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  • g++ linker error--typeinfo, but not vtable

    - by James
    I know the standard answer for a linker error about missing typeinfo usually also involves vtable and some virtual function that I forgot to actually define. I'm fairly certain that's not the situation this time. Here's the error: UI.o: In function boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::Resource::GroupByState>(boost::shared_ptr<Graphics::Resource::GroupByState> const&, boost::detail::dynamic_cast_tag)': UI.cpp:(.text._ZN5boost10shared_ptrIN8Graphics7Widgets9WidgetSetEEC1INS1_8Resource12GroupByStateEEERKNS0_IT_EENS_6detail16dynamic_cast_tagE[boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::Resource::GroupByState>(boost::shared_ptr<Graphics::Resource::GroupByState> const&, boost::detail::dynamic_cast_tag)]+0x30): undefined reference totypeinfo for Graphics::Widgets::WidgetSet' Running c++filt on the obnoxious mangled name shows that it actually is looking at .boost::shared_ptr::shared_ptr(boost::shared_ptr const&, boost::detail::dynamic_cast_tag) The inheritance hierarchy looks something like class AbstractGroup { typedef boost::shared_ptr<AbstractGroup> Ptr; ... }; class WidgetSet : public AbstractGroup { typedef boost::shared_ptr<WidgetSet> Ptr; ... }; class GroupByState : public AbstractGroup { ... }; Then there's this: class UI : public GroupByState { ... void LoadWidgets( GroupByState::Ptr resource ); }; Then the original implementation: void UI::LoadWidgets( GroupByState::Ptr resource ) { WidgetSet::Ptr tmp( boost::dynamic_pointer_cast< WidgetSet >(resource) ); if( tmp ) { ... } } Stupid error on my part (trying to cast to a sibling class with a shared parent), even if the error is kind of cryptic. Changing to this: void UI::LoadWidgets( AbstractGroup::Ptr resource ) { WidgetSet::Ptr tmp( boost::dynamic_pointer_cast< WidgetSet >(resource) ); if( tmp ) { ... } } (which I'm fairly sure is what I actually meant to be doing) left me with a very similar error: UI.o: In function boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::_Drawer::Group>(boost::shared_ptr<Graphics::_Drawer::Group> const&, boost::detail::dynamic_cast_tag)': UI.cpp:(.text._ZN5boost10shared_ptrIN8Graphics7Widgets9WidgetSetEEC1INS1_7_Drawer5GroupEEERKNS0_IT_EENS_6detail16dynamic_cast_tagE[boost::shared_ptr<Graphics::Widgets::WidgetSet>::shared_ptr<Graphics::_Drawer::Group>(boost::shared_ptr<Graphics::_Drawer::Group> const&, boost::detail::dynamic_cast_tag)]+0x30): undefined reference totypeinfo for Graphics::Widgets::WidgetSet' collect2: ld returned 1 exit status dynamic_cast_tag is just an empty struct in boost/shared_ptr.hpp. It's just a guess that boost might have anything at all to do with the error. Passing in a WidgetSet::Ptr totally eliminates the need for a cast, and it builds fine (which is why I think there's more going on than the standard answer for this question). Obviously, I'm trimming away a lot of details that might be important. My next step is to cut it down to the smallest example that fails to build, but I figured I'd try the lazy way out and take a stab on here first. TIA!

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  • Checking for a null int value from a Java ResultSet

    - by ian_scho_es
    In Java I'm trying to test for a null value, from a ResultSet, where the column is being cast to a primitive int type. int iVal; ResultSet rs = magicallyAppearingStmt.executeQuery(query); if (rs.next()) { if (rs.getObject("ID_PARENT") != null && !rs.wasNull()) { iVal = rs.getInt("ID_PARENT"); } } From the code fragment above, is there a better way to do this, and I assume that the second wasNull() test is redundant? Educate us, and Thanks

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  • Difference between DirectCast() and CType() in VB.Net

    - by Chapso
    I am an experienced C/C++/C# programmer who has just gotten into VB.NET. I generally use CType (and CInt, CBool, CStr) for casts because it is less characters and was the first way of casting which I was exposed to, but I am aware of DirectCast and TryCast as well. Simply, are there any differences (effect of cast, performance, etc.) between DirectCast and CType? I understand the idea of TryCast.

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  • How to map LINQ EntitySet to List property in property setter?

    - by jlp
    In my model I have these entities: public interface IOrder { string Name {get;set;} List<IProduct> OrderedProducts {get;set;} } public interface IProduct {} In partial class generated by linq-to-sql I map these properties on my entity properties: public partial class Order : IOrder { List<IProduct> OrderedProducts { get { return this.L2SQLProducts.Cast<IProduct>.ToList(); } set { this.L2SQLProducts = ??? } } } How should setter look like?

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  • Mssql varchar to datetime

    - by Dezigo
    I have a field varchar(14) = 20090226115644 I need convert it to - 2009-02-26 11:56:44 (datetime format) My idea. use cast and convert.. but I allways have errors. Conversion failed when converting datetime from character string. I made this, but don`t like it.. SELECT SUBSTRING(move,1,4) + '-' + SUBSTRING(move,5,2) + '-' + SUBSTRING(move,7,2) + ' ' + SUBSTRING(move,9,2) + ':' + SUBSTRING(move,11,2) + ':'+SUBSTRING(move,13,2) as new -- FROM [Test].[dbo].[container_events] where move IS not null Result :2009-02-26 11:56:44

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  • inserting only date in a column in sql server

    - by sam
    hi! Is there a way to insert only date in a datetime column in sql server without the time? for example date (datetime) =============== 12-01-2000 16-02-2000 or i should store this as a varchar and cast it when retriving so that i can convert to whatever form i need.

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  • How to infer the type of a derived class in base class?

    - by enzi
    I want to create a method that allows me to change arbitrary properties of classes that derive from my base class, the result should look like this: SetPropertyValue("size.height", 50); – where size is a property of my derived class and height is a property of size. I'm almost done with my implementation but there's one final obstacle that I want to solve before moving on, to describe this I will first have to explain my implementation a bit: Properties that can be modified are decorated with an attribute There's a method in my base class that searches for all derived classes and their decorated properties For each property I generate a "property modifier", a class that contains 2 delegates: one to set and one to get the value of the property. Property Modifiers are stored in a dictionary, with the name of the property as key In my base class, there is another dictionary that contains all property-modifier-dictionaries, with the Type of the respective class as key. What the SetPropertyValue method does is this: Get the correct property-modifier-dictionary, using the concrete type of the derived class (<- yet to solve) Get the property modifier of the property to change (e.g. of the property size) Use the get or set delegate to modify the property's value Some example code to clarify further: private static Dictionary<RuntimeTypeHandle, object> EditableTypes; //property-modifier-dictionary protected void SetPropertyValue<T>(EditablePropertyMap<T> map, string property, object value) { var property = map[property]; // get the property modifier property.Set((T)this, value); // use the set delegate (encapsulated in a method) } In the above code, T is the Type of the actual (derived) class. I need this type for the get/set delegates. The problem is how to get the EditablePropertyMap<T> when I don't know what T is. My current (ugly) solution is to pass the map in an overriden virtual method in the derived class: public override void SetPropertyValue(string property, object value) { base.SetPropertyValue((EditablePropertyMap<ExampleType>)EditableTypes[typeof(ExampleType)], property, value); } What this does is: get the correct dictionary containing the property modifiers of this class using the class's type, cast it to the appropiate type and pass it to the SetPropertyValue method. I want to get rid of the SetPropertyValue method in my derived class (since there are a lot of derived classes), but don't know yet how to accomplish that. I cannot just make a virtual GetEditablePropertyMap<T> method because I cannot infer a concrete type for T then. I also cannot acces my dictionary directly with a type and retrieve an EditablePropertyMap<T> from it because I cannot cast to it from object in the base class, since again I do not know T. I found some neat tricks to infere types (e.g. by adding a dummy T parameter), but cannot apply them to my specific problem. I'd highly appreciate any suggestions you may have for me.

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  • ArrayList and Map problem in grails

    - by xain
    Hi, I have a service that contains a map: static Map cargosMap = ['1':'item1','2':'item 2','3':'item 3'] that is returned via a method in the service: static Map getCargos() { [cargosMap] } A controller calls it like this: def mform = { Map cargos = empService.getCargos() [cargos:cargos] } In the gsp, I have the select: <g:select name="cg1" from="${cargos}" /> But I'm getting the exception: Error 500: Executing action ....caused exception: org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object ... with class 'java.util.ArrayList' to class 'java.util.Map' Any clues ? Thanks

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  • ado.net data entity problem

    - by ognjenb
    I have this error Cannot implicitly convert type 'System.Linq.IQueryable' to 'Mvc.Models.engineer'. An explicit conversion exists (are you missing a cast?) after write this code engineer Ing = new engineer(); Ing = from j in testPersons.ibekoengineer select j.Name; What is wrong?

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  • Why is "int + string" possible in statically-typed C# but not in dynamically-typed Python?

    - by Salvador Dali
    While studying C# I found it really strange, that dynamically typed Python will rise an error in the following code: i = 5 print i + " " whereas statically typed C# will normally proceed the similar code: int i = 5; Console.Write(i + " "); I would expect other way around (in python I would be able to do this without any casting, but C# would require me to cast int to string or string to int). Just to highlight, I am not asking what language is better, I am curious what was the reason behind implementing the language this way.

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  • Hibernate Initial SessionFactory creation failed

    - by user364746
    Hello.. I'm trying to use hibernate to fill my jsf selectonemenu in ApplicationBean (in Liferay). The problem is that I got Initial SessionFactory creation failed problem. Before putting my functions in the applicationbean I was setting them in sessionbean and I got no error. For now the full error Initial SessionFactory creation failed.java.lang.ClassCastException: org.hibernate.type.StringType cannot be cast to org.hibernate.type.VersionType Thanks

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  • C# - Basic question: What is '?' ?

    - by Amokrane
    Hi, I'm wondering what ? means in C# ? I'm seeing things like: DateTime? or int?. I suppose this is C# specific to C# 4.0? I can't look for it in Google because I don't know the name of this thing. The problem is I'm using DateTime and I have a lot of cast errors (from DateTime to DateTime?). Thank you

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  • Android pass a 2d int array from one activity to another ERROR

    - by user2189001
    ACTIVITY 1: Bundle bundle = new Bundle(); bundle.putSerializable("CustomLevelData", LevelCreator.LCLevelData); Intent i = new Intent(LevelCreatorPopout.this, GameView.class); i.putExtras(bundle); startActivity(i); ACTIVITY 2: LevelData=(int[][]) extras.getSerializable("CustomLevelData"); ERROR: E/AndroidRuntime(16220): FATAL EXCEPTION: main E/AndroidRuntime(16220): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.powerpoint45.maze/com.powerpoint45.maze.GameView}: java.lang.ClassCastException: java.lang.Object[] cannot be cast to int[][] I have searched but found nothing on 2d INT array passing

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  • Can you get a Func<T> (or similar) from a MethodInfo object?

    - by Dan Tao
    I realize that, generally speaking, there are performance implications of using reflection. (I myself am not a fan of reflection at all, actually; this is a purely academic question.) Suppose there exists some class that looks like this: public class MyClass { public string GetName() { return "My Name"; } } Bear with me here. I know that if I have an instance of MyClass called x, I can call x.GetName(). Furthermore, I could set a Func<string> variable to x.GetName. Now here's my question. Let's say I don't know the above class is called MyClass; I've got some object, x, but I have no idea what it is. I could check to see if that object has a GetName method by doing this: MethodInfo getName = x.GetType().GetMethod("GetName"); Suppose getName is not null. Then couldn't I furthermore check if getName.ReturnType == typeof(string) and getName.GetParameters().Length == 0, and at this point, wouldn't I be quite certain that the method represented by my getName object could definitely be cast to a Func<string>, somehow? I realize there's a MethodInfo.Invoke, and I also realize I could always create a Func<string> like: Func<string> getNameFunc = () => getName.Invoke(x, null); I guess what I'm asking is if there's any way to go from a MethodInfo object to the actual method it represents, incurring the performance cost of reflection in the process, but after that point being able to call the method directly (via, e.g., a Func<string> or something similar) without a performance penalty. What I'm envisioning might look something like this: // obviously this would throw an exception if GetActualInstanceMethod returned // something that couldn't be cast to a Func<string> Func<string> getNameFunc = (Func<string>)getName.GetActualInstanceMethod(x); (I realize that doesn't exist; I'm wondering if there's anything like it.) If what I'm asking doesn't make sense, or if I'm being unclear, I'll be happy to attempt to clarify.

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  • C# underlying types of enums

    - by Marlon
    What is the point of having enum SomeEnum : byte // <---- { SomeValue = 0x01, ... } when you have to make a cast just to assign it to the same type of variable as the enums underlying type? byte b = (byte)SomeEnum.SomeValue;

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  • Problem getting size of Website Xcode

    - by Michael Amici
    When i try and compile I come up with a warning that reads initialization makes pointer from integer without a cast. No clue why. I am just trying to get the size of a website. #import "Lockerz_RedemptionViewController.h" @implementation Lockerz_RedemptionViewController -(IBAction)startLoop:(id) sender { NSData *dataNew = [NSData dataWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://www.google.com/"]]]; NSUInteger *len = [dataNew length]; //error is here NSLog(@"%@", len); }

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