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• iGoogle Stack Overflow Gadget [closed]

  - by Charango

  Since SO's question database is becoming an excellent first point of call for finding answers to coding problems, some people (like me) might like to be able to fire up searches from their iGoogle home page, among the other searches you might launch from there. I've created a very simple gadget to do this, and put the source below. My hope is that this might provide a foundation on which community members with better ideas for performing this function, or ideas for enhancing it, can update it. Perhaps we could make it configurable to search via a site scope search from Google and / or a question search, for instance. I've hosted and registered this first version but if anyone makes changes and can host a new version / new pics elsewhere, please feel free. <?xml version="1.0" encoding="UTF-8"?> <Module> <ModulePrefs title="Stack Overflow Search" author="Community Wiki" author_email="[email protected]" author_affiliation="Stack Overflow" author_location="The Internet" author_aboutme="All sorts" author_link="http://stackoverflow.com" author_quote="Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law." description="Stack Overflow is rapidly becoming one of the best resources for finding answers to your programming questions. This gadget adds a question search box to your iGoogle homepage" screenshot="http://arkios-solutions.com/misc/sogadget/SOGadget.png" thumbnail="http://arkios-solutions.com/misc/sogadget/SOGadget_Thumbnail.png" singleton="true" title_url="http://stackoverflow.com" /> <Content type="html"><![CDATA[ <img src="http://i.stackoverflow.com/Content/Img/stackoverflow-logo-250.png" alt="Stackoverflow Logo"/> <div style="font-family:arial;font-size:0.8em;"> This gadget allows you to search the Stack Overflow question database. </div> <form name='SOQueryForm' action="http://stackoverflow.com/search" method="get" target="new"> <p>Your question: <input type='text' size='34' name='q' /></p> <p><input type='submit' value='Go' /></p> </form> ]]> </Content> </Module> The source / installable gadget xml are also hosted here.

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• Using in app purchase to unlock features vs. using free & paid app versions for iPhone

  - by yabada

  I have an app that I was going to release as a free (lite) version with some of the total functionality and a paid full version with advanced functionality. Now, with in app purchase for free apps I am thinking of going that route with the ability to unlock features as needed. I'm not talking about a trial version that expires.I want people to be able to try out the app and get an idea of the interface and functionality before deciding to purchase the full functionality of each major section of the app, basically. Here's an analogy of what my app would be like. Let's say you have a cooking app that teaches you to cook in different styles. There could be major section for French, Italian, and Chinese. Each section could have some rudiments unlocked in the free app so users can see the UI and basics of the functionality. Then, the user could decide to purchase each major section (or not) individually with in app purchase or buy the full versioned app (with the free/paid model). One concern I have with offering a free app with in app purchase would be with feedback. I would be very clear in my description in the app store that there is in app purchase for full features but I'm worried that less serious users could/would leave negative feedback. I suppose that's always a risk but curious about any experience with this. It also seems that it could be a whole lot more complicated keeping track of what portions of the app are locked and unlocked with in app purchase. I know I'd have to have all the code for the full functionality and "lock" the portions that haven't been purchased. How do people usually lock portions of their code? I'm not talking about the process of purchasing (I've read the In App Purchase Programming Guide) but after the purchase has been made. Would I just keep track of what the user has purchased and put conditionals on the sections that are initially locked? Or is there another way to do this as well? My instinct is for the in app purchase (particularly since users could purchase the major sections that they want individually).

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• Fast block placement algorithm, advice needed?

  - by James Morris

  I need to emulate the window placement strategy of the Fluxbox window manager. As a rough guide, visualize randomly sized windows filling up the screen one at a time, where the rough size of each results in an average of 80 windows on screen without any window overlapping another. It is important to note that windows will close and the space that closed windows previously occupied becomes available once more for the placement of new windows. The window placement strategy has three binary options: Windows build horizontal rows or vertical columns (potentially) Windows are placed from left to right or right to left Windows are placed from top to bottom or bottom to top Why is the algorithm a problem? It needs to operate to the deadlines of a real time thread in an audio application. At this moment I am only concerned with getting a fast algorithm, don't concern yourself over the implications of real time threads and all the hurdles in programming that that brings. So far I have two choices which I have built loose prototypes for: 1) A port of the Fluxbox placement algorithm into my code. The problem with this is, the client (my program) gets kicked out of the audio server (JACK) when I try placing the worst case scenario of 256 blocks using the algorithm. This algorithm performs over 14000 full (linear) scans of the list of blocks already placed when placing the 256th window. 2) My alternative approach. Only partially implemented, this approach uses a data structure for each area of rectangular free unused space (the list of windows can be entirely separate, and is not required for testing of this algorithm). The data structure acts as a node in a doubly linked list (with sorted insertion), as well as containing the coordinates of the top-left corner, and the width and height. Furthermore, each block data structure also contains four links which connect to each immediately adjacent (touching) block on each of the four sides. IMPORTANT RULE: Each block may only touch with one block per side. The problem with this approach is, it's very complex. I have implemented the straightforward cases where 1) space is removed from one corner of a block, 2) splitting neighbouring blocks so that the IMPORTANT RULE is adhered to. The less straightforward case, where the space to be removed can only be found within a column or row of boxes, is only partially implemented - if one of the blocks to be removed is an exact fit for width (ie column) or height (ie row) then problems occur. And don't even mention the fact this only checks columns one box wide, and rows one box tall. I've implemented this algorithm in C - the language I am using for this project (I've not used C++ for a few years and am uncomfortable using it after having focused all my attention to C development, it's a hobby). The implementation is 700+ lines of code (including plenty of blank lines, brace lines, comments etc). The implementation only works for the horizontal-rows + left-right + top-bottom placement strategy. So I've either got to add some way of making this +700 lines of code work for the other 7 placement strategy options, or I'm going to have to duplicate those +700 lines of code for the other seven options. Neither of these is attractive, the first, because the existing code is complex enough, the second, because of bloat. The algorithm is not even at a stage where I can use it in the real time worst case scenario, because of missing functionality, so I still don't know if it actually performs better or worse than the first approach. What else is there? I've skimmed over and discounted: Bin Packing algorithms: their emphasis on optimal fit does not match the requirements of this algorithm. Recursive Bisection Placement algorithms: sounds promising, but these are for circuit design. Their emphasis is optimal wire length. Both of these, especially the latter, all elements to be placed/packs are known before the algorithm begins. I need an algorithm which works accumulatively with what it is given to do when it is told to do it. What are your thoughts on this? How would you approach it? What other algorithms should I look at? Or even what concepts should I research seeing as I've not studied computer science/software engineering? Please ask questions in comments if further information is needed. [edit] If it makes any difference, the units for the coordinates will not be pixels. The units are unimportant, but the grid where windows/blocks/whatever can be placed will be 127 x 127 units.

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• Is Ogre's use of Exceptions a good way of using them?

  - by identitycrisisuk

  I've managed to get through my C++ game programming career so far virtually never touching exceptions but recently I've been working on a project with the Ogre engine and I'm trying to learn properly. I've found a lot of good questions and answers here on the general usage of C++ exceptions but I'd like to get some outside opinions from here on whether Ogre's usage is good and how best to work with them. To start with, quoting from Ogre's documentation of it's own Exception class: OGRE never uses return values to indicate errors. Instead, if an error occurs, an exception is thrown, and this is the object that encapsulates the detail of the problem. The application using OGRE should always ensure that the exceptions are caught, so all OGRE engine functions should occur within a try{} catch(Ogre::Exception& e) {} block. Really? Every single Ogre function could throw an exception and be wrapped in a try/catch block? At present this is handled in our usage of it by a try/catch in main that will show a message box with the exception description before exiting. This can be a bit awkward for debugging though as you don't get a stack trace, just the function that threw the error - more important is the function from our code that called the Ogre function. If it was an assert in Ogre code then it would go straight to the code in the debugger and I'd be able to find out what's going on much easier - I don't know if I'm missing something that would allow me to debug exceptions already? I'm starting to add a few more try/catch blocks in our code now, generally thinking about whether it matters if the Ogre function throws an exception. If it's something that will stop everything working then let the main try/catch handle it and exit the program. If it's not of great importance then catch it just after the function call and let the program continue. One recent example of this was building up a vector of the vertex/fragment program parameters for materials applied to an entity - if a material didn't have any parameters then it would throw an exception, which I caught and then ignored as it didn't need to add to my list of parameters. Does this seem like a reasonable way of dealing with things? Any specific advice for working with Ogre is much appreciated.

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• The most efficient method of drawing multiple quads in OpenGL

  - by CPatton

  I'm not very keen with OpenGL and I was wondering if someone could give me some insight on this. I'm a 'seasoned' programmer, I've read the redbook about VBOs and the like, but I was wondering from a more experienced person about the best/most efficient way of achieving this. I've been producing this 2d tile-based game engine to be used in several projects. I have a class called "ScreenObject" which is mainly composed of a Dictionary<Point, Tile> The Point key is to show where to render the Tile on the screen, and the Tile contains one or more textures to be drawn at that point. This ScreenObject is where the tiles will be modified, deleted, added, etc.. My original method of drawing the tiles in the testing I've done was to iterate through the ScreenObject and draw each quad at each location separately. From what I've read, this is a massive waste of resources. It wasn't horribly slow in the testing, but after I've completed the animation classes and effect classes, I'm sure it would be extremely slow. And one last thing, if you wouldn't mind.. As I said before, the Tile class can contain multiple textures to be drawn at the Point location on the screen. I recognize possibly two options for me here. Either add a quad at that location for each texture to be drawn, or, somehow.. use a multiple texture for the same quad (if it's possible). Even if each tile contained one texture only, that would be 64 quads to be drawn on the screen. Most of the tiles will contain 2-5 textures, so the number of total quads would increase dramatically with this method. Would it be feasible to add a quad for each new texture, or am I ignoring a better way to do this? Just need some help understanding this if you don't mind :) I've tried to be as concise as possible, and I'd greatly appreciate any responses.. and even some criticism. Programming is often a learning process and one who develops seems to never stops learning. Thanks for your time.

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• How to create a Uri instance parsed with GenericUriParserOptions.DontCompressPath

  - by Andrew Arnott

  When the .NET System.Uri class parses strings it performs some normalization on the input, such as lower-casing the scheme and hostname. It also trims trailing periods from each path segment. This latter feature is fatal to OpenID applications because some OpenIDs (like those issued from Yahoo) include base64 encoded path segments which may end with a period. How can I disable this period-trimming behavior of the Uri class? Registering my own scheme using UriParser.Register with a parser initialized with GenericUriParserOptions.DontCompressPath avoids the period trimming, and some other operations that are also undesirable for OpenID. But I cannot register a new parser for existing schemes like HTTP and HTTPS, which I must do for OpenIDs. Another approach I tried was registering my own new scheme, and programming the custom parser to change the scheme back to the standard HTTP(s) schemes as part of parsing: public class MyUriParser : GenericUriParser { private string actualScheme; public MyUriParser(string actualScheme) : base(GenericUriParserOptions.DontCompressPath) { this.actualScheme = actualScheme.ToLowerInvariant(); } protected override string GetComponents(Uri uri, UriComponents components, UriFormat format) { string result = base.GetComponents(uri, components, format); // Substitute our actual desired scheme in the string if it's in there. if ((components & UriComponents.Scheme) != 0) { string registeredScheme = base.GetComponents(uri, UriComponents.Scheme, format); result = this.actualScheme + result.Substring(registeredScheme.Length); } return result; } } class Program { static void Main(string[] args) { UriParser.Register(new MyUriParser("http"), "httpx", 80); UriParser.Register(new MyUriParser("https"), "httpsx", 443); Uri z = new Uri("httpsx://me.yahoo.com/b./c.#adf"); var req = (HttpWebRequest)WebRequest.Create(z); req.GetResponse(); } } This actually almost works. The Uri instance reports https instead of httpsx everywhere -- except the Uri.Scheme property itself. That's a problem when you pass this Uri instance to the HttpWebRequest to send a request to this address. Apparently it checks the Scheme property and doesn't recognize it as 'https' because it just sends plaintext to the 443 port instead of SSL. I'm happy for any solution that: Preserves trailing periods in path segments in Uri.Path Includes these periods in outgoing HTTP requests. Ideally works with under ASP.NET medium trust (but not absolutely necessary).

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• Fixed point math in c#?

  - by x4000

  Hi there, I was wondering if anyone here knows of any good resources for fixed point math in c#? I've seen things like this (http://2ddev.72dpiarmy.com/viewtopic.php?id=156) and this (http://stackoverflow.com/questions/79677/whats-the-best-way-to-do-fixed-point-math), and a number of discussions about whether decimal is really fixed point or actually floating point (update: responders have confirmed that it's definitely floating point), but I haven't seen a solid C# library for things like calculating cosine and sine. My needs are simple -- I need the basic operators, plus cosine, sine, arctan2, PI... I think that's about it. Maybe sqrt. I'm programming a 2D RTS game, which I have largely working, but the unit movement when using floating-point math (doubles) has very small inaccuracies over time (10-30 minutes) across multiple machines, leading to desyncs. This is presently only between a 32 bit OS and a 64 bit OS, all the 32 bit machines seem to stay in sync without issue, which is what makes me think this is a floating point issue. I was aware from this as a possible issue from the outset, and so have limited my use of non-integer position math as much as possible, but for smooth diagonal movement at varying speeds I'm calculating the angle between points in radians, then getting the x and y components of movement with sin and cos. That's the main issue. I'm also doing some calculations for line segment intersections, line-circle intersections, circle-rect intersections, etc, that also probably need to move from floating-point to fixed-point to avoid cross-machine issues. If there's something open source in Java or VB or another comparable language, I could probably convert the code for my uses. The main priority for me is accuracy, although I'd like as little speed loss over present performance as possible. This whole fixed point math thing is very new to me, and I'm surprised by how little practical information on it there is on google -- most stuff seems to be either theory or dense C++ header files. Anything you could do to point me in the right direction is much appreciated; if I can get this working, I plan to open-source the math functions I put together so that there will be a resource for other C# programmers out there. UPDATE: I could definitely make a cosine/sine lookup table work for my purposes, but I don't think that would work for arctan2, since I'd need to generate a table with about 64,000x64,000 entries (yikes). If you know any programmatic explanations of efficient ways to calculate things like arctan2, that would be awesome. My math background is all right, but the advanced formulas and traditional math notation are very difficult for me to translate into code.

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• CodeGolf: Brothers

  - by John McClane

  Hi guys, I just finished participating in the 2009 ACM ICPC Programming Conest in the Latinamerican Finals. These questions were for Brazil, Bolivia, Chile, etc. My team and I could only finish two questions out of the eleven (not bad I think for the first try). Here's one we could finish. I'm curious to seeing any variations to the code. The question in full: ps: These questions can also be found on the official ICPC website available to everyone. In the land of ACM ruled a greeat king who became obsessed with order. The kingdom had a rectangular form, and the king divided the territory into a grid of small rectangular counties. Before dying the king distributed the counties among his sons. The king was unaware of the rivalries between his sons: The first heir hated the second but not the rest, the second hated the third but not the rest, and so on...Finally, the last heir hated the first heir, but not the other heirs. As soon as the king died, the strange rivaly among the King's sons sparked off a generalized war in the kingdom. Attacks only took place between pairs of adjacent counties (adjacent counties are those that share one vertical or horizontal border). A county X attacked an adjacent county Y whenever X hated Y. The attacked county was always conquered. All attacks where carried out simultanously and a set of simultanous attacks was called a battle. After a certain number of battles, the surviving sons made a truce and never battled again. For example if the king had three sons, named 0, 1 and 2, the figure below shows what happens in the first battle for a given initial land distribution: INPUT The input contains several test cases. The first line of a test case contains four integers, N, R, C and K. N - The number of heirs (2 <= N <= 100) R and C - The dimensions of the land. (2 <= R,C <= 100) K - Number of battles that are going to take place. (1 <= K <= 100) Heirs are identified by sequential integers starting from zero. Each of the next R lines contains C integers HeirIdentificationNumber (saying what heir owns this land) separated by single spaces. This is to layout the initial land. The last test case is a line separated by four zeroes separated by single spaces. (To exit the program so to speak) Output For each test case your program must print R lines with C integers each, separated by single spaces in the same format as the input, representing the land distribution after all battles. Sample Input: Sample Output: 3 4 4 3 2 2 2 0 0 1 2 0 2 1 0 1 1 0 2 0 2 2 2 0 0 1 2 0 0 2 0 0 0 1 2 2 Another example: Sample Input: Sample Output: 4 2 3 4 1 0 3 1 0 3 2 1 2 2 1 2

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• json problems with making a ruby on rails application

  - by Prince Merdz

  So I'm using Bitnami to learn Ruby on Rails. I have also previously tried the manual installation for ruby and rails and was met by the same problem so I thought I should try first the easy package deal of Bitnami. Anyway my problem with json is that it causes the bundle install to fail. First the auto bundle install that rails new does fails because of an ssl error. Which is easily solved by changing the source in the gemfile which is https to http. However when I try to bundle install it does another error when it tries to install json. C:\RubyStack-3.2.7-0\projects\testing>bundle install Fetching gem metadata from http://rubygems.org/......... Using rake (0.9.2.2) Using i18n (0.6.0) Using multi_json (1.3.6) Installing activesupport (3.2.8) Using builder (3.0.0) Installing activemodel (3.2.8) Using erubis (2.7.0) Using journey (1.0.4) Using rack (1.4.1) Using rack-cache (1.2) Using rack-test (0.6.1) Using hike (1.2.1) Using tilt (1.3.3) Using sprockets (2.1.3) Installing actionpack (3.2.8) Using mime-types (1.19) Using polyglot (0.3.3) Using treetop (1.4.10) Using mail (2.4.4) Installing actionmailer (3.2.8) Using arel (3.0.2) Using tzinfo (0.3.33) Installing activerecord (3.2.8) Installing activeresource (3.2.8) Using bundler (1.1.5) Using coffee-script-source (1.3.3) Using execjs (1.4.0) Using coffee-script (2.2.0) Using rack-ssl (1.3.2) Installing json (1.7.5) with native extensions Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension . C:/RUBYST~1.7-0/ruby/bin/ruby.exe extconf.rb creating Makefile make 0 [main] echo 5244 open_stackdumpfile: Dumping stack trace to echo.exe.sta ckdump make: *** [generator-i386-mingw32.def] Error 5 Gem files will remain installed in C:/RUBYST~1.7-0/ruby/lib/ruby/gems/1.9.1/gems /json-1.7.5 for inspection. Results logged to C:/RUBYST~1.7-0/ruby/lib/ruby/gems/1.9.1/gems/json-1.7.5/ext/j son/ext/generator/gem_make.out An error occured while installing json (1.7.5), and Bundler cannot continue. Make sure that `gem install json -v '1.7.5'` succeeds before bundling. This is the gem_make.out file it produces after trying to install json (btw windows also produces an error that echo.exe has stopped working while running the gem install json) C:/RUBYST~1.7-0/ruby/bin/ruby.exe extconf.rb creating Makefile make 0 [main] echo 5244 open_stackdumpfile: Dumping stack trace to echo.exe.stackdump make: *** [generator-i386-mingw32.def] Error 5 I can't even start learning ror for the setup is already a huge pain. (btw I have no prior experience with web frameworks, just desktop programming). help?

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• How can I use Web Services Core to send a complex type as a parameter to a SOAP API method

  - by Matthew Brindley

  I don't do much Cocoa programming, so I'm probably missing something obvious, so please excuse the basic question. I have a SOAP method that expects a complex type as a paramater. Here's some WSDL: <s:element name="SaveTestResult"> <s:complexType> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="result" type="tns:TestItemResponse" /> </s:sequence> </s:complexType> </s:element> Here's the definition of the complex type "TestItemResponse": <s:complexType name="TestItemResponse"> <s:sequence> <s:element minOccurs="1" maxOccurs="1" name="TestItemRequestId" type="s:int" /> <s:element minOccurs="1" maxOccurs="1" name="ExternalId" type="s:int" /> <s:element minOccurs="0" maxOccurs="1" name="ApiId" type="s:string" /> <s:element minOccurs="0" maxOccurs="1" name="InboxGuid" type="s:string" /> <s:element minOccurs="0" maxOccurs="1" name="SpamResult" type="tns:SpamResult" /> <s:element minOccurs="0" maxOccurs="1" name="ResultImageSet" type="tns:ResultImageSet" /> <s:element minOccurs="1" maxOccurs="1" name="ExclusiveUseMailAccountId" type="s:int" /> <s:element minOccurs="1" maxOccurs="1" name="State" type="tns:TestItemResponseState" /> <s:element minOccurs="0" maxOccurs="1" name="ErrorShortDescription" type="s:string" /> <s:element minOccurs="0" maxOccurs="1" name="ErrorFullDescription" type="s:string" /> </s:sequence> </s:complexType> I've been using Web Services Core to call a SOAP API method that requires a simple string param, that works great. That same method returns a complex type which WSC converted into nested NSDictionaries, so no problems there. So I assumed I'd be able to convert my local TestItemResponse class into an NSDictionary and then use that as the complex type param. It almost worked, but unfortunately WSC set the object's type as "Dictionary", instead of "TestItemResponse", and the server complained. <TestItemResponse xsi:type=\"SOAP-ENC:Dictionary\"> <ErrorFullDescription xsi:type=\"xsd:string\">foo</ErrorFullDescription> ... I can't seem to find anything that allows you to override the type WSC assigns to the element in the SOAP XML. I've been using code adapted from here, I'm happy to list it, it's just quite long and this is already the longest SO question I've ever posted.

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• Rail test case fixtures not loading

  - by Deano

  Rails appears to not be loading any fixtures for unit or functional tests. I have a simple 'products.yml' that parses and appears correct: ruby: title: Programming Ruby 1.9 description: Ruby is the fastest growing and most exciting dynamic language out there. If you need to get working programs delivered fast, you should add Ruby to your toolbox. price: 49.50 image_url: ruby.png My controller functional test begins with: require 'test_helper' class ProductsControllerTest < ActionController::TestCase fixtures :products setup do @product = products(:one) @update = { :title => 'Lorem Ipsum' , :description => 'Wibbles are fun!' , :image_url => 'lorem.jpg' , :price => 19.95 } end According to the book, Rails should "magically" load the fixtures (as my test_helper.rb has fixtures :all in it. I also added the explicit fixtures load (seen above). Yes Rails complains: user @ host ~/Dropbox/Rails/depot > rake test:functionals (in /Somewhere/Users/user/Dropbox/Rails/depot) /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby -Ilib:test "/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader.rb" "test/functional/products_controller_test.rb" Loaded suite /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader Started EEEEEEE Finished in 0.062506 seconds. 1) Error: test_should_create_product(ProductsControllerTest): NoMethodError: undefined method `products' for ProductsControllerTest:Class /test/functional/products_controller_test.rb:7 2) Error: test_should_destroy_product(ProductsControllerTest): NoMethodError: undefined method `products' for ProductsControllerTest:Class /test/functional/products_controller_test.rb:7 ... I did come across the other Rails test fixture question http://stackoverflow.com/questions/1547634/rails-unit-testing-doesnt-load-fixtures, but that leads to a plugin issue (something to do with the order of loading fixtures). BTW, I am developing on Mac OS X 10.6 with Rail 2.3.5 and Ruby 1.8.7, no additional plugins (beyond the base install). Any pointers on how to debug, why the magic of Rails appears to be failing here? Is it a version problem? Can I trace code into the libraries and find the answer? There are so many "mixin" modules I can't find where the fixtures method really lives.

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• Soon to be PhD in Computer Science - Which Path to Follow?

  - by mttr

  I am going to submit my PhD thesis within the next six months. My PhD is on managing the availabiity of large-scale distributed systems, so I have some experience actually building non-trivial systems (+ I have four years experience working as a programmer). I am now trying to figure out what I should do following the PhD. I enjoy research (a quick definition: identify problem, come up with solution, ask interesting questions, find ways to answer them, build system, experiment, contribute some new knowledge and publish). I also like teaching and supervising students. It would seem that a career in academia is the ideal thing to do (can work on non-trivial problems and contribute something of use to some or more people). However, a career in academia has two significant drawbacks. First, it can be difficult to gain access to real systems with real users which then display real problems. This creates the danger that you do work that seems important (to you and maybe to some of your colleagues), but is not really relevant to anything or anyone. Second, the pay is pretty sad. Apparently, you have to sacrifice this for the privilege of doing research. I enjoy programming, but don't just want to hack some web-based system for the rest of my life. That is, working in IT for a bank is not a future I see myself enjoying. I want to work on interesting problms (that's difficult to define clearly): things where you don't know how to start, that take some time to figure out and attack, that require a rigorous approach to demonstrate that the problem has been solved, and problems that need a solution in the real world. Give the experience of people on stackoverflow, what do you think suitable options are and why (or alternatively, what gaps in my thinking does the above reveal)? Is industrial research (aka IBM Research, Microsoft Research) the only alternative avenue to a career in academia? What other areas, companies, occupations, etc. could provide me with stimulating, inspiring work? Which regions, countries am I most likely to find such work? Please share your experience.

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• Is it possible to change HANDLE that has been opened for synchronous I/O to be opened for asynchrono

  - by Martin Dobšík

  Dear all, Most of my daily programming work in Windows is nowadays around I/O operations of all kind (pipes, consoles, files, sockets, ...). I am well aware of different methods of reading and writing from/to different kinds of handles (Synchronous, asynchronous waiting for completion on events, waiting on file HANDLEs, I/O completion ports, and alertable I/O). We use many of those. For some of our applications it would be very useful to have only one way to treat all handles. I mean, the program may not know, what kind of handle it has received and we would like to use, let's say, I/O completion ports for all. So first I would ask: Let's assume I have a handle: HANDLE h; which has been received by my process for I/O from somewhere. Is there any easy and reliable way to find out what flags it has been created with? The main flag in question is FILE_FLAG_OVERLAPPED. The only way known to me so far, is to try to register such handle into I/O completion port (using CreateIoCompletionPort()). If that succeeds the handle has been created with FILE_FLAG_OVERLAPPED. But then only I/O completion port must be used, as the handle can not be unregistered from it without closing the HANDLE h itself. Providing there is an easy a way to determine presence of FILE_FLAG_OVERLAPPED, there would come my second question: Is there any way how to add such flag to already existing handle? That would make a handle that has been originally open for synchronous operations to be open for asynchronous. Would there be a way how to create opposite (remove the FILE_FLAG_OVERLAPPED to create synchronous handle from asynchronous)? I have not found any direct way after reading through MSDN and googling a lot. Would there be at least some trick that could do the same? Like re-creating the handle in same way using CreateFile() function or something similar? Something even partly documented or not documented at all? The main place where I would need this, is to determine the the way (or change the way) process should read/write from handles sent to it by third party applications. We can not control how third party products create their handles. Dear Windows gurus: help please! With regards Martin

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• Offline backup synchronization

  - by Pavan Kumar

  There is a Central Server running Windows Server 2003 and SQL Server 2005 and there are 7 client machines situated in various places and has XP Pro & SQL Server 2005 installed in all of them. They are not interconnected so they are physically seperate. One person goes to each of these centers maybe twice a month and takes the backup (Full database consisting of mdf and ldf files) with a pen drive and brings it to the Central server which contains the central database holding same schema as all the other client databases. I need to synchronize each backup database (belonging to different centers) one by one to update the existing data or inserting new data in the central database . The solution i got was Replication. The pendrive is brought to central server consisting of 7 instances of the databases and then the databases is attached to the central server one by one to the same SQL Server where the central database exists. Then my idea was to replicate the backup database one by one i.e using single subscription (Central Database) and multiple publication ( i.e 7 instances of databases in my case) toplogy by performing replication locally (i.e in the same machine). So i tried to develop a UI in C# .Net to programatically run the Transactional Replication with push subscription using RMO Programming (which is incomplete as of now because there is no point in developing when you already know it is not the solution). Transactional Replication can either be set to initialize with a snapshot or without a snapshot. If i go for the first option i.e with a snapshot , the data whatever is present in Central Database is overwritten by the new data . So the data present initially in the central database is lost. If i try to initialize without snapshot , no data (the data already has the updated and new data) will be sent from the backup database to server. The replication will work in a scenario where any incremental changes is done only after you set the replication . So the initial data whatever was present in the backup database when setting up the replication will not be replicated when running the snapshot agent for the first time to synchronize. Only changes in the backup database thereafter will be reflected to the central database .(Remember I am not going to insert new data or make any changes to the backup database after i attach it to the Central Server. ) So this solution is not feasible. I want a solution for synchronizing from one client database to central database present in the same machine using C#.NET. If you can provide me small example maybe with two databases(with same schema) DB1(Client) to DB2(Server) consisting of one or two tables it will be very helpful. The synchronization is not bidirectional.I want to only update existing data or insert new data from DB1 to DB2 (DB2 may contain some data initially). Thanks and Regards Pavan

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• Calculating multiple column average in SQLite3

  - by Benjamin Oakes

  I need to average some values in a row-wise fashion, rather than a column-wise fashion. (If I were doing a column-wise average, I could just use avg()). My specific application of this requires me ignore NULLs in averaging. It's pretty straightforward logic, but seems awfully difficult to do in SQL. Is there an elegant way of doing my calculation? I'm using SQLite3, for what it's worth. Details If you need more details, here's an illustration: I have a a table with a survey: | q1 | q2 | q3 | ... | q144 | |----|-------|-------|-----|------| | 1 | 3 | 7 | ... | 2 | | 4 | 2 | NULL | ... | 1 | | 5 | NULL | 2 | ... | 3 | (Those are just some example values and simple column names. The valid values are 1 through 7 and NULL.) I need to calculate some averages like so: q7 + q33 + q38 + q40 + ... + q119 / 11 as domain_score_1 q10 + q11 + q34 + q35 + ... + q140 / 13 as domain_score_2 ... q2 + q5 + q13 + q25 + ... + q122 / 12 as domain_score_14 ...but i need to pull out the nulls and average based on the non-nulls. So, for domain_score_1 (which has 11 items), I would need to do: Input: 3, 5, NULL, 7, 2, NULL, 3, 1, 5, NULL, 1 (3 + 5 + 7 + 2 + 3 + 1 + 5 + 1) / (11 - 3) 27 / 8 3.375 A simple algorithm I'm considering is: Input: 3, 5, NULL, 7, 2, NULL, 3, 1, 5, NULL, 1 Coalesce each value to 0 if NULL: 3, 5, 0, 7, 2, 0, 3, 1, 5, 0, 1 Sum: 27 Get the number of non-zeros by converting values 0 to 1 and sum: 3, 5, 0, 7, 2, 0, 3, 1, 5, 0, 1 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1 8 Divide those two numbers 27 / 8 3.375 But that seems like a lot more programming than this should take. Is there an elegant way of doing this that I'm not aware of? Update: Unless I'm misunderstanding something, avg() won't work for this. Example of what I would want to do: select avg(q7, q33, q38, ..., q119) from survey; Output: SQL error near line 3: wrong number of arguments to function avg()

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• Scared of Calculus - Required to pass Differential Calculus as part of my Computer science major

  - by ke3pup

  Hi guys I'm finishing my Computer science degree in university but my fear of maths (lack of background knowledge) made me to leave all my maths units til' the very end which is now. i either take them on and pass or have to give up. I've passed all my programming units easily but knowing my poor maths skills won't do i've been staying clear of the maths units. I have to pass Differential Calculus and Linear Algebra first. With a help of book named "Linear Algebra: A Modern Introduction" i'm finding myself on track and i think i can pass the Linear Algebra unit. But with differential calculus i can't find a book to help me. They're either too advanced or just too simple for what i have to learn. The things i'm required to know for this units are: Set notation, the real number line, Complex numbers in cartesian form. Complex plane, modulus. Complex numbers in polar form. De Moivre’s Theorem. Complex powers and nth roots. Definition of ei? and ez for z complex. Applications to trigonometry. Revision of domain and range of a function Working in R3. Curves and surfaces. Functions of 2 variables. Level curves.Partial derivatives and tangent planes. The derivative as a difference quotient. Geometric significance of the derivative. Discussion of limit. Higher order partial derivatives. Limits of f(x,y). Continuity. Maxima and minima of f(x,y). The chain rule. Implicit differentiation. Directional derivatives and the gradient. Limit laws, l’Hoˆpital’s rule, composition law. Definition of sinh and cosh and their inverses. Taylor polynomials. The remainder term. Taylor series. Is there a book to help me get on track with the above? Being a student i can't buy too many books hence why i'm looking for a book that covers topics I need to know. The University library has a fairly limited collection which i took as loan but didn't find useful as it was too complex.

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• Do you still limit line length in code?

  - by Noldorin

  This is a matter on which I would like to gauge the opinion of the community: Do you still limit the length of lines of code to a fixed maximum? This was certainly a convention of the past for many languages; one would typically cap the number of characters per line to a value such as 80 (and more recnetly 100 or 120 I believe). As far as I understand, the primary reasons for limiting line length are: Readability - You don't have to scroll over horizontally when you want to see the end of some lines. Printing - Admittedly (at least in my experience), most code that you are working on does not get printed out on paper, but by limiting the number of characters you can insure that formatting doesn't get messed up when printed. Past editors (?) - Not sure about this one, but I suspect that at some point in the distant past of programming, (at least some) text editors may have been based on a fixed-width buffer. I'm sure there are points that I am still missing out, so feel free to add to these... Now, when I tend to observe C or C# code nowadays, I often see a number of different styles, the main ones being: Line length capped to 80, 100, or even 120 characters. As far as I understand, 80 is the traditional length, but the longer ones of 100 and 120 have appeared because of the widespread use of high resolutions and widescreen monitors nowadays. No line length capping at all. This tends to be pretty horrible to read, and I don't see it too often, though it's certainly not too rare either. Inconsistent capping of line length. The length of some lines are limited to a fixed maximum (or even a maximum that changes depending on the file/location in code), while others (possibly comments) are not at all. My personal preference here (at least recently) has been to cap the line length to 100 in the Visual Studio editor. This means that in a decently sized window (on a non-widescreen monitor), the ends of lines are still fully visible. I can however see a few disadvantages in this, especially when you end up writing code that's indented 3 or 4 levels and then having to include a long string literal - though I often take this as a sign to refactor my code! In particular, I am curious what the C and C# coders (or anyone who uses Visual Studio for that matter) think about this point, though I would be interested in hearing anyone's thoughts on the subject. Edit Thanks for the all answers - I appreciate the variety of opinions here, all presenting sound reasons. Consensus does seem to be tipping in the direction of always (or almost always) limit the line length. Interestingly, it seems to be in various coding standards to limit the line length. Judging by some of the answers, both the Python and Google CPP guidelines set the limit at 80 chars. I haven't seen anything similar regarding C# or VB.NET, but I would be curious to see if there are ones anywhere.

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• Java - How to make a set of JInternalFrame independant of each other?

  - by Amokrane

  Hello, I'm programming a short Paint program like and I'm trying to make an MDI architecture for it. To make that happen, I used JInternalFrame inside a JDesktopPane. Although I kind of obtain multiple frames, there are not really working properly. Basically, if I have 2 JInternalFrame I can draw only on the last one. The other one seems to be disabled. Here is a short video illustrating the problem. http://bit.ly/9ydiwM Here are some part of the code. Panneau.java public class Panneau extends JDesktopPane { /** La liste de fenêtres ouvertes */ private static ArrayList<Cadre> cadres; /** Le pannel comportant la liste des formes à dessiner*/ private Pannel pannel; /** La barre d'outils */ private ToolBox toolBox; public Panneau() { this.setLayout(new BorderLayout()); // Initialisations des listes de cadres cadres = new ArrayList<Cadre>(); // En haut ToolBox toolBox = new ToolBox(); this.add(toolBox, BorderLayout.NORTH); **// Intialisation de la première internal frame Cadre cadre = new Cadre(); this.add(cadre, BorderLayout.CENTER);** cadres.add(cadre); // Ajout du pannel à gauche pannel = new Pannel(); this.add(pannel, BorderLayout.WEST); } /** * Crée une nouvelle fenêtre de dessin * */ **public void createNewInternalFrame() { Cadre cadre = new Cadre(); this.add(cadre, BorderLayout.CENTER); cadres.add(cadre); }** } public class Cadre extends JInternalFrame { /** Largeur par d'une fenêtre interne */ private int width; /** Hauteur d'une fenêtre interne */ private int height; /** Titre d'une fenêtre interne */ private String title; /** Toile associée à la fenêtre interne */ private Toile toile; public Cadre() { width = 400; height = 400; title = "Form"; toile = new Toile(); this.setTitle(title); this.setSize(width, height); this.setEnabled(true); this.setResizable(true); this.setAutoscrolls(true); this.setClosable(true); this.setIconifiable(true); this.setDoubleBuffered(true); this.setContentPane(toile); this.setVisible(true); this.pack(); } } Basically, Panneau is the main Window that contains all the differents parts of the GUI. I can create as much JInternalFrame that I want, using : Panneau.createNewInternalFrame(). Toile is basically where I draw my shapes. Any idea ? Thanks

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• How to write this Linq SQL as a Dynamic Query (using strings)?

  - by Dr. Zim

  Skip to the "specific question" as needed. Some background: The scenario: I have a set of products with a "drill down" filter (Query Object) populated with DDLs. Each progressive DDL selection will further limit the product list as well as what options are left for the DDLs. For example, selecting a hammer out of tools limits the Product Sizes to only show hammer sizes. Current setup: I created a query object, sent it to a repository, and fed each option to a SQL "table valued function" where null values represent "get all products". I consider this a good effort, but far from DDD acceptable. I want to avoid any "programming" in SQL, hopefully doing everything with a repository. Comments on this topic would be appreciated. Specific question: How would I rewrite this query as a Dynamic Query? A link to something like 101 Linq Examples would be fantastic, but with a Dynamic Query scope. I really want to pass to this method the field in quotes "" for which I want a list of options and how many products have that option. from p in db.Products group p by p.ProductSize into g select new Category { PropertyType = g.Key, Count = g.Count() } Each DDL option will have "The selection (21)" where the (21) is the quantity of products that have that attribute. Upon selecting an option, all other remaining DDLs will update with the remaining options and counts. Edit: Additional notes: .OrderBy("it.City") // "it" refers to the entire record .GroupBy("City", "new(City)") // This produces a unique list of City .Select("it.Count()") //This gives a list of counts... getting closer .Select("key") // Selects a list of unique City .Select("new (key, count() as string)") // +1 to me LOL. key is a row of group .GroupBy("new (City, Manufacturer)", "City") // New = list of fields to group by .GroupBy("City", "new (Manufacturer, Size)") // Second parameter is a projection Product .Where("ProductType == @0", "Maps") .GroupBy("new(City)", "new ( null as string)")// Projection not available later? .Select("new (key.City, it.count() as string)")// GroupBy new makes key an object Product .Where("ProductType == @0", "Maps") .GroupBy("new(City)", "new ( null as string)")// Projection not available later? .Select("new (key.City, it as object)")// the it object is the result of GroupBy var a = Product .Where("ProductType == @0", "Maps") .GroupBy("@0", "it", "City") // This fails to group Product at all .Select("new ( Key, it as Product )"); // "it" is property cast though What I have learned so far is LinqPad is fantastic, but still looking for an answer. Eventually, completely random research like this will prevail I guess. LOL. Edit:

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• What are the Tags Around Default iPhone Address Book People Phone Number Labels?

  - by rnistuk

  My question concerns markup that surrounds some of the default phone number labels in the Person entries of the Contact list on the iPhone. I have created an iPhone contact list address book entry for a person, "John Smith" with the following phone number entries: Mobile (604) 123-4567 iPhone (778) 123-4567 Home (604) 789-4561 Work (604) 456-7891 Main (604) 789-1234 megaphone (234) 567-8990 Note that the first five labels are default labels provided by the Contacts application and the last label, "megaphone", is a custom label. I wrote the following method to retrieve and display the labels and phone numbers for each person in the address book: -(void)displayPhoneNumbersForAddressBook { ABAddressBookRef book = ABAddressBookCreate(); CFArrayRef people = ABAddressBookCopyArrayOfAllPeople(book); ABRecordRef record = CFArrayGetValueAtIndex(people, 0); ABMultiValueRef multi = ABRecordCopyValue(record, kABPersonPhoneProperty); NSLog(@"---------" ); NSLog(@"displayPhoneNumbersForAddressBook" ); CFStringRef label, phone; for (CFIndex i = 0; i < ABMultiValueGetCount(multi); ++i) { label = ABMultiValueCopyLabelAtIndex(multi, i); phone = ABMultiValueCopyValueAtIndex(multi, i); NSLog(@"label: \"%@\" number: \"%@\"", (NSString*)label, (NSString*)phone); CFRelease(label); CFRelease(phone); } NSLog(@"---------" ); CFRelease(multi); CFRelease(people); CFRelease(book); } and here is the output for the address book entry that I entered: 2010-03-08 13:24:28.789 test2m[2479:207] --------- 2010-03-08 13:24:28.789 test2m[2479:207] displayPhoneNumbersForAddressBook 2010-03-08 13:24:28.790 test2m[2479:207] label: "_$!<Mobile>!$_" number: "(604) 123-4567" 2010-03-08 13:24:28.790 test2m[2479:207] label: "iPhone" number: "(778) 123-4567" 2010-03-08 13:24:28.791 test2m[2479:207] label: "_$!<Home>!$_" number: "(604) 789-4561" 2010-03-08 13:24:28.791 test2m[2479:207] label: "_$!<Work>!$_" number: "(604) 456-7891" 2010-03-08 13:24:28.792 test2m[2479:207] label: "_$!<Main>!$_" number: "(604) 789-1234" 2010-03-08 13:24:28.792 test2m[2479:207] label: "megaphone" number: "(234) 567-8990" 2010-03-08 13:24:28.793 test2m[2479:207] --------- What are the markup characters _$!< and >!$_ surrounding most, save for iPhone, of the default labels for? Can you point me to where in the "Address Book Programming Guide for iPhone OS" I can find the information? Thank you for your help.

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• Is the Scala 2.8 collections library a case of "the longest suicide note in history" ?

  - by oxbow_lakes

  First note the inflammatory subject title is a quotation made about the manifesto of a UK political party in the early 1980s. This question is subjective but it is a genuine question, I've made it CW and I'd like some opinions on the matter. Despite whatever my wife and coworkers keep telling me, I don't think I'm an idiot: I have a good degree in mathematics from the University of Oxford and I've been programming commercially for almost 12 years and in Scala for about a year (also commercially). I have just started to look at the Scala collections library re-implementation which is coming in the imminent 2.8 release. Those familiar with the library from 2.7 will notice that the library, from a usage perspective, has changed little. For example... > List("Paris", "London").map(_.length) res0: List[Int] List(5, 6) ...would work in either versions. The library is eminently useable: in fact it's fantastic. However, those previously unfamiliar with Scala and poking around to get a feel for the language now have to make sense of method signatures like: def map[B, That](f: A => B)(implicit bf: CanBuildFrom[Repr, B, That]): That For such simple functionality, this is a daunting signature and one which I find myself struggling to understand. Not that I think Scala was ever likely to be the next Java (or /C/C++/C#) - I don't believe its creators were aiming it at that market - but I think it is/was certainly feasible for Scala to become the next Ruby or Python (i.e. to gain a significant commercial user-base) Is this going to put people off coming to Scala? Is this going to give Scala a bad name in the commercial world as an academic plaything that only dedicated PhD students can understand? Are CTOs and heads of software going to get scared off? Was the library re-design a sensible idea? If you're using Scala commercially, are you worried about this? Are you planning to adopt 2.8 immediately or wait to see what happens? Steve Yegge once attacked Scala (mistakenly in my opinion) for what he saw as its overcomplicated type-system. I worry that someone is going to have a field day spreading fud with this API (similarly to how Josh Bloch scared the JCP out of adding closures to Java). Note - I should be clear that, whilst I believe that Josh Bloch was influential in the rejection of the BGGA closures proposal, I don't ascribe this to anything other than his honestly-held beliefs that the proposal represented a mistake.

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• Adding Icons next to items in Navigation Drawer

  - by DunriteJW

  I have been trying to figure this out for quite some time right now. I've looked all over this site and many others, and can't find anything that works. I simply want icons next to each item in my navigation drawer. I am currently using the method that Google's navigation drawer sample app uses. in the MainActivity.java I have the following: mColorTitles = getResources().getStringArray(R.array.colors_array); mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); mDrawerList = (ListView) findViewById(R.id.left_drawer); mColorIcons = getResources().getStringArray(R.array.color_icons); adapter = new ArrayAdapter<String>(this, R.layout.drawer_list_item, mColorTitles); // set a custom shadow that overlays the main content when the drawer opens mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START); // set up the drawer's list view with items and click listener mDrawerList.setAdapter(adapter); mDrawerList.setOnItemClickListener(new DrawerItemClickListener()); my drawer_list_item.xml: <TextView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@android:id/text1" android:layout_width="match_parent" android:layout_height="match_parent" android:textAppearance="?android:attr/textAppearanceListItemSmall" android:gravity="center_vertical" android:paddingLeft="5dp" android:paddingRight="16dp" android:textColor="#000" android:background="?android:attr/activatedBackgroundIndicator" android:minHeight="?android:attr/listPreferredItemHeightSmall"/> it currently just makes the navigation drawer display the color titles from the array. I have the icons that I want in another array, and they follow the exact same order as I want them associated with the colors. I just have no idea how to even begin inserting the icons from that array into the navigation items if it helps, here's what my arrays look like in my strings.xml (not full code) <string-array name="colors_array"> <item>Home</item> <item>Cherry</item> <item>Crimson</item> ... <array name="color_icons"> <item>@drawable/homeicon</item> <item>@drawable/cherryicon</item> <item>@drawable/crimsonicon</item> ... I've tried putting a drawable in the drawer_list_item, which works, but (of course) it always puts the same one in there. I could not think of a way to change it according to the color. I am relatively new to android programming, so if I am missing something simple, I'm sorry. If you could help me out, I would greatly appreciate it, as this is basically the last thing I need to do before I publish my application to the Play Store. Thanks in advance!

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• Zend Framework - Ruby on Rails has a screencast showing how to code a blog in 15 minutes. Does ZF ha

  - by Sootah

  Ruby on Rails has a screencast presentation they use to promote their framework that shows how to code a basic weblog system in 15 minutes with RoR. Does the Zend PHP Framework have a similar screencast/presentation/whatever demonstrating something similar? It doesn't have to be a blog specifically, but I would definitely like to find a presentation that shows some rapid application development using ZF. Where I'm coming from: I have been programming on and off for years now. I started out with QBASIC waaaaay back in the day making little programs (text adventure games, screensavers, simple little things). I then moved to C++ but never really did anything too impressive with it. Since then (probably 5 years or so now) I have started to use C# for my desktop development and PHP for my web development. I've made some pretty cool tools here and there, but am certainly not a professional programmer by any stretch of the term as it has always simply been a hobby of mine. Right now I have two major web applications that I will start work on shortly. (Like tomorrow, or later tonight ideally.. :) ) Both will be database-driven apps that will require user registration, the ability to manipulate data that is specific to their account (their posts, listings, user account details, etc), amongst other things. Currently I am evaluating different frameworks to help me develop these web apps more quickly. I've been looking at, and have heard good things about Ruby on Rails. Hulu and YellowPages.com using it is an obvious endorsement - Of course, I have heard about the scalability issues that it potentially has; but that shouldn't be an issue with what I am working on. I don't expect millions of users per day for either project. I am also seriously looking at the Zend Framework for my needs because I already have some experience with PHP. Ideally I would like to find a ZF screencast that shows an app being written quickly so that I have a roughly equal comparison between the two options I am exploring and can see first-hand how things get done in both. That said - I am not opposed to considering frameworks other than RoR or ZF. The only research I've done on the subject has been over the past couple of days so I am quite certain that there are other excellent options out there that I've not even looked at - or heard of. Of course, it'd be awesome if there is a rapid app dev presentation that I can watch for whatever else is suggested. So - Suggestions? Links to good screencasts that show rapid application development in other frameworks? Are there other PHP frameworks that I should be considering? (Ones that are easy to deploy would be ideal, so I don't have to purchase a dedicated server that I have full control over. I'd like to keep my hosting costs down assuming that it's reasonable) Thanks in advance! -Sootah

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• Architecture choice about representation of collections in Business Objects

  - by Rajarshi

  I have made certain choices in my architecture which I request the community to review and comment. I am breaking up the post in smaller sections to make it easier to understand the context and then suggest/comment. I am sorry that the post is long, but is required to explain the context. What am I building A typical business application where there are application users, security roles, business operation/action rights based on roles and several business modules like Stock Receive, Stock Transfer, Sale Order, Sale Invoice, Sale Return, Stock Audit etc. and several reports. The application is a WinForm application since it has a lot of rich and responsive UI requirements and has to operate in disconnected mode (with a local SQL Server), most of the time. What have I done I have built a framework - nothing to boast about, but just a set of libraries that serves the repetative requirements of my application, e.g. authentication, role based authorization, data access, validation, exception handling, logging, change status tracking, presentation model compliance and reasonable loose coupling between components. No, I have not written everything from scratch, you can say I have consolidated many things together like some concepts from CSLA, Martin Fowler for Presentation Model, blocks from Enterprise Library, Unity etc. to build a set of libraries that will help my developers be productive quickly without having to look up Google for many of the technical requirements. I have tried to keep the framework generic so that it can be used in typical business applications and also tried to follow some best practices that will support the same Business Objects to be used in an ASP.NET MVC environment also. My present architecture serves my objectives well, and have built several modules (on WinForm) without much trouble. The architecture also lent itself well to build some usable prototype on ASP.NET MVC with the same set of business objects, without changing a single line of code. My Dilemma I have used Custom Business Objects since that gives me a clearer OOP representation of the problem scope in my solution scope, and helps me visualize my entire solution as collection of objects with data and behavior rather than having a set of relational data (DataSet) and implement behaviours (business logic, validation) etc. separately. With rich databinding support in .NET 2.0 binding Custom Business Objects to UI was a breeze. Now while building my business objects, I am still in a dilemma about representation of collections in business objects. Currently I am using DataSets to represent collections while I have seen many suggestions to implement custom collections. For example, in my vision, a typical Sale Invoice Object will contain 'Sales Invoice Items' as a collection. Now theoritically, I can accept that the each 'Sales Invoice Item' should have its own behavior along with their data (ItemCode, Name, Qty, Price etc.) but typically managing of Sale Invoice Items in a Sale Invoice is handled by the Sale Invoice Object itself, e.g. adding/removing Items from collection. Additionally, we can also put business logic/rules for the Sales Invoice Items like "Qty should not be greater than the ordered qty", "Price should be max 10% above the price in Sale Order" etc. in the Sale Invoice object itself. With that kind of a vision, I felt that most business object child collections can be managed by the parent itself, including add/remove from collection as well and implementing business logic for the collection items, hence the collection items hold nothing but data. Additionally, typical collections are represented in UI in Grids, where ability to support DataBinding becomes very important for any collection. Implementing a custom collection, in that case would also mean, I have to implement robust DataBinding support as well, for the collection, which is of course time consuming. Now, considering child collection behaviors are implemented in the parent and the need for DataBinding of child collections, I chose DataSet to represent any child collection in my business objects. In the above example of Sale Invoice I will have 'Invoice Number', 'Date', 'Customer' etc. as attributes of the 'Sale Invoice' but 'InvoiceItems' as a DataSet. Of course, when I say DataSet, it is not a vanilla dataset but an extended DataSet that supports business rule validation and the same role based security model of my framework to allow/deny any business operation to rows/columns of the DataSet, automatically. This approach has allowed easier collection management and databinding in my business objects and my developers are able to deliver modules rapidly. Questions Do you feel that the approach is reasonable? Do you see any shortcomings of this approach? I am recently thinking of using 'Typed DataSets' as child collections, for easier representation in code, that will allow me to write 'currentInvoice.InvoiceItems' (for the DataTable) and 'invoiceItem.ProductCode' or 'invoiceItem.Qty', instead of 'drow["ProductCode"].ToString()' or '(int)drow["Qty"]' etc. Does this choice have any demerits? Thank you if you have read so far and a salute if you still have the Energy to answer.

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• Computation on db data then list them using either SimpleCursorAdapter or ArrayAdapter

  - by kc2uno

  Hi all, I juststarted programming in android a few weeks ago, so I am not entirely sure how to deal with listing values. Please help me out! I have some questions regarding displaying data sets from db in a list. Currently I have a cursor returned by my db points to a list of rows and I want display 2 columns values in a single row of the list. The row xml looks like this: <TextView android:id="@+id/text1" android:textSize="16sp" android:textStyle="bold" android:layout_width="fill_parent" android:layout_height="wrap_content"/> <TextView android:id="@+id/text2" android:textSize="14sp" android:layout_width="fill_parent" android:layout_height="wrap_content"/> so I was thinking using simplecursoradapter which supposedly makes my life easier by displaying the data in a list. However that is only true if I want to display the raw data. For the purpose of my program I need to do some computations on the raw data sets, then display them. I am not sure how to do that using SimpleCursorAdapter. Here's how I display the raw data: String[] from = new String[]{BtDbAdapter.KEY_EX_TYPE,BtDbAdapter.KEY_EX_TIMESTAMP}; int[] to = new int[]{R.id.text1, R.id.text2}; // Now create a simple cursor adapter and set it to display SimpleCursorAdapter records = new SimpleCursorAdapter(this, R.layout.exset_row, mExsetCursor, from, to); setListAdapter(records); Is there a way to do computation on the data in those rows before I bind it with the SimpleCursorAdapter? I was trying to use an alternative way of doing this by using arraylist and arrayadapter, but that way I dont know to how achieve displaying 2 items in a single row. This is my code for using arrayadapter which only display 1 text in a row instead of 2 textviews in a row: //fill in the array timestamp_arr = new ArrayList<String>(); type_arr = new ArrayList<String>(); fillRecord(); Log.d(TAG,"setting now in recordlist"); setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item,timestamp_arr)); setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item2,type_arr)); It's very obvious that it only displays one textview in a row because I set the second arrayadapter overwrites the first one! I was trying to use R.id.text1 and R.id.text2 for them, but it gave me some errors saying 04-23 01:40:58.658: ERROR/AndroidRuntime(3309): android.content.res.Resources$NotFoundException: Resource ID #0x7f070008 type #0x12 is not valid I believe the second method can achieve this, but I'm not sure how do deal with the layout problems, so if you any suggestions, please post them out. Thank you!!

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