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  • SQL Server 2008 R2

    - by kevchadders
    Hi all, I heard on the grapevine that Microsoft will be releasing SQL Server 2008 R2 within a year. Though I initially thought this was a patch for the just released 2008 version, I realised that it’s actually a completely different version that you would have to pay for. (Am I correct, if you had SQL Server 2008, would you have to pay again if you wanted to upgrade to 2008 R2?) If you’re already running SQL Server 2008, would you say it’s still worth the upgrade? Or does it depend on the size of your company and current setup. For what I’ve initially read, I do get the impression that this version would be more useful for the very high end hardware setup where you want to have very good scalability. With regard to programming, is there any extra enhancements/support in there which you’re aware of that will significantly help .NET Products/Web Development? Initially found a couple of links on it, but I was wondering if anyone had anymore info to share on subject as I couldn’t find nothing on SO about it? Thanks. New SQL Server R2 Microsoft Link on it. Microsoft SQL 2008 R2 EDIT: More information based on the Express Edition One very interesting thing about SQL Server 2008 R2 concerns the Express edition. Previous express versions of SQL Server Express had a database size limit of 4GB. With SQL Server Express 2008 R2, this has now been increased to 10GB !! This now makes the FREE express edition a much more viable option for small & medium sized applications that are relatively light on database requirements. Bear in mind, that this limit is per database, so if you coded your application cleverly enough to use a separate database for historical/archived data, you could squeeze even more out of it! For more information, see here: http://blogs.msdn.com/sqlexpress/archive/2010/04/21/database-size-limit-increased-to-10gb-in-sql-server-2008-r2-express.aspx

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  • In an Android application, should I have one content provider per table or only one for the entire a

    - by Andrew Dyer
    I have years of experience with Microsoft .NET development (primarily C#) and have been working to come up to speed on Android and Java. So far, I've built a small application with a couple screens and a working content provider. All of the examples I've seen for developing content providers typically work with a single table, so I got the impression that this was the convention. I built a couple more content providers for other tables and ran into the "Unknown URI" IllegalArgumentException when I tried to test them. The exception is being thrown by one of my content providers, but not the one I was intending to call. It appears that my application is using the first content provider in the AndroidManifest.xml file, which now has me wondering if I should only have a single content provider for the entire application. Are there any best practices and/or examples for working with multiple tables in an Android application? Should I have one content provider per table or only one for the entire application? If the former, how do I resolve URIs to the proper provider? If the latter, how do I keep my content provider code from being polluted with switch statements?

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  • Compiling GWT 2.6.1 at Java 7 source level

    - by Neeko
    I've recently updated my GWT project to 2.6.1, and started to make use of Java 7 syntax since 2.6 now supports Java 7. However, when I attempt to compile, I'm receiving compiler errors such as [ERROR] Line 42: '<>' operator is not allowed for source level below 1.7 How do I specify the GWT compiler to target 1.7? I was under the impression that it would do that by default, but I guess not. I've attempted cleaning the project, including deleting the gwt-unitCache directory but to no avail. Here is my Ant compile target. <target name="compile" depends="prepare"> <javac includeantruntime="false" debug="on" debuglevel="lines,vars,source" srcdir="${src.dir}" destdir="${build.dir}"> <classpath refid="project.classpath"/> </javac> </target> <target name="gwt-compile" depends="compile"> <java failonerror="true" fork="true" classname="com.google.gwt.dev.Compiler"> <classpath> <!-- src dir is added to ensure the module.xml file(s) are on the classpath --> <pathelement location="${src.dir}"/> <pathelement location="${build.dir}"/> <path refid="project.classpath"/> </classpath> <jvmarg value="-Xmx256M"/> <arg value="${gwt.module.name}"/> </java> </target>

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  • Can Haskell's monads be thought of as using and returning a hidden state parameter?

    - by AJM
    I don't understand the exact algebra and theory behind Haskell's monads. However, when I think about functional programming in general I get the impression that state would be modelled by taking an initial state and generating a copy of it to represent the next state. This is like when one list is appended to another; neither list gets modified, but a third list is created and returned. Is it therefore valid to think of monadic operations as implicitly taking an initial state object as a parameter and implicitly returning a final state object? These state objects would be hidden so that the programmer doesn't have to worry about them and to control how they gets accessed. So, the programmer would not try to copy the object representing the IO stream as it was ten minutes ago. In other words, if we have this code: main = do putStrLn "Enter your name:" name <- getLine putStrLn ( "Hello " ++ name ) ...is it OK to think of the IO monad and the "do" syntax as representing this style of code? putStrLn :: IOState -> String -> IOState getLine :: IOState -> (IOState, String) main :: IOState -> IOState -- main returns an IOState we can call "state3" main state0 = putStrLn state2 ("Hello " ++ name) where (state2, name) = getLine state1 state1 = putStrLn state0 "Enter your name:"

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  • Controller actions appear to be synchronous though on different requests?

    - by Oded
    I am under the impression that the below code should work asynchronously. However, when I am looking at firebug, I see the requests fired asynchronously, but the results coming back synchronously: Controller: [HandleError] public class HomeController : Controller { public ActionResult Status() { return Content(Session["status"].ToString()); } public ActionResult CreateSite() { Session["status"] += "Starting new site creation"; Thread.Sleep(20000); // Simulate long running task Session["status"] += "<br />New site creation complete"; return Content(string.Empty); } } Javascript/jQuery: $(document).ready(function () { $.ajax({ url: '/home/CreateSite', async: true, success: function () { mynamespace.done = true; } }); setTimeout(mynamespace.getStatus, 2000); }); var mynamespace = { counter: 0, done: false, getStatus: function () { $('#console').append('.'); if (mynamespace.counter == 4) { mynamespace.counter = 0; $.ajax({ url: '/home/Status', success: function (data) { $('#console').html(data); } }); } if (!mynamespace.done) { mynamespace.counter++; setTimeout(mynamespace.getStatus, 500); } } } Addtional information: IIS 7.0 Windows 2008 R2 Server Running in a VMWare virutual machine Can anyone explain this? Shouldn't the Status action be returning practically immediately instead of waiting for CreateSite to finish? Edit: How can I get the long running process to kick off and still get status updates?

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  • SQL Server race condition issue with range lock

    - by Freek
    I'm implementing a queue in SQL Server (please no discussions about this) and am running into a race condition issue. The T-SQL of interest is the following: set transaction isolation level serializable begin tran declare @RecordId int declare @CurrentTS datetime2 set @CurrentTS=CURRENT_TIMESTAMP select top 1 @RecordId=Id from QueuedImportJobs with (updlock) where Status=@Status and (LeaseTimeout is null or @CurrentTS>LeaseTimeout) order by Id asc if @@ROWCOUNT> 0 begin update QueuedImportJobs set LeaseTimeout = DATEADD(mi,5,@CurrentTS), LeaseTicket=newid() where Id=@RecordId select * from QueuedImportJobs where Id = @RecordId end commit tran RecordId is the PK and there is also an index on Status,LeaseTimeout. What I'm basically doing is select a record of which the lease happens to be expired, while simultaneously updating the lease time with 5 minutes and setting a new lease ticket. So the problem is that I'm getting deadlocks when I run this code in parallel using a couple of threads. I've debugged it up to the point where I found out that the update statement sometimes gets executing twice for the same record. Now, I was under the impression that the with (updlock) should prevent this (it also happens with xlock btw, not with tablockx). So it actually look like there is a RangeS-U and a RangeX-X lock on the same range of records, which ought to be impossible. So what am I missing? I'm thinking it might have something to do with the top 1 clause or that SQL Server does not know that where Id=@RecordId is actually in the locked range? Deadlock graph: Table schema (simplified):

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  • Square Brackets in Python Regular Expressions (re.sub)

    - by user1479984
    I'm migrating wiki pages from the FlexWiki engine to the FOSwiki engine using Python regular expressions to handle the differences between the two engines' markup languages. The FlexWiki markup and the FOSwiki markup, for reference. Most of the conversion works very well, except when I try to convert the renamed links. Both wikis support renamed links in their markup. For example, Flexwiki uses: "Link To Wikipedia":[http://www.wikipedia.org/] FOSwiki uses: [[http://www.wikipedia.org/][Link To Wikipedia]] both of which produce something that looks like I'm using the regular expression renameLink = re.compile ("\"(?P<linkName>[^\"]+)\":\[(?P<linkTarget>[^\[\]]+)\]") to parse out the link elements from the FlexWiki markup, which after running through something like "Link Name":[LinkTarget] is reliably producing groups <linkName> = Link Name <linkTarget = LinkTarget My issue occurs when I try to use re.sub to insert the parsed content into the FOSwiki markup. My experience with regular expressions isn't anything to write home about, but I'm under the impression that, given the groups <linkName> = Link Name <linkTarget = LinkTarget a line like line = renameLink.sub ( "[[\g<linkTarget>][\g<linkName>]]" , line ) should produce [[LinkTarget][Link Name]] However, in the output to the text files I'm getting [[LinkTarget [[Link Name]] which breaks the renamed links. After a little bit of fiddling I managed a workaround, where line = renameLink.sub ( "[[\g<linkTarget>][ [\g<linkName>]]" , line ) produces [[LinkTarget][ [[Link Name]] which, when displayed in FOSwiki looks like <[[Link Name> <--- Which WORKS, but isn't very pretty. I've also tried line = renameLink.sub ( "[[\g<linkTarget>]" + "[\g<linkName>]]" , line ) which is producing [[linkTarget [[linkName]] There are probably thousands of instances of these renamed links in the pages I'm trying to convert, so fixing it by hand isn't any good. For the record I've run the script under Python 2.5.4 and Python 2.7.3, and gotten the same results. Am I missing something really obvious with the syntax? Or is there an easy workaround?

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  • Agile methodologies. Is it a by-product of mind control techniques as NLP / Scientology?

    - by Bobb
    The more I read about contemporary methods combinging scrum, tdd and xp, the more I feel like I already seen the methods. I am not arguing that agile approach is much more progressive than older rigid structures like waterfall, what I am saying is that it seems to me that agile methodologies are ideal to be used as a nest for a brainwashing business. I read few articles which kept referring to authors which I checked afterwards and they call themselves - coaches, trainers (usual thing when NLP specialists are involved) with no apparent software development history. Also I met a guy who is a scrum faciltator (term widly used in relation to scientology) in a high profile company. I talked to him less than 5 min but I got complete feeling that he is either on drugs or he has been programmed by a powerful NLP specialist. The way to talk and his body movements witnessed he is not an average normal person (in terms of normal distribution :))... Please dont get me wrong. I am not a fun of conspiracy theories. But I had an experience with a member of church of scientology tried to invade a commercial firm and actually went half way through to very top in just 3 weeks. I saw his work. For now I have complete impression is that psycho manipulators are now invading IT industry through the convenient door of agile techniques. Anyone has the same feeling/thoughts?

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  • How to organize RMI Client-Server eBanking architecture

    - by xenom
    I am developing a secured eBanking service in RMI with a GUI both for Server and Client. The Server must be able to log every operations (new User, deleted User, Withdrawal, Lodgement...) The Client will do these operations. As everything is secured, the Client must at first, create an account with a name and a password in the GUI. After that, the GUI adds the User in the Bank UserList(arrayList) as a new Customer and the User can do several operations. It seems straightforward at first but I think my conception is not correct. Is it correct to send the whole Bank by RMI ? Because at first I thought Bank would be the server but I cannot find another way to do that. Currently, the Client GUI asks for a login and a password, and receives the Bank by RMI. A User is characterized by a name and a hash of the password. private String name; private byte[] passwordDigest; In fact the GUI is doing every security checking and I don't know if it's relevant. When you type login//password, it will search the login in the Bank and compare the hash of the password. In fact I have the impression that the Client knows too much information because when you have the Bank you have everything.. Does it seem correct or do I need to change my implementation ?

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  • variables in abstract classes C++

    - by wyatt
    I have an abstract class CommandPath, and a number of derived classes as below: class CommandPath { public: virtual CommandResponse handleCommand(std::string) = 0; virtual CommandResponse execute() = 0; virtual ~CommandPath() {} }; class GetTimeCommandPath : public CommandPath { int stage; public: GetTimeCommandPath() : stage(0) {} CommandResponse handleCommand(std::string); CommandResponse execute(); }; All of the derived classes have the member variable 'stage'. I want to build a function into all of them which manipulates 'stage' in the same way, so rather than defining it many times I thought I'd build it into the parent class. I moved 'stage' from the private sections of all of the derived classes into the protected section of CommandPath, and added the function as follows: class CommandPath { protected: int stage; public: virtual CommandResponse handleCommand(std::string) = 0; virtual CommandResponse execute() = 0; std::string confirmCommand(std::string, int, int, std::string, std::string); virtual ~CommandPath() {} }; class GetTimeCommandPath : public CommandPath { public: GetTimeCommandPath() : stage(0) {} CommandResponse handleCommand(std::string); CommandResponse execute(); }; Now my compiler tells me for the constructor lines that none of the derived classes have a member 'stage'. I was under the impression that protected members are visible to derived classes? The constructor is the same in all classes, so I suppose I could move it to the parent class, but I'm more concerned about finding out why the derived classes aren't able to access the variable. Also, since previously I've only used the parent class for pure virtual functions, I wanted to confirm that this is the way to go about adding a function to be inherited by all derived classes.

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  • F# How to tokenise user input: separating numbers, units, words?

    - by David White
    I am fairly new to F#, but have spent the last few weeks reading reference materials. I wish to process a user-supplied input string, identifying and separating the constituent elements. For example, for this input: XYZ Hotel: 6 nights at 220EUR / night plus 17.5% tax the output should resemble something like a list of tuples: [ ("XYZ", Word); ("Hotel:", Word); ("6", Number); ("nights", Word); ("at", Operator); ("220", Number); ("EUR", CurrencyCode); ("/", Operator); ("night", Word); ("plus", Operator); ("17.5", Number); ("%", PerCent); ("tax", Word) ] Since I'm dealing with user input, it could be anything. Thus, expecting users to comply with a grammar is out of the question. I want to identify the numbers (could be integers, floats, negative...), the units of measure (optional, but could include SI or Imperial physical units, currency codes, counts such as "night/s" in my example), mathematical operators (as math symbols or as words including "at" "per", "of", "discount", etc), and all other words. I have the impression that I should use active pattern matching -- is that correct? -- but I'm not exactly sure how to start. Any pointers to appropriate reference material or similar examples would be great.

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  • Sending custom app logs to developer

    - by Templar
    I'm planning to release a new app in the future. I have a custom logging function which logs some application data (not crashes) into a file (location manager state, app foreground-background transitions, main actions...). These logs helped me a lot to debug problems which were app-related, but not causing a crash. Until now these were in the documents directory (shared in iTunes) and the testers sent them to me after they saw some incorrect behaviors, however I don't want to share them anymore because this directory contains the app's database too. I'd like to obtain these logs even when the app will be on App Store, but I don't know how this should be done. As I wrote, it is a new app and even after the test phase may exist minor bugs. I know that the users can report problems in iTunes or on the Dev site, but without a detailed scenario or log it is really hard to correct a bug. Should I make some kind of in-app bug report functionality (even if this creates a wrong user impression) ? How is this usually handled ? Thanks

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  • How to understand "if ( obj.length === +obj.length )" Javascript condition statement?

    - by humanityANDpeace
    I have run across a condition statement which I have some difficulties to understand. It looks like (please note the +-sign on the right-hand-side) this: obj.length === +obj.length. Can this condition and its purpose/syntax be explained? Looking at the statement (without knowing it) provokes the impression that it is a dirty hack of some sort, but I am almost certain that underscore.js is rather a well designed library, so there must be a better explanation. Background I found this statement used in some functions of the underscore.js library (underscore.js annotated source). My guesswork is that this condition statement is somehow related to testing for a variable obj to be of Array type? (but I am totally unsure). I have tried to test this using this code. var myArray = [1,2,3]; testResult1 = myArray.length === +myArray.length; console.log( testResult1 ); //prints true var myObject = { foo : "somestring", bar : 123 }; testResult2 = myObject.length === +myObject.length; console.log( testResult2 ); //prints false

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  • Parallelize or vectorize all-against-all operation on a large number of matrices?

    - by reve_etrange
    I have approximately 5,000 matrices with the same number of rows and varying numbers of columns (20 x ~200). Each of these matrices must be compared against every other in a dynamic programming algorithm. In this question, I asked how to perform the comparison quickly and was given an excellent answer involving a 2D convolution. Serially, iteratively applying that method, like so list = who('data_matrix_prefix*') H = cell(numel(list),numel(list)); for i=1:numel(list) for j=1:numel(list) if i ~= j eval([ 'H{i,j} = compare(' char(list(i)) ',' char(list(j)) ');']); end end end is fast for small subsets of the data (e.g. for 9 matrices, 9*9 - 9 = 72 calls are made in ~1 s). However, operating on all the data requires almost 25 million calls. I have also tried using deal() to make a cell array composed entirely of the next element in data, so I could use cellfun() in a single loop: # who(), load() and struct2cell() calls place k data matrices in a 1D cell array called data. nextData = cell(k,1); for i=1:k [nextData{:}] = deal(data{i}); H{:,i} = cellfun(@compare,data,nextData,'UniformOutput',false); end Unfortunately, this is not really any faster, because all the time is in compare(). Both of these code examples seem ill-suited for parallelization. I'm having trouble figuring out how to make my variables sliced. compare() is totally vectorized; it uses matrix multiplication and conv2() exclusively (I am under the impression that all of these operations, including the cellfun(), should be multithreaded in MATLAB?). Does anyone see a (explicitly) parallelized solution or better vectorization of the problem?

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  • Java: Inputting text from a file using split

    - by 00PS
    I am inputting an adjacency list for a graph. There are three columns of data (vertex, destination, edge) separated by a single space. Here is my implementation so far: FileStream in = new FileStream("input1.txt"); Scanner s = new Scanner(in); String buffer; String [] line = null; while (s.hasNext()) { buffer = s.nextLine(); line = buffer.split("\\s+"); g.add(line[0]); System.out.println("Added vertex " + line[0] + "."); g.addEdge(line[0], line[1], Integer.parseInt(line[2])); System.out.println("Added edge from " + line[0] + " to " + line[1] + " with a weight of " + Integer.parseInt(line[2]) + "."); } System.out.println("Size of graph = " + g.size()); Here is the output: Added vertex a. Added edge from a to b with a weight of 9. Exception in thread "main" java.lang.NullPointerException at structure5.GraphListDirected.addEdge(GraphListDirected.java:93) at Driver.main(Driver.java:28) I was under the impression that line = buffer.split("\\s+"); would return a 2 dimensional array of Strings to the variable line. It seemed to work the first time but not the second. Any thoughts? I would also like some feedback on my implementation of this problem. Is there a better way? Anything to help out a novice! :)

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  • Mathmatic errors in basic C++ program

    - by Heather
    I am working with a basic C++ program to determine the area and perimeter of a rectangle. My program works fine for whole numbers but falls apart when I use any number with a decimal. I get the impression that I am leaving something out, but since I'm a complete beginner, I have no idea what. Below is the source: #include <iostream> using namespace std; int main() { // Declared variables int length; // declares variable for length int width; // declares variable for width int area; // declares variable for area int perimeter; // declares variable for perimeter // Statements cout << "Enter the length and the width of the rectangle: "; // states what information to enter cin >> length >> width; // user input of length and width cout << endl; // closes the input area = length * width; // calculates area of rectangle perimeter = 2 * (length + width); //calculates perimeter of rectangle cout << "The area of the rectangle = " << area << " square units." <<endl; // displays the calculation of the area cout << "The perimeter of the rectangle = " << perimeter << " units." << endl; // displays the calculation of the perimeter system ("pause"); // REMOVE BEFORE RELEASE - testing purposes only return 0; }

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  • Mathematics errors in basic C++ program

    - by H Bomb1013
    I am working with a basic C++ program to determine the area and perimeter of a rectangle. My program works fine for whole numbers but falls apart when I use any number with a decimal. I get the impression that I am leaving something out, but since I'm a complete beginner, I have no idea what. Below is the source: #include <iostream> using namespace std; int main() { // Declared variables int length; // declares variable for length int width; // declares variable for width int area; // declares variable for area int perimeter; // declares variable for perimeter // Statements cout << "Enter the length and the width of the rectangle: "; // states what information to enter cin >> length >> width; // user input of length and width cout << endl; // closes the input area = length * width; // calculates area of rectangle perimeter = 2 * (length + width); //calculates perimeter of rectangle cout << "The area of the rectangle = " << area << " square units." <<endl; // displays the calculation of the area cout << "The perimeter of the rectangle = " << perimeter << " units." << endl; // displays the calculation of the perimeter system ("pause"); // REMOVE BEFORE RELEASE - testing purposes only return 0; }

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  • PHP and storing stats

    - by John
    Using PHP5 and the latest version of MySQL I want to be able to track impressions and clicks for business listings. My question is if I did this myself what would be the best method in storing it so I can run reports? Before I just had a table that had the listing id, user ip address and if it was a click or impression as well as the date it was tracked. However the database itself is approaching 2GB of data and its very slow, part of the problem is its a pretty simple script that includes impressions and clicks from anyone including search engines and basically anyone or anything that accesses the listing page. Is there an api or file out there that has an update to date list that can detect if the person viewing is a actually person and not a spider so I dont fill up the database with unneeded stats? Just looking for suggestions, do I just have a raw database that gets just the hits then a cron job at night tally up for the day for each listing for each ip and store the cumulative stats in a different table? Also what type of database should it be? Innodb? MyISAM?

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  • How to get from JRuby a correctly typed ruby implementation of a Java interface?

    - by Guss
    I'm trying to use JRuby (through the JSR233 interface included in JRuby 1.5) from a Java application to load a ruby implementation of a Java interface. My sample implementation looks like this: Interface: package some.package; import java.util.List; public interface ScriptDemoIf { int fibonacci(int d); List<String> filterLength(List<String> source, int maxlen); } Ruby Implementation: require 'java' include Java class ScriptDemo java_implements some.package.ScriptDemoIf java_signature 'int fibonacci(int d)' def fibonacci(d) d < 2 ? d : fibonacci(d-1) + fibonacci(d-2) end java_signature 'List<String> filterLength(List<String> source, int maxlen)' def filterLength(source, maxlen) source.find_all { |str| str.length <= maxlen } end end Class loader: public ScriptDemoIf load(String filename) throws ScriptException { ScriptEngine engine = new ScriptEngineManager().getEngineByName("jruby"); FileReader script = new FileReader(filename); try { engine.eval(new FileReader(script)); } catch (FileNotFoundException e) { throw new ScriptException("Failed to load " + filename); } return (ScriptDemoIf) m_engine.eval("ScriptDemo.new"); } (Obviously the loader is a bit more generic in real life - it doesn't assume that the implementation class name is "ScriptDemo" - this is just for simplicity). Problem - I get a class cast exception in the last line of the loader - the engine.eval() return a RubyObject type which doesn't cast down nicely to my interface. From stuff I read all over the web I was under the impression that the whole point of use java_implements in the Ruby section was for the interface implementations to be compiled in properly. What am I doing wrong?

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  • Is there a jQuery Equivalent of YUI 2 Custom Event Publish/Subscribe Event Model?

    - by Abe
    Hello! I learned how to develop in Javascript using the YUI 2 library and was wondering if there is a jQuery equivalent of Custom Events (http://developer.yahoo.com/yui/event/#customevent) Specifically, I want to be able to define custom events without having to attach the listeners initially. In YUI, I would create a page class and declare different custom events that can be subscribed to. Below is some example code to demonstrate what I want to do, but with jQuery function ListPage() { var me = this; this.initEvent = new YAHOO.util.CustomEvent("initEvent"); this.init = function() { // initialize events, DOM, etc this.initEvent.fire(me); } } In application Javascript, I would then like to subscribe to the initEvent. var page = new ListPage(); page.initEvent.subscribe( function (type, args) { // do stuff here } ); page.init(); Are there any tutorials/examples of something this in jQuery? I understand I can do something similar using bind() and trigger(), but the impression I get is I have to pass in the event handler when I call bind(). Is it possible in jQuery to create the custom event, but pass in the event handler later? I hope my question makes sense. thanks!

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  • Why is it possible to enumerate a LinqToSql query after calling Dispose() on the DataContext?

    - by DanM
    I'm using the Repository Pattern with some LinqToSql objects. My repository objects all implement IDisposable, and the Dispose() method does only thing--calls Dispose() on the DataContext. Whenever I use a repository, I wrap it in a using person, like this: public IEnumerable<Person> SelectPersons() { using (var repository = _repositorySource.GetNew<Person>(dc => dc.Person)) { return repository.GetAll(); } } This method returns an IEnumerable<Person>, so if my understanding is correct, no querying of the database actually takes place until Enumerable<Person> is traversed (e.g., by converting it to a list or array or by using it in a foreach loop), as in this example: var persons = gateway.SelectPersons(); // Dispose() is fired here var personViewModels = ( from b in persons select new PersonViewModel { Id = b.Id, Name = b.Name, Age = b.Age, OrdersCount = b.Order.Count() }).ToList(); // executes queries In this example, Dispose() gets called immediately after setting persons, which is an IEnumerable<Person>, and that's the only time it gets called. So, a couple questions: How does this work? How can a disposed DataContext still query the database for results when I walk the IEnumerable<Person>? What does Dispose() actually do? I've heard that it is not necessary (e.g., see this question) to dispose of a DataContext, but my impression was that it's not a bad idea. Is there any reason not to dispose of it?

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  • cocos2d - how to draw a bottle sprite with dynamically changing water level

    - by Oliver
    I am trying to draw a (2d) sprite in cocos2d showing a bottle. The bottle shall be able to have a dynamic water level (i.e. the amount of water in the bottle can change over the lifetime of the sprite). I am wondering how to do this. I currently have a PNG file of the empty bottle. I adjusted the alpha channel of that PNG so when rendering the sprite I can draw a blue rectangle and render the bottle texture over it. That will give the impression of the water being inside the bottle. However, the bottle's shape is not a rectangle itself of course, so the water can be seen out of the bounds of the bottle. I can change the bottle image in a way that only the bottle itself is transparent and set the "outside world" to an opaque color & alpha channel value, but that again prevents the "world background" to be visible in that area. I simply don't have a clue how to realize this in a sane manner. Do I really have to read every pixel of the bottle image, identify which pixel is "inside" of the bottle and then draw the water pixel by pixel? There must be an easier way, right? ;) Any best practices for these kinds of tasks? edit: see picture below, to make somewhat clearer, what I am talking about ;) http://i47.tinypic.com/10rqww0.png

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  • What is PHP like as a programming language?

    - by seanlinmt
    I am not really familiar with PHP, but I get the impression that it is like JavaScript (syntax-wise). What are the benefits of a dynamically typed language, when compared to a strongly typed language like C# or Java, and how would this help in the context of web development? What would make a dynamically typed language so attractive? Or, does the popularity of PHP have more to do with it being free? Okay, I think I better give a little more background to get more meaningful answers, because I am not wanting a flame war. I come from a C background, and when I moved into C# and Visual Studio. Having code completion, integration with an SQL database, huge existing class libraries and easy to access documentation, as well as new tools such as LINQ and ReSharper was like heaven. I didn't enjoy JavaScript before JQuery, but now I love it as well. Recently, I ported a PHP project over to C# and I used Zend to help me debug and understand more while porting - instead of maintaining two code streams. That also cut down on the cost of the server and maintenance. Getting into PHP would be nice. I think that Visual Studio has spoiled me - but again Eclipse is also equally spoiling. It would be nice to have an answer from someone who has experience developing both under PHP and .NET.

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  • Triangulation in 3D Space

    - by w3b_wizzard
    Disclaimer: This is for class, however I'm fresh out of ideas and a nudge in the right direction would be much appreciated. Also, this needs to be implemented in raw C, so no fancy libraries can be used. I have to write a search and rescue simulator for submarines, it has to find a probe that is randomly placed in 3D space in a grid from of the MAX_XYZ (100000). The only tools I'm given are a "ping" which will give the magnitude of the distance between a certain sub and the probe. The goal is to optimize the costs of this entire operation so a brute force attempt, like looking at every single coordinate, won't work. Hence I was thinking triangulation. Now, it makes loads of sense to me, place three subs, each one of them uses their ping to get the distance between them and the probe. Since each sub have a known distance relative to one another, it's easy to build the base of a tetrahedron with them, and the results of the ping will point to a certain coordinate, the problem I'm having is how to figure out the elevation, or the height, of the tetrahedron. So what I have as data is the following: Distances between subs (In vector format) Angles between each subs (very easy to compute) Distance between each sub and the probe (3 segments from the base to the peak) Angles inside each of the outer 3 surfaces of the tetrahedron. I tried finding some sort of relationship with the vertices of the tetrahedron and the relative angles in each of them, however all I found had to deal with tetrahedrons built with equilateral triangles, which isn't much help. I have the impression this can be easily solved with trig but either I'm not seeing it or I need more coffee. Any suggestions would be appreciated!

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  • What is the point of having a key_t if what will be the key to access shared memory is the return value of shmget()?

    - by devoured elysium
    When using shared memory, why should we care about creating a key key_t ftok(const char *path, int id); in the following bit of code? key_t key; int shmid; key = ftok("/home/beej/somefile3", 'R'); shmid = shmget(key, 1024, 0644 | IPC_CREAT); From what I've come to understand, what is needed to access a given shared memory is the shmid, not the key. Or am I wrong? If what we need is the shmid, what is the point in not just creating a random key every time? Edit @link text one can read: What about this key nonsense? How do we create one? Well, since the type key_t is actually just a long, you can use any number you want. But what if you hard-code the number and some other unrelated program hardcodes the same number but wants another queue? The solution is to use the ftok() function which generates a key from two arguments. Reading this, it gives me the impression that what one needs to attach to a shared-memory block is the key. But this isn't true, is it? Thanks

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