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  • Entity framework with Linq to Entities performance

    - by mare
    If I have a static method like this public static string GetTicClassificationTitle(string classI, string classII, string classIII) { using (TicDatabaseEntities ticdb = new TicDatabaseEntities()) { var result = from classes in ticdb.Classifications where classes.ClassI == classI where classes.ClassII == classII where classes.ClassIII == classIII select classes.Description; return result.FirstOrDefault(); } } and use this method in various places in foreach loops or just plain calling it numerous times, does it create and open new connection every time? If so, how can I tackle this? Should I cache the results somewhere, like in this case, I would cache the entire Classifications table in Memory Cache? And then do queries vs this cached object? Or should I make TicDatabaseEntities variable static and initialize it at class level? Should my class be static if it contains only static methods? Because right now it is not.. Also I've noticed that if I return result.First() instead of FirstOrDefault() and the query does not find a match, it will issue an exception (with FirstOrDefault() there is no exception, it returns null). Thank you for clarification.

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  • jsp getServletContext() error

    - by Reigel
    html <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <title>Murach's Java Servlets and JSP</title> </head> <body> <%-- import packages and classes needed by the scripts --%> <%@ page import="business.*, data.*" %> <% //get parameters from the request String firstName = request.getParameter("firstName"); String lastName = request.getParameter("lastName"); String emailAddress = request.getParameter("emailAddress"); // get the real path for the EmailList.txt file ServletContext sc = this.getServletContext(); String path = sc.getRealPath("/WEB-INF/EmailList.txt"); // use regular Java objects User user = new User(firstName, lastName, emailAddress); UserIO.add(user, path); %> <h1>Thanks for joining our email list</h1> <p>Here is the information that you entered: </p> <table cellspacing="5" cellpadding="5" border="1"> <tr> <td align="right">First name:</td> <td><%= firstName %></td> </tr> <tr> <td align="right">Last name:</td> <td><%= lastName %></td> </tr> <tr> <td align="right">Email Address:</td> <td><%= emailAddress %></td> </tr> </table> <p>To enter another email address, click on the Back <br /> button in your browser or the Return button shown <br /> below.</p> <form action="index.jsp" method="post"> <input type="submit" value="Return" /> </form> </body> </html> and it's giving me this error page... Compilation of 'C:\bea\user_projects\domains\mydomain.\myserver.wlnotdelete\extract\myserver_sample01_WebContent\jsp_servlet__display_email_entry.java' failed: C:\bea\user_projects\domains\mydomain.\myserver.wlnotdelete\extract\myserver_sample01_WebContent\jsp_servlet__display_email_entry.java:140: cannot resolve symbol probably occurred due to an error in /display_email_entry.jsp line 19: ServletContext sc = this.getServletContext(); Full compiler error(s): C:\bea\user_projects\domains\mydomain.\myserver.wlnotdelete\extract\myserver_sample01_WebContent\jsp_servlet__display_email_entry.java:140: cannot resolve symbol symbol : method getServletContext () location: class jsp_servlet.__display_email_entry     ServletContext sc = this.getServletContext(); //[ /display_email_entry.jsp; Line:19]                                    ^ 1 error Thu Jun 03 15:56:09 CST 2010 any hint? I'm really new to JSP, and this is my first learning practice... can't find it by google.com.... thanks!

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  • .NET Application with SQL Server CE Database

    - by blu
    I just started using SQL Server CE 3.5 in my WinForms Application (C# in VS 2008 SP1). I've noticed a couple of interesting things I'd like some input on: 1. Copying of sdf file to bin My sdf file is located inside of an Infrastructure project that houses my repository implementations. When the application is first debugged the sdf was copied to debug\bin. This is where all future reads/writes operate. At some point when this is deployed the file will go into a data folder using Click Once, but during development where should I be putting this sdf? Is having it in the bin typical, or are there any other recommendations? 2. Updating sdf It appears that writing to the sdf file does not immediately update the database. I am using Linq-to-SQL and am calling SubmitChanges, but on read the values are not returned. However if I close the application and re-open it the added value is there. Is there an additional flush step I need to take? What is causing this, file locking, buffering, something else? Update 3. Unit Tests I have an MS test project, and the sdf file is not being copied to the correct output directory. I have the settings: Build Action: Content Copy to Output Directory: Copy Always The message is: System.Data.SqlServerCe.SqlCeException: The database file cannot be found. Check the path to the database. I appreciate any guidance on these questions, thanks. If there is a tutorial other than what is on MSDN that you know about that would be great too. Working with CE is proving to be a difficult task and I welcome any help I can find.

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  • Why would using a Temp table be faster than a nested query?

    - by Mongus Pong
    We are trying to optimise some of our queries. One query is doing the following: SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, INTO [#Gadget] FROM task t SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) as Client FROM [#Gadget] order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC DROP TABLE [#Gadget] (I have removed the complex subquery, cos I dont think its relevant other than to explain why this query has been done as a two stage process.) Now I would have thought it would be far more efficient to merge this down into a single query using subqueries as : SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) FROM ( SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, FROM task t ) as sub order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC This would give the optimiser better information to work out what was going on and avoid any temporary tables. It should be faster. But it turns out it is a lot slower. 8 seconds vs under 5 seconds. I cant work out why this would be the case as all my knowledge of databases imply that subqueries would always be faster than using temporary tables. Can anyone explain what could be going on!?!?

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  • SQL Compact performance on device

    - by Ben M
    My SQL Compact database is very simple, with just three tables and a single index on one of the tables (the table with 200k rows; the other two have less than a hundred each). The first time the .sdf file is used by my Compact Framework application on the target Windows Mobile device, the system hangs for well over a minute while "something" is done to the database: when deployed, the DB is 17 megabytes, and after this first usage, it balloons to 24 megs. All subsequent usage is pretty fast, so I'm assuming there's some sort of initialization / index building going on during this first usage. I'd rather not subject the user to this delay, so I'm wondering what this initialization process is and whether it can be performed before deployment. For now, I've copied the "initialized" database back to my desktop for use in the setup project, but I'd really like to have a better answer / solution. I've tried "full compact / repair" in the VS Database Properties dialog, but this made no difference. Any ideas? For the record, I should add that the database is only read from by the device application -- no modifications are made by that code.

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  • "Ghost" values in PHP/Smarty.

    - by Kyle Sevenoaks
    I've been working on a site for a while changing the layout and skin of a webshop checkout process. I've noticed that if you go all the way through the process until the last page, then click the link to go back to the view products page, the delivery method price displays underneath the navigation buttons, until you refresh and it goes away again. I've downloaded both sourced from the browser (Chrome, but this bug applies to all browsers) and used a file difference tool to display the differences, the result being only: < error.html vs > normal.html 34c34 < <link href="gzip.php?file=167842c1496093fbcd391b41cf7b03da.css&time=1272272181" rel="Stylesheet" type="text/css"/> --- > <link href="gzip.php?file=167842c1496093fbcd391b41cf7b03da.css&time=1272272348" rel="Stylesheet" type="text/css"/> Which is just the way it zips up the CSS stylesheets. (afaik) Has anyone ever encountered such a problem, or anything similar? Normal: Error: I can't even hazard a guess as to what is causing this, at all. I've searched over Google for anything and come up with nothing. What could be causing this? The site in question is Euroworker.no. HTML @ Pastebin. Smarty snippet: {if !$CANONICAL} {canonical}{self}{/canonical} {/if} <link rel="canonical" href="{$CANONICAL}" /> <!-- Css includes --> {includeCss file="frontend/Frontend.css"} {includeCss file="backend/stat.css"} {if {isRTL}} {includeCss file="frontend/FrontendRTL.css"} {/if} {compiledCss glue=true nameMethod=hash} <!--[if lt IE 8]> <link href="stylesheet/frontend/FrontendIE.css" rel="Stylesheet" type="text/css"/> {if $ieCss} <link href="{$ieCss}" rel="Stylesheet" type="text/css"/> {/if} <![endif]--> Thanks.

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  • Deterministic floating point and .NET

    - by code2code
    How can I guarantee that floating point calculations in a .NET application (say in C#) always produce the same bit-exact result? Especially when using different versions of .NET and running on different platforms (x86 vs x86_64). Inaccuracies of floating point operations do not matter. In Java I'd use strictfp. In C/C++ and other low level languages this problem is essentially solved by accessing the FPU / SSE control registers but that's probably not possible in .NET. Even with control of the FPU control register the JIT of .NET will generate different code on different platforms. Something like HotSpot would be even worse in this case... Why do I need it? I'm thinking about writing a real-time strategy (RTS) game which heavily depends on fast floating point math together with a lock stepped simulation. Essentially I will only transmit user input across the network. This also applies to other games which implement replays by storing the user input. Not an option are: decimals (too slow) fixed point values (too slow and cumbersome when using sqrt, sin, cos, tan, atan...) update state across the network like an FPS: Sending position information for hundreds or a few thousand units is not an option Any ideas?

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  • How to access web.config connection string in C#?

    - by salvationishere
    I have a 32-bit XP running VS 2008 and I am trying to decrypt my connection string from my web.config file in my C# ASPX file. Even though there are no errors returned, my current connection string doesn't display contents of my selected AdventureWorks stored procedure. I entered it: C:\Program Files\Microsoft Visual Studio 9.0\VC>Aspnet_regiis.exe -pe "connectionStrings" -app "/AddFileToSQL2" Then it said "Succeeded". And my web.config section looks like: <connectionStrings> <add name="Master" connectionString="server=MSSQLSERVER;database=Master; Integrated Security=SSPI" providerName="System.Data.SqlClient" /> <add name="AdventureWorksConnectionString" connectionString="Data Source=SIDEKICK;Initial Catalog=AdventureWorks;Integrated Security=True" providerName="System.Data.SqlClient" /> <add name="AdventureWorksConnectionString2" connectionString="Data Source=SIDEKICK;Initial Catalog=AdventureWorks;Persist Security Info=true; " providerName="System.Data.SqlClient" /> </connectionStrings> And my C# code behind looks like: string connString = ConfigurationManager.ConnectionStrings["AdventureWorksConnectionString2"].ConnectionString; Is there something wrong with the connection string in the web.config or C# code behind file?

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  • lapply slower than for-loop when used for a BiomaRt query. Is that expected?

    - by ptocquin
    I would like to query a database using BiomaRt package. I have loci and want to retrieve some related information, let say description. I first try to use lapply but was surprise by the time needed for the task to be performed. I thus tried a more basic for-loop and get a faster result. Is that expected or is something wrong with my code or with my understanding of apply ? I read other posts dealing with *apply vs for-loop performance (Here, for example) and I was aware that improved performance should not be expected but I don't understand why performance here is actually lower. Here is a reproducible example. 1) Loading the library and selecting the database : library("biomaRt") athaliana <- useMart("plants_mart_14") athaliana <- useDataset("athaliana_eg_gene",mart=athaliana) 2) Querying the database : loci <- c("at1g01300", "at1g01800", "at1g01900", "at1g02335", "at1g02790", "at1g03220", "at1g03230", "at1g04040", "at1g04110", "at1g05240" ) I create a function for the use in lapply : foo <- function(loci) { getBM("description","tair_locus",loci,athaliana) } When I use this function on the first element : > system.time(foo(cwp_loci[1])) utilisateur système écoulé 0.020 0.004 1.599 When I use lapply to retrieve the data for all values : > system.time(lapply(loci, foo)) utilisateur système écoulé 0.220 0.000 16.376 I then created a new function, adding a for-loop : foo2 <- function(loci) { for (i in loci) { getBM("description","tair_locus",loci[i],athaliana) } } Here is the result : > system.time(foo2(loci)) utilisateur système écoulé 0.204 0.004 10.919 Of course, this will be applied to a big list of loci, so the best performing option is needed. I thank you for assistance. EDIT Following recommendation of @MartinMorgan Simply passing the vector loci to getBM greatly improves the query efficiency. Simpler is better. > system.time(lapply(loci, foo)) utilisateur système écoulé 0.236 0.024 110.512 > system.time(foo2(loci)) utilisateur système écoulé 0.208 0.040 116.099 > system.time(foo(loci)) utilisateur système écoulé 0.028 0.000 6.193

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  • Why doesn't line-height work on FF/3.5.8(Mac)?

    - by Znarkus
    I can't get line-height on a text input to work on Firefox 3.5.8/(Mac). Works flawlessly on: IE6 IE7 IE8 FF3.6/PC FF3.6/Mac Safari Test code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <title>asd</title> <link rel="stylesheet" type="text/css" href="http://yui.yahooapis.com/2.8.0r4/build/reset/reset-min.css" /> </head> <body> <input type="text" value="Hello" style="line-height:50px;height:50px;font-size:16px;" /> <input type="text" value="Hello" style="padding:17px 0;font-size:16px;" /> </body> </html> Is there an alternate solution or any idea how to fix this? Edit: Updated the test code, to compare line-height vs. padding technique. Padding works on all above browsers except IE8. Whaat? I can't test on FF/3.5.8 anymore, could someone please report the result from this browser on any plattform? I'm now thinking this is a Firefox 3.5.8 issue, plattform independent.

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  • Using Dynamic Proxies to centralize JPA code

    - by Daziplqa
    Hi All, Actually, This is not a question but really I need your opinions in a matter... I put his post here because I know you always active, so please don't consider this a bad question and share me your opinions. I've used Java dynamic proxies to Centralize The code of JPA that I used in a standalone mode, and Here's the dynamic proxy code: package com.forat.service; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.logging.Level; import java.util.logging.Logger; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; import com.forat.service.exceptions.DAOException; /** * Example of usage : * <pre> * OnlineFromService onfromService = * (OnlineFromService) DAOProxy.newInstance(new OnlineFormServiceImpl()); * try { * Student s = new Student(); * s.setName("Mohammed"); * s.setNationalNumber("123456"); * onfromService.addStudent(s); * }catch (Exception ex) { * System.out.println(ex.getMessage()); * } *</pre> * @author mohammed hewedy * */ public class DAOProxy implements InvocationHandler{ private Object object; private Logger logger = Logger.getLogger(this.getClass().getSimpleName()); private DAOProxy(Object object) { this.object = object; } public static Object newInstance(Object object) { return Proxy.newProxyInstance(object.getClass().getClassLoader(), object.getClass().getInterfaces(), new DAOProxy(object)); } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { EntityManagerFactory emf = null; EntityManager em = null; EntityTransaction et = null; Object result = null; try { emf = Persistence.createEntityManagerFactory(Constants.UNIT_NAME); em = emf.createEntityManager();; Method entityManagerSetter = object.getClass(). getDeclaredMethod(Constants.ENTITY_MANAGER_SETTER_METHOD, EntityManager.class); entityManagerSetter.invoke(object, em); et = em.getTransaction(); et.begin(); result = method.invoke(object, args); et.commit(); return result; }catch (Exception ex) { et.rollback(); Throwable cause = ex.getCause(); logger.log(Level.SEVERE, cause.getMessage()); if (cause instanceof DAOException) throw new DAOException(cause.getMessage(), cause); else throw new RuntimeException(cause.getMessage(), cause); }finally { em.close(); emf.close(); } } } And here's the link that contains more info (http://m-hewedy.blogspot.com/2010/04/using-dynamic-proxies-to-centralize-jpa.html) (plz don't consider this as adds, as I can copy and past the entire topic here if you want that) So, Please give me your opinions. Thanks.

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  • Noise with multi-threaded raytracer

    - by herber88
    This is my first multi-threaded implementation, so it's probably a beginners mistake. The threads handle the rendering of every second row of pixels (so all rendering is handled within each thread). The problem persists if the threads render the upper and lower parts of the screen respectively. Both threads read from the same variables, can this cause any problems? From what I've understood only writing can cause concurrency problems... Can calling the same functions cause any concurrency problems? And again, from what I've understood this shouldn't be a problem... The only time both threads write to the same variable is when saving the calculated pixel color. This is stored in an array, but they never write to the same indices in that array. Can this cause a problem? Multi-threaded rendered image (Spam prevention stops me from posting images directly..) Ps. I use the exactly same implementation in both cases, the ONLY difference is a single vs. two threads created for the rendering.

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  • INotifyPropertyChanged Setter Style

    - by Ivovic
    In order to reflect changes in your data to the UI you have to implement INotifyPropertyChanged, okay. If I look at examples, articles, tutorials etc most of the time the setters look like something in that manner: public string MyProperty { //get [...] set { if (_correspondingField == value) { return; } _correspondingField = value; OnPropertyChanged("MyProperty"); } } No problem so far, only raise the event if you have to, cool. But you could rewrite this code to this: public string MyProperty { //get [...] set { if (_correspondingField != value) { _correspondingField = value; OnPropertyChanged("MyProperty"); } } } It should do the same (?), you only have one place of return, it is less code, it is less boring code and it is more to the point ("only act if necessary" vs "if not necessary do nothing, the other way round act"). So if the second version has its pros compared to the first one, why I see this style rarely? I don't consider myself being smarter than those people that write frameworks, published articles etc, therefore the second version has to have drawbacks. Or is it wrong? Or do I think too much? Thanks in advance

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  • In the meantime, to be or not to be ... productive!

    - by Jan Kuboschek
    I just moved back to Europe from the US after living there for 7 years. Apart from major adjustment issues, I'm currently looking for a job over here. I'm mainly interested in (IT) Consulting and, since these jobs typically require programming knowledge, such as Java, I'm trying to think of something productive to write (perhaps to demo my skills) while I'm waiting for my interviews (starting in two weeks. Folks here are a bit slower than in the US apparently...). I graduated from college about a year and a half ago and have a 4 year degree in international management/economics and about 3/4 of a 2 year degree in computer science finished. I've written my fair share of web software over the years, but nothing concrete that I could show, especially not in Java. Now, I've never had the problem of not having any idea what to write. Basic games I could write, but I'm not sure how well that'll come over when I walk into my interview and say "hey, I was bored. Take a look at my multiplayer space invaders game! Wanna try beating me??". Any thoughts? I browsed SourceForge the other day to find a nice little project to contribute to, but decided that I don't want to commit to someone else's project at this time. Any ideas, perhaps from someone who has been, or currently is, in a similar position would be much appreciated. Oh, and lastly: Instead of developing a program or two to demonstrate my skills, I could spend my time brushing up on UML and Perl. Any suggestions regarding that? Writing a demo vs. learning something new?

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  • Managed WMI Event class is not an event class???

    - by galets
    I am using directions from here: http://msdn.microsoft.com/en-us/library/ms257351(VS.80).aspx to create a managed event class. Here's the code that I wrote: [ManagementEntity] [InstrumentationClass(InstrumentationType.Event)] public class MyEvent { [ManagementKey] public string ID { get; set; } [ManagementEnumerator] static public IEnumerable<MyEvent> EnumerateInstances() { var e = new MyEvent() { ID = "9A3C1B7E-8F3E-4C54-8030-B0169DE922C6" }; return new MyEvent[] { e }; } } class Program { static void Main(string[] args) { var thisAssembly = typeof(Program).Assembly; var wmi_installer = new AssemblyInstaller(thisAssembly, null); wmi_installer.Install(null); wmi_installer.Commit(null); InstrumentationManager.RegisterAssembly(thisAssembly); Console.Write("Press Enter..."); Console.ReadLine(); var e = new MyEvent() { ID = "A6144A9E-0667-415B-9903-220652AB7334" }; Instrumentation.Fire(e); Console.Write("Press Enter..."); Console.ReadLine(); wmi_installer.Uninstall(null); } } I can run a program, and it properly installs. Using wbemtest.exe I can browse to the event, and "show mof": [dynamic: ToInstance, provider("WmiTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null")] class MyEvent { [read, key] string ID; }; Notice, the class does not inherit from __ExtrinsicEvent, which is weird... I can also run select * from MyEvent, and get the result. Instrumentation.Fire() also returns no error. However, when I'm trying to subscribe to event using "Notification Query" option, I'm getting 0x80041059 Number: 0x80041059 Facility: WMI Description: Class is not an event class. What am I doing wrong, and is there a correct way to create managed WMI event?

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  • Conditionally colour data points outside of confidence bands in R

    - by D W
    I need to colour datapoints that are outside of the the confidence bands on the plot below differently from those within the bands. Should I add a separate column to my dataset to record whether the data points are within the confidence bands? Can you provide an example please? Example dataset: ## Dataset from http://www.apsnet.org/education/advancedplantpath/topics/RModules/doc1/04_Linear_regression.html ## Disease severity as a function of temperature # Response variable, disease severity diseasesev<-c(1.9,3.1,3.3,4.8,5.3,6.1,6.4,7.6,9.8,12.4) # Predictor variable, (Centigrade) temperature<-c(2,1,5,5,20,20,23,10,30,25) ## For convenience, the data may be formatted into a dataframe severity <- as.data.frame(cbind(diseasesev,temperature)) ## Fit a linear model for the data and summarize the output from function lm() severity.lm <- lm(diseasesev~temperature,data=severity) jpeg('~/Desktop/test1.jpg') # Take a look at the data plot( diseasesev~temperature, data=severity, xlab="Temperature", ylab="% Disease Severity", pch=16, pty="s", xlim=c(0,30), ylim=c(0,30) ) title(main="Graph of % Disease Severity vs Temperature") par(new=TRUE) # don't start a new plot ## Get datapoints predicted by best fit line and confidence bands ## at every 0.01 interval xRange=data.frame(temperature=seq(min(temperature),max(temperature),0.01)) pred4plot <- predict( lm(diseasesev~temperature), xRange, level=0.95, interval="confidence" ) ## Plot lines derrived from best fit line and confidence band datapoints matplot( xRange, pred4plot, lty=c(1,2,2), #vector of line types and widths type="l", #type of plot for each column of y xlim=c(0,30), ylim=c(0,30), xlab="", ylab="" )

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  • Should .net comments start with a capital letter and end with a period?

    - by Hamish Grubijan
    Depending on the feedback I get, I might raise this "standard" with my colleagues. This might become a custom StyleCop rule. is there one written already? So, Stylecop already dictates this for summary, param, and return documentation tags. Do you think it makes sense to demand the same from comments? On related note: if a comment is already long, then should it be written as a proper sentence? For example (perhaps I tried too hard to illustrate a bad comment): //if exception quit vs. // If an exception occurred, then quit. If figured - most of the time, if one bothers to write a comment, then it might as well be informative. Consider these two samples: //if exception quit if (exc != null) { Application.Exit(-1); } and // If an exception occurred, then quit. if (exc != null) { Application.Exit(-1); } Arguably, one does not need a comment at all, but since one is provided, I would think that the second one is better. Please back up your opinion. Do you have a good reference for the art of commenting, particularly if it relates to .Net? Thanks.

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  • When to use reinterpret_cast?

    - by HeretoLearn
    I am little confused with the applicability of reinterpret_cast vs static_cast. From what I have read the general rules are to use static cast when the types can be interpreted at compile time hence the word static. This is the cast the C++ compiler uses internally for implicit casts also. reinterpret_cast are applicable in two scenarios, convert integer types to pointer types and vice versa or to convert one pointer type to another. The general idea I get is this is unportable and should be avoided. Where I am a little confused is one usage which I need, I am calling C++ from C and the C code needs to hold on to the C++ object so basically it holds a void*. What cast should be used to convert between the void * and the Class type? I have seen usage of both static_cast and reinterpret_cast? Though from what I have been reading it appears static is better as the cast can happen at compile time? Though it says to use reinterpret_cast to convert from one pointer type to another?

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  • .Net Hash Codes no longer persistent?

    - by RobV
    I have an API where various types have custom hash codes. These hash codes are based on getting the hash of a string representation of the object in question. Various salting techniques are used so that as far as possible Hash Codes do not collide and that Objects of different types with equivalent string representations have different Hash Codes. Obviously since the Hash Codes are based on strings there are some collisions (infinite strings vs the limited range of 32 bit integers). I use hashes based on string representations since I need the hashes to persist over sessions and particularly for use in database storage of objects. Suddenly today my code has started generating different hash codes for Objects which is breaking all kinds of things. It was working earlier today and I haven't touched any of the code involved in Hash Code generation. I'm aware that the .Net documentation allows for implementation of hash codes between .Net framework versions to change (and between 32 and 64 bit versions) but I haven't changed the framework version and there has been no framework updates recently as far as I can remember Any ideas because this seems really weird? Edit Hash Codes are generated like follows: //Compute Hash Code this._hashcode = (this._nodetype + this.ToString() + PlainLiteralHashCodeSalt).GetHashCode();

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  • How to query an .NET assembly's required framework (not CLR) version?

    - by Bonfire Burns
    Hi, we are using some kind of plug-in architecture in one of our products (based on .NET). We have to consider our customers or even 3rd party devs writing plug-ins for the product. The plug-ins will be .NET assemblies that are loaded by our product at run-time. We have no control about the quality or capabilities of the external plug-ins (apart from checking whether they implement the correct interfaces). So we need to implement some kind of safety check while loading the plug-ins to make sure that our product (and the hosting environment) can actually host the plug-in or deliver a meaningful error message ("The plug-in your are loading needs .NET version 42.42 - the hosting system is only on version 33.33."). Ideally the plug-ins would do this check internally, but our experience regarding their competence is so-so and in any case our product will get the blame, so we want to make sure that this "just works". Requiring the plug-in developers to provide the info in the metadata or to explicitly provide the information in the interface is considered "too complicated". I know about the Assembly.ImageRuntimeVersion property. But to my knowledge this tells me only the needed CLR version, not the framework version. And I don't want to check all of the assembly's dependencies and match them against a table of "framework version vs. available assemblies". Do you have any ideas how to solve this in a simple and maintainable fashion? Thanks & regards, Bon

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  • Compiling my Boost/NTL program with c++ on Linux.

    - by Martin Lauridsen
    Hi SO, I wrote a client program and a server program, that uses the NTL library and Boost::Asio, to do client/server communication for an integer factorization application, in C++. Both sides consist of several headers and cpp files. Both project compile fine individually on Windows in Visual Studio. All I did, was add the include path of NTL and Boost to both projects: Additional include paths: "D:\Downloads\WinNTL-5_5_2\include";D:\boost_1_42_0 Furthermore, for both projects, I added the two library paths to both projects in VS: Additional library directories: D:\boost_1_42_0\stage\lib;"D:\Documents\Visual Studio 2008\Projects\ntl\Debug" And added under Additional dependencies: ntl.lib As said, it compiles fine on Windows. But when I put the code on a Linux machine provided by university, I try to compile with the following statement c++ -I/appl/htopopt/Linux_x86_64/NTL-5.4.2/include -I/appl/htopopt/Linux_x86_64/boost_1_43_0/include client_protocol.cpp mpqs_client.cpp mpqs_sieve.cpp mpqs_helper.cpp -o mpqs_helper -L/appl/htopopt/Linux_x86_64/NTL-5.4.2/lib -lntl -L/appl/htopopt/Linux_x86_64/gmp-4.2.1/lib -lgmp -lm -L/appl/htopopt/Linux_x86_64/boost_1_43_0/lib -lboost_system -static Upon doing this, I get a huuuge error, which I posted here. Any idea how to fix this, please??

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  • Is there a Designer for MFC in Visual Studio like for windows forms in .NET?

    - by claws
    I'm a .NET programmer. I've never developed anything in MFC. Currently I had to write a C++ application (console) for some image processing task. I finished writing it. But the point is I need to design GUI also for this. Well, there won't be anything complex. Just a window with few Buttons, RadioButtons, Check Boxes, PicturesBox & few sliders. thats it. I'm using VS 2008 and was expecting a .NET style form designer. Just to test, I created a MFC project (with all default configuration) and these files were created by default: ChildFrm.cpp MainFrm.cpp mfc.cpp mfcDoc.cpp mfcView.cpp stdafx.cpp Now, I'm unable to find a Designer. There is no View Designer. I've opened all the above *.cpp and in the code editor right clicked to see "Designer View". ToolBox is just empty because I'm in code editor mode. When I built the project. This is the window I get. How to open a designer?

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  • how to make it easy for users to register at my site?

    - by rob
    I want to make it dirt simple for users coming to my site to register so they can post comments, vote on things, etc. I would like for them to be able to use their facebook id, twitter id, yahoo mail id, gmail id, AIM id, msn id, or whatever else people are likely to have (not necessarily all of those, but the more the better). I want my mom to be able to do it in 30 seconds or less. (that is, no "enter your open id url here" type thing that would confuse her). I prefer they not have to pick a unique name, as that gets annoying as the site gets more users and it gets hard to find one that is unique. What is the best option here? I'm not quite sure about OpenId vs. OAuth, and whether there are other options. And I'd like it to be as simple for me, the developer, as possible (of course!). I don't want to spend forever learning some protocol, nor have to structure my whole app around this. It would be great if there was a site with sample code that is pretty easy to drop in. BTW, StackOverflow is a good example of a site that was easy for me to register for.

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  • Java saying XML Document Not Well Formed

    - by Pyroclastic
    Hey all. Java's XML parser seems to be thinking that my XML document is not well formed following the root element, but I've validated it with several tools and they all disagree. It's probably an error in my code rather than in the document itself, I'd really appreciate any help you all could offer me. Here is my Java method: private void loadFromXMLFile(File f) throws ParserConfigurationException, IOException, SAXException { File file = f; DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db; Document doc = null; db = dbf.newDocumentBuilder(); doc = db.parse(file); doc.getDocumentElement().normalize(); String desc = ""; String due = ""; String comment = ""; NodeList tasksList = doc.getElementsByTagName("task"); for (int i = 0; i < tasksList.getLength(); i++) { NodeList attributes = tasksList.item(i).getChildNodes(); for (int j = 0; i < attributes.getLength(); j++) { Node attribute = attributes.item(i); if (attribute.getNodeName() == "description") { desc = attribute.getTextContent(); } if (attribute.getNodeName() == "due") { due = attribute.getTextContent(); } if (attribute.getNodeName() == "comment") { comment = attribute.getTextContent(); } tasks.add(new Task(desc, due, comment)); } desc = ""; due = ""; comment = ""; } } And here is the XML file I'm trying to load: <?xml version="1.0"?> <tasklist> <task> <description>Task 1</description> <due>Due date 1</due> <comment>Comment 1</comment> <completed>false</completed> </task> <task> <description>Task 2</description> <due>Due date 2</due> <comment>Comment 2</comment> <completed>false</completed> </task> <task> <description>Task 3</description> <due>Due date 3</due> <comment>Comment 3</comment> <completed>true</completed> </task> </tasklist> And here is the error message java is throwing for me: run: [Fatal Error] tasks.xml:28:3: The markup in the document following the root element must be well-formed. May 17, 2010 6:07:02 PM todolist.TodoListGUI SEVERE: null org.xml.sax.SAXParseException: The markup in the document following the root element must be well-formed. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:239) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283) at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:208) at todolist.TodoListGUI.loadFromXMLFile(TodoListGUI.java:199) at todolist.TodoListGUI.(TodoListGUI.java:42) at todolist.Main.main(Main.java:25) BUILD SUCCESSFUL (total time: 19 seconds) For reference TodoListGUI.java:199 is doc = db.parse(file); If context is helpful to anyone here, I'm trying to write a simple GUI application to manage a todo list that can read and write to and from XML files defining the tasks. Any advice is appreciated!

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  • Can g++ fill uninitialized POD variables with known values?

    - by Bob Lied
    I know that Visual Studio under debugging options will fill memory with a known value. Does g++ (any version, but gcc 4.1.2 is most interesting) have any options that would fill an uninitialized local POD structure with recognizable values? struct something{ int a; int b; }; void foo() { something uninitialized; bar(uninitialized.b); } I expect uninitialized.b to be unpredictable randomness; clearly a bug and easily found if optimization and warnings are turned on. But compiled with -g only, no warning. A colleague had a case where code similar to this worked because it coincidentally had a valid value; when the compiler upgraded, it started failing. He thought it was because the new compiler was inserting known values into the structure (much the way that VS fills 0xCC). In my own experience, it was just different random values that didn't happen to be valid. But now I'm curious -- is there any setting of g++ that would make it fill memory that the standard would otherwise say should be uninitialized?

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