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  • Designing a class in such a way that it doesn't become a "God object"

    - by devoured elysium
    I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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  • I can not use Session In Page_Load and I got error bellow

    - by LostLord
    hi my dear friends .... why i got this error : Object reference not set to an instance of an object. when i put this code in my page_load.: protected void Page_Load(object sender, EventArgs e) { BackEndUtils.OverallLoader(); string Teststr = Session["Co_ID"].ToString(); } ========================================================================== this session is made when user logins to my web site and this session works in other areas... thanks for your attention ========================================================================== thanks for your answers i removed BackEndUtils.OverallLoader(); but error still exists i tried Teststr = Convert.ToString(Session["Co_ID"]); and error disappeared - but i don't know why that session is null in other areas that session works perfectly = such as a button in that form what is the matter? my web page markup is like this : <%@ Page Title="" Language="C#" MasterPageFile="~/Admin/AdminBackend.Master" AutoEventWireup="true" CodeBehind="Personel.aspx.cs" Inherits="Darman.Admin.Personel" Theme="DefaultTheme" %> ================================================================================= i put this code in a button like this : string Teststr = Convert.ToString(Session["Co_ID"]); when i press that button THIS code in page Load(POSTBACK) + IN Button_Click works perfectly and shows me 23 (my Co_ID) But when i run my page in browser (first time) this code in page load shows me null. why? thanks a lot

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  • File Enumeration with ANT

    - by 1ndivisible
    I feel like I'm missing something obvious at the moment. I want to collect a set of dirs / files together in ANT. I know I can do it using a fileset with an optional patternset inside it, but that involves searching for files based a specific criterior - filetype, name etc. I already know the paths to the files I want to collect. I have n properties which reference these paths. I want a way to collect these paths in a fileset, though I cannot find a way to do it. This represents what I want to achieve (I know it isn't valid code, but hopefully it will describe what I mean): <fileset> <path>${src.dir}</path> <path>${test.dir}</path> <path>${third.party.src.dir}</path> <path>${bin.dir}</path> <path>${docs.build.txt}</path> </fileset>

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  • Getting response status code 0 in SmartGWT webservice call using json

    - by Girish
    I have developed application using SmartGWT, now i need to call webservice using json to another application which is deployed in another server for submitting username and password. When i make a request with url and POST method, getting the response status code as 0 and response text as blank. Here is my code, public void sendRequest() throws Exception { // Get login json data to be sent to server. String strData = createLoginReqPacket(); String url = "some url"; RequestBuilder builder = new RequestBuilder(RequestBuilder.POST, url); builder.setHeader("Content-Type", "application/json"); builder.setHeader("Content-Length", strData.length() + ""); Request response = builder.sendRequest(strData, new RequestCallback() { @Override public void onResponseReceived(Request request, Response response) { int statusCode = response.getStatusCode(); System.out.println("Response code ----"+response.getStatusCode()+""); if (statusCode == Response.SC_OK) { String responseBody = response.getText(); System.out.println("Respose :" + responseBody); // do something with the response } else { GWT.log("Response error at server side ----",null); // do in case of server error } }// end of method. @Override public void onError(Request request, Throwable exception) { GWT.log("**** Error in service call ******",null); }// end of method. }); builder.send(); }// end of send request. Please anybody knows the solution?? Give some reference code or links for this. Thanks.

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  • Why is a NullReferenceException thrown when a ToolStrip button is clicked twice with code in the `Click` event handler?

    - by Patrick
    I created a clean WindowsFormsApplication solution, added a ToolStrip to the main form, and placed one button on it. I've added also an OpenFileDialog, so that the Click event of the ToolStripButton looks like the following: private void toolStripButton1_Click(object sender, EventArgs e) { openFileDialog1.ShowDialog(); } I didn't change any other properties or events. The funny thing is that when I double-click the ToolStripButton (the second click must be quite fast, before the dialog opens), then cancel both dialogs (or choose a file, it doesn't really matter) and then click in the client area of main form, a NullReferenceException crashes the application (error details attached at the end of the post). Please note that the Click event is implemented while DoubleClick is not. What's even more strange that when the OpenFileDialog is replaced by any user-implemented form, the ToolStripButton blocks from being clicked twice. I'm using VS2008 with .NET3.5. I didn't change many options in VS (only fontsize, workspace folder and line numbering). Does anyone know how to solve this? It is 100% replicable on my machine, is it on others too? One solution that I can think of is disabling the button before calling OpenFileDialog.ShowDialog() and then enabling the button back (but it's not nice). Any other ideas? And now the promised error details: System.NullReferenceException was unhandled Message="Object reference not set to an instance of an object." Source="System.Windows.Forms" StackTrace: at System.Windows.Forms.NativeWindow.WindowClass.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.PeekMessage(MSG& msg, HandleRef hwnd, Int32 msgMin, Int32 msgMax, Int32 remove) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.Run(Form mainForm) at WindowsFormsApplication1.Program.Main() w C:\Users\Marchewek\Desktop\Workspaces\VisualStudio\WindowsFormsApplication1\Program.cs:line 20 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException:

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  • NHibernate listener/event to replace object before insert/update

    - by vIceBerg
    Hi! I have a Company class which have a collection of Address. Here's my Address class:(written top of my head): public class Address { public string Civic; public string Street; public City City; } This is the City class: public class City { public int Id; public string Name; public string SearchableName{ get { //code } } } Address is persisted in his own table and have a reference to the city's ID. City are also persisted in is own table. The City's SearchableName is used to prevent some mistakes in the city the user type. For example, if the city name is "Montréal", the searchable name will be "montreal". If the city name is "St. John", the searchable name will be "stjohn", etc. It's used mainly to to search and to prevent having multiple cities with a typo in it. When I save an address, I want an listener/event to check if the city is already in the database. If so, cancel the insert and replace the user's city with the database one. I would like the same behavior with updates. I tried this: public bool OnPreInsert(PreInsertEvent @event) { City entity = (@event.Entity as City); if (entity != null) { if (entity.Id == 0) { var city = (from c in @event.Session.Linq<City>() where c.SearchableName == entity.SearchableName select c).SingleOrDefault(); if (city != null) { //don't know what to do here return true; } } } return false; } But if there's already a City in the database, I don't know what to do. @event.Entity is readonly, if I set @event.Entity.Id, I get an "null identifier" exception. I tried to trap insert/update on Address and on Company, but the City if the first one to get inserted (it's logic...) Any thoughts? Thanks

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  • Hibernate noob fetch join problem

    - by Bruce
    Hi all I have two classes, Test2 and Test3. Test2 has an attribute test3 that is an instance of Test3. In other words, I have a unidirectional OneToOne association, with test2 having a reference to test3. When I select Test2 from the db, I can see that a separate select is being made to get the details of the associated test3 class. This is the famous 1+N selects problem. To fix this to use a single select, I am trying to use the fetch=join annotation, which I understand to be @Fetch(FetchMode.JOIN) However, with fetch set to join, I still see separate selects. Here are the relevant portions of my setup.. hibernate.cfg.xml: <property name="max_fetch_depth">2</property> Test2: public class Test2 { @OneToOne (cascade=CascadeType.ALL , fetch=FetchType.EAGER) @JoinColumn (name="test3_id") @Fetch(FetchMode.JOIN) public Test3 getTest3() { return test3; } NB I set the FetchType to EAGER out of desperation, even though it defaults to EAGER anyway for OneToOne mappings, but it made no difference. Thanks for any help! Edit: I've pretty much given up on trying to use FetchMode.JOIN - can anyone confirm that they have got it to work ie produce a left outer join? In the docs I see that "Usually, the mapping document is not used to customize fetching. Instead, we keep the default behavior, and override it for a particular transaction, using left join fetch in HQL" If I do a left join fetch instead: query = session.createQuery("from Test2 t2 left join fetch t2.test3"); then I do indeed get the results I want - ie a left outer join in the query.

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  • No output got after execution.

    - by wilson88
    I am still stuck with getting output for a copied vector. Probably something am not doing right. I get no output. void Auctioneer::accept_bids(const BidList& bid){ BidList list; BidList list2; BidList::const_iterator iter; copy (list.begin(),list.end(), back_inserter(list2)); for(iter=list2.begin(); iter != list2.end(); iter++) { const Bid& bid = *iter; // Get a reference to the Bid object that the iterator points to cout << "Bid id : " << bid.bidId << endl; cout << "Trd id : " << bid.trdId << endl; cout << "Quantity: " << bid.qty << endl; cout << "Price : " << bid.price << endl; cout << "Type : " << bid.type << endl; } }

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  • List of fonts installed by default in versions of Windows?

    - by Ricket
    I've been seeing more and more websites using fancy antialiased fonts. Every time I hit one, I think to myself "hmm, what web-safe font is that?" - but after looking at the CSS I typically find some font name in quotes, like "Palatino Linotype". Obviously not web-safe, but according to the Wikipedia article, "Palatino Linotype is shipped with Windows 2000 or later, and Microsoft Office Professional Edition 2003." So that covers what, 95% of users that might visit your website? And thanks to the power of CSS, the website can fallback to a similar generic font typename such as 'serif' for non-Windows users with a line like this: font: 16px/20px "Palatino Linotype", serif; Awesome! I want to start using fancy fonts! Is there a set of lists out there, of the fonts that are preinstalled by default in Windows 98, 2000, NT, ME, XP, 2003, etc., and maybe for the Mac OSX versions and various Linux distributions as well? It would be a great reference for picking web font faces! (if not, someone should compile it!) I had never before heard of Palatino Linotype and I want to know what other fonts have existed since old Windows versions that I've never known about!

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  • How to use html.grid control in spark view for asp.net mvc?

    - by Anusha
    class person() { public int Id{get;set;} public string Name{get;set;} } HomeController.cs ActionResult Index() { IList list=new[]{ new person { Id = 1, Name = "Name1" }, new person { Id = 2, Name = "Name2" }, new person { Id = 3, Name = "Name3" } }; ViewData["mygrid"]=list; return view(); } Home\Index.spark !{Html.Grid[[person]]("mygrid", (column=>{ column.For(c=>c.Id); column.For(c=>c.Name); })) Am getting the error Dynamic view compilation failed..error CS1501: No overload for method 'Grid' takes '2' arguments. I have added reference to MvcContrib.dll And added following namespace in the _global.spark file <use namespace="MvcContrib.UI"/> <use namespace="MvcContrib.UI.Grid"/> <use namespace="MvcContrib.UI.Pager"/> <use namespace="MvcContrib.UI.Grid.ActionSyntax"/> <use namespace="Microsoft.Web.Mvc.Controls"/> I want to bind the data to my grid in spark view.Can anybody help.

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  • KODO: how set up fetch plan for bidirectional relationships?

    - by BestPractices
    Running KODO 4.2 and having an issue inefficient queries being generated by KODO. This happens when fetching an object that contains a collection where that collection has a bidrectional relationship back to the first object. Class Classroom { List<Student> _students; } Class Student { Classroom _classroom; } If we create a fetch plan to get a list of Classrooms and their corresponding Students by setting up the following fetch plan: fetchPlan.addField(Classroom.class,”_students”); This will result in two queries (get the classrooms and then get all students that are in those classrooms), which is what we would expect. However, if we include the reference back to the classroom in our fetch plan in order for the _classroom field to get populated by doing fetchPlan.addField(Student.class, “_classroom”), this will result in X number of additional queries where X is the number of students in each classroom. Can anyone explain how to fix this? KODO already has the original Classroom objects at the point that it's executing the queries to retrieve the Classroom objects and set them in each Student object's _classroom field. So I would expect KODO to simply set those objects in the _classroom field on each Student object accordingly and not go back to the database. Once again, the documentation is sorely lacking with Kodo/JDO/OpenJPA but from what I've read it should be able to do this more efficiently. Note-- EAGER_FETCH.PARALLEL is turned on and I have tried this with caching (query and data caches) turned on and off and there is no difference in the resultant queries.

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  • ASMX schema varies when using WCF Service

    - by Lijo
    Hi, I have a client (created using ASMX "Add Web Reference"). The service is WCF. The signature of the methods varies for the client and the Service. I get some unwanted parameteres to the method. Note: I have used IsRequired = true for DataMember. Service: [OperationContract] int GetInt(); Client: proxy.GetInt(out requiredResult, out resultBool); Could you please help me to make the schame non-varying in both WCF clinet and non-WCF cliet? Do we have any best practices for that? using System.ServiceModel; using System.Runtime.Serialization; namespace SimpleLibraryService { [ServiceContract(Namespace = "http://Lijo.Samples")] public interface IElementaryService { [OperationContract] int GetInt(); [OperationContract] int SecondTestInt(); } public class NameDecorator : IElementaryService { [DataMember(IsRequired=true)] int resultIntVal = 1; int firstVal = 1; public int GetInt() { return firstVal; } public int SecondTestInt() { return resultIntVal; } } } Binding = "basicHttpBinding" using NonWCFClient.WebServiceTEST; namespace NonWCFClient { class Program { static void Main(string[] args) { NonWCFClient.WebServiceTEST.NameDecorator proxy = new NameDecorator(); int requiredResult =0; bool resultBool = false; proxy.GetInt(out requiredResult, out resultBool); Console.WriteLine("GetInt___"+requiredResult.ToString() +"__" + resultBool.ToString()); int secondResult =0; bool secondBool = false; proxy.SecondTestInt(out secondResult, out secondBool); Console.WriteLine("SecondTestInt___" + secondResult.ToString() + "__" + secondBool.ToString()); Console.ReadLine(); } } } Please help.. Thanks Lijo

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  • URL equals and checking Internet access

    - by James P.
    On http://java.sun.com/j2se/1.5.0/docs/api/java/net/URL.html it states that: Compares this URL for equality with another object. If the given object is not a URL then this method immediately returns false. Two URL objects are equal if they have the same protocol, reference equivalent hosts, have the same port number on the host, and the same file and fragment of the file. Two hosts are considered equivalent if both host names can be resolved into the same IP addresses; else if either host name can't be resolved, the host names must be equal without regard to case; or both host names equal to null. Since hosts comparison requires name resolution, this operation is a blocking operation. Note: The defined behavior for equals is known to be inconsistent with virtual hosting in HTTP. According to this, equals will only work if name resolution is possible. Since I can't be sure that a computer has internet access at a given time, should I just use Strings to store addresses instead? Also, how do I go about testing if access is available when requested?

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  • AS3 and the loader class

    - by Acti67
    Hi, I write here, because after looking for a solution, I could not resolve my error... var test:MovieClip; var sign:Loader = new Loader(); sign.contentLoaderInfo.addEventListener(Event.COMPLETE, completSIGN); sign.load(new URLRequest("http://files.zebest-3000.com/278374/3011/3011.swf")); function completSIGN(e:Event):void { test = MovieClip(e.target.content); addChild(test); } This is the error: TypeError: Error #1009: Il est impossible d'accéder à la propriété ou à la méthode d'une référence d'objet nul. at Main::StateManager() So, the movie (some videos work perfectly and others not) does not want to load in my container ; it seems there is a problem in the mapping... and can't modify the distant movie. Is there an other method of loading a movie inside one other (I have try also to load with bytearray, but it's the same)? Can we catch this error and relocate the instance to help him to find the correct way?

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  • KeyStore, HttpClient, and HTTPS: Can someone explain this code to me?

    - by stormin986
    I'm trying to understand what's going on in this code. KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType()); FileInputStream instream = new FileInputStream(new File("my.keystore")); try { trustStore.load(instream, "nopassword".toCharArray()); } finally { instream.close(); } SSLSocketFactory socketFactory = new SSLSocketFactory(trustStore); Scheme sch = new Scheme("https", socketFactory, 443); httpclient.getConnectionManager().getSchemeRegistry().register(sch); My Questions: trustStore.load(instream, "nopassword".toCharArray()); is doing what exactly? From reading the documentation load() will load KeyStore data from an input stream (which is just an empty file we just created), using some arbitrary "nopassword". Why not just load it with null as the InputStream parameter and an empty string as the password field? And then what is happening when this empty KeyStore is being passed to the SSLSocketFactory constructor? What's the result of such an operation? Or -- is this simply an example where in a real application you would have to actually put a reference to an existing keystore file / password?

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  • Automatically hyper-link URL's and Email's using C#, whilst leaving bespoke tags in place

    - by marcusstarnes
    I have a site that enables users to post messages to a forum. At present, if a user types a web address or email address and posts it, it's treated the same as any other piece of text. There are tools that enable the user to supply hyper-linked web and email addresses (via some bespoke tags/markup) - these are sometimes used, but not always. In addition, a bespoke 'Image' tag can also be used to reference images that are hosted on the web. My objective is to both cater for those that use these existing tools to generate hyper-linked addresses, but to also cater for those that simply type a web or email address in, and to then automatically convert this to a hyper-linked address for them (as soon as they submit their post). I've found one or two regular expressions that convert a plain string web or email address, however, I obviously don't want to perform any manipulation on addresses that are already being handled via the sites bespoke tagging, and that's where I'm stuck - how to EXCLUDE any web or email addresses that are already catered for via the bespoke tagging - I wan't to leave them as is. Here are some examples of bespoke tagging for the variations that I need to be left alone: [URL=www.msn.com]www.msn.com[/URL] [URL=http://www.msn.com]http://www.msn.com[/URL] [[email protected]][email protected][/EMAIL] [IMG]www.msn.com/images/test.jpg[/IMG] [IMG]http://www.msn.com/images/test.jpg[/IMG] The following examples would however ideally need to be automatically converted into web & email links respectively: www.msn.com http://www.msn.com [email protected] Ideally, the 'converted' links would just have the appropriate bespoke tags applied to them as per the initial examples earlier in this post, so rather than: <a href="..." etc. they'd become: [URL=http://www.. etc.) Unfortunately, we have a LOT of historic data stored with this bespoke tagging throughout, so for now, we'd like to retain that rather than implementing an entirely new way of storing our users posts. Any help would be much appreciated. Thanks.

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  • Django: How to dynamically add tag field to third party apps without touching app's source code

    - by Chris Lawlor
    Scenario: large project with many third party apps. Want to add tagging to those apps without having to modify the apps' source. My first thought was to first specify a list of models in settings.py (like ['appname.modelname',], and call django-tagging's register function on each of them. The register function adds a TagField and a custom manager to the specified model. The problem with that approach is that the function needs to run BEFORE the DB schema is generated. I tried running the register function directly in settings.py, but I need django.db.models.get_model to get the actual model reference from only a string, and I can't seem to import that from settings.py - no matter what I try I get an ImportError. The tagging.register function imports OK however. So I changed tactics and wrote a custom management command in an otherwise empty app. The problem there is that the only signal which hooks into syncdb is post_syncdb which is useless to me since it fires after the DB schema has been generated. The only other approach I can think of at the moment is to generate and run a 'south' like database schema migration. This seems more like a hack than a solution. This seems like it should be a pretty common need, but I haven't been able to find a clean solution. So my question is: Is it possible to dynamically add fields to a model BEFORE the schema is generated, but more specifically, is it possible to add tagging to a third party model without editing it's source. To clarify, I know it is possible to create and store Tags without having a TagField on the model, but there is a major flaw in that approach in that it is difficult to simultaneously create and tag a new model.

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  • Linker error: wants C++ virtual base class destructor

    - by jdmuys
    Hi, I have a link error where the linker complains that my concrete class's destructor is calling its abstract superclass destructor, the code of which is missing. This is using GCC 4.2 on Mac OS X from XCode. I saw http://stackoverflow.com/questions/307352/g-undefined-reference-to-typeinfo but it's not quite the same thing. Here is the linker error message: Undefined symbols: "ConnectionPool::~ConnectionPool()", referenced from: AlwaysConnectedConnectionZPool::~AlwaysConnectedConnectionZPool()in RKConnector.o ld: symbol(s) not found collect2: ld returned 1 exit status Here is the abstract base class declaration: class ConnectionPool { public: static ConnectionPool* newPool(std::string h, short p, std::string u, std::string pw, std::string b); virtual ~ConnectionPool() =0; virtual int keepAlive() =0; virtual int disconnect() =0; virtual sql::Connection * getConnection(char *compression_scheme = NULL) =0; virtual void releaseConnection(sql::Connection * theConnection) =0; }; Here is the concrete class declaration: class AlwaysConnectedConnectionZPool: public ConnectionPool { protected: <snip data members> public: AlwaysConnectedConnectionZPool(std::string h, short p, std::string u, std::string pw, std::string b); virtual ~AlwaysConnectedConnectionZPool(); virtual int keepAlive(); // will make sure the connection doesn't time out. Call regularly virtual int disconnect(); // disconnects/destroys all connections. virtual sql::Connection * getConnection(char *compression_scheme = NULL); virtual void releaseConnection(sql::Connection * theConnection); }; Needless to say, all those members are implemented. Here is the destructor: AlwaysConnectedConnectionZPool::~AlwaysConnectedConnectionZPool() { printf("AlwaysConnectedConnectionZPool destructor call"); // nothing to destruct in fact } and also maybe the factory routine: ConnectionPool* ConnectionPool::newPool(std::string h, short p, std::string u, std::string pw, std::string b) { return new AlwaysConnectedConnectionZPool(h, p, u, pw, b); } I can fix this by artificially making my abstract base class concrete. But I'd rather do something better. Any idea? Thanks

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  • How should I name a native DLL distributed in both 32-bit and 64-bit form?

    - by Spike0xff
    I have a commercial product that's a DLL (native 32-bit code), and now it's time to build a 64-bit version of it. So when installing on 64-bit Windows, the 32-bit version goes into Windows\SysWOW64, and the 64-bit version goes into... Windows\System32! (I'm biting my tongue here...) Or the DLL(s) can be installed alongside the client application. What should I name the 64-bit DLL? Same name as 32-bit: Two files that do the same thing, have the same name, but are totally non-interchangeable. Isn't that a recipe for confusion and support problems? Different names (e.g. product.dll and product64.dll): Now client applications have to know whether they are running 32-bit or 64-bit in order to reference my DLL, and there are languages where that isn't known until run-time - .NET being just one example. And now all the statically compiled clients have to conditionalize the import declarations: IF target=WIN64 THEN import Blah from "product64.dll" ELSE import Blah from "product.dll" ENDIF The product contains massive amounts of C code, and a large chunk of C++ - porting it to C# is not an option. Advice? Suggestions?

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  • Is a call to the following method considered late binding?

    - by AspOnMyNet
    1) Assume: • B1 defines methods virtualM() and nonvirtualM(), where former method is virtual while the latter is non-virtual • B2 derives from B1 • B2 overrides virtualM() • B2 is defined inside assembly A • Application app doesn’t have a reference to assembly A In the following code application app dynamically loads an assembly A, creates an instance of a type B2 and calls methods virtualM() and nonvirtualM(): Assembly a=Assembly.Load(“A”); Type t= a.GetType(“B2”); B1 a = ( B1 ) Activator.CreateInstance ( “t” ); a.virtualM(); a.nonvirtualM(); a) Is call to a.virtualM() considered early binding or late binding? b) I assume a call to a.nonvirtualM() is resolved during compilation time? 2) Does the term late binding refer only to looking up the target method at run time or does it also refer to creating an instance of given type at runtime? thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) The method slot is determined at compile time I assume that by method slot you’re referring to the entry point in V-table?

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  • Class initialization and synchronized class method

    - by nybon
    Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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  • StrcutureMap Wiring - Sanity Check Please

    - by Steve Ward
    Hi - Im new to IOC and StructureMap and have an n-level application and am looking at how to setup the wirings (ForRequestedType ...) and just want to check with people with more experience that this is the best way of doing it! I dont want my UI application object to reference my persistence layer directly so am not able to wire everything up in this UI project. I now have it working by defining a Registry class in each project which wires up the types in the project as needed. The layer above registers its types and also calls the assembly below and looks for registries so that all types are registered throught the hierrachy. E.g. I have UI, Service, Domain, and Persistence libraries. In my service layer the registry looks like Scan(x => { x.Assembly("MyPersistenceProject"); x.LookForRegistries(); }); ForRequestedType<IService>().TheDefault.Is.OfConcreteType<MyService>(); Is this a recommended way of doing this in a setup such as this? Are there better ways and what are the advantages / disadvantages of these approaches in this case?

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  • Natural problems to solve using closures

    - by m.u.sheikh
    I have read quite a few articles on closures, and, embarassingly enough, I still don't understand this concept! Articles explain how to create a closure with a few examples, but I don't see any point in paying much attention to them, as they largely look contrived examples. I am not saying all of them are contrived, just that the ones I found looked contrived, and I dint see how even after understanding them, I will be able to use them. So in order to understand closures, I am looking at a few real problems, that can be solved very naturally using closures. For instance, a natural way to explain recursion to a person could be to explain the computation of n!. It is very natural to understand a problem like computing the factorial of a number using recursion. Similarly, it is almost a no-brainer to find an element in an unsorted array by reading each element, and comparing with the number in question. Also, at a different level, doing Object-oriented programming also makes sense. So I am trying to find a number of problems that could be solved with or without closures, but using closures makes thinking about them and solving them easier. Also, there are two types to closures, where each call to a closure can create a copy of the environment variables, or reference the same variables. So what sort of problems can be solved more naturally in which of the closure implementations?

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  • Which technology should I use to pop up a simple form in my add-in DLL?

    - by Decker
    I'm building an assembly that runs as an "add-on" to a vendor's Outlook add-in. When it is time for me to execute my "action", I have to put up a simple window with a few simple controls. The vendor's add-in provides me with the parent window's integer handle. I am able to put up a form pretty easily with WinForms by adding are reference to System.Windows.Forms from my assembly and with the following code: FrmHistoryDisplay frm = new FrmHistoryDisplay(); frm.ShowDialog(new ParentWindowWrapper(_parentWindowHandle)); where ParentWindowWrapper is a shim class around the window handle I'm given private class ParentWindowWrapper : IWin32Window { private int _parentWindowHandle; public ParentWindowWrapper(int parentWindowHandle) { _parentWindowHandle = parentWindowHandle; } public IntPtr Handle { get { return new IntPtr(_parentWindowHandle); } } } The Form's ShowDialog method takes an IWin32Window implementor to wrap the parent's window handle. This all works and seems simple enough. I was just wondering whether something similar can be done with a WPF window rather than a WinForm Form? Should I care?

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  • Do COM Dll References Require Manual Disposal? If so, How?

    - by Drew
    I have written some code in VB that verifies that a particular port in the Windows Firewall is open, and opens one otherwise. The code uses references to three COM DLLs. I wrote a WindowsFirewall class, which Imports the primary namespace defined by the DLLs. Within members of the WindowsFirewall class I construct some of the types defined by the DLLs referenced. The following code isn't the entire class, but demonstrates what I am doing. Imports NetFwTypeLib Public Class WindowsFirewall Public Shared Function IsFirewallEnabled as Boolean Dim icfMgr As INetFwMgr icfMgr = CType(System.Activator.CreateInstance(Type.GetTypeFromProgID("HNetCfg.FwMgr")), INetFwMgr) Dim profile As INetFwProfile profile = icfMgr.LocalPolicy.CurrentProfile Dim fIsFirewallEnabled as Boolean fIsFirewallEnabled = profile.FirewallEnabled return fIsFirewallEnabled End Function End Class I do not reference COM DLLs very often. I have read that unmanaged code may not be cleaned up by the garbage collector and I would like to know how to make sure that I have not introduced any memory leaks. Please tell me (a) if I have introduced a memory leak, and (b) how I may clean it up. (My theory is that the icfMgr and profile objects do allocate memory that remains unreleased until after the application closes. I am hopeful that setting their references equal to nothing will mark them for garbage collection, since I can find no other way to dispose of them. Neither one implements IDisposable, and neither contains a Finalize method. I suspect they may not even be relevant here, and that both of those methods of releasing memory only apply to .Net types.)

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