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• Custom .NET DSL

  - by Dmitriy Nagirnyak

  Hi, I am thinking about implementing a templating engine using only the plain C#/.NET 4 syntax with the benefit of static typing. Then on top of that templating language we could create Domain Specific Languages (let's say HTML4, XHTML, HTML5, RSS, Atom, Multipart Emails and so on). One of the best DSLs in .NET 4 (if not only one) is SharpDOM. It implements HTML-specific DSL. Looking at SharpDOM, I am really impressed of what you can do using .NET (4). So I believe there are some not-so-well-known ways for implementing custom DSLs in .NET 4. Possibly not as well as in Ruby, but still. So my the question would be: what are the C# (4) specific syntax features that can be used for implementing custom DSLs? Examples I can think of right now: // HTML - doesn't look tooo readable :) div(clas: "head", ul(clas: "menu", id: "main-menu", () => { foreach(var item in allItems) { li(item.Name) } }) // See how much noise it has with all the closing brackets? ) // Plain text (Email or something) - probably too simple Line("Dear {0}", user.Name); Line("You have been kicked off from this site"); For me it is really hard to come up with the syntax with least amount of noise. Please NOTE that I am not talking about another language (Boo, IronRuby etc), neither I am not talking about different templating engines (NHaml, Spark, StringTemplate etc). Thanks, Dmitriy.

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• Instantiate type variable in Haskell

  - by danportin

  EDIT: Solved. I was unware that enabling a language extension in the source file did not enable the language extension in GHCi. The solution was to :set FlexibleContexts in GHCi. I recently discovered that type declarations in classes and instances in Haskell are Horn clauses. So I encoded the arithmetic operations from The Art of Prolog, Chapter 3, into Haskell. For instance: fac(0,s(0)). fac(s(N),F) :- fac(N,X), mult(s(N),X,F). class Fac x y | x -> y instance Fac Z (S Z) instance (Fac n x, Mult (S n) x f) => Fac (S n) f pow(s(X),0,0) :- nat(X). pow(0,s(X),s(0)) :- nat(X). pow(s(N),X,Y) :- pow(N,X,Z), mult(Z,X,Y). class Pow x y z | x y -> z instance (N n) => Pow (S n) Z Z instance (N n) => Pow Z (S n) (S Z) instance (Pow n x z, Mult z x y) => Pow (S n) x y In Prolog, values are insantiated for (logic) variable in a proof. However, I don't understand how to instantiate type variables in Haskell. That is, I don't understand what the Haskell equivalent of a Prolog query ?-f(X1,X2,...,Xn) is. I assume that :t undefined :: (f x1 x2 ... xn) => xi would cause Haskell to instantiate xi, but this gives a Non type-variable argument in the constraint error, even with FlexibleContexts enabled.

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• Pitfalls and practical Use-Cases: Toplink, Hibernate, Eclipse Link, Ibatis ...

  - by Martin K.

  I worked a lot with Hibernate as my JPA implementation. In most cases it works fine! But I have also seen a lot of pitfalls: Remoting with persisted Objects is difficult, because Hibernate replaces the Java collections with its own collection implementation. So the every client must have the Hibernate .jar libraries. You have to take care on LazyLoading exceptions etc. One way to get around this problem is the use of webservices. Dirty checking is done against the Database without any lock. "Delayed SQL", causes that the data access isn't ACID compliant. (Lost data...) Implict Updates So we don't know if an object is modified or not (commit causes updates). Are there similar issues with Toplink, Eclipse Link and Ibatis? When should I use them? Have they a similar performance? Are there reasons to choose Eclipse Link/Toplink... over Hibernate?

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• Is there a standard lexer/parser tool for Python?

  - by Salim Fadhley

  A volunteer job requires us to convert a large number of LaTeX documents into ePub format. It's a series of open-source fiction book which has so far only been produced only on paper via a print on demand service. We'd like to be able to offer the book to users of book-reader devices (such as Kindle) which require the ePub format for best results. Fortunately, ePub is a very simple format, however there's no trivial way for LaTeX to produce the XHTML outut required. We experimented with alternative LaTeX compilers (e.g. plastex) but in the end we figured that it would probably be a lot easier to simply write our own compiler which understands a tiny subset of the LaTeX language and compiles directly to XHTML / ePub. Previously I used a tool on Windows called GOLD. This allowed me to go directly from BNF grammars to a stub parser. It also alllowed me to implement the parser in any language I liked. (I'd choose Python). This product has to work on Linux, so I'm wondering if there's an equivalent toolchain that works as well under Ubutnu / Eclipse / Python. The idea is that we will take the grammar of TeX and just implement a teeny subset of that, but we do not want to spend a huge amount of time worrying about grammar and parsing. A parser generator would obviously save us a great deal of time. Sal UPDATE 1: Bonus marks for a solution with excellent documentation or tutorials.

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• How to get around the jslint error 'Don't make functions within a loop.'

  - by Ernelli

  I am working on making all of our JS code pass through jslint, sometimes with a lot of tweaking with the options to get legacy code pass for now on with the intention to fix it properly later. There is one thing that jslint complains about that I do not have a workround for. That is when using constructs like this, we get the error 'Don't make functions within a loop.' for (prop in newObject) { // Check if we're overwriting an existing function if (typeof newObject[prop] === "function" && typeof _super[prop] === "function" && fnTest.test(newObject[prop])) { prototype[prop] = (function (name, func) { return function () { var result, old_super; old_super = this._super; this._super = _super[name]; result = func.apply(this, arguments); this._super = old_super; return result; }; })(prop, newObject[prop]); } This loop is part of a JS implementation of classical inheritance where classes that extend existing classes retain the super property of the extended class when invoking a member of the extended class. Just to clarify, the implementation above is inspired by this blog post by John Resig. But we also have other instances of functions created within a loop. The only workaround so far is to exclude these JS files from jslint, but we would like to use jslint for code validation and syntax checking as part of our continuous integration and build workflow. Is there a better way to implement functionality like this or is there a way to tweak code like this through jslint?

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• How to use routing in a ASP MVC website to localize in two languages - But keeping exiting URLs

  - by Anders Pedersen

  We have a couple ASP MVC websites just using the standard VS templates default settings - Working as wanted. But now I want to localize these website ( They are now in Dutch and I will add the English language ) I would like to use routing and not Resource because: 1. Languages will differ in content, numbers of pages, etc. 2. The content is mostly text. I would like the URLs to look some thing like this - www.domain.com/en/Home/Index, www.domain.nl/nl/Home/Index. But the last one should also work with - www.domain.nl/Home/Index - Witch is the exciting URLs. I have implemented Phil Haacks areas ViewEngine from this blogpost - http://haacked.com/archive/2008/11/04/areas-in-aspnetmvc.aspx. But only putting the English website in the areas and keeping the Dutch in old structure. Witch are served as Phils default fallback. But the problem is here that I have to duplicate my controllers for both language's. So I tried the work method described in this tread - http://stackoverflow.com/questions/1712167/asp-net-mvc-localization-route. It works OK with the ?en? and /nl/ but not with the old URLs. When using this code in the global.asax the URL without the culture isn't working. public static void RegisterRoutes(RouteCollection routes) { //routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{culture}/{controller}/{action}/{id}", // URL with parameters new { culture = "nl-NL", controller = "Home", action = "Index", id = "" } // Parameter defaults ); routes.MapRoute( "DefaultWitoutCulture", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = "" } // Parameter defaults ); } I properly overlooking some thing simple but I can't get this to work for me. Or are there a better way of doing this?

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• How to serialize object containing NSData?

  - by AO

  I'm trying to serialize an object containing a number of data fields...where one of the fields is of datatype NSData which won't serialize. I've followed instructions at http://www.isolated.se but my code (see below) results in the error "[NSConcreteData data]: unrecognized selector sent to instance...". How do I serialize my object? Header file: @interface Donkey : NSObject<NSCoding> { NSString* s; NSData* d; } @property (nonatomic, retain) NSString* s; @property (nonatomic, retain) NSData* d; - (NSData*) serialize; @end Implementation file: @implementation Donkey @synthesize s, d; static NSString* const KEY_S = @"string"; static NSString* const KEY_D = @"data"; - (void) encodeWithCoder:(NSCoder*)coder { [coder encodeObject:self.s forKey:KEY_S]; [coder encodeObject:self.d forKey:KEY_D]; } - (id) initWithCoder:(NSCoder*)coder; { if(self = [super init]) { self.s = [coder decodeObjectForKey:KEY_STRING]; self.d [coder decodeObjectForKey:KEY_DATA]; } return self; } - (NSData*) serialize { return [NSKeyedArchiver archivedDataWithRootObject:self]; } @end

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• RSS feed created with PHP only shows the title in the feed reader

  - by James Simpson

  I am using the following PHP code to generate the XML for an RSS feed, but it doesn't seem to be working correctly. No short description is displayed in the feed reader, all I see is the title of the article. Also, all of the articles say they were published at the same time. This is the first time I have tried to setup an RSS feed, so I'm sure I've made several stupid mistakes. $result = mysql_query("SELECT * FROM blog ORDER BY id DESC LIMIT 10"); $date = date(DATE_RFC822); header('Content-type: text/xml'); echo ("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"); echo ("<rss version=\"2.0\">\n"); echo ("<channel>\n"); echo ("<lastBuildDate>$date</lastBuildDate>\n"); echo ("<pubDate>$date</pubDate>\n"); echo ("<title>my website name</title>\n"); echo ("<description><![CDATA[the description]]></description>\n"); echo ("<link>http://my-domain.com</link>\n"); echo ("<language>en</language>\n"); $ch=100; while ($a = mysql_fetch_array($result)) { $headline = htmlentities(stripslashes($a['subject'])); $posturl = $a[perm_link]; $content = $a['post']; $date = date(DATE_RFC822, $a['posted']); echo ("<item>\n"); echo ("<title>$headline</title>\n"); echo ("<link>$posturl</link>\n"); echo ("<description><![CDATA[$content]]></description>\n"); echo ("<guid isPermaLink=\"true\">$posturl</guid>\n"); echo ("<pubDate>$date2</pubDate>\n"); echo ("</item>\n"); } echo ("</channel>\n"); echo ("</rss>\n");

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• Does JAXWS client make difference between an empty collection and a null collection value as returne

  - by snowflake

  Since JAX-WS rely on JAXB, and since I observed the code that unpack the XML bean in JAX-B Reference Implementation, I guess the difference is not made and that a JAXWS client always return an empty collection, even the webservice result was a null element: public T startPacking(BeanT bean, Accessor<BeanT, T> acc) throws AccessorException { T collection = acc.get(bean); if(collection==null) { collection = ClassFactory.create(implClass); if(!acc.isAdapted()) acc.set(bean,collection); } collection.clear(); return collection; } I agree that for best interoperability service contracts should be non ambiguous and avoid such differences, but it seems that the JAX-WS service I'm invoking (hosted on a Jboss server with Jbossws implementation) is returning as expected either null either empty collection (tested with SoapUI). I used for my test code generated by wsimport. Return element is defined as: @XmlElement(name = "return", nillable = true) protected List<String> _return; I even tested to change the Response class getReturn method from : public List<String> getReturn() { if (_return == null) { _return = new ArrayList<String>(); } return this._return; } to public List<String> getReturn() { return this._return; } but without success. Any helpful information/comment regarding this problem is welcome !

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• How to force c# binary int division to return a double?

  - by Wayne

  How to force double x = 3 / 2; to return 1.5 in x without the D suffix or casting? Is there any kind of operator overload that can be done? Or some compiler option? Amazingly, it's not so simple to add the casting or suffix for the following reason: Business users need to write and debug their own formulas. Presently C# is getting used like a DSL (domain specific language) in that these users aren't computer science engineers. So all they know is how to edit and create a few types of classes to hold their "business rules" which are generally just math formulas. But they always assume that double x = 3 / 2; will return x = 1.5 however in C# that returns 1. A. they always forget this, waste time debugging, call me for support and we fix it. B. they think it's very ugly and hurts the readability of their business rules. As you know, DSL's need to be more like natural language. Yes. We are planning to move to Boo and build a DSL based on it but that's down the road. Is there a simple solution to make double x = 3 / 2; return 1.5 by something external to the class so it's invisible to the users? Thanks! Wayne

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• How to force c# binary int division to return a double?

  - by Wayne

  How to force double x = 3 / 2; to return 1.5 in x without the D suffix or casting? Is there any kind of operator overload that can be done? Or some compiler option? Amazingly, it's not so simple to add the casting or suffix for the following reason: Business users need to write and debug their own formulas. Presently C# is getting used like a DSL (domain specific language) in that these users aren't computer science engineers. So all they know is how to edit and create a few types of classes to hold their "business rules" which are generally just math formulas. But they always assume that double x = 3 / 2; will return x = 1.5 however in C# that returns 1. A. they always forget this, waste time debugging, call me for support and we fix it. B. they think it's very ugly and hurts the readability of their business rules. As you know, DSL's need to be more like natural language. Yes. We are planning to move to Boo and build a DSL based on it but that's down the road. Is there a simple solution to make double x = 3 / 2; return 1.5 by something external to the class so it's invisible to the users? Thanks! Wayne

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• How do I correctly use Unity to pass a ConnectionString to my repository classes?

  - by GenericTypeTea

  I've literally just started using the Unity Application Blocks Dependency Injection library from Microsoft, and I've come unstuck. This is my IoC class that'll handle the instantiation of my concrete classes to their interface types (so I don't have to keep called Resolve on the IoC container each time I want a repository in my controller): public class IoC { public static void Intialise(UnityConfigurationSection section, string connectionString) { _connectionString = connectionString; _container = new UnityContainer(); section.Configure(_container); } private static IUnityContainer _container; private static string _connectionString; public static IMovementRepository MovementRepository { get { return _container.Resolve<IMovementRepository>(); } } } So, the idea is that from my Controller, I can just do the following: _repository = IoC.MovementRepository; I am currently getting the error: Exception is: InvalidOperationException - The type String cannot be constructed. You must configure the container to supply this value. Now, I'm assuming this is because my mapped concrete implementation requires a single string parameter for its constructor. The concrete class is as follows: public sealed class MovementRepository : Repository, IMovementRepository { public MovementRepository(string connectionString) : base(connectionString) { } } Which inherits from: public abstract class Repository { public Repository(string connectionString) { _connectionString = connectionString; } public virtual string ConnectionString { get { return _connectionString; } } private readonly string _connectionString; } Now, am I doing this the correct way? Should I not have a constructor in my concrete implementation of a loosely coupled type? I.e. should I remove the constructor and just make the ConnectionString property a Get/Set so I can do the following: public static IMovementRepository MovementRepository { get { return _container.Resolve<IMovementRepository>( new ParameterOverrides { { "ConnectionString", _connectionString } }.OnType<IMovementRepository>() ); } } So, I basically wish to know how to get my connection string to my concrete type in the correct way that matches the IoC rules and keeps my Controller and concrete repositories loosely coupled so I can easily change the DataSource at a later date.

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• Custom Cocoa Framework and a problem using it

  - by happyCoding25

  Hello, I made a custom cocoa framework just to experiment and find the best way to make one but ran in to a problem using it. The framework project builds and compiles just fine, but when I use it in an xcode project I get the error, 'LogTest' undeclared. The name of the framework is LogTest Heres the code to my app that uses the framework: AppDelegate.h: #import <Cocoa/Cocoa.h> #import <LogTest/LogTest.h> @interface TestAppDelegate : NSObject <NSApplicationDelegate> { NSWindow *window; } @property (assign) IBOutlet NSWindow *window; @end AppDelegate.m: #import "TestAppDelegate.h" @implementation TestAppDelegate @synthesize window; - (void)awakeFromNib { [LogTest logStart:@"testing 123":@"testing 1234"]; //This is the line where the error occurs } @end Framework Code........ LogTest.h: #import <Cocoa/Cocoa.h> #import "Method.h" @protocol LogTest //Not sure if this is needed I just wanted a blank header @end Method.h: #import <Cocoa/Cocoa.h> @interface Method : NSObject { } + (void)logStart:(NSString *)test:(NSString *)test2; @end Method.m: #import "Method.h" @implementation Method + (void)logStart:(NSString *)test:(NSString *)test2 { NSLog(test); NSLog(test2); } @end If anyone knows why I am getting this error please reply. Thanks for any help

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• Practical Scheme Programming

  - by Ixmatus

  It's been a few months since I've touched Scheme and decided to implement a command line income partitioner using Scheme. My initial implementation used plain recursion over the continuation, but I figured a continuation would be more appropriate to this type of program. I would appreciate it if anyone (more skilled with Scheme than I) could take a look at this and suggest improvements. I'm that the multiple (display... lines is an ideal opportunity to use a macro as well (I just haven't gotten to macros yet). (define (ab-income) (call/cc (lambda (cc) (let ((out (display "Income: ")) (income (string->number (read-line)))) (cond ((<= income 600) (display (format "Please enter an amount greater than $600.00~n~n")) (cc (ab-income))) (else (let ((bills (* (/ 30 100) income)) (taxes (* (/ 20 100) income)) (savings (* (/ 10 100) income)) (checking (* (/ 40 100) income))) (display (format "~nDeduct for bills:---------------------- $~a~n" (real->decimal-string bills 2))) (display (format "Deduct for taxes:---------------------- $~a~n" (real->decimal-string taxes 2))) (display (format "Deduct for savings:-------------------- $~a~n" (real->decimal-string savings 2))) (display (format "Remainder for checking:---------------- $~a~n" (real->decimal-string checking 2)))))))))) Invoking (ab-income) asks for input and if anything below 600 is provided it (from my understanding) returns (ab-income) at the current-continuation. My first implementation (as I said earlier) used plain-jane recursion. It wasn't bad at all either but I figured every return call to (ab-income) if the value was below 600 kept expanding the function. (please correct me if that apprehension is incorrect!)

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• how to specify open id realm in openid4java 0.9.5

  - by Salvin Francis

  my url @ development : http://192.168.0.1:8888/com.company.MyEntryPoint/MyEntrypoint.html my url @ live env : http://www.example.com/com.company.MyEntryPoint/MyEntrypoint.html I need users to authenticate using open id, this is how i want my realm to be: *.company.MyEntryPoint I wrote a simple code to specify realm: AuthRequest authReq = manager.authenticate( discovered, returnToUrl, "*.company.MyEntryPoint" ); it does not work. Exception: org.openid4java.message.MessageException: 0x301: Realm verification failed (2) for: *.company.MyEntryPoint at org.openid4java.message.AuthRequest.validate(AuthRequest.java:354) at org.openid4java.message.AuthRequest.createAuthRequest(AuthRequest.java:101) at org.openid4java.consumer.ConsumerManager.authenticate(ConsumerManager.java:1073) Of all the combinations I tried, curiously, the following worked: AuthRequest authReq = manager.authenticate( discovered, returnToUrl, "http://localhost:8888/com.capgent.MyEntryPoint" ); This does not solves my issue but rather complicates it :) According to google and open id spec it should have worked complete code snippet: List discoveries = manager.discover(clientUrl); DiscoveryInformation discovered = manager.associate(discoveries); AuthRequest authReq = manager.authenticate(discovered, returnToUrl,"*.company.MyEntryPoint"); FetchRequest fetch = FetchRequest.createFetchRequest(); fetch.addAttribute("email", "http://schema.openid.net/contact/email", true); fetch.addAttribute("country", "http://axschema.org/contact/country/home", true); fetch.addAttribute("firstname", "http://axschema.org/namePerson/first", true); fetch.addAttribute("lastname", "http://axschema.org/namePerson/last", true); fetch.addAttribute("language", "http://axschema.org/pref/language", true); authReq.addExtension(fetch); String returnStr; if (!discovered.isVersion2()) { returnStr = authReq.getDestinationUrl(true); } else { returnStr = authReq.getDestinationUrl(false); } What am I doing wrong over here ?

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• [Haskell] Problem when mixing type classes and type families

  - by Giuseppe Maggiore

  Hi! This code compiles fine: {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, UndecidableInstances, FlexibleContexts, EmptyDataDecls, ScopedTypeVariables, TypeOperators, TypeSynonymInstances, TypeFamilies #-} class Sel a s b where type Res a s b :: * instance Sel a s b where type Res a s b = (s -> (b,s)) instance Sel a s (b->(c,a)) where type Res a s (b->(c,a)) = (b -> s -> (c,s)) but as soon as I add the R predicate ghc fails: {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, UndecidableInstances, FlexibleContexts, EmptyDataDecls, ScopedTypeVariables, TypeOperators, TypeSynonymInstances, TypeFamilies #-} class Sel a s b where type Res a s b :: * instance Sel a s b where type Res a s b = (s -> (b,s)) class R a where type Rec a :: * cons :: a -> Rec a elim :: Rec a -> a instance Sel a s (b->(c,Rec a)) where type Res a s (b->(c,Rec a)) = (b -> s -> (c,s)) complaining that: Illegal type synonym family application in instance: b -> (c, Rec a) In the instance declaration for `Sel a s (b -> (c, Rec a))' what does it mean and (most importantly) how do I fix it? Thanks

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• Libraries for developing NCPDP SCRIPT based systems (a standard for e-prescribing)

  - by Kaveh Shahbazian

  What are (based on experiences) best (commercial or open source) libraries for developing NCPDP-based systems? Background: NCPDP (National Council for Prescription Drug Programs) is a not-for-profit, ANSI-accredited, standards development organization. One of it's standards is the SCRIPT Standard for Electronic Prescribing, which allows PHARMACY, PRESCRIBER (i.e. Physician) and PAYERS (patient or more often insurer) communicate. So the SCRIPT standard is about data transmission. Problem: One step in implementing such systems is to develop models for data based on SCRIPT standard. These models should have utilities for serializing/deserializing to/from SCRIPT binary format and SCRIPT XML format (there are two distinct formats here; both must be supported). Here rises the problem (for me at least). To develop this subsystem for handling the model, implementing serializing and deserializing facilities and keep it uptodate with the SCRIPT standard specifications is a lot of work; it needs it's own team and team management issues (to support a standard implementation). So I am looking for a solution to this problem; to keep standard implementation out of the way and focusing on main problems. Thanks to all (Thankyou Freiheit for your hints!) Edit 2: Thanks to all for help! NCPDP (National Council for Prescription Drug Programs) is an standard for e-prescribing. It defines two formats for message transmission: binary and XML. Implementing XML is somehow easier because it is a standard format which in turn gives us more tooling options. The binary format has a very big specification and time-consuming to implement. I did not find an open source solution to work with. So I am looking for commercial alternatives. Edit 1: Please guide me; what's wrong with this question?

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• SignalR - Handling disconnected users

  - by guilhermeGeek

  Hy, I'm using the signalR library on a project to handle an notification and chat modules. I've a table on an database to keep a track of online users. The HUB for chat is inheriting IDisconnect where i disconnect the user. After disconnecting the user, i warm the users about that event. At this point, i check if the disconnect user is the client. If it's, then i call an method on HUB to reconnect the user (just update the table). I do this because with the current implementation, once the user closes a tab on the browser it calls the Disconnect task but he could have another tab opened. I've not tested (with larger requests) this module yet, but on my development server it could take a few seconds between the IDisconnect event, and the request from the user to connect again. I'm concerned with my implementation to handle disconnected users from the chat but i can't see another way to improve this. If possible, could someone give me a advice on this, or this is the only solution that i've?

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• trying to make a simple grid-class, non-lvalue in assignment

  - by Tyrfing

  I'm implementing a simple C++ grid class. One Function it should support is accessed through round brackets, so that I can access the elements by writing mygrid(0,0). I overloaded the () operator and i am getting the error message: "non-lvalue in assignment". what I want to be able to do: //main cGrid<cA*> grid(5, 5); grid(0,0) = new cA(); excerpt of my implementation of the grid class: template class cGrid { private: T* data; int mWidth; int mHeight; public: cGrid(int width, int height) : mWidth(width), mHeight(height) { data = new T[width*height]; } ~cGrid() { delete data; } T operator ()(int x, int y) { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } const T &operator ()(int x, int y) const { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } The rest of the code deals with the implementation of an iterator and should not be releveant.

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• Graph drawing for the Web 2.0

  - by tokel

  Hi. There are a lot of chart drawing libraries out there, but what I am looking for is an interactive(!) graph (nodes and edges) drawing library. At best some kind of AJAX, but I am also open for other technologies (Java, Flash). However I would really prefer an AJAX implementation. Also only Open Source framework suggestions please (I already know about yFiles). The thing I have in mind is a bit like GWTUML. That is quite nice already, but misses an API for their graph drawing. It seems that it is an custom implementation for their product. Also some layout algorithms would be nice. Is there really no library around for that task? I wonder a bit as there are so many chart libraries available. Let me emphasize again (seems to be necessary cause of the first two comments): I am NOT looking for another chart library! Regards, Kai P.S. Things I know about already: JUNG (Java), Prefuse (Java), GINY (Java), yFiles (AJAX, but not Open Source). Just another graph library I found (Javascript, not sure if it is still maintained): Graph Gear

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• Is this a good way to expose generic base class methods through an interface?

  - by Nate Heinrich

  I am trying to provide an interface to an abstract generic base class. I want to have a method exposed on the interface that consumes the generic type, but whose implementation is ultimately handled by the classes that inherit from my abstract generic base. However I don't want the subclasses to have to downcast to work with the generic type (as they already know what the type should be). Here is a simple version of the only way I can see to get it to work at the moment. public interface IFoo { void Process(Bar_base bar); } public abstract class FooBase<T> : IFoo where T : Bar_base { abstract void Process(T bar); // Explicit IFoo Implementation void IFoo.Process(Bar_base bar) { if (bar == null) throw new ArgumentNullException(); // Downcast here in base class (less for subclasses to worry about) T downcasted_bar = bar as T; if (downcasted_bar == null) { throw new InvalidOperationException( string.Format("Expected type '{0}', not type '{1}'", T.ToString(), bar.GetType().ToString()); } //Process downcasted object. Process(downcasted_bar); } } Then subclasses of FooBase would look like this... public class Foo_impl1 : FooBase<Bar_impl1> { void override Process(Bar_impl1 bar) { //No need to downcast here! } } Obviously this won't provide me compile time Type Checking, but I think it will get the job done... Questions: 1. Will this function as I think it will? 2. Is this the best way to do this? 3. What are the issues with doing it this way? 4. Can you suggest a different approach? Thanks!

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• Query for rows including child rows

  - by MAD9

  A few weeks ago, I asked a question about how to generate hierarchical XML from a table, that has a parentID column. It all works fine. The point is, according to the hierarchy, I also want to query a table. I'll give you an example: Thats the table with the codes: ID CODE NAME PARENTID 1 ROOT IndustryCode NULL 2 IND Industry 1 3 CON Consulting 1 4 FIN Finance 1 5 PHARM Pharmaceuticals 2 6 AUTO Automotive 2 7 STRAT Strategy 3 8 IMPL Implementation 3 9 CFIN Corporate Finance 4 10 CMRKT Capital Markets 9 From which I generate (for displaying in a TreeViewControl) this XML: <record key="1" parentkey="" Code="ROOT" Name="IndustryCode"> <record key="2" parentkey="1" Code="IND" Name="Industry"> <record key="5" parentkey="2" Code="PHARM" Name="Pharmaceuticals" /> <record key="6" parentkey="2" Code="AUTO" Name="Automotive" /> </record> <record key="3" parentkey="1" Code="CON" Name="Consulting"> <record key="7" parentkey="3" Code="STRAT" Name="Strategy" /> <record key="8" parentkey="3" Code="IMPL" Name="Implementation" /> </record> <record key="4" parentkey="1" Code="FIN" Name="Finance"> <record key="9" parentkey="4" Code="CFIN" Name="Corporate Finance"> <record key="10" parentkey="9" Code="CMRKT" Name="Capital Markets" /> </record> </record> </record> As you can see, some codes are subordinate to others, for example AUTO << IND << ROOT What I want (and have absolutely no idea how to realise or even, where to start) is to be able to query another table (where one column is this certain code of course) for a code and get all records with the specific code and all subordinate codes For example: I query the other table for "IndustryCode = IND[ustry]" and get (of course) the records containing "IND", but also AUTO[motive] and PHARM[aceutical] (= all subordinates) Its an SQL Express Server 2008 with Advanced Services.

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• Types issue in F#

  - by Andry

  Hello! In my ongoing adventure deep diving into f# I am understanding a lot of this powerful language but there are things that I still do not understand so clearly. One of the most important issues I need to master is types. Well the book I am reading is very straight forward and introduces entities and main functionalities with a direct approach. The first thing I could get start with is types. It introduces the main types as list, option, tuples, and so on... It is clearly underlined that all these types are IMMUTABLE for many reasons regarding functional programming and data consistance in functional programing. Well, no problems until now... But now I am getting started with Concrete Types... Well... I have problems in managing with types like list, option, tuples, types created through new operator and concrete types created using type keyword (for abbreviations, concrete types...). So my question is: how can I efficently catalogue/distinguish all types of data in f#???? I can create a perfect separation among types in C#, VB.NET... FOr example in VB.NET there are value and reference types while in C# there are only references and also int, double are treated as objects (they are objects while in VB.NET a value type is not a object and there is a split in types for this reason). Well in F# I cannot create such differences among types in the language. Can you help me? I hope I was clear.

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• purpose of 3rd party mvc ?

  - by Honey

  ive seen many third party mvcs or frameworks such as codeignitor , cakephp, and so on. what i want to know is what are their purposes? ive created my own framework call it an mvc or framework (in my opinion their all the same). in my framework i have all the classes in one folder called classes and all functions in another. its all organized and when a new project comes in i am able to complete it fast. i have looked at the applications that i mentioned and it seems to have huge articles and tutorials to study. what is the purpose? why not study the main language such as php, javascript/ajax or jquery, and so on then build something that you know the ins and outs of so that any project comes your way you know what to do. ive known some people who use cakephp and for every project they get stuck and need to figure out what to do. another guy i knew worked with joomla and every basic company website that came his way he would reverse engineer joomla to make it work with the site. are people using these applications because they lack knowledge in the languages? or sometimes have no choice but to make a site while lacking language and put something together.

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• Replacing unversioned files in WiX major upgrade.

  - by Joshua

  I am still having this problem. This is the closest I have come to a solution that works, and yet it doesn't quite work. Here is (most of) the code: <Product Id='$(var.ProductCode)' UpgradeCode='$(var.UpgradeCode)' Name="Pathways" Version='$(var.ProductVersion)' Manufacturer='$(var.Manufacturer)' Language='1033'> Maximum="$(var.ProductVersion)" IncludeMaximum="no" Language="1033" Property="OLDAPPFOUND" / -- -- -- There is a later version of this program installed. The problem I am having is that I need the two files in the Database component to replace the previous copies. Since these files are unversioned, I have attempted to use the CompanionFile tag set to the PathwaysExe since that is the main executable of the application, and it IS being updated, even if the log says it isn't! The strangest thing about this is that the PathwaysLdf file IS BEING UPDATED CORRECTLY, and the PathwaysMdf file IS NOT. The log seems to indicate that the "Existing file is of an equal version (Checked using version of companion)". This is very strange because that file is being replaced just fine. The only idea I have left is that this problem has to do with the install sequence, and I'm not sure how to proceed! I have the InstallExecuteSequence set like I do because of the SettingsXml file, and my need to NOT overwrite that file, which is actually working now, so whatever solution works for the database files can't break the working settings file! ;) The full log is located at: http://pastebin.com/HFiGKuKN PLEASE AND THANK YOU!

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