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  • No speed-up with useless printf's using OpenMP

    - by t2k32316
    I just wrote my first OpenMP program that parallelizes a simple for loop. I ran the code on my dual core machine and saw some speed up when going from 1 thread to 2 threads. However, I ran the same code on a school linux server and saw no speed-up. After trying different things, I finally realized that removing some useless printf statements caused the code to have significant speed-up. Below is the main part of the code that I parallelized: #pragma omp parallel for private(i) for(i = 2; i <= n; i++) { printf("useless statement"); prime[i-2] = is_prime(i); } I guess that the implementation of printf has significant overhead that OpenMP must be duplicating with each thread. What causes this overhead and why can OpenMP not overcome it?

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  • Advice on String Similarity Metrics (Java). Distance, sounds like or combo?

    - by andreas
    Hello, A part of a process requires to apply String Similarity Algorithms. The results of this process will be stored and produce lets say SS_Dataset. Based on this Dataset, further decisions will have to be made. My questions are: Should i apply one or more string similarity algorithms to produce SS_Dataset ? Any comparisons between algorithms that calculate the 'distance' and the 'Sounds Like' similarity ? Does one family of algorithms produces more accurate results over the other? Does a combination give more accurate results on similarity? Can you recommend implementations that you have worked with? My implementation will include packages from the following libraries http://www.dcs.shef.ac.uk/~sam/simmetrics.html http://jtmt.sourceforge.net/ Regards,

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  • Best practices book for CRUD apps

    - by Kevin L.
    We will soon be designing a new tool to calculate commissions across multiple business units. This new compensation scheme is pretty clever and well thought-out, but the complexity that the implementation will involve will make the Hubble look like a toaster. A significant portion of the programming industry involves CRUD apps; updating insurance data, calculating commissions (Joel included) ...even storing questions and answers for a programmer Q&A site. We as programmers have Code Complete for the low-level formatting/style and Design Patterns for high-level architecture (to name just a few). Where’s the comparable book that teaches best practices for CRUD?

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  • How to change to a grouped table view in xcode without using Interface Builder

    - by Dave
    I have a table that I created within xcode so there is no nib file in this case. I want to make my table into the 'Grouped' style but im not sure how. I think it has somthing to do with the method below, the problem is Im not really sure how to call it, I do understand how methods work I'm just not too sure on where to start with this one: - (id)initWithFrame:(CGRect)frame style:(UITableViewStyle)UITableViewStyleGrouped So could someone tell me how to call it? The problem is that its not a method I wrote its a built in one so I could put that line into my header file but how would I use it in my implementation file? Thanks guys,

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  • A good file path builder library for C#?

    - by Igor Brejc
    System.IO.Path in .NET is notoriously clumsy to work with. In my various projects I keep encountering the same usage scenarios which require repetitive, verbose and thus error-prone code snippets that use Path.Combine, Path.GetFileName, Path.GetDirectoryName, String.Format, etc. Scenarios like: changing the extension for a given file name changing the directory path for a given file name building a file path using string formatting (like "Package{0}.zip") building a path without resorting to using hard-coded directory delimiters like \ (since they don't work on Linux on Mono) etc etc Before starting to write my own PathBuilder class or something similar: is there a good (and proven) open-source implementation of such a thing in C#?

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  • Implementing IPermission

    - by joniba
    Hi there, I'm considering writing a custom IPermission implementation but am not clear as to how it should work. I've already implemented IPrincipal and IIdentity. What I would like to accomplish is to be able to check permissions vis a vis the current IPrincipal's authorizations rather than its roles. Generally, authorizations are read/add-delete/update/none for a given type. So I would like to write something like this: [CustomPermission(SecurityAction.Demand, Type = typeof(Foo), MinimumAuthorization = AuthorizationFlags.Read)] public void SomeMethod(){} Is this possible? I've looked over the code at http://msdn.microsoft.com/en-us/library/system.security.ipermission.aspx. This shows how to implement the interface, but I don't understand how the above pseudo-code would be able to check against the IPrincipal's authorizations for the type. Any help or resource references would be appreciated. Joni

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  • Performance of DrawingVisual vs Canvas.OnRender for lots of constantly changing shapes

    - by romkyns
    I'm working on a game-like app which has up to a thousand shapes (ellipses and lines) that constantly change at 60fps. Having read an excellent article on rendering many moving shapes, I implemented this using a custom Canvas descendant that overrides OnRender to do the drawing via a DrawingContext. The performance is quite reasonable, although the CPU usage stays high. However, the article suggests that the most efficient approach for constantly moving shapes is to use lots of DrawingVisual instances instead of OnRender. Unfortunately though it doesn't explain why that should be faster for this scenario. Changing the implementation in this way is not a small effort, so I'd like to understand the reasons and whether they are applicable to me before deciding to make the switch. Why could the DrawingVisual approach result in lower CPU usage than the OnRender approach in this scenario?

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  • Apple documentation incorrect about MKMapView -regionThatFits: ?

    - by jtrim
    In the Apple documentation for the -regionThatFits: method of the MKMapView, it says that this will return a new region centered on the same point as the region that's passed in, only with the regions bounds corrected for the iPhone screen aspect ratio. This seems to be incorrect in implementation...before the call to this method, my region shows up as: $5 = { center = { latitude = 37.322898864746094, longitude = -122.03209686279297 }, span = { latitudeDelta = 14.278411865234375, longitudeDelta = 1.5202401876449585 } } ..however, after the call to this method, I end up with: $6 = { center = { latitude = 36.973427342552824, longitude = -122.03209686279297 }, span = { latitudeDelta = 14.521333317196799, longitudeDelta = 14.0625 } } This is quite a big difference on the map - this translates to the distance between Cupertino, CA and Santa Cruz, CA. Anyone else experience this discrepancy?

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  • Linq to SQL problem

    - by Ronnie Overby
    I have a local collection of recordId's (integers). I need to retrieve records that have every one of their child records' ids in that local collection. Here is my query: public List<int> OwnerIds { get; private set; } ... filteredPatches = from p in filteredPatches where OwnerIds.All(o => p.PatchesOwners.Select(x => x.OwnerId).Contains(o)) select p; I am getting this error: Local sequence cannot be used in Linq to SQL implementation of query operators except the Contains() operator. I get that .All() isn't supported by Linq to SQL, but is there a way to do what I am trying to do?

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  • Verification GetHashCode and Equals

    - by nettguy
    Does the following code show the correct implementation of overriding GetHashCode ? public class Person { public string fName{get;set;} public string lName { get; set; } public int age { get; set; } public override bool Equals(object obj) { Person p = obj as Person; if (p == null) return false; return ( p.GetType()==this.GetType() && p.fName==this.fName &&p.lName==this.lName && p.age==this.age ); } //I took the below code from Marc Gravell's post,I am not sure whether i have implemented it properly public override int GetHashCode() { unchecked { int hash = 13; hash = (hash * 7) + fName.GetHashCode(); hash = (hash * 7) + lName.GetHashCode(); hash = (hash * 7) + age.GetHashCode(); return hash; } } }

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  • Why is thread local storage so slow?

    - by dsimcha
    I'm working on a custom mark-release style memory allocator for the D programming language that works by allocating from thread-local regions. It seems that the thread local storage bottleneck is causing a huge (~50%) slowdown in allocating memory from these regions compared to an otherwise identical single threaded version of the code, even after designing my code to have only one TLS lookup per allocation/deallocation. This is based on allocating/freeing memory a large number of times in a loop, and I'm trying to figure out if it's an artifact of my benchmarking method. My understanding is that thread local storage should basically just involve accessing something through an extra layer of indirection, similar to accessing a variable via a pointer. Is this incorrect? How much overhead does thread-local storage typically have? Note: Although I mention D, I'm also interested in general answers that aren't specific to D, since D's implementation of thread-local storage will likely improve if it is slower than the best implementations.

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  • Persisting details in Master Detail relation EF4 POCO

    - by Roger Alsing
    Scenario: Entity Framework 4 , POCO templates and Master Detail relation. Lets say I have a master type like this: //partial implementation of master entity partial class Master { public void AddDetail(x,y,z) { var detail = new Detail() { X = x, Y = y, Z = z, }; //add the detail to the master this.Details.Add(detail); } } If I then add a master instance to my context and commit, the details will not be saved: var masterObject = new Master(); masterObject.AddDetail(1,2,3); myContext.MasterSet.AddObject(masterObject); Is there any way to make the details to be persisted by reachabillity when using POCO templates? Or any other way? the Details collection in the Master entity is a FixUpCollection, so it ought to track the changes IMO. So, any ideas how to make this work W/O killing the POCO'ness too much?

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  • Search algorithm for a sorted double linked list

    - by SalamiArmi
    As a learning excercise, I've just had an attempt at implementing my own 'merge sort' algorithm. I did this on an std::list, which apparently already had the functions sort() and merge() built in. However, I'm planning on moving this over to a linked list of my own making, so the implementation is not particuarly important. The problem lies with the fact that a std::list doesnt have facilities for accessing random nodes, only accessing the front/back and stepping through. I was originally planning on somehow performing a simple binary search through this list, and finding my answer in a few steps. The fact that there are already built in functions in an std::list for performing these kinds of ordering leads me to believe that there is an equally easy way to access the list in the way I want. Anyway, thanks for your help in advance!

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  • Lobo Cobra HtmlPanel does not update GUI after JavaScript action

    - by Markus Lausberg
    HI, I started implementing a HTML Browser in Swing. I want to use the Lobo Cobra toolkit because this toolkit inclused a renderer and parser for CSS and JavaScript. The pages are looking very nice and it is easy to use (one class implementation to show a html page). I want to show HTML pages in swing which can show javascript generated and modified objects, like a flashing circle. As far as i know, the cobra toolkit can show static javascript commands like 'document.write' or closwWindow() implementations, but not updating the GUI from a JavaScript. Did someone works with Lobo Cobra Toolkit before and give me some sample code or tips for showing HTML pages with animated JavaScript objects inside.

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  • Nullable Date column merge problem

    - by Vladimir
    I am using JPA with openjpa implementation beneath, on a Geronimo application server. I am also using MySQL database. I have a problem with updating object with nullable Date property. When I'm trying to merge entity with Date property set to null, no sql update script is generated (or when other fields are modified, sql update script is generated, but date field is ommited from it). If date field is set to some other not null value, update script is properly generated. Did anyone have problem like that?

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  • Use C++ with Objective-C in XCode

    - by prosseek
    I want to use/reuse C++ object with Objective-C. I have a hello.h that has the class definition, and hello.cpp for class implementation. class Hello { int getX() ... }; And I use this class in Objective-C function. #include "hello.h" ... - (IBAction) adderTwo:(id)sender { Hello *hi = new Hello(); int value = hi->getX(); NSLog(@"Hello %d", value); [textField setIntValue:value]; When I compile the code in Xcode, I get this error message. class Hello *XXXXX Users/smcho/Desktop/cocoa/adderTwo/hello.h:9:0 /Users/smcho/Desktop/cocoa/adderTwo/hello.h:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'Hello' Q: What went wrong? Am I missing something?

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  • Test Driven Development For Complex Methods involving external dependency

    - by bill_tx
    I am implementing a Service Contract for WCF Service. As per TDD I wrote a test case to just pass it using hardcoded values. After that I started to put real logic into my Service implementation. The actual logic relies on 3-4 external service and database. What should I do to my original test case that I wrote ? If i Keep it same in order to make test pass it will have to call several other external services. So I have question in general what should I do if I write a test case for a Business Facade first using TDD and later when I add real logic, if it involves external dependency.

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  • iphone OCMockObject and unit-testing a class that inherits from NSURLConnection

    - by Justin Galzic
    I want to unit test the custom init method of a class that inherits from NSURLConnection -- how would I do this if the init of my testable class invokes NSURLConnection's initWithRequest? I'm using OCMock and normally, I can mock objects that are contained within my test class. For this inheritance scenario, what's the best approach to do this? - (void)testInit { id urlRequest = [OCMockObject mockForClass:[NSURLRequest class]]; MyURLConnectionWrapper *conn = [[MyURLConnectionWrapper alloc] initWithRequest:urlRequest delegate:self someData:extraneousData]; } My class is implemented like this: @interface MyURLConnectionWrapper : NSURLConnection { } - (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate someData:(NSString *)fooData @end @implementation MyURLConnectionWrapper - (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate someData:(NSString *)fooData { if (self = [super initWithRequest:request delegate:delegate]) { // do some additional work here } return self; } Here's the error I get: OCMockObject[NSURLRequest]: unexpected method invoked: _CFURLRequest

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  • asp.net mvc log4postsharp

    - by mike
    Hi Iam trying to use log4post sharp for logging purposes, As far as Iam aware I have followed the instructions to get this up and running, I have not installed postsharp, rather I got the library files and midified my cs proj file to target those file, I have also tried installing postsharp on my machine. In either case I end up with this error Error 5 The plug-in "Log4PostSharp" required by the type "Log4PostSharp.LogAttribute" was not found. I have tried googling this and it seems there is no trace of this issue anywhere on the web. One difference between my implementation with other examples is that the postsharp dll that they use is PostSharp.public, mine is just PostSharp. I have tried searching for the former dll but cannot find it anywhere, the download only contains PostSharp.dll. I feel this may be the issue as I have followd all the insturctions to the letter to get this up and running. Any Ideas People?

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  • DefaultSchedulerService in ASP.NET application

    - by Samir P
    Hi, My project has a requirement to implement look-ahead caching i.e. triggering another request on invokation of a specific request. The following details in short the implementation - HttpModule parses the SOAPRequest and matches entry in a configuration file for look-ahead candidate. If the request matches, it prepares the Parameters dictionary and starts appropriate workflow. Single workflow runtime is used across all requests is ensured through initializing the runtime instance at Application_Start event and stored in Application Dictionary. Using persistence service and DefaultScheduler service. We can't implement windows service model, as current requirement mandates passing the SOAPRequest parameters as arguments. ManualSchedulerService is not in contention due to synchronous nature of it's actual behaviour. Still the performance is pretty bad and product team is not happy. Can anybody suggest me better solution? Thanks, Samir

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  • What relational database innovations have there been in the last 10 years

    - by Simon Munro
    The SQL implementation of relational databases has been around in their current form for something like 25 years (since System R and Ingres). Even the main (loosely adhered to) standard is ANSI-92 (although there were later updates) is a good 15 years old. What innovations can you think of with SQL based databases in the last ten years or so. I am specifically excluding OLAP, Columnar and other non-relational (or at least non SQL) innovations. I also want to exclude 'application server' type features and bundling (like reporting tools) Although the basic approach has remained fairly static, I can think of: Availability Ability to handle larger sets of data Ease of maintenance and configuration Support for more advanced data types (blob, xml, unicode etc) Any others that you can think of?

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  • Scala isn't allowing me to execute a batch file whose path contains spaces.Same Java code does.What

    - by Geo
    Here's the code I have: var commandsBuffer = List[String]() commandsBuffer ::= "cmd.exe" commandsBuffer ::= "/c" commandsBuffer ::= '"'+vcVarsAll.getAbsolutePath+'"' commandsBuffer ::= "&&" otherCommands.foreach(c => commandsBuffer ::= c) val asArray = commandsBuffer.reverse.toArray val processOutput = processutils.Proc.executeCommand(asArray,true) return processOutput otherCommands is an Array[String], containing the following elements: vcbuild /rebuild path to a .sln file vcVarsAll contains the path to Visual Studio's vcvarsall.bat. It's path is C:\tools\microsoft visual studio 2005\vc\vcvarsall.bat. The error I receive is: 'c:\Tools\Microsoft' is not recognized as an internal or external command, operable program or batch file.. The processutils.Proc.executeCommand has the following implementation: def executeCommand(params:Array[String],display:Boolean):(String,String) = { val process = java.lang.Runtime.getRuntime.exec(params) val outStream = process.getInputStream val errStream = process.getErrorStream ... } The same code, executed from Java/Groovy works. What am I doing wrong?

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  • Keep an object for the time the connection is running in ASP.NET

    - by vtortola
    Hi, I'm developing a web service with ASP.NET, is not an .asmx or WCF, it's a custom one, so I'm working with the Http classes (context, request, response, etc..). Session is disabled. I'm working with my own handler and module. I'd like to keep a object alive and accessible for the time the connection is alive. I mean, a request enters, I assign a DbCommand to it and that connection will use that command as long is doing things, when that connection is ended, the object should be disposed. I've thought, that I can add it to my IPrincipal implementation, then when the connection is authenticated in the module and the user retrieved, I can add that DbCommand to the IPrincipal, so I can retrieve it from wherever I want in the code, and after in the module EndRequest event, I can dispose it, but I don't know if there is a better approach to do this. What do you think? cheers

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  • UITextView Delegate shouldChangeTextInRange (or any over) doesn't get called

    - by justas wza
    Hello, I need to track changes in my UITextView method (actianly for limiting number of lines), but none of UITextViewDelegate methods are being called when editing in UITextView begins. Not even - (void)textViewDidChange:(UITextView *)textView; I dont know what Im doing wrong I added UITextViewDelegate method to header file like that: @interface PirmasViewController : UIViewController <UITextViewDelegate, MFMa...... And I put any methods for tracking changes in my implementation file: - (void)textViewDidChange:(UITextView *)textView{NSLog(@"something changed");} - (BOOL)textView:(UITextView *)aTextView shouldChangeTextInRange:(NSRange)aRange replacementText:(NSString*)aText{ NSLog(@"something changed"); return YES; }` but no rezults.

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  • Prefer extension methods for encapsulation and reusability?

    - by tzaman
    edit4: wikified, since this seems to have morphed more into a discussion than a specific question. In C++ programming, it's generally considered good practice to "prefer non-member non-friend functions" instead of instance methods. This has been recommended by Scott Meyers in this classic Dr. Dobbs article, and repeated by Herb Sutter and Andrei Alexandrescu in C++ Coding Standards (item 44); the general argument being that if a function can do its job solely by relying on the public interface exposed by the class, it actually increases encapsulation to have it be external. While this confuses the "packaging" of the class to some extent, the benefits are generally considered worth it. Now, ever since I've started programming in C#, I've had a feeling that here is the ultimate expression of the concept that they're trying to achieve with "non-member, non-friend functions that are part of a class interface". C# adds two crucial components to the mix - the first being interfaces, and the second extension methods: Interfaces allow a class to formally specify their public contract, the methods and properties that they're exposing to the world. Any other class can choose to implement the same interface and fulfill that same contract. Extension methods can be defined on an interface, providing any functionality that can be implemented via the interface to all implementers automatically. And best of all, because of the "instance syntax" sugar and IDE support, they can be called the same way as any other instance method, eliminating the cognitive overhead! So you get the encapsulation benefits of "non-member, non-friend" functions with the convenience of members. Seems like the best of both worlds to me; the .NET library itself providing a shining example in LINQ. However, everywhere I look I see people warning against extension method overuse; even the MSDN page itself states: In general, we recommend that you implement extension methods sparingly and only when you have to. (edit: Even in the current .NET library, I can see places where it would've been useful to have extensions instead of instance methods - for example, all of the utility functions of List<T> (Sort, BinarySearch, FindIndex, etc.) would be incredibly useful if they were lifted up to IList<T> - getting free bonus functionality like that adds a lot more benefit to implementing the interface.) So what's the verdict? Are extension methods the acme of encapsulation and code reuse, or am I just deluding myself? (edit2: In response to Tomas - while C# did start out with Java's (overly, imo) OO mentality, it seems to be embracing more multi-paradigm programming with every new release; the main thrust of this question is whether using extension methods to drive a style change (towards more generic / functional C#) is useful or worthwhile..) edit3: overridable extension methods The only real problem identified so far with this approach, is that you can't specialize extension methods if you need to. I've been thinking about the issue, and I think I've come up with a solution. Suppose I have an interface MyInterface, which I want to extend - I define my extension methods in a MyExtension static class, and pair it with another interface, call it MyExtensionOverrider. MyExtension methods are defined according to this pattern: public static int MyMethod(this MyInterface obj, int arg, bool attemptCast=true) { if (attemptCast && obj is MyExtensionOverrider) { return ((MyExtensionOverrider)obj).MyMethod(arg); } // regular implementation here } The override interface mirrors all of the methods defined in MyExtension, except without the this or attemptCast parameters: public interface MyExtensionOverrider { int MyMethod(int arg); string MyOtherMethod(); } Now, any class can implement the interface and get the default extension functionality: public class MyClass : MyInterface { ... } Anyone that wants to override it with specific implementations can additionally implement the override interface: public class MySpecializedClass : MyInterface, MyExtensionOverrider { public int MyMethod(int arg) { //specialized implementation for one method } public string MyOtherMethod() { // fallback to default for others MyExtension.MyOtherMethod(this, attemptCast: false); } } And there we go: extension methods provided on an interface, with the option of complete extensibility if needed. Fully general too, the interface itself doesn't need to know about the extension / override, and multiple extension / override pairs can be implemented without interfering with each other. I can see three problems with this approach - It's a little bit fragile - the extension methods and override interface have to be kept synchronized manually. It's a little bit ugly - implementing the override interface involves boilerplate for every function you don't want to specialize. It's a little bit slow - there's an extra bool comparison and cast attempt added to the mainline of every method. Still, all those notwithstanding, I think this is the best we can get until there's language support for interface functions. Thoughts?

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