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• ASP.NET 2.0 in Virtual Trying to Use SQL State Server

  - by user251660

  We have IIS 6 running on a W2003 Server. The root web site is running a v1.1 site. Under this site we have a virtual running a v2.0 site (with a separate application pool). The web.config for the root site is using SQL as its state server and has a 1.1 SQL state server database installed. The 2.0 virtual web.config does not need state and its web.config has no reference to a state server. When we attempt to call the virtual we receive this error message. "Unable to use SQL Server because ASP.NET version 2.0 Session State is not installed on the SQL server. Please install ASP.NET Session State SQL Server version 2.0 or above. This issue is currently only occurring on one web server. The rest are able to run the 2.0 virtual application. I also notice that if we call the 2.0 virtual with the IP address it does not generate the error, however if we call it with the host header name it generates the error (this behavior is only on the 1 web server with the error, all the others can be called with either the ip or host header without error). As an additional note the root and virtual are running with SSL. My theory is that the virtual 2.0 application is inheriting the 1.1 web.config state server entry from the root and when it looks at the state server it sees it as a 1.1 version and reports the error that it needs a 2.0 state server. I however cannot understand why the other servers are not behaving in this matter. All of the servers are on the same OS service pack as well as the same version of .net framework. Any ideas? Thanks

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• Run code before class instanciation in ActionScript 3

  - by soow.fr

  I need to run code in a class declaration before its instanciation. This would be especially useful to automatically register classes in a factory. See: // Main.as public class Main extends Sprite { public function Main() : void { var o : Object = Factory.make(42); } } // Factory.as public class Factory { private static var _factory : Array = new Array(); public static function registerClass(id : uint, c : Class) : void { _factory[id] = function () : Object { return new c(); }; } public static function make(id : uint) : Object { return _factory[id](); } } // Foo.as public class Foo { // Run this code before instanciating Foo! Factory.registerClass(42, Foo); } AFAIK, the JIT machine for the ActionScript language won't let me do that since no reference to Foo is made in the Main method. The Foo class being generated, I can't (and don't want to) register the classes in Main: I'd like to register all the exported classes in a specific package (or library). Ideally, this would be done through package introspection, which doesn't exist in ActionScript 3. Do you know any fix (or other solution) to my design issue?

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• Doctrine: How to traverse from an entity to another 'linked' entity?

  - by ropstah

  I'm loading 3 different tables using a cross-join in Doctrine_RawSql. This brings me back the following object: User -> User class (doctrine base class) Settings -> DoctrineCollection of Setting User_Settings -> DoctrineCollection of User_Setting The object above is the result of a many-to-many relationship between User and Setting where User_Setting acts as a reference table. User_Setting also contains another field named value. This obviously contains the value of the corresponding Setting. All good so far, however the Settings and User_Settings properties of the returned User object are in no way linked to each other (apart from the setting_id field ofcourse). Is there any direct way to traverse directly from the Settings property to the corresponding User_Settings property? This is the corresponding query: $sets = new Doctrine_RawSql(); $sets->select('{us.*}, {s.*}, {uset.*}') ->from('(User us CROSS JOIN Setting s) LEFT JOIN User_Setting uset ON us.user_id = uset.user_id AND s.setting_id = uset.setting_id') ->addComponent('us', 'User us') ->addComponent('uset', 'us.User_Setting uset') ->addComponent('s', 'us.Setting s') ->where('s.category_id = ? AND us.usr_auto_key = ?',array(1, 1)); $sets = $sets->execute();

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• Issue displaying a local image from XAML

  - by Flack

  Hello, I have the below simple xaml: <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="300" Width="300"> <Grid> <Image Source="happyface.jpg"/> </Grid> </Window> happyface.jpg is included in the project and its Build Action is set to "Content" and Copy To Ouptput Directory is set to "Copy Always". When looking at the app through the VS designer, everything is ok and I see the image. However, when I run the app, no image is displayed. I see the image is copied to the out out directory. If I put in the entire path as the source (C:\SANDBOX\WpfApplication1\WpfApplication1\bin\Debug") it works. Any ideas as to why the image is not displayed when I run the app? I read about pack URIs but thought that to just simply reference a loose image in the current directory, I can just use the image name. Thank you.

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• How can I manage building library projects that produce both a static lib and a dll?

  - by Scott Langham

  I've got a large visual studio solution with ~50 projects. There are configurations for StaticDebug, StaticRelease, Debug and Release. Some libraries are needed in both dll and static lib form. To get them, we rebuild the solution with a different configuration. The Configuration Manager window is used to setup which projects need to build in which flavours, static lib, dynamic dll or both. This can by quite tricky to manage and it's a bit annoying to have to build the solution multiple times and select the configurations in the right order. Static versions need building before non-static versions. I'm wondering, instead of this current scheme, might it be simpler to manage if, for the projects I needed to produce both a static lib and dynamc dll, I created two projects. Eg: CoreLib CoreDll I could either make both of these projects reference all the same files and build them twice, or I'm wondering, would it be possible to build CoreLib and then get CoreDll to link it to generate the dll? I guess my question is, do you have any advice on how to structure your projects in this kind of situation? Thanks.

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• What are the Limitations for Connecting to an Access Query in Excel

  - by thornomad

  I have an Access 2007 database that has a number of tables, some are fairly large (100,000+ records); I have created a union query to pull some of the same types of data from multiple tables into one large query for pivot table manipulation and reporting. For example: SELECT Language FROM Table1 UNION ALL SELECT Language FROM Table2 UNION ALL SELECT Language FROM Table3; This works. I found, quickly, however, that a union query will not show up when connecting to the datasource from Excel 2007. So, I created a second query to reference the union query. Like so: SELECT * FROM [The Above Union Query]; This query works and it, initially, was accessible from Excel. Time passed, I've added more data. Suddenly, when I connect to my Access database from Excel my query referencing the union has disappeared. MS Access shows no signs of an issue (data displays in Access) and my other non-union queries are showing up in Excel 2007 ... but not the one that references the union. What could be going on? Why did it disappear? I noticed if I switch some of the referenced tables in the union query to a smaller table (with less rows) all of sudden the query appears in Excel again. At least, I think that's what the difference is. I really can't put my finger on why some of the union queries won't show up and some will. Am stumped and need some guidance. Thanks.

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• Mono Develop 2.4.1 + linq error.

  - by Nev_Rahd

  I just started to learn Mono Develop Installed Mono Develop 2.4.1 and trial version of Mono Touch. my Code: using System; using System.Xml.Linq; using System.Collections.Generic; namespace RSSReader { public static class RSSRepository { public static IList<FeedItem> GetFeeds(string url) { XDocument rssFeed = XDocument.Load(url); Console.Write(rssFeed.ToString()); var feeds = new List<FeedItem>(); try { var query = from item in rssFeed.Descendants("item") select new FeedItem { Title = item.Element("title").Value, Published = DateTime.Parse(item.Element("pubDate").Value), Url = item.Element("link").Value }; feeds = query.ToList(); } catch (Exception ex){ Console.WriteLine(ex.Message); } return feeds; } } } This is throwing an error: An implementation of 'select' query expression pattern could not be found. Are you missing 'System.linq' using directive or 'System.Core.dll' assembly reference? I got both references to System.Xml.Linq and System.Core What am i missing ?

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• Javascript inheritance: call super-constructor or use prototype chain?

  - by Jeremy S.

  Hi folks, quite recently I read about javascript call usage in MDC https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/call one linke of the example shown below, I still don't understand. Why are they using inheritance here like this Prod_dept.prototype = new Product(); is this necessary? Because there is a call to the super-constructor in Prod_dept() anyway, like this Product.call is this just out of common behaviour? When is it better to use call for the super-constructor or use the prototype chain? function Product(name, value){ this.name = name; if(value >= 1000) this.value = 999; else this.value = value; } function Prod_dept(name, value, dept){ this.dept = dept; Product.call(this, name, value); } Prod_dept.prototype = new Product(); // since 5 is less than 1000, value is set cheese = new Prod_dept("feta", 5, "food"); // since 5000 is above 1000, value will be 999 car = new Prod_dept("honda", 5000, "auto"); Thanks for making things clearer

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• Some ASP.NET and Access

  - by Fazleh

  Good Day all, I have a big problem but i think its minor for you guys in Stackoverflow. I am creating a web application that has two main parts. The Payment part and Requisition part. It backbone is using access and the script is in ASP.NET. I managed to sort out most of the application. But I have been having a few problems. I have pasted the link to the project in http://www.mediafire.com/download/p09fefreifidud3/Inyatsi.rar so it will be easy for someone to see what I am blabbing about. Now for my problems: The AddRequisition.aspx/AddPayment.aspx: both have a reference number. I wanted it to be unique number(but not a primary key). I wanted it to be in the following format: DDMMYY(TransactionNo)(UserID) eg: 24061101PK. I have tried and tried but have not been able to sort it out. The AmountINWords gets the value from Amount. It converts the Amount into words. Thats not all. It picks what currncy was picked in the CurrencyPaidIn and pust the respective currency inside. eg. 123.45 USD becomes One Hundred and twenty three dollars and forty five cents. I tried using queries but as you will see that went all wrong. Those are the only two things that I cant seem to get my head around. I do know that there are some things that are not conventional ASP.NET and some text boxes are not the right size. I was thinking of sorting out those after I get those two fixed because they are simple to do. I really need some help with this application please. If someone can just have a look at the code and add a few things here and there. Thanks in advance. Faz

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• JSP displaying source code instead of executing

  - by DJStroky

  I'm new to jsp and have ran into some trouble. Initially, the jsp file and associated java classes were built and tested fine on a test Tomcat server. Now, they've been transitioned to another server of what I believe is the same setup (except it's linux now instead of windows). But when the jsp page is accessed the source code is displayed instead of the jsp actually executing. I've googled for a while but received no success. I had thought that this page might solve the problem since there was no reference to the jsp file I was using or even the following snippets in my web.xml file in the WEB-INF folder: <servlet> <servlet-name>jsp</servlet-name> <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class> <init-param> <param-name>logVerbosityLevel</param-name> <param-value>WARNING</param-value> </init-param> <load-on-startup>3</load-on-startup> </servlet> <servlet-mapping> <servlet-name>jsp</servlet-name> <url-pattern>*.jsp</url-pattern> </servlet-mapping> I tried inserting these lines and restarting Tomcat, but no success. Any ideas?

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• eclipse error with android: id cannot be resolved or is not a field

  - by Jaynathan Leung

  Hi, I just started playing around with android development, and already with just an attempt at making a button, I have encountered a problem. The error I'm given in the following code is right on "R.id.button1". It says id cannot be resolved or is not a field. Do I need to manually reference every single object I make in the layout xml file? I found that this did work, but it does seem to be a bit much for every button I want to make... package com.example.helloandroid; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class HelloAndroid extends Activity { /** Called when the activity is first created. */ private Button button1; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); button1 = (Button)findViewById(R.id.button1); button1.setOnClickListener(new OnClickListener() { public void onClick(View v) { finish(); } }); } }

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• Question about using an access database as a resource file in Visual Studio.

  - by user354303

  Hi I am trying to embed a Microsoft Access database file into my Class assembly DLL. I want my code to reference the resource file and use it with a ADODB.Connection object. Any body know a simpler way, or an easier way? Or what is wrong with my code, when i added the resource file it added me dataset definitions, but i have no idea what to do with those. The connection string I am trying below is from an automatically generated app.config. I did add the item as a resource... using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; using ConsoleApplication1.Resources;//SPPrinterLicenses using System.Data.OleDb; using ADODB; using System.Configuration; namespace ConsoleApplication1 { class SharePointPrinterManager { public static bool IsValidLicense(string HardwareID) { OleDbDataAdapter da = new OleDbDataAdapter(); DataSet ds = new DataSet(); ADODB.Connection adoCn = new Connection(); ADODB.Recordset adoRs = new Recordset(); //**open command below fails** adoCn.Open( @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\Resources\SPPrinterLicenses.accdb;Persist Security Info=True", "", "", 1); adoRs.Open("Select * from AllWorkstationLicenses", adoCn, ADODB.CursorTypeEnum.adOpenForwardOnly, ADODB.LockTypeEnum.adLockReadOnly, 1); da.Fill(ds, adoRs, "AllworkstationLicenses"); adoCn.Close(); DataTable dt = new DataTable(); //ds.Tables. return true; } } }

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• Linq - reuse expression on child property

  - by user175528

  Not sure if what I am trying is possible or not, but I'd like to reuse a linq expression on an objects parent property. With the given classes: class Parent { int Id { get; set; } IList<Child> Children { get; set; } string Name { get; set; } } class Child{ int Id { get; set; } Parent Dad { get; set; } string Name { get; set; } } If i then have a helper Expression<Func<Parent,bool> ParentQuery() { Expression<Func<Parent,bool> q = p => p.Name=="foo"; } I then want to use this when querying data out for a child, along the lines of: using(var context=new Entities.Context) { var data=context.Child.Where(c => c.Name=="bar" && c.Dad.Where(ParentQuery)); } I know I can do that on child collections: using(var context=new Entities.Context) { var data=context.Parent.Where(p => p.Name=="foo" && p.Childen.Where(childQuery)); } but cant see any way to do this on a property that isnt a collection. This is just a simplified example, actually the ParentQuery will be more complex and I want to avoid having this repeated in multiple places as rather than just having 2 layers I'll have closer to 5 or 6, but all of them will need to reference the parent query to ensure security.

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• Parallel doseq for Clojure

  - by andrew cooke

  I haven't used multithreading in Clojure at all so am unsure where to start. I have a doseq whose body can run in parallel. What I'd like is for there always to be 3 threads running (leaving 1 core free) that evaluate the body in parallel until the range is exhausted. There's no shared state, nothing complicated - the equivalent of Python's multiprocessing would be just fine. So something like: (dopar 3 [i (range 100)] ; repeated 100 times in 3 parallel threads... ...) Where should I start looking? Is there a command for this? A standard package? A good reference? So far I have found pmap, and could use that (how do I restrict to 3 at a time? looks like it uses 32 at a time - no, source says 2 + number of processors), but it seems like this is a basic primitive that should already exist somewhere. clarification: I really would like to control the number of threads. I have processes that are long-running and use a fair amount of memory, so creating a large number and hoping things work out OK isn't a good approach (example which uses a significant chunk available mem). update: Starting to write a macro that does this, and I need a semaphore (or a mutex, or an atom i can wait on). Do semaphores exist in Clojure? Or should I use a ThreadPoolExecutor? It seems odd to have to pull so much in from Java - I thought parallel programming in Clojure was supposed to be easy... Maybe I am thinking about this completely the wrong way? Hmmm. Agents?

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• Symbols (pdb) for native dll are not loaded due to post build step

  - by sean e

  I have a native release dll that is built with symbols. There is a post build step that modifies the dll. The post build step does some compression and probably appends some data. The pdb file is still valid however neither WinDbg nor Visual Studio 2008 will load the symbols for the dll after the post build step. What bits in either the pdb file or the dll do we need to modify to get either WinDbg or Visual Studio to load the symbols when it loads a dump in which our release dll is referenced? Is it filesize that matters? A checksum or hash? A timestamp? Modify the dump? or modify the pdb? modify the dll before it is shipped? (We know the pdb is valid because we are able to use it to manually get symbol names for addresses in dump callstacks that reference the released dll. It's just a total pain in the *ss do it by hand for every address in a callstack in all the threads.)

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• Best practice for managing changes to 3rd party open source libraries?

  - by Jeff Knecht

  On a recent project, I had to modify an open source library to address a functional deficiency. I followed the SVN best practice of creating a "vendor source" repository and made my changes there. I also submitted the patch to the mailing list of that project. Unfortunately, the project only has a couple of maintainers and they are very slow to commit updates. At some point, I expect the library to be updated, and I expect that my project will want to use the upgraded library. But now I have a potential problem... I don't know whether my patch will have been applied to this future release of the 3rd party library. I also don't know whether my patch will even still be compatible with the internal implementation of the upgraded components. And in all likelihood, someone else will be maintaining my project by that point. Should I name the library in a special way so it is clear that we made special modifications (eg. commons-lang-2.x-for-my-project.jar)? Should I just document the patch and reference the SVN location and a link to the mailing list item in a README? No option that I can think of seems to be fool-proof in an upgrade scenario. What is the best practice for this?

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• How to create a generic method in C# that's all applicable to many types - ints, strings, doubles et

  - by satyajit

  Let's I have a method to remove duplicates in an integer Array public int[] RemoveDuplicates(int[] elems) { HashSet<int> uniques = new HashSet<int>(); foreach (int item in elems) uniques.Add(item); elems = new int[uniques.Count]; int cnt = 0; foreach (var item in uniques) elems[cnt++] = item; return elems; } How can I make this generic such that now it accepts a string array and remove duplicates in it? How about a double array? I know I am probably mixing things here in between primitive and value types. For your reference the following code won't compile public List<T> RemoveDuplicates(List<T> elems) { HashSet<T> uniques = new HashSet<T>(); foreach (var item in elems) uniques.Add(item); elems = new List<T>(); int cnt = 0; foreach (var item in uniques) elems[cnt++] = item; return elems; } The reason is that all generic types should be closed at run time. Thanks for you comments

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• @dynamic property needs setter with multiple behaviors

  - by ambertch

  I have a class that contains multiple user objects and as such has an array of them as an instance variable: NSMutableArray *users; The tricky part is setting it. I am deserializing these objects from a server via Objective Resource, and for backend reasons users can only be returned as a long string of UIDs - what I have locally is a separate dictionary of users keyed to UIDs. Given the string uidString of comma separated UIDs I override the default setter and populate the actual user objects: @dynamic users; - (void)setUsers:(id)uidString { users = [NSMutableArray arrayWithArray: [[User allUsersDictionary] objectsForKeys:[(NSString*)uidString componentsSeparatedByString:@","]]]; } The problem is this: I now serialize these to database using SQLitePO, which stores these as the array of user objects, not the original string. So when I retrieve it from database the setter mistakenly treats this array of user objects as a string! Where I actually want to adjust the setter's behavior when it gets this object from DB vs. over the network. I can't just make the getter serialize back into a string without tearing up large code that reference this array of user objects, and I tried to detect in the setter whether I have a string or an array coming in: if ([uidString respondsToSelector:@selector(addObject)]) { // Already an array, so don't do anything - just assign users = uidString but no success... so I'm kind of stuck - any suggestions? Thanks in advance!

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• Dimension Reduction in Categorical Data with missing values

  - by user227290

  I have a regression model in which the dependent variable is continuous but ninety percent of the independent variables are categorical(both ordered and unordered) and around thirty percent of the records have missing values(to make matters worse they are missing randomly without any pattern, that is, more that forty five percent of the data hava at least one missing value). There is no a priori theory to choose the specification of the model so one of the key tasks is dimension reduction before running the regression. While I am aware of several methods for dimension reduction for continuous variables I am not aware of a similar statical literature for categorical data (except, perhaps, as a part of correspondence analysis which is basically a variation of principal component analysis on frequency table). Let me also add that the dataset is of moderate size 500000 observations with 200 variables. I have two questions. Is there a good statistical reference out there for dimension reduction for categorical data along with robust imputation (I think the first issue is imputation and then dimension reduction)? This is linked to implementation of above problem. I have used R extensively earlier and tend to use transcan and impute function heavily for continuous variables and use a variation of tree method to impute categorical values. I have a working knowledge of Python so if something is nice out there for this purpose then I will use it. Any implementation pointers in python or R will be of great help. Thank you.

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• C As Principal Class For Mac App

  - by CodaFi

  So, I've got a c file raring to go and be the main class behind an all-C mac-app, however, a combination of limiting factors are preventing the application from being launched. As it currently stands, the project is just a main.m and a class called AppDelegate.c, so I entered "AppDelegate" as the name of the principal class in the info.plist, and to my complete surprise, the log printed: Unable to find class: AppDelegate, exiting This would work perfectly well in iOS, because the main function accepts the name of a delegate class, and handles it automatically, but NSApplicationMain() takes no such argument. Now, I know this stems from the fact that there are no @interface/@implementation directives in C, and that's really what the OS seems to be looking for, so I wrote a simple NSApplication subclass and provided it as the Principal Class to the plist, and it launched perfectly well. My question is, how could one go about setting a c file as the principal class in a mac application and have it launch correctly? PS, don't ask what or why I'm doing this for, the foundation must be dug. For @millimoose's amusement, here be the AppDelegate.c file: #include <objc/runtime.h> #include <objc/message.h> struct AppDel { Class isa; id window; }; // This is a strong reference to the class of the AppDelegate // (same as [AppDelegate class]) Class AppDelClass; BOOL AppDel_didFinishLaunching(struct AppDel *self, SEL _cmd, void *application, void *options) { self->window = objc_msgSend(objc_getClass("NSWindow"), sel_getUid("alloc")); self->window = objc_msgSend(self->window, sel_getUid("init")); objc_msgSend(self->window, sel_getUid("makeKeyAndOrderFront:"), self); return YES; }

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• Configure nHibernate for multiple-project solution

  - by NoOne

  Hello, Im doing a project with C# winforms. This project is composed by: Client project: Windows Forms where user will do CRUD operations on the models; Server project; Common Project: This project will hold the models (in the image only have the model Item); ListSingleton: Remote Object that will do the operations on the models; I already have all the communication working, but now I need to work on the persistence of the data in a mysql database. I was trying to use nHibernate but I’m having some troubles. My main problem is how to organize my hibernate configuration. In which project do I keep the mapping? Common project? In which project do I keep the hibernate configuration file (App.config)? ListSingleton project? In which project do I do this: Configuration cfg = new Configuration(); cfg.AddXmlFile("Item.hbm.xml"); ISessionFactory factory = cfg.BuildSessionFactory(); ISession session = factory.OpenSession(); ITransaction transaction = session.BeginTransaction(); Item newItem = new Item("BLAA"); // Tell NHibernate that this object should be saved session.Save(newItem); // commit all of the changes to the DB and close the ISession transaction.Commit(); session.Close(); In the ListSingleton project? Altho I had reference to the Common Project in the ListSingleton I keep getting error in the addXml line… My mapping is correct because I tried with a one-project solution and it worked :X

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• Static member function pointer to hold non static member function

  - by user1425406

  This has defeated me. I want to have a static class variable which is a pointer to a (non-static) member function. I've tried all sorts of ways, but with no luck (including using typedefs, which just seemed to give me a different set of errors). In the code below I have the static class function pointer funcptr, and I can call it successfully from outside the class, but not from within the member function CallFuncptr - which is what I want to do. Any suggestions? #include <stdio.h> class A { public: static int (A::*funcptr)(); int Four() { return 4;}; int CallFuncptr() { return (this->*funcptr)(); } // doesn't link - undefined reference to `A::funcptr' }; int (A::*funcptr)() = &A::Four; int main() { A fred; printf("four? %d\n", (fred.*funcptr)()); // This works printf("four? %d\n", fred.CallFuncptr()); // But this is the way I want to call it }

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• How to cancel a deeply nested process

  - by Mystere Man

  I have a class that is a "manager" sort of class. One of it's functions is to signal that the long running process of the class should shut down. It does this by setting a boolean called "IsStopping" in class. public class Foo { bool isStoping void DoWork() { while (!isStopping) { // do work... } } } Now, DoWork() was a gigantic function, and I decided to refactor it out and as part of the process broke some of it into other classes. The problem is, Some of these classes also have long running functions that need to check if isStopping is true. public class Foo { bool isStoping void DoWork() { while (!isStopping) { MoreWork mw = new MoreWork() mw.DoMoreWork() // possibly long running // do work... } } } What are my options here? I have considered passing isStopping by reference, which I don't really like because it requires there to be an outside object. I would prefer to make the additional classes as stand alone and dependancy free as possible. I have also considered making isStopping a property, and then then having it call an event that the inner classes could be subscribed to, but this seems overly complex. Another option was to create a "Process Cancelation Token" class, similar to what .net 4 Tasks use, then that token be passed to those classes. How have you handled this situation? EDIT: Also consider that MoreWork might have a EvenMoreWork object that it instantiates and calls a potentially long running method on... and so on. I guess what i'm looking for is a way to be able to signal an arbitrary number of objects down a call tree to tell them to stop what they're doing and clean up and return.

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• Speed comparison - Template specialization vs. Virtual Function vs. If-Statement

  - by Person

  Just to get it out of the way... Premature optimization is the root of all evil Make use of OOP etc. I understand. Just looking for some advice regarding the speed of certain operations that I can store in my grey matter for future reference. Say you have an Animation class. An animation can be looped (plays over and over) or not looped (plays once), it may have unique frame times or not, etc. Let's say there are 3 of these "either or" attributes. Note that any method of the Animation class will at most check for one of these (i.e. this isn't a case of a giant branch of if-elseif). Here are some options. 1) Give it boolean members for the attributes given above, and use an if statement to check against them when playing the animation to perform the appropriate action. Problem: Conditional checked every single time the animation is played. 2) Make a base animation class, and derive other animations classes such as LoopedAnimation and AnimationUniqueFrames, etc. Problem: Vtable check upon every call to play the animation given that you have something like a vector<Animation>. Also, making a separate class for all of the possible combinations seems code bloaty. 3) Use template specialization, and specialize those functions that depend on those attributes. Like template<bool looped, bool uniqueFrameTimes> class Animation. Problem: The problem with this is that you couldn't just have a vector<Animation> for something's animations. Could also be bloaty. I'm wondering what kind of speed each of these options offer? I'm particularly interested in the 1st and 2nd option because the 3rd doesn't allow one to iterate through a general container of Animations. In short, what is faster - a vtable fetch or a conditional?

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• Why strings behave like ValueType

  - by AJP

  I was perplexed after executing this piece of code, where strings seems to behave as if they are value types. I am wondering whether the assignment operator is operating on values like equality operator for strings. Here is the piece of code I did to test this behavior. using System; namespace RefTypeDelimma { class Program { static void Main(string[] args) { string a1, a2; a1 = "ABC"; a2 = a1; //This should assign a1 reference to a2 a2 = "XYZ"; //I expect this should change the a1 value to "XYZ" Console.WriteLine("a1:" + a1 + ", a2:" + a2);//Outputs a1:ABC, a2:XYZ //Expected: a1:XYZ, a2:XYZ (as string being a ref type) Proc(a2); //Altering values of ref types inside a procedure //should reflect in the variable thats being passed into Console.WriteLine("a1: " + a1 + ", a2: " + a2); //Outputs a1:ABC, a2:XYZ //Expected: a1:NEW_VAL, a2:NEW_VAL (as string being a ref type) } static void Proc(string Val) { Val = "NEW_VAL"; } } } In the above code if I use a custom classes instead of strings, I am getting the expected behavior. I doubt is this something to do with the string immutability? welcoming expert views on this.

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