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• Multiple Audio Issues

  - by Lerp

  I am having issues with my audio on Ubuntu 12.04, I will try and give as much detail as possible so sorry if there's too much detail. The Problem Audio plays from both speakers and headphone regardless of what connector I choose and regardless of the profile I use. The microphone is constantly being played through headphones & speakers. The headphone audio is extremely quiet but plays from both ears when I select "Headphones" for the connector in Sound Settings. The headphone audio only plays from one ear and is quiet (but not as quiet as above) when I select "Analogue Output" for the connector in Sound Settings. I can only select "Headphones" as the connector in Sound Settings if I set the profile to either "Analogue Stereo Output/Duplex", all others only allow me to choose "Analogue Output" for the connector. Despite the headphone sound issues, the speaker sound is fine apart from the fact that I am not able to select which output is used, they just both play. My headphone and microphone are plugged into the front and my speakers are plugged into the back. What I have tried I have put everything in alsamixer to 100 apart from "Front Mic Boost" which I have set to 0. Command Output aplay -l **** List of PLAYBACK Hardware Devices **** card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog] Subdevices: 0/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 1: AD198x Digital [AD198x Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 2: AD198x Headphone [AD198x Headphone] Subdevices: 1/1 Subdevice #0: subdevice #0 arecord -l **** List of CAPTURE Hardware Devices **** card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog] Subdevices: 2/3 Subdevice #0: subdevice #0 Subdevice #1: subdevice #1 Subdevice #2: subdevice #2 cat /proc/asound/cards 0 [Intel ]: HDA-Intel - HDA Intel HDA Intel at 0xf7ff8000 irq 70 cat /proc/asound/modules 0 snd_hda_intel cat /proc/asound/card*/codec* | grep "Codec" Codec: Analog Devices AD1989B cat /etc/modprobe.d/alsa-base.conf # autoloader aliases install sound-slot-0 /sbin/modprobe snd-card-0 install sound-slot-1 /sbin/modprobe snd-card-1 install sound-slot-2 /sbin/modprobe snd-card-2 install sound-slot-3 /sbin/modprobe snd-card-3 install sound-slot-4 /sbin/modprobe snd-card-4 install sound-slot-5 /sbin/modprobe snd-card-5 install sound-slot-6 /sbin/modprobe snd-card-6 install sound-slot-7 /sbin/modprobe snd-card-7 # Cause optional modules to be loaded above generic modules install snd /sbin/modprobe --ignore-install snd $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-ioctl32 ; /sbin/modprobe --quiet --use-blacklist snd-seq ; } # # Workaround at bug #499695 (reverted in Ubuntu see LP #319505) install snd-pcm /sbin/modprobe --ignore-install snd-pcm $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-pcm-oss ; : ; } install snd-mixer /sbin/modprobe --ignore-install snd-mixer $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-mixer-oss ; : ; } install snd-seq /sbin/modprobe --ignore-install snd-seq $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; /sbin/modprobe --quiet --use-blacklist snd-seq-oss ; : ; } # install snd-rawmidi /sbin/modprobe --ignore-install snd-rawmidi $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; : ; } # Cause optional modules to be loaded above sound card driver modules install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-emu10k1-synth ; } install snd-via82xx /sbin/modprobe --ignore-install snd-via82xx $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq ; } # Load saa7134-alsa instead of saa7134 (which gets dragged in by it anyway) install saa7134 /sbin/modprobe --ignore-install saa7134 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist saa7134-alsa ; : ; } # Prevent abnormal drivers from grabbing index 0 options bt87x index=-2 options cx88_alsa index=-2 options saa7134-alsa index=-2 options snd-atiixp-modem index=-2 options snd-intel8x0m index=-2 options snd-via82xx-modem index=-2 options snd-usb-audio index=-2 options snd-usb-caiaq index=-2 options snd-usb-ua101 index=-2 options snd-usb-us122l index=-2 options snd-usb-usx2y index=-2 # Ubuntu #62691, enable MPU for snd-cmipci options snd-cmipci mpu_port=0x330 fm_port=0x388 # Keep snd-pcsp from being loaded as first soundcard options snd-pcsp index=-2 # Keep snd-usb-audio from beeing loaded as first soundcard options snd-usb-audio index=-2 Hopefully I have provided enough information, I will happily provide anymore information needed. Thank you. Update Reinstalling alsa-base and pulseaudio fixed the headphone issues I was having.

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• GNU Octave - question about graphs and plotting

  - by Twórca

  I've had task to do - to make an graphical interpretation of adding two functions together: sin(8x) and multiplied -sign(x) in Octave, as shown on image above. And I've done that, but I don't know how to get rid of these lines, which link up gaps between separated values (for example, -1 and 1). I don't want them to be seen especially in third graph. To make helping me easier, I'm going to tell you what I did: I made linear series of numbers, from -100 to 99 (tempx). tempy = -sign(tempx) y1 = [tempy tempy tempy tempy] (this line is kinda funny, if you know Polish language) Creating y2 - sinus function y3 = y2 + y1 Plotting, subplotting... Screenshot Awaiting for instructions...

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• Simple Math Multiplayer game - is Ajax sufficient?

  - by Christian Strang

  I'm planning to create a simple math multiplayer game and I plan to just use Ajax for the server/client communication but I'm not sure if this is sufficient or if I need a socket server. The game will look like this: 2-4 users all get a simple math task (like: "37 + 14") they have to solve it as fast as possible first user who solves it is the winner I will track the time for each user, since the game started, on the client side and everytime a user gives an answer, the answer and the passed time will be send to the server. Additionally I'll add a function which will check every 3 seconds if the other users finished, how much time they needed and who won. Do you think this is possible just using Ajax? What alternatives are there?

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• What's the most effective way to perform code reviews?

  - by Paddyslacker

  I've never found the ideal way to perform code reviews and yet often my customers require them. Each customer seems to do them in a different way and I've never felt satisfied in any of them. What has been the most effective way for you to perform code reviews? For example: Is one person regarded as the gatekeeper for quality and reviews the code, or do the team own the standard? Do you do review code as a team exercise using a projector? Is it done in person, via email or using a tool? Do you eschew reviews and use things like pair programming and collective code ownership to ensure code quality?

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• Level and Player objects - which should contain which?

  - by Thane Brimhall

  I've been working on a several simple games, and I've always come to a decision point where I have to choose whether to have the Level object as an attribute of the Player class or the Player as an attribute of the Level class. I can see arguments for both: The Level should contain the player because it also contains every other entity. In fact it just makes sense this way: "John is in the room." It makes it a bit more difficult to move the player to a new level, however, because then each level has to pass its player object to an upcoming level. On the other hand, it makes programming sense to me to leave the player as the top-level object that is persistent between levels, and the environment changes because the player decides to change his level and location. It becomes very easy to change levels, because all I have to do is replace the level variable on the player. What's the most common practice here? Or better yet, is there a "right" way to architecture this relationship?

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• In which object should I implement wait()/notify()?

  - by Christopher Francisco

  I'm working in an Android project with multithreading. Basically I have to wait to the server to respond before sending more data. The data sending task is delimited by the flag boolean hasServerResponded so the Thread will loop infinitely without doing anything until the flag becomes true. Since this boolean isn't declared as volatile (yet), and also looping without doing anything wastes resources, I thought maybe I should use AtomicBoolean and also implement wait() / notify() mechanism. Should I use the AtomicBoolean object notify() and wait() methods or should I create a lock Object?

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• Which tips helped you learn touch-typing? [closed]

  - by julien

  I've been learning touch-typing for about two weeks now, and I'm really commited to mastering this skill. Eventhough I'm doing ok with prose already, I'm struggling with programming syntax and even more with keybindings. Those stray you away from the home row more than regular words, and aren't as easy to practice. So I often hunt and peck in order to just get it out, but when reverting to old habits like this, I find it hard to get back into the touch-typing mindframe quickly. One little trick that has helped me so far when getting lost is to reposition every finger on its home row key, and mentally visualize the layout bias of the keyboard, ie the backslash kind of alignment of key columns. It's hard to describe though and probably a bit weird... Hope you guys have better tips !

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• Aren't there compilers better at telling the programmer what's wrong in a code ?

  - by jokoon

  I have worked a little while with the Microsoft compiler from Visual C++ but I worked a long time with G++, and I remember often having bad times understanding what was wrong in my code with the former. Beside binary code generation and optimisation, I think this is a very important feature of a C++ compiler: giving the programmer a clue that makes him understand as fast as possible what is wrong with his/her code. I can understand some programmers understand programming as some sort of "competition" to make less errors, but to me that's a counter productive opinion. I once tried Clang compiler for C from the LLVM thingie, I didn't use it for a long time, but I was impressed on how explicit and easy to understand the error messages were. What are your experiences, and how do you think this matters ? Some WIP of C++ Clang: http://clang.llvm.org/cxx_status.html

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• Which version of ubuntu is compatible with ACER Aspire 5732Z?

  - by Mehdi Bateni

  I have an ACER Aspire 5732Z Laptop, and 6 days ago I have installed Ubuntu 11.10 on my laptop, But I found black screen in login. I have tried a lot of ways to solve this problem, but there is no way. So can you tell me which version is compatible with this ACER Aspire (5732Z)? Detail: Intel-Pentium-processor T4400 (2.2 GHz, 800 MHz FSB), Intel-GMA 4500M, 15.6" HD LCD, 2GB Memory, 320 GB HDD, Acer Nplify(TM) 802.11b/g/n. Thank You. .. And finally, I found that Linux Mint is best for my ACER-ASPIRE5732Z. It is also compatible with Ubuntu codes, because as I know it is base on Ubuntu.

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• When should one use the Abstract, Implements, or extends keywords?

  - by kdavis8

  I'm just now moving from a beginner to intermediate level android programmer in the java language. i can successfully write a game framework of classes that work together to accomplish a task beyond basic things, like hello world. but i'm having issues with some pretty basic OOP concepts; When should i derive from an abstract class? When is it more efficient to use an Interface instead of simply sub classing a parent? Basically, between extends, implements, and the abstract keywords, which keywords should be used instead of the others? i'm not looking for a basic definition, as i know them. i need to no when and why i should apply them to my code? what advantages does one have over the other? which is best for game development?

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• SEO and Spelling mistakes in keyword

  - by Sushil

  I am about to register a domain name (suppose) someone.com (with proper spelling), in mind targeting the keyword "SOMEONE". But then I discovered on 'google keyword research tool' that not this but a typo "SOME1" seems to be more popular and people search this significantly more often than the proper keyword. And luckily someone.com and some1.com both are available. I understand that I can register both the domains, but I don't know on which should I keep my website and redirect the other one. Should I make the typo "some1.com" my base site? But that's a typo. P.S., my site has a totally relevant content and not just keyword targeted worthless site. What do you guys suggest? I am confused. How would that affect my SEO ranking?? EDIT: Because the competition for the keyword I am targeting is fairly low, I think nevertheless whatever domain I choose, it will appear on the search engine first page.

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• How to create a reasonably sized urban area manually but efficiently

  - by Overv

  I have a game concept that only really works in an urban area that is of reasonable scale and diversity. In terms of what it should look like, think GTA, in terms of the size think more like a small neighbourhood with residents and a few local shops, perhaps a supermarket. I'm mostly experienced in programming and not at all with modelling, texturing or drawing, but I've found that SketchUp allows me to design interesting looking buildings that I model after real world buildings in my own neighbourhood. Designing these buildings and other objects can take from a few tens of minutes to a few hours. My question is: what is the best approach for a one man army like me who does manage to model buildings to create an interesting city environment in a reasonable amount of time? My game will not be based on procedural generation, the environment will actually be modelled like GTA cities.

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• How To Use Flash on Any Website in Modern Internet Explorer 10

  - by Chris Hoffman

  The modern (or “Metro”) version of Internet Explorer in Windows 8 supports Flash, but only for some Microsoft-approved websites. You can add your own favorite websites to Microsoft’s whitelist to view Flash on any website. The desktop version of IE supports Flash on every website, but you don’t have to leave the new Windows 8 user interface if you don’t want to. This trick works on both Windows 8 and Windows RT. What Is the Purpose of the “Do Not Cover This Hole” Hole on Hard Drives? How To Log Into The Desktop, Add a Start Menu, and Disable Hot Corners in Windows 8 HTG Explains: Why You Shouldn’t Use a Task Killer On Android

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• Which numeral systems are useful in computer science?

  - by authchir

  I am wondering which numeral system different programmers are using, or would use if their language has support for them. As an example, in C++ we can use: Octal by prefixing with 0 (e.g. 0377) Decimal by default (e.g. 255) Hexadecimal by prefixing with 0x (e.g. 0xff) When working with bitmask, I am using hexadecimal but would sometimes want to be able to express binary numbers directly. I know some programming language support it with 0b syntax (e.g. 0b11111111). Is there any other numeric system useful in some computer science domain (e.g. cryptography, codecs, 3D graphics, etc)?

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• 7 Steps To Cut Recruiting Costs & Drive Exceptional Business Results

  - by Oracle Accelerate for Midsize Companies

  By Steve Viarengo, Vice President Product Management, Oracle Taleo Cloud Services  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 In good times, trimming operational costs is an ongoing goal. In tough times, it’s a necessity. In both good times and bad, however, recruiting occurs. Growth increases headcount in good times, and opportunistic or replacement hiring occurs in slow business cycles. By employing creative recruiting strategies in tandem with the latest technology developments, you can reduce recruiting costs while driving exceptional business results. Here are some critical areas to focus on. 1.  Target Direct Cost Savings Total recruiting process expenses are the sum of external costs plus internal labor costs. Most organizations can reduce recruiting expenses with direct cost savings. While additional savings on indirect costs can be realized from process improvement and efficiency gains, there are direct cost savings and benefits readily available in three broad areas: sourcing, assessments, and green recruiting. 2. Sourcing: Reduce Agency Costs Agency search firm fees can amount to 35 percent of a new employee’s annual base salary. Typically taken from the hiring department budget, these fees may not be visible to HR. By relying on internal mobility programs, referrals, candidate pipelines, and corporate career Websites, organizations can reduce or eliminate this agency spend. And when you do have to pay third-party agency fees, you can optimize the value you receive by collaborating with agencies to identify referred candidates, ensure access to candidate data and history, and receive automatic notifications and correspondence. 3. Sourcing: Reduce Advertising Costs You can realize significant cost reductions by placing all job positions on your corporate career Website. This will allow you to reap a substantial number of candidates at minimal cost compared to job boards and other sourcing options. 4.  Sourcing: Internal Talent Pool Internal talent pools provide a way to reduce sourcing and advertising costs while delivering improved productivity and retention. Internal redeployment reduces costs and ramp-up time while increasing retention and employee satisfaction. 5.  Sourcing: External Talent Pool Strategic recruiting requires identifying and matching people with a given set of skills to a particular job while efficiently allocating sourcing expenditures. By using an e-recruiting system (which drives external talent pool management) with a candidate relationship database, you can automate prescreening and candidate matching while communicating with targeted candidates. Candidate relationship management can lower sourcing costs by marketing new job opportunities to candidates sourced in the past. By mining the talent pool in this fashion, you eliminate the need to source a new pool of candidates for each new requisition. Managing and mining the corporate candidate database can reduce the sourcing cost per candidate by as much as 50 percent. 6.  Assessments: Reduce Turnover Costs By taking advantage of assessments during the recruitment process, you can achieve a range of benefits, including better productivity, superior candidate performance, and lower turnover (providing considerable savings). Assessments also save recruiter and hiring manager time by focusing on a short list of qualified candidates. Hired for fit, such candidates tend to stay with the organization and produce quality work—ultimately driving revenue.  7. Green Recruiting: Reduce Paper and Processing Costs You can reduce recruiting costs by automating the process—and making it green. A paperless process informs candidates that you’re dedicated to green recruiting. It also leads to direct cost savings. E-recruiting reduces energy use and pollution associated with manufacturing, transporting, and recycling paper products. And process automation saves energy in mailing, storage, handling, filing, and reporting tasks. Direct cost savings come from reduced paperwork related to résumés, advertising, and onboarding. Improving the recruiting process through sourcing, assessments, and green recruiting not only saves costs. It also positions the company to improve the talent base during the recession while retaining the ability to grow appropriately in recovery. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";}

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• I studied electrical engineering. Can I work as a developer? [closed]

  - by FailedDev

  A while ago I finished my Msc in Electrical Engineering and started working as an engineering consultant where I mostly do development work. I am good at picking up languages/technologies tools. I have fiddled with C/C++/C#/perl/ant/bash/html/css etc. Although I have never had a complain for my work, rather the contrary, I just feel that some day, someone will ask me a real hard task which would maybe seem rather trivial for a computer scientist but hard for me. Should I read/do something to become a better developer. Should I pick up a book about design patterns or algorithms for example? Is this normal that I have this kind of "fear"? Sorry if this is the wrong place to post this question. Please notify me so I can close it if this is the case.

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• Why does a computer science degree matter to a professional programmer?

  - by P.Brian.Mackey

  I have a degree in computer science. It has been great for opening doors, getting a job. As far as helping me in the professional field of C# .NET programming (the most popular platform and language in the area I work if not the entire united states on hands down the most popular OS in the world) its hardly useful. Why do you think it helps you as a programmer in your professional career (outside spouting off to prims algorithm to impress some interviewer)? In today's world adaptation, a quick mind, strong communication, OO and fundamental design skills enable a developer to write software that a customer will accept. These skills are only skimmed over in the cs program. In my mind, reading a 500 page C# book by Wrox offers far more useable a skillset than 4 years of the comp sci math blaster courses. Many disagree. So, why does a computer science degree matter?

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• How to Implement a Parallel Workflow

  - by Paul

  I'm trying to implement a parallel split task using a workflow system. I'm using .NET but my process is very simple and I don't want to use WF or anything heavy like that. I've tried using Stateless. So far is was easy to set up and run, but I may be using the wrong tool for the job because I'm not sure how you're supposed to model parallel split workflows, where you have multiple sub-tasks required before you can advance to the next state, but the steps don't require being performed in any particular order. I can easily use the dynamic configuration options to check my data model manually to see if the model is in the correct state (all sub-tasks completed) and can transition to the next state, but this seems to completely break the workflow paradigm. What is the proper, orthodox way to implement a parallel split process? Thanks

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• API design and versioning using EJB

  - by broschb

  I have an API that is EJB based (i.e. there are remote interfaces defined) that most of the clients use. As the client base grows there are issues with updates to the API and forcing clients to have to update to the latest version and interface definition. I would like to possibly look at having a couple versions of the API deployed at a time (i.e. have multiple EAR files deployed with different versions of the API) to support not forcing the clients to update as frequently. I am not concerned about the actual deployment of this, but instead am looking for thoughts and experiences that others have on using EJB's as an API client. How do you support updating versions, are clients required to update? Does anyone run multiple versions in a production environment? Are there pro's cons? Any other experiences or thoughts on this approach, and having an EJB centric API?

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• How to make a great functional specification

  - by sfrj

  I am going to start a little side project very soon, but this time i want to do not just the little UML domain model and case diagrams i often do before programming, i thought about making a full functional specification. Is there anybody that has experience writing functional specifications that could recommend me what i need to add to it? How would be the best way to start preparing it? Here i will write down the topics that i think are more relevant: Purpose Functional Overview Context Diagram Critical Project Success Factors Scope (In & Out) Assumptions Actors (Data Sources, System Actors) Use Case Diagram Process Flow Diagram Activity Diagram Security Requirements Performance Requirements Special Requirements Business Rules Domain Model (Data model) Flow Scenarios (Success, alternate…) Time Schedule (Task Management) Goals System Requirements Expected Expenses What do you think about those topics? Shall i add something else? or maybe remove something?

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• Using dot To Access Object Attribute and Proper abstraction

  - by cobie

  I have been programming in python and java for quite a number of years and one thing i find myself doing is using the setters and getters from java in python but a number of blogs seem to think using the dot notation for access is the pythonic way. What I would like to know is if using dot to access methods does not violate abstraction principle. If for example I implement an attribute as a single object and use dot notation to access, if I wanted to change the code later so that the attribute is represented by a list of objects, that would require quite some heavy lifting which violates abstraction principle.

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• Having MSc or Bsc with Experience, whats worth in industrial environments?

  - by Abimaran

  I'm a fresh graduate in Electronic & Telecommunication field, and in our University, we can have major and minor fields in the relevant subjects. So, I majored in telecommunication and minored in Software Engineering. As I learned programing long before, Now I'm passionate in SE and programming. And, I want drive into the SE field. And, It came to know that, in industries, most of them expecting the candidates to have the Bsc + experience of two+ years, or having a MSc in the related field. [I'm referring my surrounding environment, not all the industries]. My Question, How do they consider those MSc and BSc + experience guys in the industries? IMO, having MSc is great assert with comparing to have experience. Because, in the industry, you can drive in a particular technology (Java, .Net or some thing else), not all, and with MSc, we can get the domain knowledge, not a particular technology! Thanks!

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• Alternative to "inheritance v composition??"

  - by Frank

  I have colleagues at work who claim that "Inheritance is an anti-pattern" and want to use composition systematically instead, except in (rare, according to them) cases where inheritance is really the best way to go. I want to suggest an alternative where we continue using inheritance, but it is strictly forbidden (enforced by code reviews) to use anything but public members of base classes in derived classes. For a case where we don't need to swap components of a class at runtime (static inheritance), would that be equivalent enough to composition? Or am I forgetting some other important aspect of composition?

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• Forking project on Github etiquette

  - by Mike Wills

  There is a project on Github that I mostly like and want to use. There are a few things I want to do differently/remove that doesn't make sense for what I want/need. Also I want to add a few things as well. As I understand it, I should fork the project and I can make whatever changes I want and push back to my fork. From there, I also want to occasionally pull into my fork the changes from the original project so I get the latest bug fixes/features. Am I off-base of how I think it should work? How would bring in the changes from the original project?

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• Inside BackgroundWorker

  - by João Angelo

  The BackgroundWorker is a reusable component that can be used in different contexts, but sometimes with unexpected results. If you are like me, you have mostly used background workers while doing Windows Forms development due to the flexibility they offer for running a background task. They support cancellation and give events that signal progress updates and task completion. When used in Windows Forms, these events (ProgressChanged and RunWorkerCompleted) get executed back on the UI thread where you can freely access your form controls. However, the logic of the progress changed and worker completed events being invoked in the thread that started the background worker is not something you get directly from the BackgroundWorker, but instead from the fact that you are running in the context of Windows Forms. Take the following example that illustrates the use of a worker in three different scenarios: – Console Application or Windows Service; – Windows Forms; – WPF. using System; using System.ComponentModel; using System.Threading; using System.Windows.Forms; using System.Windows.Threading; class Program { static AutoResetEvent Synch = new AutoResetEvent(false); static void Main() { var bw1 = new BackgroundWorker(); var bw2 = new BackgroundWorker(); var bw3 = new BackgroundWorker(); Console.WriteLine("DEFAULT"); var unspecializedThread = new Thread(() => { OutputCaller(1); SynchronizationContext.SetSynchronizationContext( new SynchronizationContext()); bw1.DoWork += (sender, e) => OutputWork(1); bw1.RunWorkerCompleted += (sender, e) => OutputCompleted(1); // Uses default SynchronizationContext bw1.RunWorkerAsync(); }); unspecializedThread.IsBackground = true; unspecializedThread.Start(); Synch.WaitOne(); Console.WriteLine(); Console.WriteLine("WINDOWS FORMS"); var windowsFormsThread = new Thread(() => { OutputCaller(2); SynchronizationContext.SetSynchronizationContext( new WindowsFormsSynchronizationContext()); bw2.DoWork += (sender, e) => OutputWork(2); bw2.RunWorkerCompleted += (sender, e) => OutputCompleted(2); // Uses WindowsFormsSynchronizationContext bw2.RunWorkerAsync(); Application.Run(); }); windowsFormsThread.IsBackground = true; windowsFormsThread.SetApartmentState(ApartmentState.STA); windowsFormsThread.Start(); Synch.WaitOne(); Console.WriteLine(); Console.WriteLine("WPF"); var wpfThread = new Thread(() => { OutputCaller(3); SynchronizationContext.SetSynchronizationContext( new DispatcherSynchronizationContext()); bw3.DoWork += (sender, e) => OutputWork(3); bw3.RunWorkerCompleted += (sender, e) => OutputCompleted(3); // Uses DispatcherSynchronizationContext bw3.RunWorkerAsync(); Dispatcher.Run(); }); wpfThread.IsBackground = true; wpfThread.SetApartmentState(ApartmentState.STA); wpfThread.Start(); Synch.WaitOne(); } static void OutputCaller(int workerId) { Console.WriteLine( "bw{0}.{1} | Thread: {2} | IsThreadPool: {3}", workerId, "RunWorkerAsync".PadRight(18), Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread); } static void OutputWork(int workerId) { Console.WriteLine( "bw{0}.{1} | Thread: {2} | IsThreadPool: {3}", workerId, "DoWork".PadRight(18), Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread); } static void OutputCompleted(int workerId) { Console.WriteLine( "bw{0}.{1} | Thread: {2} | IsThreadPool: {3}", workerId, "RunWorkerCompleted".PadRight(18), Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread); Synch.Set(); } } Output: //DEFAULT //bw1.RunWorkerAsync | Thread: 3 | IsThreadPool: False //bw1.DoWork | Thread: 4 | IsThreadPool: True //bw1.RunWorkerCompleted | Thread: 5 | IsThreadPool: True //WINDOWS FORMS //bw2.RunWorkerAsync | Thread: 6 | IsThreadPool: False //bw2.DoWork | Thread: 5 | IsThreadPool: True //bw2.RunWorkerCompleted | Thread: 6 | IsThreadPool: False //WPF //bw3.RunWorkerAsync | Thread: 7 | IsThreadPool: False //bw3.DoWork | Thread: 5 | IsThreadPool: True //bw3.RunWorkerCompleted | Thread: 7 | IsThreadPool: False As you can see the output between the first and remaining scenarios is somewhat different. While in Windows Forms and WPF the worker completed event runs on the thread that called RunWorkerAsync, in the first scenario the same event runs on any thread available in the thread pool. Another scenario where you can get the first behavior, even when on Windows Forms or WPF, is if you chain the creation of background workers, that is, you create a second worker in the DoWork event handler of an already running worker. Since the DoWork executes in a thread from the pool the second worker will use the default synchronization context and the completed event will not run in the UI thread.

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