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• How would I implement separate databases for reading and writing operations?

  - by Matt

  I am interested in implementing an architecture that has two databases one for read operations and the other for writes. I have never implemented something like this and have always built single database, highly normalised systems so I am not quite sure where to begin. I have a few parts to this question. 1. What would be a good resource to find out more about this achitecture? 2. Is it just a question of replicating between two identical schemas, or would your schemas differ depending on the operations, would normalisation vary too? 3. How do you insure that data written to one database is immediately available for reading from the second? Any further help, tips, resources would be appreciated. Thanks.

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• Is it good practice to avoid declaring a pointer to BOOL type in objective C?

  - by Krishnan

  I read this question in stackoverflow. The excerpt answer provided by bbum is below: The problem isn't the assignment, it is much more likely that you declared your instance variable to be BOOL *initialBroadcast;. There is no reason to declare the instance variable to be a pointer (at least not unless you really do need a C array of BOOLs).. Remove the * from the declaration. 1.Is there anything wrong in using a pointer variable even when I do not have to maintain an array of BOOLs? 2.I think even if avoiding them a good practice, it is not specific to objective-C and applies to all programming languages which has pointers. Please answer my questions.

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• Trust metrics and related algorithms

  - by Nick Gerakines

  I'm trying to learn more about trust metrics (including related algorithms) and how user voting, ranking and rating systems can be wired to stiffle abuse. I've read abstract articles and papers describing trust metrics but haven't seen any actual implementations. My goal is to create a system that allows users to vote on other users and the content of other users and with those votes and related meta-data, determine if those votes can be applied to a users level or popularity. Have you used or seen some sort of trust system within a social graph? How did it work and what were its areas of strength and weaknesses?

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• What exactly does "adopt a protocol" mean in the Objective-C / Cocoa documentation ?

  - by driis

  I am a C# developer getting started on Objective-C / Cocoa Touch programming. I think I might have gotten some terms wrong because I keep thinking about them "the C# way". Specifically, I have come around the term "protocol" in various documentation and tutorials. In Objective-C, what exactly is a protocol ? Can it be compared to a C# interface ? Is the following declaration the same as saying "The class is implementing the protocol UITextFieldDelegate" ? Or is UITextFieldDelegate to be compared with a generic type parameter in C# ? @interface MyViewController : UIViewController <UITextFieldDelegate> { }

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• Best approach to creating a database driven Java website?

  - by Craig Whitley

  I'm fairly new to programming and new to java, but I'd like to jump in the deep end with a little database driven website project. I've read quite a lot about requirements in the 'real world' requesting experience with Spring and Hibernate, so I have those installed on netbeans and a project created (if I hit run I get the default spring page). Now I just need a little guidance as to where to start designing my app (please tell me if I'm getting in a bit too over my head for a beginner!). Should I start off with my classes? - create all my classes as they map to my database tables and decide which attributes and methods each will require? Can anyone suggest any good books for maybe.. making a java based website from scratch (i.e. from design right through to deployment) that might be useful for a beginner? Any help appreciated thanks.

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• System.Net.Mail.SmtpClient cannot authenticate against a POP3 server, right?

  - by Herchu

  One of our customer seems to have a very old email system, those that ask you to authenticate to the POP3 server before allowing you to send messages through the SMTP server. Regrettably, we have to believe in what our customer tell us for we cannot access their facilities. But as far as I remember, years ago there were mail systems that once you log into the POP3, the STMP server is kept open for a few minutes for the client IP. Our application sends messages by using System.Net.Mail.SmtpClient which seems to be unable to authenticate to those kinds of servers. Is that correct? If so, what would be the simplest workaround? I was thinking of a minimal POP3 implementation (just the login part of the protocol). Would that work? Thanks in advance.

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• Brief Explanation of C Supersets?

  - by Ben Hooper

  I'm getting more and more confused in regards to C's supersets the further I venture into the programming world. There's just so many versions.. C, C++, C#, Objective-C, Objective-C++ and God knows what else. I only know tidbits about these languages (some are object-oriented, some are procedural, C was originally developed for UNIX, C++ started as an extension and is used primarily on the Windows OS, Objective-C is primarily used on Linux and Mac OS/iOS, etc), but I'm not even sure that what I know is correct. I would just like someone to shed some light on what I "know" - a little bit more information about which are successive versions, which platforms each are generally used on, which are the best versions to learn, etc if anyone is feeling generous. :) Thanks. :)

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• How does compiling circular dependencies work?

  - by Fabio F.

  I've made the example in Java but I think (not tested) that it works in other (all?) languages. You have 2 files. First, M.java: public class MType { XType x; MType() {x = null;} } Second, another file (in the same directory), XType.java: public class XType { MType m; public XType(MType m) {this.m = m;} } Ok it's bad programming, but if you run javac XType it compiles: compiles even MType because XType needs it. But ... MType needs XType ... how does that work? How does the compiler know what is happening? Probably this is a stupid question, but I would like to know how the compiler (javac or any other compilers you know) manages that situation, not how to avoid it. I'm asking because i'm writing a precompiler and I would like to manage that situation.

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• After tar extract, Changing Permissions

  - by Moe

  Just a Question Regarding unix and PHP today. What I am doing on my PHP is using the Unix system to untar a tarred file. exec("tar -xzf foo.tar.gz"); Generally everything works fine until I run into this particular foo.tar.gz, which has a file system as follows: Applications/ Library/ Systems/ After running the tar command, it seems that the file permissions get changed to 644 (instead of 755). This causes Permission denied (errno 13) and therefore disabling most of my code. (I'm guessing from lack of privileges) Any way I can stop this tar command completely ruining my permissions? Thanks. Oh and this seems to only happen when I have a foo.tar.gz file that Has this particular file system. Anything else and I'm good.

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• T4 Template Interception

  - by JeffN825

  I'm wondering if anyone out there knows of any T4 template based method interception systems? We are beginning to write mobile applications (currently with MonoTouch for IOS). We have a very nice core set of DI/IoC functionality and I'd like to leverage this in development for the new platform. Since runtime code generation Reflection.Emit is not supported, I'm hoping to use T4 templates to implement the dynamic interception functionality (+ TinyIoC as a container for resolution). We are currently using Castle Windsor (and intend to continue doing so for our SL and full .NET development), but all of the Windsor specific ties are completely encapsulated, so given a suitable T4 solution, it shouldn't be hard to implement an adapter that uses a T4 based implementation instead of Windsor.

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• What's the deal with rubygems on Debian? It's different and strange.

  - by JSW

  I've noticed at least the following oddities around rubygems on Debian (5.0 lenny in my case): Packages go into a different installation location: /var/lib/gems vs /usr/lib/ruby/gems The debian package is rubygems 1.3.6, and updating rubygems to the latest version (1.3.7) doesn't work: $ sudo gem update --system ERROR: While executing gem ... (RuntimeError) gem update --system is disabled on Debian. RubyGems can be updated using the official Debian repositories by aptitude or apt-get. Not all gems appear to work like they do on other systems. For instance, when installing Phusion Passenger, it did not detect the "rack" gem even though it was definitely installed. Manually installing rubygems using the source tarball and reinstalling all my gems (to /usr/lib/ruby/gems) made my problems go away. What's the deal? Why is debian's package different?

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• Retrieving content of a txt file from URL to Android

  - by eightx2

  I would like to be able to retrieve contents of a .txt file from the internet, and load it in an EditText. I tried using the code on this page: Reading Text File From Server on Android It didn't work, as you might have guessed. I've read on numerous sites about this type of problem, but I can't get anything to work. Someone suggested AndroidHttpClient (http://developer.android.com/reference/android/net/http/AndroidHttpClient.html), but I simply can't find any examples with this. As I'm a newbie in Android programming, I would love if someone could please give me a small example.

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• What books help one to learn to read code?

  - by Daniel

  Lion's Commentary on Unix Sixth Edition with Source Code is a wonderful book to learn how to read code. Reading code is important -- how does one learn how to write excellent code without having read excellent code? But, sadly, while great writers, of fiction and non-fiction, all spend a great deal of time reading stuff, we, programmers, seem to avoid it like the plague. Worse still, programming books usually go the same way. They might show a pattern or a style, but they often avoid showing good, complex code, and helping one go through it. There are exceptions, of course. I hope. So, with that in mind, what books are to be found which help one learn how to read code?

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• First and last window don't show up.

  - by SirGregg

  Hi, I'm creating a WinApi application for my programming course. The program is supposed to show an LED clock using a separate window for each 'block'. I have figured most of it out, except for one thing: when creating the two-dimensional array of windows, the first and last window never show up. Here's the piece of code from the InitInstance function: for (int x=0;x<8;x++) for (int y=0;y<7;y++) { digitWnd[x][y] = CreateWindowEx((WS_EX_LAYERED | WS_EX_TRANSPARENT | WS_EX_NOACTIVATE | WS_EX_STATICEDGE), szWindowClass, szTitle, (WS_POPUP| WS_BORDER), NULL, NULL, NULL, NULL, dummyWnd, NULL, hInstance, NULL); ShowWindow(digitWnd[x][y], nCmdShow); UpdateWindow(digitWnd[x][y]); } The same loop bounds are used everytime I interact with the windows (set position and enable/disable). All the windows seem to be working fine, except for digitWnd[0][0] and digitWnd[7][6]... Any ideas as to what is happening?

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• Python editor/IDE for OS X

  - by TheJuice

  As a (reasonably) new Python programmer, what IDEs or editors would you recommend for Python programming on OS X and why (i.e. what features/capabilities/workflow techniques really help)? I've used Xcode and played a bit with TextMate but I can't really say that either have really hit the spot for me (although TextMate's code completion is pretty neat, I think i've been spoilt with code-completion facilities provided by editors for statically-typed languages so maybe i'm subconsciously comparing apples and oranges) I'm looking to increase my efficacy with Python and any tips would be appreciated. I know people have asked similar questions for Python IDEs in general but I am specifically concentrating on OS X and the 'Mac way'. If Xcode or TextMate are thought highly of, perhaps some suggestions as to how I could get the most benefit from the tools would help.

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• Manipulating both unicode and ASCII character set in C#

  - by Murlex

  I have this mapping in my C# application string [,] unicode2Ascii = { { "&#3001;", "\x86" } }; ஹ - is the unicode value for a tamil literal "ஹ". This is the raw hex literal for the unicode value saved by MS Word as a byte sequence. I am trying to map these unicode value "strings" to a hex value under 255 (so as to accommodate non-unicode supported systems). I trying to use string.replace like this: S = S.replace(unicode2Ascii[0,0], unicode2Ascii[0,1]); However the resultant ouput has a ? instead of the actual hex 0x86 stored. Any pointer on how I could set the encoding for the second element of that array to something like windows-1252? Or is there a better way to do this conversion? thanks in advance

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• General question: Filesystem or database?

  - by poeschlorn

  Hey guys, i want to create a small document management system. there are several users who store their files. each file which is uploaded contains an info which user uploaded it and the document content itself. In a view there are displayed all files of ONE specific user, ordered by date. What would be better: 1) giving the documents a name or metadata(XML) which contain the date and user (and iterate through them to get the metadata) or 2) giving the files a random/unique name and store metadata in a DB? something like this: date | user | filename What would you say and why? The used programming language is java and the DB is MySQL.

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• Debugging ASP.NET in VS

  - by negligible

  A lot of what I'm doing at the moment is figuring out other peoples code and adding or adapting functions, so currently I am debugging more than I am writing code of my own. I'm still new to this, Junior Developer, and I am always finding new ways to improve what I am doing. For example I recently found This Guide which had some excellent tips, such as overriding the ToString() method in your classes so children are readable from their parents. So I am looking for any other tips or tricks to make my debugging more efficient, as I recognise it as a big part of programming, that you more experienced programmers may have picked up or found. Anything appreciated, I can read websites just fine so no need to explain it yourself if you have a good link!

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• why am i getting an error SyntaxError : invalid syntax for this code

  - by eragon1189

  This is a code in python which calculates f (x) =? ((-1)*x)/(x*x+n*n) n from 1 to infinite.... correct to 0.0001, for the range 1 < x < 100 in steps of 0.1.But i am getting an syntax error,as i am new to programming in python... from scipy import * from matplotlib.pyplot import * x=arange(0.1,100,0.1) f=zeros(len(x)) s=-1 for n in range (1,10000): t=s*x/(x*x+n*n) f +=t s =-s if max(abs(t))< 1e-4 break for xx in c_[x,f]: print "%f %f" % (xx[0],xx[1])

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• Existing SQL database android help

  - by basketball4567

  Hey guys, I am new to android programming and i am trying to make an app that will interface with a website i have. It is a movie website with all of its information stored in SQL database. I know how to write the requests and queries in .asp but dont know how to get information from the database in my app. I want the user to be able to enter a movie title, and through a couple of stored procedures that are in my SQL database, return the info on that movie(actor, budget, genre....). I would like to have little info stored on the device, have all of the queries being sent to my SQL server and just have the info being returned. So my question boils down to, how do i link my existing SQL database with an android app. Any help would be great. Thanks Basketball4567

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• Where's the definitive resource online about how to carry out Agile development?

  - by jdk

  I want to start Agile practices in a team. I'm assuming the information is available for free online about how to specifically carry it out. Online I can locate the manifesto, the alliances and corporations involved but where is the actual central guide or root instruction set about how to do it? (Maybe the practices themselves are more ethereal or subjective than I expect and it's found in multiple places?) Edit to summarize solutions: Agile is a concept so that's what's to be found online about it. However specific processes or methods of Agile development have been created like Scrum and Extreme programming to provide concrete solutions to teams who want to adopt Agile and reap its proposed benefits. Find the shoe (or method) that fits best. Maybe create it. If looking for solutions online to implement Agile development in your organization or for your project, seek out the specific methods too and decide among them.

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• Questions about "casting operation" in OOP

  - by rhapsodyn

  When programming, we usually use some type-casting operations. When the casting happens on the objects "on the same level", it feels ok. But when it happens on the ojects "on the different levels"(mainly between father and son), it feels weird. Considering this: Class Son extends Father WhenSon s = (Son)father;, it's absolutely unreasonable. Because a "Son" is not a "Father" anymore, "Son" may grow up with some new properties "Father" doesn't have, the casting operation makes these properties unknown. On the other hand, Father f = (Father)son seems reasonable, but according to LSP "An instance of a derived should be able to replace any instance of its superclass" A "Son" can do anything his "Father" can, so the casting operation seems useless. So can i say that these casting operations are agaisnt OO design principle but necessary?

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• Crowdsourcing translation for mobile developers?

  - by superg

  I am developing applications for mobile phones with different operating systems (Android, Symbian, iPhone). Applications are sold internationally so they need to be translated to different languages in addition to english version. I assume most mobile developers do the translations using some paid external service each time. This approach does not look very cost-effective to me. Would it make sense to have a website where simple translations would be done using crowdsourcing (other developers)? Most strings in mobile applications are very simple and short, for example "OK, "Cancel", "Are you sure?", "Please enter your password". Also the same strings are used in hundreds of applications. Instead of paying for translating all strings, developers could save money by only buying their difficult application specific translations. Does anyone agree with this idea? I have seen many opensource projects doing the translations succesfully using volunteers.

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• Searching for a complex and well-designed PHP OOP application to learn from

  - by Raveren

  Basically, I am diving ever deeper into complex programming practices. I've almost no friends that are experienced (or more experienced than me) programmers to learn from, so I am looking for the next best thing - learning from the work of strangers. Can anyone recommend a real world finished and working application written well and OOP-centered. I'd like to take and analyze its source. Bonus if it's based on Zend Framework. What I am interested most in is objects that unlike desktop applications, have only one real operation done to them (or to their representation in DB or session) during their lifetime (or pageload), like user-logIn(). I'm interested in optimal and reusable design patterns and their real life implementations.

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• Best directory to store application data with read\write rights for all users?

  - by Wodzu

  Hi guys. Until Windows Vista I was saving my application data into the directory where the program was located. The most common place was "C:\Program Files\MyApplication". As we know, under Vista and later the common user does't have rights to write under "Program Files" folder. So my first idea was to save the application data under "All Useres\Application Data" folder. But it seams that this folder has writing restrictions too! So to sum up, my requirements are: Folder should exist under Windows XP and above Microsoft's systems. All useres of the system should read\write\creation rights to this folder and it subfolders and files. I want to have only one copy of file\files for all useres. Thanks for your time.

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