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  • What wording in the C++ standard allows static_cast<non-void-type*>(malloc(N)); to work?

    - by ben
    As far as I understand the wording in 5.2.9 Static cast, the only time the result of a void*-to-object-pointer conversion is allowed is when the void* was a result of the inverse conversion in the first place. Throughout the standard there is a bunch of references to the representation of a pointer, and the representation of a void pointer being the same as that of a char pointer, and so on, but it never seems to explicitly say that casting an arbitrary void pointer yields a pointer to the same location in memory, with a different type, much like type-punning is undefined where not punning back to an object's actual type. So while malloc clearly returns the address of suitable memory and so on, there does not seem to be any way to actually make use of it, portably, as far as I have seen.

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  • Benefit of outputting JSON as opposed to plain HTML

    - by Franco
    Hey guys, Just wondering which is best here. I want to output data from a table in my DB then put a lot of this data into a html table on the fly on my page. Im working with Java on the server side. Basically I pull the results form the DB and have the raw data..just what next? There is a chance I may want to take data from multiple tables in order to combine it into one table for my site. I retrieve the results of the query from the DB, now do i create a text from it in the form of json which i can parse as json using jquery upon the return of the object to my browser?(kind of a sub question of this question: Is just using a stringbuilder the correct way to make a json object to output?) Or.. Should i build the HTML as a string and output that to the browser instead? Which is better and why? Thanks in advance!

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  • Autofac: Reference from a SingleInstance'd type to a HttpRequestScoped

    - by Michael Wagner
    I've got an application where a shared object needs a reference to a per-request object. Shared: Engine | Per Req: IExtensions() | Request If i try to inject the IExtensions directly into the constructor of Engine, even as Lazy(Of IExtension), I get a "No scope matching [Request] is visible from the scope in which the instance was requested." exception when it tries to instantiate each IExtension. How can I create a HttpRequestScoped instance and then inject it into a shared instance? Would it be considered good practice to set it in the Request's factory (and therefore inject Engine into RequestFactory)?

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  • Memory leak when declaring NSString from ABRecordCopyValue

    - by Ben Thompson
    I am using the following line of code... NSString *clientFirstName = (NSString *)ABRecordCopyValue(person, kABPersonFirstNameProperty); The 'analyse' feature on Xcode is saying that this giving rise to a potential memory leak. I am not releasing clientFirstName at all as I have neither alloc or retain'd it. However, I am conscious that ABRecordCopyValue may not be returning an object as say a command like [NSMutableArray arrayWithArray:someArray] would which might mean I am indeed creating a new object that I control and must release. Keen to hear thoughts...

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  • Why use event listeners over function calls?

    - by Organiccat
    I've been studying event listeners lately and I think I've finally gotten them down. Basically, they are functions that are called on another object's method. My question is, why create an event listener when calling the function will work just fine? Example, I want to call player.display_health(), and when this is fired, the method player.get_health() should be fired and stored so that display_health() has access to it. Why should I use an event listener over simply calling the function? Even if display_health() were in another object, this still doesn't appear to be a problem to me. If you have another example that fits the usage better, please let me know. Perhaps particular languages don't benefit from it as much? (Javascript, PHP, ASP?)

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  • Python/C "defs" file - what is it?

    - by detly
    In the nautilus-python bindings, there is a file "nautilus.defs". It contains stanzas like (define-interface MenuProvider (in-module "Nautilus") (c-name "NautilusMenuProvider") (gtype-id "NAUTILUS_TYPE_MENU_PROVIDER") ) or (define-method get_mime_type (of-object "NautilusFileInfo") (c-name "nautilus_file_info_get_mime_type") (return-type "char*") ) Now I can see what most of these do (eg. that last one means that I can call the method "get_mime_type" on a "FileInfo" object). But I'd like to know: what is this file, exactly (ie. what do I search the web for to find out more info)? Is it a common thing to find in Python/C bindings? What is the format, and where is it documented? What program actually processes it? (So far, I've managed to glean that it gets transformed into a C source file, and it looks a bit like lisp to me.)

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  • Navigating from VB.NET code to C# code problem

    - by user181218
    Hi, There seemes to be a consistent problem with the following situation: Say you have a VS2008 solution, consisting of a (say console) application written in vb.net, and a class library written in c#. The application references the class library project. This, of course, complies and works well. However, when you right-click (in the vb.net application code) a function prototype/object type defined in the class library, and select "Go to definition", the object browser opens providing you with the the list of methods available for the class the class library consists of. BAD. However, if you try to do the same when both the application and cl are in c#, this works just fine and you navigate driectly to the relevant function/class.GOOD. Known issue? Solvable?

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  • Is it possible to get last modified date from an assets file?

    - by Nathan Fig
    Hi, all Bizarre question: is it possible to get the last modified date of a file in the assets folder, or would that be pointless and impossible? I ask because I'm copying a read-only database out of there into the data folder on application start up, but would rather only perform the copy if the existing file is older than the one stored in the assets folder (or if the file doesn't exist). If that's not possible, anyone know of a better convention? I can post that in a separate question if needed. TIA!

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  • error with string list in C#

    - by Chelsea_cole
    Same namespace: 2 forms. public class Account //frm1 { public string Username; public string Password; } public class ListAcc { public static List<Account> UserList; } private void button1_Click(object sender, EventArgs e) { List<Account> UserList = new List<Account>(); Account acc = new Account(); acc.Username = textBox1.Text; acc.Password = textBox2.Text; UserList.Add(acc); } private void button2_Click(object sender, EventArgs e) //frm2 { string p = frmDangky.ListAcc.UserList[0].Username; // null ->error string p = frmDangky.ListAcc.UserList[0].Password; // null ->error } Someone help me? :( why my string is NULL???????? The textBox is not empty... Thanks!

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  • How to observe NSScroller changes?

    - by Paperflyer
    I have an NSScrollView subclass and I would like to update another NSView based on the current scroll position. I tried KVC-observing the value of [self horizontalScroller] but that never gets called. // In awakeFromNib [[self horizontalScroller] addObserver:self forKeyPath:@"value" options:NSKeyValueObservingOptionNew context:NULL]; // Later in the file - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { if (object == [self horizontalScroller] && [keyPath isEqualToString:@"value"]) { // This never gets called } } Do you see an error in my reasoning or know a better method of how to observe the scrolling of an NSScrollview?

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  • InvalidOperationException sequence contains more than one element even when only one element

    - by user310256
    I have three tables, tblCompany table, tblParts table and a link table between them tblLinkCompanyParts. Since tblLinkCompanyParts is a link table so the columns that it has are LinkCompanyPartID(primary key), CompanyID from tblCompany table and PartID from tblParts as foreign keys. I have tied them up in the dbml file. In code if I write LinkCompanyParts.Parts (where LinkCompanyParts is an object of the tblLinkCompanyParts type) to get to the corresponding Part object I get the "InvalidOperationException: Sequence constains more than one element". I have looked at the data in the database and there is only one Parts record associated with the LinkCompanyPartID. The stack trace reads like at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source) at System.Data.Linq.EntityRef`1.get_Entity() at ... I read about SingleOrDefault vs FirstOrDefault but since the link table should have a one-one mapping therefore I think SingleOrDefault should work and besides "SingleOrDefault" statement is being generated behind the scenes in the designer.cs file at the following line return this._Part.Entity; Any ideas?

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  • How to avoid Eclipse warnings when using legacy code without generics?

    - by Paul Crowley
    I'm using JSON.simple to generate JSON output from Java. But every time I call jsonobj.put("this", "that"), I see a warning in Eclipse: Type safety: The method put(Object, Object) belongs to the raw type HashMap. References to generic type HashMap should be parameterized The clean fix would be if JSONObject were genericized, but since it isn't, I can't add any generic type parameters to fix this. I'd like to switch off as few warnings as possible, so adding "@SuppressWarnings("unchecked")" to lots of methods is unappealing, but do I have any other option besides putting up with the warnings?

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  • hibernate search

    - by Odelya
    Hi! I am using Hibernate. I am looking for a free text engine. Before I investigate into it I need your experience. I have in my applications user, role and object table. Where a user is connected to one or more roles, and a role is connected to one or more objects. In my free text search, the user can reach only data that he is allowed to watch by object table. Can Hibernate search help me with it?

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  • grails and flash movie

    - by ziftech
    Is it possibe to insert into GSP simple flash movie? I tried this way: <object type="application/x-shockwave-flash" data="${resource(dir:'flash',file:'movie.swf')}" width="400" height="400"> <param name="movie" value="${resource(dir:'flash',file:'movie.swf')}" /> <param name="bgcolor" value="#ffffff" /> <param name="AllowScriptAccess" value="always" /> <param name="flashvars" value="feed=${resource(dir:'flash',file:'movie.xml')}" /> <p>This widget requires Flash Player 9 or better</p> </object> It seems that movie is loaded but .xml and pictures are not...

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  • How do I make PyScripter work? Says it cant find python26.dll

    - by Alex
    I installed PyScript to try it out but it just wont start. It only gives me the error: "Error126: Could not open Dll "python26.dll" followed by: "Python could not be properly initialized. We must quit." I think this may have something to do with the PYTHONPATH but since I'm a newbie and dont know what it is or exactly what to put in the PYTHONPATH, after some googling, I ask here. Also, when I tried to install wxPython it was impossible becouse the PYTHONPATH could not be found.(Just a side note) I have installed ActivePython 2.6 and the PATH is set so I can access python in cmd.

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  • Using a ref Parameter with the this Keyword?

    - by grefly
    Is there a way to force the this keyword to act as a ref argument? I would like to pass in a visitor that modifies multiple properties on the object, but this only wants to act like a value parameter. Code in Object: public void Accept(Visitor<MyObject> visitor) { visitor.Visit(this); } Code in Visitor: public void Visit(ref Visitor<MyObject> receiver) { receiver.Property = new PropertyValue(); receiver.Property2 = new PropertyValue(); }

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  • PHP MySQLi and MySQLi_STMT: Which insert_id to use?

    - by Carvell Fenton
    Hello all, Both the MySQLi and MySQLi_STMT classes have an $insert_id property. If I am connected to my database using a MySQLi object (say $db), and then I perform an INSERT with a MySQLi_STMT object (say $stmt), to get the id of the last INSERT, should I use: $last_id = $db->insert_id; or $last_id = $stmt->insert_id; Or would they be the same, in which case it doesn't matter? I thought this might be a quick answer for someone, and save me the time of writing the test code to check it. Thanks in advance as always.

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  • Running The JVM From Within An MXML Component

    - by Joshua
    Thinking outside of the box here... What possible basic approaches could be taken in an effort to create a Flex component that could run Java? I know I can easily use flex to browse to or launch a Java app, but there are things I can only do if I can run the Java from WITHIN an MXML Component. I the strictest sense, I know it's not impossible (ie: if you had all the source code for flex and for the jvm), but what's the least impractical means to this end? Showcase your creativity.

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  • Run a SQL Script Against MySQL using Powershell

    - by abarr
    I have a Powershell script that backs up my MySQL DB's each night using mysqldump. This all works fine but I would like to extend the script to update a reporting db (db1) from the backup of the prod db (db2). I have written the following test script but it does not work. I have a feeling the problem is the reading of the sql file to the CommandText but I am not sure how to debug. [system.reflection.assembly]::LoadWithPartialName("MySql.Data") $mysql_server = "localhost" $mysql_user = "root" $mysql_password = "password" write-host "Create coonection to db1" # Connect to MySQL database 'db1' $cn = New-Object -TypeName MySql.Data.MySqlClient.MySqlConnection $cn.ConnectionString = "SERVER=$mysql_server;DATABASE=db1;UID=$mysql_user;PWD=$mysql_password" $cn.Open() write-host "Running backup script against db1" # Run Update Script MySQL $cm = New-Object -TypeName MySql.Data.MySqlClient.MySqlCommand $sql = Get-Content C:\db2.sql $cm.Connection = $cn $cm.CommandText = $sql $cm.ExecuteReader() write-host "Closing Connection" $cn.Close() Any assistance would be appreciated. Thanks.

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  • how to deal with a static analyzer output

    - by Jim
    We have started using a static analyzer (Coverity) on our code base. We were promptly stupefied by the sheer amount of warnings we received (its in the hundreds of thousands) , it will take the entire team a few mounts to clear them all (obliviously impossible). the options we discussed so far are 1) hire a contractor to sort out the warning and fix them - he drawback: we will probably need very experiences people to do all these modifications, and no contractor will have required understanding of the code. 2) filter out the warning and deal only with the dangerous ones - the problem here is that our static analysis output will always be cluttered by warning making it difficult for us to isolate problems. also the filtering of the warning is also a major effort. either way, bringing our code to a state when the static analyzer can be a useful tool for us seems a monumental task. so how is it possible to work with the static analyzer without braining current development efforts into a complete stand still?

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  • How do I draw an arrow on a histogram drawn using ggplot2?

    - by jon
    Here is dataset: set.seed(123) myd <- data.frame (class = rep(1:4, each = 100), yvar = rnorm(400, 50,30)) require(ggplot2) m <- ggplot(myd, aes(x = yvar)) p <- m + geom_histogram(colour = "grey40", fill = "grey40", binwidth = 10) + facet_wrap(~class) + theme_bw( ) p + opts(panel.margin=unit(0 ,"lines")) I want to add labels to bars which each subject class fall into and produce something like the post-powerpoint processed graph. Is there way to do this within R ? ...... Edit: we can think of different pointer such as dot or error bar, if arrow is not impossible Let's say the following is subjects to be labelled: class name yvar 2 subject4 104.0 3 subject3 8.5 3 subject1 80.0 4 subject2 40.0 4 subject1 115.0 classd <- data.frame (class = c(2,3,3,4,4), name = c ("subject4", "subject3", "subject1", "subject2", "subject1"), yvar = c(104.0, 8.5,80.0,40.0, 115.0))

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  • Only one instance of a scriptmanager can exist on a page

    - by dotnetdev
    Hi, I design an ASP.NET web usercontrol and with a maskeditor and scriptmanager, I always get an object reference not set to an instance of an object exception at runtime. Stacktrace is: [InvalidOperationException: Only one instance of a ScriptManager can be added to the page.] System.Web.UI.ScriptManager.OnInit(EventArgs e) +384613 System.Web.UI.Control.InitRecursive(Control namingContainer) +333 System.Web.UI.Control.InitRecursive(Control namingContainer) +210 System.Web.UI.Control.InitRecursive(Control namingContainer) +210 System.Web.UI.Control.InitRecursive(Control namingContainer) +210 System.Web.UI.Control.InitRecursive(Control namingContainer) +210 System.Web.UI.Control.InitRecursive(Control namingContainer) +210 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +378 What causes this? Thanks

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  • Rails: unexpected behavior updating a shared instance

    - by Pascal Lindelauf
    I have a User object, that is related to a Post object via two different association paths: Post --(has_many)-- comments --(belongs to)-- writer (of type User) Post --(belongs to)-- writer (of type User) Say the following hold: user1.name == "Bill" post1.comments[1].writer == user1 post1.writer == user1 Now when I retrieve the post1 and its comments from the database and I update post1.comments[1].writer like so: post1.comments[1].writer.name = "John" I would expect post1.writer to equal "John" too. But it doesn't! It still equals "Bill". So there seems to be some caching going on, but the kind I would not expect. I would expect Rails to be clever enough to load exactly one instance of the user with name "Bill"; instead is appears to load two individual ones: one for each association path. Can someone explain how this works exactly and how I am to handle these types of situations the "Rails way"?

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  • JSF2 - use view scope managed bean to pass value between navigation

    - by Fekete Kamosh
    Hi all, I am solving how to pass values from one page to another without making use of session scope managed bean. For most managed beans I would like to have only Request scope. I created a very, very simple calculator example which passes Result object resulting from actions on request bean (CalculatorRequestBean) from 5th phase as initializing value for new instance of request bean initialized in next phase lifecycle. In fact - in production environment we need to pass much more complicated data object which is not as primitive as Result defined below. What is your opinion on this solution which considers both possibilities - we stay on the same view or we navigate to the new one. But in both cases I can get to previous value stored passed using view scoped managed bean. Calculator page: <?xml version='1.0' encoding='UTF-8' ?> <!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" xmlns:h="http://java.sun.com/jsf/html"> <h:head> <title>Calculator</title> </h:head> <h:body> <h:form> <h:panelGrid columns="2"> <h:outputText value="Value to use:"/> <h:inputText value="#{calculatorBeanRequest.valueToAdd}"/> <h:outputText value="Navigate to new view:"/> <h:selectBooleanCheckbox value="#{calculatorBeanRequest.navigateToNewView}"/> <h:commandButton value="Add" action="#{calculatorBeanRequest.add}"/> <h:commandButton value="Subtract" action="#{calculatorBeanRequest.subtract}"/> <h:outputText value="Result:"/> <h:outputText value="#{calculatorBeanRequest.result.value}"/> <h:outputText value="DUMMY" rendered="#{resultBeanView.dummy}"/> </h:panelGrid> </h:form> </h:body> Object to be passed through lifecycle: package cz.test.calculator; import java.io.Serializable; /** * Data object passed among pages. * Lets imagine it holds something much more complicated than primitive int */ public class Result implements Serializable { private int value; public void setValue(int value) { this.value = value; } public int getValue() { return value; } } Request scoped managed bean used on view "calculator.xhtml" package cz.test.calculator; import javax.annotation.PostConstruct; import javax.faces.bean.ManagedBean; import javax.faces.bean.ManagedProperty; import javax.faces.bean.RequestScoped; @ManagedBean @RequestScoped public class CalculatorBeanRequest { @ManagedProperty(value="#{resultBeanView}") ResultBeanView resultBeanView; private Result result; private int valueToAdd; /** * Should perform navigation to */ private boolean navigateToNewView; /** Creates a new instance of CalculatorBeanRequest */ public CalculatorBeanRequest() { } @PostConstruct public void init() { // Remember already saved result from view scoped bean result = resultBeanView.getResult(); } // Dependency injections public void setResultBeanView(ResultBeanView resultBeanView) { this.resultBeanView = resultBeanView; } public ResultBeanView getResultBeanView() { return resultBeanView; } // Getters, setter public void setValueToAdd(int valueToAdd) { this.valueToAdd = valueToAdd; } public int getValueToAdd() { return valueToAdd; } public boolean isNavigateToNewView() { return navigateToNewView; } public void setNavigateToNewView(boolean navigateToNewView) { this.navigateToNewView = navigateToNewView; } public Result getResult() { return result; } // Actions public String add() { result.setValue(result.getValue() + valueToAdd); return isNavigateToNewView() ? "calculator" : null; } public String subtract() { result.setValue(result.getValue() - valueToAdd); return isNavigateToNewView() ? "calculator" : null; } } and finally view scoped managed bean to pass Result variable to new page: package cz.test.calculator; import java.io.Serializable; import javax.annotation.PostConstruct; import javax.faces.bean.ManagedBean; import javax.faces.bean.ViewScoped; import javax.faces.context.FacesContext; @ManagedBean @ViewScoped public class ResultBeanView implements Serializable { private Result result = new Result(); /** Creates a new instance of ResultBeanView */ public ResultBeanView() { } @PostConstruct public void init() { // Try to find request bean ManagedBeanRequest and reset result value CalculatorBeanRequest calculatorBeanRequest = (CalculatorBeanRequest)FacesContext.getCurrentInstance().getExternalContext().getRequestMap().get("calculatorBeanRequest"); if(calculatorBeanRequest != null) { setResult(calculatorBeanRequest.getResult()); } } /** No need to have public modifier as not used on view * but only in managed bean within the same package */ void setResult(Result result) { this.result = result; } /** No need to have public modifier as not used on view * but only in managed bean within the same package */ Result getResult() { return result; } /** * To be called on page to instantiate ResultBeanView in Render view phase */ public boolean isDummy() { return false; } }

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  • correct way to store an exception in a variable

    - by Evan Teran
    I have an API which internally has some exceptions for error reporting. The basic structure is that it has a root exception object which inherits from std::exception, then it will throw some subclass of that. Since catching an exception thrown in one library and catching it in another can lead to undefined behavior (at least Qt complains about it and disallows it in many contexts). I would like to wrap the library calls in functions which will return a status code, and if an exception occurred, a copy of the exception object. What is the best way to store an exception (with it's polymorphic behavior) for later use? I believe that the c++0x futures API makes use of something like this. So what is the best approach? The best I can think of is to have a clone() method in each exception class which will return a pointer to an exception of the same type. But that's not very generic and doesn't deal with standard exceptions at all. Any thoughts?

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