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How to Debug an exception: Type is not marked as serializable... when the type is marked as serializ

- by rism

I'm trying to: ((Request.Params["crmid"] != null)) in a web page. But it keeps throwing a serialzation exception: Type 'QC.Security.SL.SiteUser' in assembly 'QC.Security, Version=1.0.0.1, Culture=neutral, PublicKeyToken=null' is not marked as serializable. The type is however marked as serializable as follows: [Serializable()] public class SiteUser : IIdentity { private long _userId; public long UserId { get { return _userId; } set { _userId = value; } } private string _name; public string Name { get { return _name; } } private bool _isAuthenticated; public bool IsAuthenticated { get { return _isAuthenticated; } } private string _authenticationType; public string AuthenticationType { get { return _authenticationType; } } I've no idea how to debug this as I cant step into the serializer code to find out why its falling over. The call stack is only one frame deep before it hits [External Code]. And the error message is next to useless given that type is clearly marked as serializable. It was working fine. But now "all of a sudden" it doesn't which typically means some dumb bug in Visual Studio but rebooting doesn't help "this" time. So now I dont know if it's a stupid VS bug or a completely unrelated error for which Im getting a serialization exception or something I'm doing wrong. The truth is I just dont trust VS anymore given the number of wild goose chases Ive been on over the last several months which were "fixed" by rebooting VS 2008 or some other rediculous workaround.

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Type-conditional controls in Haskell

- by estanford

I'm going through the 99 Haskell problems to build my proficiency with the language. On problem 7 ("Flatten a nested list structure"), I found myself wanting to define a conditional behavior based on the type of argument passed to a function. That is, since *Main> :t 1 1 :: (Num t) => t *Main> :t [1,2] [1,2] :: (Num t) => [t] *Main> :t [[1],[2]] [[1],[2]] :: (Num t) => [[t]] (i.e. lists nested at different levels have different data types) it seems like I should be able to write a function that can read the type of the argument, and then behave accordingly. My first attempt was along these lines: listflatten l = do if (:t l) /= ((Num t) => [t]) then listflatten (foldl (++) [] l) else id l But when I try to do that, Haskell returns a parse error. Is Haskell flexible enough to allow this sort of type manipulation, do I need to find another way?

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Full Text Index type column is empty

- by RemotecUk

I am trying to create an index on a VarBinary(max) field in my SQL Server 2008 database. The steps I am taking are as follows: Table: dbo.Records Right click on table and select "Full Text Index" Then select "Define Index..." I choose the primary key which is the PK of my table (field name Id, type UniqueIndentifier). I then get the screen with the options Available Columns, Language for Word Breaker and Type Column I select my VarBinary(max) field called Chart as the Available Column by ticking the box. I select "English" as the Language for Word Breaker field. Then... I try to select the Type Column but there are no entries in here. I cannot proceed by clicking "Next" until this column is populated. Why are there no entries in this column for selection and what should be in there? Note 1: The VarBinary(max) field is linked to a file group if that makes any difference. Note 2: Also noticed that in the table designer I cannot set the full text option on that same field to "Yes" - its permanently stuck on "No". Thanks.

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"Pattern matching" of algebraic type data constructors

- by jetxee

Let's consider a data type with many constructors: data T = Alpha Int | Beta Int | Gamma Int Int | Delta Int I want to write a function to check if two values are produced with the same constructor: sameK (Alpha _) (Alpha _) = True sameK (Beta _) (Beta _) = True sameK (Gamma _ _) (Gamma _ _) = True sameK _ _ = False Maintaining sameK is not much fun, it is potentially buggy. For example, when new constructors are added to T, it's easy to forget to update sameK. I omitted one line to give an example: -- it’s easy to forget: -- sameK (Delta _) (Delta _) = True The question is how to avoid boilerplate in sameK? Or how to make sure it checks for all T constructors? The workaround I found is to use separate data types for each of the constructors, deriving Data.Typeable, and declaring a common type class, but I don't like this solution, because it is much less readable and otherwise just a simple algebraic type works for me: {-# LANGUAGE DeriveDataTypeable #-} import Data.Typeable class Tlike t where value :: t -> t value = id data Alpha = Alpha Int deriving Typeable data Beta = Beta Int deriving Typeable data Gamma = Gamma Int Int deriving Typeable data Delta = Delta Int deriving Typeable instance Tlike Alpha instance Tlike Beta instance Tlike Gamma instance Tlike Delta sameK :: (Tlike t, Typeable t, Tlike t', Typeable t') => t -> t' -> Bool sameK a b = typeOf a == typeOf b

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Java - Class type from inside static initialization block

- by DutrowLLC

Is it possible to get the class type from inside the static initialization block? This is a simplified version of what I currently have:: class Person extends SuperClass { String firstName; static{ // This function is on the "SuperClass": // I'd for this function to be able to get "Person.class" without me // having to explicitly type it in but "this.class" does not work in // a static context. doSomeReflectionStuff(Person.class); // IN "SuperClass" } } This is closer to what I am doing, which is to initialize a data structure that holds information about the object and its annotations, etc... Perhaps I am using the wrong pattern? public abstract SuperClass{ static void doSomeReflectionStuff( Class<?> classType, List<FieldData> fieldDataList ){ Field[] fields = classType.getDeclaredFields(); for( Field field : fields ){ // Initialize fieldDataList } } } public abstract class Person { @SomeAnnotation String firstName; // Holds information on each of the fields, I used a Map<String, FieldData> // in my actual implementation to map strings to the field information, but that // seemed a little wordy for this example static List<FieldData> fieldDataList = new List<FieldData>(); static{ // Again, it seems dangerous to have to type in the "Person.class" // (or Address.class, PhoneNumber.class, etc...) every time. // Ideally, I'd liken to eliminate all this code from the Sub class // since now I have to copy and paste it into each Sub class. doSomeReflectionStuff(Person.class, fieldDataList); } }

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Linq Getting Customers group by date and then by their type

- by Nitin varpe

I am working on generating report for showing customer using LINQ in C#. I want to show no. of customers of each type. There are 3 types of customer registered, guest and manager. I want to group by customers by registered date and then by type of customer. i.e If today 3 guest, 4 registered and 2 manager are inserted. and tomorrow 4,5 and 6 are registered resp. then report should show Number of customers registerd on the day . separate row for each type. DATE TYPEOF CUSTOMER COUNT 31-10-2013 GUEST 3 31-10-2013 REGISTERED 4 31-10-2013 MANAGER 2 30-10-2013 GUEST 5 30-10-2013 REGISTERED 10 30-10-2013 MANAGER 3 LIKE THIS . var subquery = from eat in _customerRepo.Table group eat by new { yy = eat.CreatedOnUTC.Value.Year, mm = eat.CreatedOnUTC.Value.Month, dd = eat.CreatedOnUTC.Value.Day } into g select new { Id = g.Min(x => x.Id) }; var query = from c in _customerRepo.Table join cin in subquery.Distinct() on c.Id equals cin.Id select c; By above query I get minimum cutomers registerd on that day Thanks in advance

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What's the difference between an option type and a nullable type?

- by Peter Olson

In F# mantra there seems to be a visceral avoidance of null, Nullable<T> and its ilk. In exchange, we are supposed to instead use option types. To be honest, I don't really see the difference. My understanding of the F# option type is that it allows you to specify a type which can contain any of its normal values, or None. For example, an Option<int> allows all of the values that an int can have, in addition to None. My understanding of the C# nullable types is that it allows you to specify a type which can contain any of its normal values, or null. For example, a Nullable<int> a.k.a int? allows all of the values that an int can have, in addition to null. What's the difference? Do some vocabulary replacement with Nullable and Option, null and None, and you basically have the same thing. What's all the fuss over null about?

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Python: circular imports needed for type checking

- by phild

First of all: I do know that there are already many questions and answers to the topic of the circular imports. The answer is more or less: "Design your Module/Class structure properly and you will not need circular imports". That is true. I tried very hard to make a proper design for my current project, I in my opinion I was successful with this. But my specific problem is the following: I need a type check in a module that is already imported by the module containing the class to check against. But this throws an import error. Like so: foo.py: from bar import Bar class Foo(object): def __init__(self): self.__bar = Bar(self) bar.py: from foo import Foo class Bar(object): def __init__(self, arg_instance_of_foo): if not isinstance(arg_instance_of_foo, Foo): raise TypeError() Solution 1: If I modified it to check the type by a string comparison, it will work. But I dont really like this solution (string comparsion is rather expensive for a simple type check, and could get a problem when it comes to refactoring). bar_modified.py: from foo import Foo class Bar(object): def __init__(self, arg_instance_of_foo): if not arg_instance_of_foo.__class__.__name__ == "Foo": raise TypeError() Solution 2: I could also pack the two classes into one module. But my project has lots of different classes like the "Bar" example, and I want to seperate them into different module files. After my own 2 solutions are no option for me: Has anyone a nicer solution for this problem?

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Casting to specify unknown object type?

- by fuzzygoat

In the following code I have a view object that is an instance of UIScrollView, if I run the code below I get warnings saying that "UIView might not respond to -setContentSize etc." UIImage *image = [UIImage imageNamed:@"Snowy_UK.jpg"]; imageView = [[UIImageView alloc] initWithImage:image]; [[self view] addSubview:imageView]; [[self view] setContentSize:[image size]]; [[self view] setMaximumZoomScale:2.0]; [[self view] setMinimumZoomScale: [[self view] bounds].size.width / [image size].width]; I have checked the type of the object and [self view] is indeed a UIScrollView. I am guessing that this is just the compiler making a bad guess as to the type and the solution is simply to cast the object to the correct type manually, am I getting this right? UIScrollView *scrollView = (UIScrollView *)[self view]; UIImage *image = [UIImage imageNamed:@"Snowy_UK.jpg"]; imageView = [[UIImageView alloc] initWithImage:image]; [[self view] addSubview:imageView]; [scrollView setContentSize:[image size]]; [scrollView setMaximumZoomScale:2.0]; [scrollView setMinimumZoomScale: [scrollView bounds].size.width / [image size].width]; cheers Gary.

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LinQ XML mapping to a generic type

- by Manuel Navarro

I´m trying to use an external XML file to map the output from a stored procedure into an instance of a class. The problem is that my class is of a generic type: public class MyValue<T> { public T Value { get; set; } } Searching through a lot of blogs an articles I've managed to get this: <?xml version="1.0" encoding="utf-8" ?> <Database Name="" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007"> <Table Name="MyValue" Member="MyNamespace.MyValue`1" > <Type Name="MyNamespace.MyValue`1"> <Column Name="Category" Member="Value" DbType="VarChar(100)" /> </Type> </Table> <Function Method="GetResourceCategories" Name="myprefix_GetResourceCategories" > <ElementType Name="MyNamespace.MyValue`1"/> </Function> </Database> The MyNamespace.MyValue`1 trick works fine, and the class is recognized. I expect four rows from the stored procedure, and I'm getting four MyValue<string> instances, but the big problem is that the property Value for the all four instances is null. The property is not getting mapped and I don't really get why. Maybe worth noting that the property Value is generic, and that when the mapping is done using attributes it works perfect. Anyone have a clue? BTW the method GetResourceCategories: public ISingleResult<MyValue<string>> GetResourceCategories() { IExecuteResult result = this.ExecuteMethodCall( this, (MethodInfo)MethodInfo.GetCurrentMethod()); return (ISingleResult<MyValue<string>>)result.ReturnValue; }

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How can I get the type I want?

- by Danny Chen

There are a lot of such classes in my project (very old and stable code, I can't do many changes to them, maybe slight changes are OK) public class MyEntity { public long ID { get; set; } public string Name { get; set; } public decimal Salary { get; set; } public static GetMyEntity ( long ID ) { MyEntity e = new MyEntity(); // load data from DB and bind to this instance return e; } } For some reasons, now I need to do this: Type t = Type.GetType("XXX"); // XXX is one of the above classes' name MethodInfo staticM= t.GetMethods(BindingFlags.Public | BindingFlags.Static).FirstOrDefault();// I'm sure I can get the correct one var o = staticM.Invoke(...); //returns a object, but I want the type above! If I pass "MyEntity" at beginning, I hope I can get o as MyEntity! Please NOTE that I know the "name of the class" only. MyEntity e = staticM.Invoke(...) as MyEntity; can't be used here.

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Cloning input type file and set the value

- by jribeiro

I know that it isn't possible to set the value of an input type="file" for security reasons... My problem is: I needed to style an input type="file" so what I did was have a button and hide the file input. like: <a href="#" onclick="$('input[name="photo1"]').click(); return false;" id="photo1-link"></a> <input type="file" name="photo1" class="fileInput jqtranformdone validate[required]" id="photo1" /> These works great in all browsers except IE which gives me an access denied error on submitting through ajax. I'm using the ajaxSubmit jquery plugin (malsup.com/jquery/form/) So after reading for a while I tried to do: var photo1Val = $('#photo1').val(); var clone1 = $('#photo1').clone().val(photo1Val); $('#photo1').remove(); clone1.appendTo('form'); console.log(photo1Val) //prints the right value C:/fakepath/blablabla.jpg $('form').ajaxSubmit(options); The problem is that after this the value of $('#photo1') is empty... Any ideas how to work around this? Thanks

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Adding string items to a list of type Person C#

- by user1862808

Im makeing a simple registration application and I have an assignment to learn more about lists. I have an assignment that says that i am to create a class called Persons and in that class set the values from the text fields in variables and add this to a list of type Person. So far: in the Person class: string strSocialSecurityNumber = string.Empty;//---( This will not be used now.) string strFirstName = string.Empty; string strLastName = string.Empty; string strFullName = string.Empty; string strAge = string.Empty; string strAll = string.Empty; int intAge = 0; List<Person> lstPerson = new List<Person>(); public void SetValues(string FirstName, string LastName, int Age) { strFirstName = FirstName; strLastName = LastName; strFullName = strFirstName + " " + strLastName; intAge = Age; strAge = Convert.ToString(intAge); strAll = strAge + " " + strFullName; } public List<Person> Person() { lstPerson.Add(strAll); return lstPerson; } Error message: "can not convert from string to Person" The assignment says that the list is to be of the type Person so i am suppose to add strings to it and ive looked how to do this but I dont know how. I have seen that there are options like "ConvertAll" But im not sure if I am allowed to use it since the list should be of type Person. Thank you!

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Detecting const-ness of nested type

- by Channel72

Normally, if I need to detect whether a type is const I just use boost::is_const. However, I ran into trouble when trying to detect the const-ness of a nested type. Consider the following traits template, which is specialized for const types: template <class T> struct traits { typedef T& reference; }; template <class T> struct traits<const T> { typedef T const& reference; }; The problem is that boost::is_const doesn't seem to detect that traits<const T>::reference is a const type. For example: std::cout << std::boolalpha; std::cout << boost::is_const<traits<int>::reference>::value << " "; std::cout << boost::is_const<traits<const int>::reference>::value << std::endl; This outputs: false false Why doesn't it output false true?

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Omit return type in C++0x

- by Clinton

I've recently found myself using the following macro with gcc 4.5 in C++0x mode: #define RETURN(x) -> decltype(x) { return x; } And writing functions like this: template <class T> auto f(T&& x) RETURN (( g(h(std::forward<T>(x))) )) I've been doing this to avoid the inconvenience having to effectively write the function body twice, and having keep changes in the body and the return type in sync (which in my opinion is a disaster waiting to happen). The problem is that this technique only works on one line functions. So when I have something like this (convoluted example): template <class T> auto f(T&& x) -> ... { auto y1 = f(x); auto y2 = h(y1, g1(x)); auto y3 = h(y1, g2(x)); if (y1) { ++y3; } return h2(y2, y3); } Then I have to put something horrible in the return type. Furthermore, whenever I update the function, I'll need to change the return type, and if I don't change it correctly, I'll get a compile error if I'm lucky, or a runtime bug in the worse case. Having to copy and paste changes to two locations and keep them in sync I feel is not good practice. And I can't think of a situation where I'd want an implicit cast on return instead of an explicit cast. Surely there is a way to ask the compiler to deduce this information. What is the point of the compiler keeping it a secret? I thought C++0x was designed so such duplication would not be required.

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Java Generic Type and Reflection

- by Tom Tucker

I have some tricky generic type problem involving reflection. Here's the code. public @interface MyConstraint { Class<? extends MyConstraintValidator<?>> validatedBy(); } public interface MyConstraintValidator<T extends Annotation> { void initialize(T annotation); } /** @param annotation is annotated with MyConstraint. */ public void run(Annotation annotation) { Class<? extends MyConstraintValidator<? extends Annotation>> validatorClass = annotation.annotationType().getAnnotation(MyConstraint.class).validatedBy(); validatorClass.newInstance().initialize(annotation) // will not compile! } The run() method above will not compile because of the following error. The method initialize(capture#10-of ? extends Annotation) in the type MyConstraintValidator<capture#10-of ? extends Annotation> is not applicable for the arguments (Annotation) If I remove the wild cards, then it compiles and works fine. What would be the propert way to declare the type parameter for the vairable validatorClass? Thanks.

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Method not being resolved for dynamic generic type

- by kelloti

I have these types: public class GenericDao<T> { public T Save(T t) { return t; } } public abstract class DomainObject { // Some properties protected abstract dynamic Dao { get; } public virtual void Save() { var dao = Dao; dao.Save(this); } } public class Attachment : DomainObject { protected dynamic Dao { get { return new GenericDao<Attachment>(); } } } Then when I run this code it fails with RuntimeBinderException: Best overloaded method match for 'GenericDAO<Attachment.Save(Attachment)' has some invalid arguments var obj = new Attachment() { /* set properties */ }; obj.Save(); I've verified that in DomainObject.Save() "this" is definitely Attachment, so the error doesn't really make sense. Can anyone shed some light on why the method isn't resolving? Some more information - It succeeds if I change the contents of DomainObject.Save() to use reflection: public virtual void Save() { var dao = Dao; var type = dao.GetType(); var save = ((Type)type).GetMethod("Save"); save.Invoke(dao, new []{this}); }

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C#: How to get all public (both get and set) string properties of a type

- by Svish

I am trying to make a method that will go through a list of generic objects and replace all their properties of type string which is either null or empty with a replacement. How is a good way to do this? I have this kind of... shell... so far: public static void ReplaceEmptyStrings<T>(List<T> list, string replacement) { var properties = typeof(T).GetProperties( -- What BindingFlags? -- ); foreach(var p in properties) { foreach(var item in list) { if(string.IsNullOrEmpty((string) p.GetValue(item, null))) p.SetValue(item, replacement, null); } } } So, how do I find all the properties of a type that are: Of type string Has public get Has public set ? I made this test class: class TestSubject { public string Public; private string Private; public string PublicPublic { get; set; } public string PublicPrivate { get; private set; } public string PrivatePublic { private get; set; } private string PrivatePrivate { get; set; } } The following does not work: var properties = typeof(TestSubject) .GetProperties(BindingFlags.Instance|BindingFlags.Public) .Where(ø => ø.CanRead && ø.CanWrite) .Where(ø => ø.PropertyType == typeof(string)); If I print out the Name of those properties I get there, I get: PublicPublic PublicPrivate PrivatePublic In other words, I get two properties too much. Note: This could probably be done in a better way... using nested foreach and reflection and all here... but if you have any great alternative ideas, please let me know cause I want to learn!

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I want a function to return a type of the subclass its invoked from

- by Jay

I want to have a function defined in a superclass that returns a value of the type of the subclass that is used to invoke the function. That is, say I have class A with a function plugh. Then I create subclasses B and C that extend A. I want B.plugh to return a B and C.plugh to return a C. Yes, they could return an A, but then the caller would have to either cast it to the right subtype, which is a pain when used a lot, or declare the receiving variable to be of the supertype, which loses type safety. So I was trying to do this with generics, writing something like this: class A<T extends A> { private T foo; public T getFoo() { return foo; } } class B extends A<B> { public void calcFoo() { foo=... whatever ... } } class C extends A<C> { public void calcFoo() { foo=... whatever ... } } This appears to work but it looks pretty ugly. For one thing, I get warnings on "class A". The compiler says that A is generic and I should specify the type. I guess it wants me to say "class A". But what would I put in for x? I think I could get stuck in an infinite loop here. It seems weird to write "class B extends A", but this causes no complaints, so maybe that's just fine. Is this the right way to do it? Is there a better way?

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A Question about dereferencing pointer to incomplete type In C programming

- by user552279

Hi, can you explain this error for me? Blockquote /////////////////////////////// In my A.h file: struct TreeNode; struct TreeHead; typedef struct TreeNode * Node; typedef struct TreeHead * Head; /////////////////////////////// In my A.c file: struct TreeNode { char* theData; Node Left; Node Right; } ; struct TreeHead{ int counter; char type; Node Root; }; Head Initialisation() { Head treeHead; treeHead = malloc(sizeof (struct TreeHead)); treeHead-Root = malloc(sizeof (struct TreeNode)); return treeHead; } /////////////////////////////// In my Main.c file: Head head; Node tree; int choose =5; head = Initialisation(); (head-Root) = tree; //When compiling, this line has an error: error: dereferencing pointer to incomplete type Blockquote haed-Root will return a Node pointer, tree is also a Node pointer. So why error is dereferencing pointer to "incomplete" type?

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<input type="file"> reads only file name not full path

- by Deep

I am using Glassfish Server.I have seen the apache file upload to solve it...but i want to implement it in glassfish server. image.html <form action="" method="post" enctype="multipart/form-data"> Select a file: <input type="file" name="first" id="first"/> <br /> <input type="button" name="button" value="upload" id="button" /> <p id="test"></p> <img src='Unknown.png' id="profile_img" height="200px" width="150px"/> </form> test.js $(document).ready(function() { var filepath= $("#first"); $('#button').click(function() { $.ajax({ type: "post", url: "imageservlet", data: "user="+filepath.val(), success: function(msg) { $("#profile_img").attr('src',msg); $("#test").html(msg) .fadeIn("fast"); } }); }); }); imageservlet.java String user=request.getParameter("user"); out.print(user); the output is file name not full path.

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Why Is the sender type null when dealing with events

- by ChloeRadshaw

From C# Via CLR: Note A lot of people wonder why the event pattern requires the sender parameter to always be of type Object After all, since the MailManager will be the only type raising an event with a NewMail EventArgs object, it makes more sense for the callback method to be prototyped like this: void MethodName(Mai l Manager sender, NewMail EventArgs e); The pattern requires the sender parameter to be of type Object mostly because of inheritance What if Mai lManager were used as a base class for SmtpMailManager? In this case, the callback method should have the sender parameter prototyped as SmtpMailManager instead of Mail Manager, but this can’t happen because SmtpMai lManager just inherited the NewMai l event So the code that was expecting SmtpMail Manager to raise the event must still have to cast the sender argument to SmtpMailManager In other words, the cast is still required, so the sender parameter might as well be typed as Obj ect The next reason for typing the sender parameter as Obj ect is just fexibility It allows the delegate to be used by multiple types that offer an event that passes a NewMail EventArgs object For example, a PopMai lManager class could use the delegate even if this class were not derived from Mail Manager I just simply cannot understand why the sender is an object - Why can it not be generified? so most of the time we do not need to do generic casts

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Visual Studio 2008 having problems with namespaces when used as type in Generic coolection

- by patrick

I just upgraded last week from Visual Studio 2005 to 2008. I am having an issue with compiler resolving namespaces when I use a class as a type in a Generic collection. Intellisense recognizes the class and the compiler generates no errors when I use the class except when it is a type in a Generic collection declaration either as return type for a Property or as a parameter to a method. This is happening in my only project that is targeting the 3.5 framework, but changing the project containing the class to use the 3.5 framework doesn't fix the problem. Examples Compile fine MyClass myClass = new MyClass(); SortedList <DateTime,MyClass> listOfClasses = new SortedList<DateTime,MyClass> Compile error - Namespace could not be found public SortedList<DateTime,MyClass> ClassList { get; set; } private void DoSomethingToLists(SortedList<DateTime,MyClass> classList) Intellisense has no problem resolving the namespace, only the compiler. Is this a known bug or am I missing something obvious? Will SP1 fix it? I was able to create a new library containing just this class targeting 3.5 and am now able to successfully use this in both 3.5 and 2.0 projects. My guess is that even though I tried to change the target of my original library, since it was still referencing 2.0 projects there was some conflict.

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Using input type="submit" to change content

- by Conti

Okay, I'm pretty sure I'm missing something very obvious here, but I just couldn't find a proper solution so far. What I'm trying to do is simple: Have a user write something into a form, have him submit the form, and write that input into a textarea on the same page. This is my code: <html><head></head> <body> <form name='registration'> <label for="input">Input:</label> <input type="text" id="input"/> <input type="submit" id="submit" value="Submit" onclick="execute()"/> </form> <div id="results"> <span>Result</span> <span><textarea cols="30" rows="5" id="resulttext" readonly="readonly"></textarea> </span> </div> <script> function execute() { var result = document.getElementById("input").value document.getElementById("resulttext").value=result; } </script> </body> </html> Now what happens if I enter something into the form is that the textarea briefly shows my input before reverting back to showing nothing. My guess is that the textarea field is only changed for the duration of the execute() function. When I change input type="submit" to a <button> everything works as intended, but I'm pretty sure I'm not supposed to do that.

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C++ universal data type

- by Gokul

I have a universal data type, which is passed by value, but does not maintain the type information. We store only pointers and basic data types(like int, float etc) inside this. Now for the first time, we need to store std::string inside this. So we decided to convert it into std::string* and store it. Then comes the problem of destruction. We don't like to copy the std::string every time. So i am thinking of an approach like this. Say the data type looks like this class Atom { public : enum flags { IS_STRING, IS_EMPTY, HAS_GOT_COPIED, MARKER }; private: void* m_value; std::bitset<MARKER> m_flags; public: ..... Atom( Atom& atm ) { atm.m_flags.set( HAS_GOT_COPIED ); ..... } ..... ~Atom() { if( m_flags.test(IS_STRING) && !m_flags.test(HAS_GOT_COPIED) ) { std::string* val = static_cast<std::string*>(m_value); delete val; } } }; Is this a good approach to find out whether there is no more reference to std::string*? Any comments.. Thanks, Gokul.

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