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• Do database tables need to have IDs?

  - by Arturas M

  Is an ID field is always needed in database tables? In my case I have a user with firstName, lastName and email fields. email is unique and not null, so it could be used as an ID, right? So in that case, could/should I try to remove the ID? Also I want to have another table which extends this one. Let's say its called patient and it has it's own field additionalData and I would like to link the relationship through the email of user I mentioned. So the relationship should be 1 to 1, right? and I wouldn't need the IDs? Somehow MySQL Workbench wants me to use the IDs. What do you guys think. Any suggestions on this topic?

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• Whats the thing the report bugs in php?

  - by Max Hazard

  Currently I am learning php. Php is understood by browser itself right from php sdk right? SDK include libraries right? So browser is like an interpreter of php codes. I want to know that whenever I type a wrong php syntax what is the thing report me the error? Obviously the browser is reporting the error. But what part of it? I mean I don't get it. Like writing a compiler we do lexical analysis and make the compiler which report any bug in source code. I assume here browser is analogous to compiler. I don't know exactly but compiler contains bug report functions or methods which is debugger. Debugger is part of compiler which report bugs. Does the browser contains such debuggers? Can there be any browser which doesn't understand php?

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• Synchronizing local and remote cache in distributed caching

  - by ltfishie

  With a distributed cache, a subset of the cache is kept locally while the rest is held remotely. In a get operation, if the entry is not available locally, the remote cache will be used and and the entry is added to local cache. In a put operation, both the local cache and remote cache are updated. Other nodes in the cluster also need to be notified to invalidate their local cache as well. What's a simplest way to achieve this if you implemented it yourself, assuming that nodes are not aware of each other. Edit My current implementation goes like this: Each cache entry contains a time stamp. Put operation will update local cache and remote cache Get operation will try local cache then remote cache A background thread on each node will check remote cache periodically for each entry in local cache. If the timestamp on remote is newer overwrite the local. If entry is not found in remote, delete it from local.

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• How to use OO for data analysis? [closed]

  - by Konsta

  In which ways could object-orientation (OO) make my data analysis more efficient and let me reuse more of my code? The data analysis can be broken up into get data (from db or csv or similar) transform data (filter, group/pivot, ...) display/plot (graph timeseries, create tables, etc.) I mostly use Python and its Pandas and Matplotlib packages for this besides some DB connectivity (SQL). Almost all of my code is a functional/procedural mix. While I have started to create a data object for a certain collection of time series, I wonder if there are OO design patterns/approaches for other parts of the process that might increase efficiency?

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• Quickly compute added and removed lines

  - by Philippe Marschall

  I'm trying to compare two text files. I want to compute how many lines were added and removed. Basically what git diff --stat is doing. Bonus points for not having to store the entire file contents in memory. The approach I'm currently having in mind is: read each line of the old file compute a hash (probably MD5 or SHA-1) for each line store the hashes in a set do the same for each line in the new file every hash from the old file set that's missing in the new file set was removed every hash from the new file set that's missing in the old file set was added I'll probably want to exclude empty and all white space lines. There is a small issue with duplicated lines. This can either be solved by additionally storing how often a hash appears or comparing the number of lines in the old and new file and adjust either the added or removed lines so that the numbers add up. Do you see room for improvements or a better approach?

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• Teaching programming (languages) in central/northern Europe

  - by canavanin

  I hope this question is not going to be off-topic; in case you think there'd be a better place to ask it, please let me know. Anyway, I'm currently doing my PhD working in bioinformatics. I would, however, like to turn away from academia eventually and instead go into teaching programming or, preferably, programming languages (e.g. Perl, which feels like my "mother tongue"...) - not as a school teacher, but with a company (in Germany or Scandinavia). It'll take me another one to one and a half years to complete my PhD, so I would like to know how I could/should use that time to raise my chances of getting into the profession I'd be interested in. Are there any Perl certificates I should aim to obtain, for example? In case there's anything that comes to mind when reading this, please let me know. Thanks a lot in advance!

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• Can a NodeJS webserver handle multiple hostnames on the same IP?

  - by Matthew Patrick Cashatt

  I have just begun learning NodeJS and LOVE it so far. I have set up a Linux box to run it and, in learning to use the event-driven model, I am curious if I can use a common IP for multiple domain names. Could I point, for example, www.websiteA.com, www.websiteB.com, and www.websiteC.com all to the same IP (node webserver) and then route to the appropriate source files based on the request? Would this cause certain doom when it came to scaling to any reasonable size?

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• Is Query Performance different for different versions of SQL Server?

  - by Ronak Mathia

  I have fired 3 update queries in my stored procedure for 3 different tables. Each table contains almost 2,00,000 records and all records have to be updated. I am using indexing to speed up the performance. It quite working well with SQL Server 2008. stored procedure takes only 12 to 15 minutes to execute. (updates almost 1000 rows in 1 second in all three tables) But when I run same scenario with SQL Server 2008 R2 then stored procedure takes more time to complete execution. its about 55 to 60 minutes. (updates almost 100 rows in 1 second in all three tables). I couldn't find any reason or solution for that. I have also tested same scenario with SQL Server 2012. but result is same as above. Please give suggestions.

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• Very simple OOP question

  - by Mosty Mostacho

  I was creating and discussing a class diagram with a partner of mine. To simplify things, I've modify the real domain we're working on and made up the following diagram: Basically, a company works on constructions that are quite different one from each other but are still constructions. Note I've added one field for each class but there should be many more. Now, I thought this was the way to go but my partner told me that if in the future new construction classes appear we would have to modify the Company class, which is correct. So the new proposed class diagram would be this: Now I've been wondering: Should the fact that in no place of the application will there be mixed lists of planes and bridges affect the design in any way? When we have to list only planes for a company, how are we supposed to distinguish them from the other elements in the list without checking for their class names? Related to the previous question, is it correct to assume that this type of diagram should be high-level and this is something it shouldn't matter at this stage but rather be thought and decided at implementation time? Any comment will be appreciated.

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• Commercial product using a GPL OS

  - by pfried

  we are planning to create a commercial product. The product consists of come MCUs and a small computer (we are developping on a raspberry pi at the moment). The computer needs an operating system as we would like keep things like WLAN and booting as simple as possible. We create some software running on this computer (node.js application). The most operating systems like Arch Linux are licenced under the GPL. The product we would sell contains the computer with preinstalled OS and software. This system operates as a central access point to MCU devices and is able to control them. We use other's software in our product. We do not modify their source code. The product (the computer part) consists of a computer, an OS and software we create. How does the use of an OS affect our own code (licence)? Is there a possibility of avoiding GPL for our own code? eg. shipping the software seperated? Are there any effects to other components of our product, eg. the MCU part? The node.js application delivers a WebApp to the client where it is executed. Are there any effects (As we would like to sell parts of the code as an additional App on the App Stores)? I know we make use of the work of the community and i respect this. The problem is: The software alone is kind of useless without the MCU devices. I do not expect a legal advice.

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• How do I create my own programming language and a compiler for it

  - by Dave

  I am thorough with programming and have come across languages including BASIC, FORTRAN, COBOL, LISP, LOGO, Java, C++, C, MATLAB, Mathematica, Python, Ruby, Perl, JavaScript, Assembly and so on. I can't understand how people create programming languages and devise compilers for it. I also couldn't understand how people create OS like Windows, Mac, UNIX, DOS and so on. The other thing that is mysterious to me is how people create libraries like OpenGL, OpenCL, OpenCV, Cocoa, MFC and so on. The last thing I am unable to figure out is how scientists devise an assembly language and an assembler for a microprocessor. I would really like to learn all of these stuff and I am 15 years old. I always wanted to be a computer scientist someone like Babbage, Turing, Shannon, or Dennis Ritchie. I have already read Aho's Compiler Design and Tanenbaum's OS concepts book and they all only discuss concepts and code in a high level. They don't go into the details and nuances and how to devise a compiler or operating system. I want a concrete understanding so that I can create one myself and not just an understanding of what a thread, semaphore, process, or parsing is. I asked my brother about all this. He is a SB student in EECS at MIT and hasn't got a clue of how to actually create all these stuff in the real world. All he knows is just an understanding of Compiler Design and OS concepts like the ones that you guys have mentioned (i.e. like Thread, Synchronization, Concurrency, memory management, Lexical Analysis, Intermediate code generation and so on)

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• Solutions for software using many calls to a server

  - by Val

  I am developing software that uses many calls to a server. On a client side it's a Silverlight application. Almost every time a user clicks on a button in it, it sends 1-5 WCF calls to a server. There can be up to dozen or so users at a time. The server is a database server that serves data to a client. I am an intermediate level developer and am thinking about caching some data and syncing my changes from time to time. Are there any official solutions or technologies for it, like, patterns and such?

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• Is there an alternative to HTML Web Sockets, now that Firefox 4 has disabled them?

  - by Pino

  I've been checking out some of the latest multiplayer engines in HTML all supporting multi-user games (Very nice) - I believe all these engines use Web Sockets for communication. That’s why we’ve decided to disable support for WebSocket in Firefox 4, starting with beta 8 due to a protocol-level security issue. Beta 7 of Firefox has support for the -76 version of the protocol, the same version that’s included with Chrome and Safari. Beta 8 of Firefox 4 will remove that support. Anne van Kesteren of Opera also announced that Opera are dropping Websocket support. We are confident that other browser developers will follow. Source: Websockets Disabled in FireFox 4 I've just come accross the above, so no sockets in Firefox 4 or Opera.... thats big. Is anyone aware of an alternate or is it Chrome or do we need to just sit and wait for the next release of the major browsers. More info : Rocket Engine appears to work with all browsers including IE8 (http://rocketpack.fi/engine/) what will it be using as a method of communication?

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• Do you test your SQL/HQL/Criteria ?

  - by 0101

  Do you test your SQL or SQL generated by your database framework? There are frameworks like DbUnit that allow you to create real in-memory database and execute real SQL. But its very hard to use(not developer-friendly so to speak), because you need to first prepare test data(and it should not be shared between tests). P.S. I don't mean mocking database or framework's database methods, but tests that make you 99% sure that your SQL is working even after some hardcore refactoring.

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• JS closures - Passing a function to a child, how should the shared object be accessed

  - by slicedtoad

  I have a design and am wondering what the appropriate way to access variables is. I'll demonstrate with this example since I can't seem to describe it better than the title. Term is an object representing a bunch of time data (a repeating duration of time defined by a bunch of attributes) Term has some print functionality but does not implement the print functions itself, rather they are passed in as anonymous functions by the parent. This would be similar to how shaders can be passed to a renderer rather than defined by the renderer. A container (let's call it Box) has a Schedule object that can understand and use Term objects. Box creates Term objects and passes them to Schedule as required. Box also defines the print functions stored in Term. A print function usually takes an argument and uses it to return a string based on that argument and Term's internal data. Sometime the print function could also use data stored in Schedule, though. I'm calling this data shared. So, the question is, what is the best way to access this shared data. I have a lot of options since JS has closures and I'm not familiar enough to know if I should be using them or avoiding them in this case. Options: Create a local "reference" (term used lightly) to the shared data (data is not a primitive) when defining the print function by accessing the shared data through Schedule from Box. Example: var schedule = function(){ var sched = Schedule(); var t1 = Term( function(x){ // Term.print() return (x + sched.data).format(); }); }; Bind it to Term explicitly. (Pass it in Term's constructor or something). Or bind it in Sched after Box passes it. And then access it as an attribute of Term. Pass it in at the same time x is passed to the print function, (from sched). This is the most familiar way for my but it doesn't feel right given JS's closure ability. Do something weird like bind some context and arguments to print. I'm hoping the correct answer isn't purely subjective. If it is, then I guess the answer is just "do whatever works". But I feel like there are some significant differences between the approaches that could have a large impact when stretched beyond my small example.

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• Who does code coverage testing?

  - by Athiruban

  Recently, I was given an opportunity to increase the code coverage in a project based on Java Swing, MySQL and other technologies. They told me to bring the code coverage to 100%, while it was only 45% at the time I joined. I am just starting, not a professional developer, right from the beginning I felt bad even though I write and understand computer programs well. (The developed code contains a lot of technical stuff like Generics and no documentation about the code is available.) Has anyone experienced the same situation before? Please tell who is the right person to do the job.

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• How to host a site in another site - with little or no coding

  - by tunmise fasipe

  SUMMARY: All of these happens on Site A User visits site A User enter username and password User click on Login Button User authenticated on Site B behind the scene User is shown a page on Site A that contains his/her profile from Site B as layout/styled from Site B User can click links in the Profile page that links to other area in Site B Meaning: Session has to be maintained somehow I have web application where I store users' password and username. If you logon to this site, you can login with the password and username to have access to your profile. There is another option that requires you to login to my site from your site and have your profile displayed within your site. This is because you might already have a site that your clients know you with. This link is close to what I want to do: http://aspmessageboard.com/showthread.php?t=235069 A user on Site A login to Site B and have the information on site B showing in site A. He should not know whether Site B exists. It should be as if everything is happening in Site A This latter part is what I don't know to implement. I have these ideas: Have a fixed IFrame within your site to contain my site: but I am concerned about size/layout since different clients have different layout/size for their content section. I am thinking of how to maintain session too A webservice: I don't know how feasible this is since the Password and ID are on my server. You may have to send them back and forth. It means client would have to code with my API. But I am not just returning data, I have to show them a page that contains the profile details OpenID, Single-SignOn: Just guessing - but the authentication and data resides on my server. there is nothing to access on your side in this case Examples: like login into facebook within my site and still be able to do post updates, receive notifications Facebook implement some of these with IFrame e.g. the Like button *NOTE: * I have tested the IFrame option. It worked but I still have to remove my site specific content like my page Banner, Side Navigation etc. I was able to login normally as if I was actually on the site. This show my GUI but - style sheet was missing - content not styled with CSS - Any relative url won't work. It would look for that resource relative to the current server. Unless I change links to absolute - Clicking on the LogIn button produces this error: The state information is invalid for this page and might be corrupted. UPDATE: I was reading about REST webservice few days ago and I got this idea: What about the idea of returning an XML from a webservice [REST or SOAP] and providing an XSLT (that I can provide) to display it. Thus they won't have to do much coding?

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• How different is WPF from ASP.NET [closed]

  - by Tom

  I have been quickly moved over to a different project at work because the project needs more help. I was chosen because they are confident in my abilities and they thought I would be best fit for the next couple weeks to help finish the application out. I am a little nervous. I do tend to pick things up quickly. I was moved to a different project at the beginning of this year and now I know it like the back of my hand. Previously I was on another project. Both of these projects were an ASP.NET web application, which I believe is considered a winforms web application? The project I am moving to is a desktop WPF application. I have read that many people enjoy developing their applications with WPF. I just have never dealt/worked with WPF before. I like to consider myself pretty good at ASP.NET/C# and I do a solid job. We deal with a lot of data processing from the database and report generation. So I do get to experience C# more so than some web applications where the C# end of it is mostly just event driven and simple instructions. How different are the two? Will it be completely foreign to me? Or is it just a different way of looking at a problem and I can familiarize myself quickly? Thanks for the input.

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• How forgiving do you need to be on new employees?

  - by Arcturus

  Recently we have a new developer in our team. We are getting him up to speed and he is picking it all up quite fast, but a new developer means new (foreign) coding styles and ways to solve things. It feels kinda petty to start whining about coding styles at the first three classes he codes, but how forgiving are you guys when dealing with new developers? Do you let them muddle on, and point it out later? Or do you wield the scepter of intolerance immediately? When do you draw the line, or if not, why not? P.S. New guy, if you read this: you are doing great, keep up the good work ;) Edit: I've accepted the most up-voted answer, as most answers share the same message: Be nice, but tell them asap! Thanks all for the nice answers! Really appreciated it!

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• Semantic Versioning and splitting apart a library, providing a bundled build

  - by Derick Bailey

  I've got a nice, fairly popular JavaScript library that is following Semantic Versioning. The current library has a few dependency libraries, which are available either as separate downloads or as part of a single bundled download. I see a need to head down this path further. I want to extract additional, smaller libraries out of the one larger library. Each of these extracted libraries would be available as separate files, or inside of the one bundled build, again. If I go down this path of extracting the libraries, and providing a bundled version of the final code, does this require a full version change in semantic versioning? Would I have to bump from 1.x to 2.x? My first thought it no: I will not change any public API, so I don't have to change the major version number. But then I wonder... well, I am restructuring a lot of things, even though the final API for the bundled version would be the same. Is there a clear answer from semver on something like this? Do I need to bump first, second or third dot? Or something else?

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• whats the name of this pattern?

  - by Wes

  I see this a lot in frameworks. You have a master class which other classes register with. The master class then decides which of the registered classes to delegate the request to. An example based passed in class may be something this. public interface Processor { public boolean canHandle(Object objectToHandle); public void handle(Object objectToHandle); } public class EvenNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isEven(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } public class OddNumberProcessor extends Processor { public boolean canHandle(Object objectToHandle) { if (!isNumeric(objectToHandle)){ return false } return isOdd(objectToHandle); } public void handle(objectToHandle) { //Optionally call canHandleAgain to ensure the calling class is fufilling its contract doSomething(); } } //Can optionally implement processor interface public class processorDelegator { private List processors; public void addProcessor(Processor processor) { processors.add(processor); } public void process(Object objectToProcess) { //Lookup relevant processor either by keeping a list of what they can process //Or query each one to see if it can process the object. chosenProcessor=chooseProcessor(objectToProcess); chosenProcessor.handle(objectToProcess); } } Note there are a few variations I see on this. In one variation the sub classes provide a list of things they can process which the ProcessorDelegator understands. The other variation which is listed above in fake code is where each is queried in turn. This is similar to chain of command but I don't think its the same as chain of command means that the processor needs to pass to other processors. The other variation is where the ProcessorDelegator itself implements the interface which means you can get trees of ProcessorDelegators which specialise further. In the above example you could have a numeric processor delegator which delegates to an even/odd processor and a string processordelegator which delegates to different strings. My question is does this pattern have a name.

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• Do you need to know Java before trying Scala

  - by gizgok

  I'm interested in learning Scala. I've been reading a lot about it, but a lot of people value it because it has an actor model which is better for concurrency, it handles xml in a much better way, solves the problem of first class functions. My question is do you need to know Java to understand/appreciate the way things work in Scala? Is it better to first take a stab at Java and then try Scala or you can start Scala with absolutely no java backround?

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• What tools are available to generate end user documentation?

  - by Rowland Shaw

  End user documentation on how to use applications is an important part of the user experience of applications, irrespective of whether they are winforms, wpf or even asp applications. In a startup or internal development team situation, where there isn't a dedicated documentation department, it can take a lot of resources to maintain screen shots and associated user documentation, such as on-line help or even printable manuals. What tools are available to assist in creating screenshots of all the "screens" within an application (be they winforms, wpf or aspx) to help automate the capture of screen shots, and associating with the relevant documentation? In addiiton, are there any that allow automation of annotations of a particular control (so use cases like: Draw a red box around the Username control with a callout to say "This is where you'd enter your user name, in the form '[email protected]'")?

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• Reasons for either 32-bit or 64-bit as development machine

  - by vartec

  I'm about to make a new Linux install, which will be primarily used for programming. I've seen benchmarks showing speed improvement of 64-bit version, however, I have hard time of telling how much these benchmarks translate to improvement in every day usage. And of course there are other aspects to consider. Usage I have in mind: mainly programming Python, with occasional C, C++ and Java; IDEs, which are using Java platforms (Eclipse and IntelliJ); on very rare occasions having to compile for 32-bit platform; not planning to have more than 64GB of RAM anytime soon (and I don't mind using PAE kernels); machine in question has 4GB RAM and Athlon II X2; What are pros and cons of choosing either i386 or x86_64 distro?

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• How can I sell a legacy program rewrite to the business?

  - by Wil

  We have a legacy classic ASP application that's been around since 2001. It badly needs to be re-written, but it's working fine from an end user perspective. The reason I feel like a rewrite is necessary is that when we need to update it (which is admittedly not that often) then it takes forever to go through all the spaghetti code and fix problems. Also, adding new features is also a pain since it was architect-ed and coded badly. I've run cost analysis for them on maintenance but they are willing to spend more for the small maintenance jobs than a rewrite. Any suggestions on convincing them otherwise?

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