static methods to create your object. The method names could be different. This is weak because static methods don't get inherited. You could create different objects to force the types to be different (i.e., make a PrimaryKey class and a SerialNumber class). I like this because it seems to be a better design, but it also is a pain to refactor if serialNumber is a String everywhere else.

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  • alsa - sound issues on ubuntu 12.04

    - by tam_ubuuser
    i am having an sony E series laptop.i have an HDMI port .at this stage ,i have tested my sound card , which provides audio out on my laptop i.e i could hear songs .my laptop has two sound cards amd 5450 and an intel-hda(alsamixer shows that as s/pdif) . i decided to connect HDMI output to my new HD-TV.but, i could get only visuals on my TV,NO AUDIO OUTPUT ( HDMI cable works fine with win 7).my laptop has two sound cards.but i couldn't switch output to other card.( i don't know ,how to do that) i decided to update alsa. complied the following code in terminal. sudo apt-add-repository ppa:ubuntu-audio-dev/alsa-daily sudo apt-get update sudo apt-get install alsa-hda-dkms then,strangely no login sound, and no audio output on my laptop at all .then, started complied code from step1 sound troubleshooting procedure from offical ubuntu site.then, my speaker icon taskbar disappeared .obivously $aplay -l ,provided output as no soundcards detected . so , i implemented step 4 from that guide, it provides a output of all hardware devices in my laptop. *-multimedia UNCLAIMED description: Audio device product: Cedar HDMI Audio [Radeon HD 5400/6300 Series] vendor: Hynix Semiconductor (Hyundai Electronics) physical id: 0.1 bus info: pci@0000:01:00.1 version: 00 width: 64 bits clock: 33MHz capabilities: pm pciexpress msi bus_master cap_list configuration: latency=0 resources: memory:f0040000-f0043fff *-multimedia UNCLAIMED description: Audio device product: 5 Series/3400 Series Chipset High Definition Audio vendor: Intel Corporation physical id: 1b bus info: pci@0000:00:1b.0 version: 05 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: latency=0 resources: memory:f5e00000-f5e03fff that command displayed output name of the two cards . but , still i have no positive output on $aplay -l. so therfore, i think alsa couldn't detect my sound cards . is there solution to this problem? it could be better,if alsa would channel output from multiple sound cards ? how should install and configure alsa such that detects HDMI cable as soon i connect to my HD tv? is it possible to alsa and pluseaudio 2.0 to co-exist, if so how?

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  • How to Create tree type CVL in Content server(UCM)

    - by rajeev.y.ranjan-oracle
    Steps to create tree choice list:1)Create a table "tblStates" with column "stateID" and "stateName". Click on "ADD Recommended".2) Create another table "tblCities with columns "cityID", "stateID" and "cityName".3)Then create two views on these tables namely "tblstateview" and "tblcityview".3)In "StateView" added two rows with values as JH and MH in stateID column.Jharkhand and Maharastra in stateName.4)Similarly in tblcityview added two rows with values as:BO and RA in cityID column.JH and MH in stateID columnBokaro and Mumbai in cityname column.5)Created relationship with Parentinfo "tblStates" and stateID and  childinfo with tblCities and stateID.6)Created metadata by name "Newtest"Enable option list,go to the configure ,Select use tree,Click on go edit definition 7)Tree Definition at level 1: a)Choose" tblstateView"b)Choose relation "newstatecity"At Level2:a)Choose cityView.Log out of the NativeUI and ContentUI and test the tree created by name "Newtest".

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  • Prevent collisions between mobs/npcs/units piloted by computer AI : How to avoid mobile obstacles?

    - by Arthur Wulf White
    Lets says we have character a starting at point A and character b starting at point B. character a is headed to point B and character b is headed to point A. There are several simple ways to find the path(I will be using Dijkstra). The question is, how do I take preventative action in the code to stop the two from colliding with one another? case2: Characters a and b start from the same point in different times. Character b starts later and is the faster of the two. How do I make character b walk around character a without going through it? case3:Lets say we have m such characters in each side and there is sufficient room to pass through without the characters overlapping with one another. How do I stop the two groups of characters from "walking on top of one another" and allow them pass around one another in a natural organic way. A correct answer would be any algorithm, that given the path to the destination and a list of mobile objects that block the path, finds an alternative path or stops without stopping all units when there is sufficient room to traverse.

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  • error: no such partition after 11.10 upgrade to 12.04

    - by Alan King
    -I recently upgraded my 11.10 install to 12.04 LTS and got the above error message upon reboot after a GNU GRUB version ubuntu3 display showing Ubuntu 3.2.0-23-generic pae and other kernels or memory tests to choose from. The upgrade had to be done by CD because the Update Manager did not show the 12.04 upgrade option. After selecting the default install option of upgrading 11.10 to 12.04, I was presented with a screen saying that I had not specified a swap partition. Upon selection the 'back' key, I was taken to a partition page which listed two current partitions (only Ubuntu 11.10 had been installed - no Windoz): an ext4 partition plus a small 1.8GB partition. I double clicked the small partition and selected it as the swap partition even though I wondered at the time why this even came up. I can see the two user folders under home from the file manager screen while runnning 12.04 from the CD but if I try to access either one an error message is displayed saying I do not have permission while I get a loading message in the lower right corner of the window that does not go away. I have two questions: Can I access the user folders prior to recovery via the Terminal? If so, how? How do I fix the GRUB issue?

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  • Is using a dedicated thread just for sending gpu commands a good idea?

    - by tigrou
    The most basic game loop is like this : while(1) { update(); draw(); swapbuffers(); } This is very simple but have a problem : some drawing commands can be blocking and cpu will wait while he could do other things (like processing next update() call). Another possible solution i have in mind would be to use two threads : one for updating and preparing commands to be sent to gpu, and one for sending these commands to the gpu : //first thread while(1) { update(); render(); // use gamestate to generate all needed triangles and commands for gpu // put them in a buffer, no command is send to gpu // two buffers will be used, see below pulse(); //signal the other thread data is ready } //second thread while(1) { wait(); // wait for second thread for data to come send_data_togpu(); // send prepared commands from buffer to graphic card swapbuffers(); } also : two buffers would be used, so one buffer could be filled with gpu commands while the other would be processed by gpu. Do you thing such a solution would be effective ? What would be advantages and disadvantages of such a solution (especially against a simpler solution (eg : single threaded with triple buffering enabled) ?

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  • How can my team avoid frequent errors after refactoring?

    - by SDD64
    to give you a little background: I work for a company with roughly twelve Ruby on Rails developers (+/- interns). Remote work is common. Our product is made out of two parts: a rather fat core, and thin up to big customer projects built upon it. Customer projects usually expand the core. Overwriting of key features does not happen. I might add that the core has some rather bad parts that are in urgent need of refactorings. There are specs, but mostly for the customer projects. The worst part of the core are untested (as it should be...). The developers are split into two teams, working with one or two PO for each sprint. Usually, one customer project is strictly associated with one of the teams and POs. Now our problem: Rather frequently, we break each others stuff. Some one from Team A expands or refactors the core feature Y, causing unexpected errors for one of Team B's customer projects. Mostly, the changes are not announced over the teams, so the bugs hit almost always unexpected. Team B, including the PO, thought about feature Y to be stable and did not test it before releasing, unaware of the changes. How to get rid of those problems? What kind of 'announcement technique' can you recommend me?

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  • How could there still not be a mysqldb module for Python 3? [closed]

    - by itsadok
    This SO question is now more than two years old. MySQL is an incredibly popular database engine, Python is an incredibly popular programming language, and Python 3 has been officially released two years ago, and was available even before that. What's more, the whole mysqldb module is just a layer translating Python's db-api to MySQL's API. It's not that big of a library. I must be missing something here. How come almost* nobody in the entire open source community has spent the (I'm guessing) two weeks it takes to port this lib? Is Python 3 that unpopular? Is the combination of python and mysql not as common as I assume? Or maybe it's just a lot harder to port mysqldb than I assume? Anyone know the inside story on this? * Now I see that this guy has done it, which takes some of the wind out of my question, but it still seems to little and too late to make sense. EDIT: OK, I'm aware that the stock answers for these kind of questions cover this one as well. Patches welcome, scratch your itch, we don't work for you and we don't have the time, etc. I actually took a shot at porting this about a year ago, but it was my first time doing anything with Python C extensions, and I failed. My point in writing this was not a plea for somebody to write it, but genuine curiosity: it seems that some much more complicated libraries have been ported to python 3 already, and in the poll for which libraries should be ported, mysqldb is not even nominated! That suggests that maybe (2) is the right answer. UPDATE: I found that there are several new libraries that provide mysql support under Python 3, I just wasn't googling hard enough. That explains everything.

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  • Context switches much slower in new linux kernels

    - by Michael Goldshteyn
    We are looking to upgrade the OS on our servers from Ubuntu 10.04 LTS to Ubuntu 12.04 LTS. Unfortunately, it seems that the latency to run a thread that has become runnable has significantly increased from the 2.6 kernel to the 3.2 kernel. In fact the latency numbers we are getting are hard to believe. Let me be more specific about the test. We have a program that has two threads. The first thread gets the current time (in ticks using RDTSC) and then signals a condition variable once a second. The second thread waits on the condition variable and wakes up when it is signaled. It then gets the current time (in ticks using RDTSC). The difference between the time in the second thread and the time in the first thread is computed and displayed on the console. After this the second thread waits on the condition variable once more. So, we get a thread to thread signaling latency measurement once a second as a result. In linux 2.6.32, this latency is somewhere on the order of 2.8-3.5 us, which is reasonable. In linux 3.2.0, this latency is somewhere on the order of 40-100 us. I have excluded any differences in hardware between the two host hosts. They run on identical hardware (dual socket X5687 {Westmere-EP} processors running at 3.6 GHz with hyperthreading, speedstep and all C states turned off). We are changing the affinity to run both threads on physical cores of the same socket (i.e., the first thread is run on Core 0 and the second thread is run on Core 1), so there is no bouncing of threads on cores or bouncing/communication between sockets. The only difference between the two hosts is that one is running Ubuntu 10.04 LTS with kernel 2.6.32-28 (the fast context switch box) and the other is running the latest Ubuntu 12.04 LTS with kernel 3.2.0-23 (the slow context switch box). Have there been any changes in the kernel that could account for this ridiculous slow down in how long it takes for a thread to be scheduled to run?

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  • after BIOS splash, will not boot -- asks me to select an OS, but it just reboots

    - by user92040
    I'm running Linux Mint 13 MATE 64-bit. Everything has been working for several weeks. Yesterday, when I tried to boot up my computer, after the BIOS screen flashes I reach a screen with a black background that reads at the top: GNU GRUB version1.99-21ubuntu3.4 Then there is a box in which I can select from the following lines: Linux Mint 13 MATE 64-bit, 3.2.0-31-generic (/dev/sdb2) Linux Mint 13 MATE 64-bit, 3.2.0-31-generic (/dev/sdb2) -- recovery mode Previous Linux versions Memory test (memtest86+) Memory test (memtest86+, serial console 115200) At the bottom it reads: Use the ? and ? keys to select which entry is highlighed. Press enter to boot the selected OS, 'e' to edit the commands before booting or 'c' for a command-line. I have no idea why it started doing this and, worse, I have no idea how to get out of here. No matter which option I select, I can't get it to boot the OS. If I select either of the first two, it reboots to splash the BIOS and then I'm right back where I started. If I choose "Previous Linux versions" I get essentially the same screen with only two choices (which are the same as the first two choices listed above, Linux 13 MATE and the recovery mode). Again, choosing either one of those results in a reboot. If I try to run either of the memtest options, it reads: error: unknown command 'linux16', Press any key to continue... Then it brings me back to the same screen Can anyone help me please? Intel Core i5-2500 ASUS P8Z68-V LX Intel Motherboard G. Skill Ripjaws series F3-12800CL9D-8GBRL (4GB x2) Plextor 128GB M5S Series SSD

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  • WiFi problems on several Ubuntu installations

    - by Rickyfresh
    Okay this is the first time I have ever had to ask a question as usually the Ubuntu community have answered everything already but on this occasion there are many people asking for the answer but not one good solution has become available so far so someone please help or I will have to install Windows on my sons and my girlfriends PCs and that would be a disaster as I am trying to help convince people to move from Windows. I installed 12.04 on three computers on the same day. Dell Inspiron (Works Perfect) Toshiba Satellite Home built Desktop The Dell works perfect but the other two either keep losing connection to the wireless Internet and even when they are connected they stop connecting to web sites, for some reason it searches Google fine but will not connect to web sites when a link is clicked. So far people have recommended in other forums: Removing network manager and installing wicd (didn't solve it) Changing the MTU in the wireless settings (didn't solve it) All sorts of messing about with Firefox settings (this doesn't solve it and even if it did this would leave most average PC users scratching their heads and wishing they had stuck to windows) The problem exists on two very different machines and different wireless cards so I doubt its a driver or hardware issue, also many other Ubuntu users are having the same problem with a vast array of different machines and wireless cards. Can someone please give a good solution to this as its going to turn a lot of people away from Ubuntu if they cannot get this sorted. I would give some PC specs but the two machines are vastly different and the other people complaining of this problem also have very different systems all showing the same problem.

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  • How should VertexBuffers be used with Multiple Monitors in DirectX 9

    - by Joshua C
    I am currently using DirectX 9 on a machine with two GPUs and three monitors. I am currently trying to draw a triangle on each monitor using vertexbuffers; A directx helloworld with multiple monitors if you will. I am familiar with some DirectX coding, but new to multiple monitor DirectX coding. I may be going about this the wrong way, so please do correct me if I'm doing something wrong. I have created a Direct3D Device for each enumerated adapter sharing the same Form handle. This allows me to successfully use all three monitors in full-screen mode. For Each Adapter In Direct3D.Adapters Dim PresentParameters As New PresentParameters 'Setup PresentParameters PresentParameters.Windowed = False PresentParameters.DeviceWindowHandle = MainForm.Handle Dim Device as New Device(Direct3D, Adapter.Adapter, DeviceType.Hardware, PresentParameters.DeviceWindowHandle, CreateFlags.HardwareVertexProcessing, PresentParameters) Device.SetRenderState(RenderState.Lighting, False) Devices.Add(Device) Next I can also draw text to each device successfully using a different Font for each Device. When I render a triangle using a different VertexBuffer for each Device, only two monitors display the triangle. One of the two monitors on the same GPU, and the monitor on it's own GPU display properly. VertexBuffer = New VertexBuffer(Device, 4 * Marshal.SizeOf(GetType(ColoredVertex)), Usage.WriteOnly, VertexFormat.None, Pool.Managed) Dim Verts = VertexBuffer.Lock(0, 0, LockFlags.None) Verts.WriteRange({ New ColoredVertex(-.5, -.5, 1, ForeColor), New ColoredVertex(0, .5, 1, ForeColor), New ColoredVertex(.5, -.5, 1, ForeColor) }) VertexBuffer.Unlock() VertexDeclaration = New VertexDeclaration(Device, { New VertexElement(0, 0, DeclarationType.Float3, DeclarationMethod.Default, DeclarationUsage.Position, 0), New VertexElement(0, 12, DeclarationType.Color, DeclarationMethod.Default, DeclarationUsage.Color, 0), VertexElement.VertexDeclarationEnd }) Render Code: Device.SetStreamSource(0, VertexBuffer, 0, Marshal.SizeOf(GetType(ColoredVertex))) Device.VertexDeclaration = VertexDeclaration Device.DrawPrimitives(PrimitiveType.TriangleList, 0, 1) I have to assume the fact that they share the same physical card comes into play. Should I use multiple buffers on the same card, and if so, how? Or what is the way I should access the VertexBuffer across Devices? Another thought I had was the non working monitor acts like there are no lights. Is turning off lighting on each device on the same card causing issues somehow?

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