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  • How to approach copying objects with smart pointers as class attributes?

    - by tomislav-maric
    From the boost library documentation I read this: Conceptually, smart pointers are seen as owning the object pointed to, and thus responsible for deletion of the object when it is no longer needed. I have a very simple problem: I want to use RAII for pointer attributes of a class that is Copyable and Assignable. The copy and assignment operations should be deep: every object should have its own copy of the actual data. Also, RTTI needs to be available for the attributes (their type may also be determined at runtime). Should I be searching for an implementation of a Copyable smart pointer (the data are small, so I don't need Copy on Write pointers), or do I delegate the copy operation to the copy constructors of my objects as shown in this answer? Which smart pointer do I choose for simple RAII of a class that is copyable and assignable? (I'm thinking that the unique_ptr with delegated copy/assignment operations to the class copy constructor and assignment operator would make a proper choice, but I am not sure) Here's a pseudocode for the problem using raw pointers, it's just a problem description, not a running C++ code: // Operation interface class ModelOperation { public: virtual void operate = (); }; // Implementation of an operation called Special class SpecialModelOperation : public ModelOperation { private: // Private attributes are present here in a real implementation. public: // Implement operation void operate () {}; }; // All operations conform to ModelOperation interface // These are possible operation names: // class MoreSpecialOperation; // class DifferentOperation; // Concrete model with different operations class MyModel { private: ModelOperation* firstOperation_; ModelOperation* secondOperation_; public: MyModel() : firstOperation_(0), secondOperation_(0) { // Forgetting about run-time type definition from input files here. firstOperation_ = new MoreSpecialOperation(); secondOperation_ = new DifferentOperation(); } void operate() { firstOperation_->operate(); secondOperation_->operate(); } ~MyModel() { delete firstOperation_; firstOperation_ = 0; delete secondOperation_; secondOperation_ = 0; } }; int main() { MyModel modelOne; // Some internal scope { // I want modelTwo to have its own set of copied, not referenced // operations, and at the same time I need RAII to work for it, // as soon as it goes out of scope. MyModel modelTwo (modelOne); } return 0; }

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  • WPF DataGrid, Help with Binding to a List<X> where each X has a Dictionary<Y,object> property.

    - by panamack
    I'm building an application which helps someone manage an event and works with data originating from Excel. I want to use the WPF Toolkit DataGrid to display the incoming data but can't guarantee how many Columns there are going to be or what information they will contain. I'd like to have an Info class that stores column information and have each Visitor at my Event own a Dictionary that uses shared references to Info objects for the keys. Here's the general gist: public class Info{ public string Name{get;set;} public int InfoType{get;set;} } public class Visitor{ public Dictionary<Info,object> VisitorInfo {get;set;} } public class Event{ public List<Visitor> Visitors{get;set;} public Event(){ Info i1 = new Info(){ Name = "ID", InfoType = 0};// type 0 for an id Info i2 = new Info(){ Name = "Name", InfoType = 1};// type 1 for a string Info i3 = new Info(){ Name = "City", InfoType = 1}; Visitor v1 = new Visitor(); v1.VisitorInfo.Add(i1, 0); v1.VisitorInfo.Add(i2, "Foo Harris"); v1.VisitorInfo.Add(i3, "Barsville"); Visitor v2 = new Visitor(); ... this.Visitors.Add(v1); this.Visitors.Add(v2); ... } } XAML: <!-- Window1.xaml --> ... <local:Event x:Key="MyEvent"/> ... <wpftk:DataGrid DataContext="{StaticResource MyEvent}" ItemsSource="{Binding Path=Visitors}" /> Disappointingly, DataGrid just sees a collection of Visitors each having a VisitorInfo property and displays one column called VisitorInfo with the string "(Collection)" once for each Visitor. As a workaround I've created a ListTVisitorToDataTableConverter that maps Infos to DataColumns and Visitors to DataRows and used it like this: <wpftk:DataGrid DataContext="{StaticResource Event}" ItemsSource{Binding Path=Visitors, Converter={StaticResource MySmellyListTVisitorToDataTableConverter}}" /> I don't think this is good though, I haven't started trying to convert back yet which I guess I'll need to do if I want to be able to edit any data! How can I do better? Thanks.

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  • Bind Icon depending on Enum in WPF Treeview

    - by phenevo
    Hi, I have at treeeview TextBox, and I want convert my Enum: <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="{Binding Path=AcceptationStatusGlobalFlag}" /> public enum AcceptationStatusGlobalFlag { NotReady = 0, Ready = 1, AcceptedByAdmin=2 } To Icons. There will be 3 icons, let say ready.jpg, notready.jpg and AcceptedByAdmin.jpg Country and Region has pool AcceptationStatusGlobalFlag and on both I want to display this enum/Icon <TreeView Name="structureTree" SelectedItemChanged="structureTree_SelectedItemChanged" Grid.Row="0" Grid.Column="0" ItemsSource="{Binding}" Height="413" ScrollViewer.VerticalScrollBarVisibility="Visible" ScrollViewer.HorizontalScrollBarVisibility="Visible" Width="Auto" PreviewMouseRightButtonUp="structureTree_PreviewMouseRightButtonUp" FontFamily="Verdana" FontSize="12"> <TreeView.Resources> <HierarchicalDataTemplate DataType="{x:Type ServiceMy:Country}" ItemsSource="{Binding Path=ListOfRegions}"> <StackPanel Orientation="Horizontal"> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="{Binding Path=Name}"/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text=" H:"/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="{Binding Path=NumberOfHotels}"/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text=" "/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text=" FG:"/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="{Binding Path=AcceptationStatusGlobalFlag}" /> <!--<Button Name="BTNAddRegion" Height="20" Content="+" Click="BTNAddRegion_Click"></Button>--> </StackPanel> </HierarchicalDataTemplate> <HierarchicalDataTemplate DataType="{x:Type ServiceMy:Region}" ItemsSource="{Binding Path=ListOfProvinces}"> <StackPanel Orientation="Horizontal"> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="{Binding Path=Name}"/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text=" H:"/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text="{Binding Path=NumberOfHotels}"/> <TextBlock TextAlignment="Justify" VerticalAlignment="Center" Text=" "/> <!--<Button Name="BTNAddProvince" Height="20" Content="+" Click="BTNAddProvince_Click"></Button>--> </StackPanel> </DataTemplate> </TreeView.Resources> </TreeView> </GroupBox> </StackPanel> </Grid>

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  • STI and subclasses

    - by markiv
    Hi All, I want to know, what is a rails way of converting a subclass record to another subclass record, just changing type isn't working and also superclass to subclass and vice versa. Thanks in advance Markiv

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  • python object to native c++ pointer

    - by Lodle
    Im toying around with the idea to use python as an embedded scripting language for a project im working on and have got most things working. However i cant seem to be able to convert a python extended object back into a native c++ pointer. So this is my class: class CGEGameModeBase { public: virtual void FunctionCall()=0; virtual const char* StringReturn()=0; }; class CGEPYGameMode : public CGEGameModeBase, public boost::python::wrapper<CGEPYGameMode> { public: virtual void FunctionCall() { if (override f = this->get_override("FunctionCall")) f(); } virtual const char* StringReturn() { if (override f = this->get_override("StringReturn")) return f(); return "FAILED TO CALL"; } }; Boost wrapping: BOOST_PYTHON_MODULE(GEGameMode) { class_<CGEGameModeBase, boost::noncopyable>("CGEGameModeBase", no_init); class_<CGEPYGameMode, bases<CGEGameModeBase> >("CGEPYGameMode", no_init) .def("FunctionCall", &CGEPYGameMode::FunctionCall) .def("StringReturn", &CGEPYGameMode::StringReturn); } and the python code: import GEGameMode def Ident(): return "Alpha" def NewGamePlay(): return "NewAlpha" def NewAlpha(): import GEGameMode import GEUtil class Alpha(GEGameMode.CGEPYGameMode): def __init__(self): print "Made new Alpha!" def FunctionCall(self): GEUtil.Msg("This is function test Alpha!") def StringReturn(self): return "This is return test Alpha!" return Alpha() Now i can call the first to functions fine by doing this: const char* ident = extract< const char* >( GetLocalDict()["Ident"]() ); const char* newgameplay = extract< const char* >( GetLocalDict()["NewGamePlay"]() ); printf("Loading Script: %s\n", ident); CGEPYGameMode* m_pGameMode = extract< CGEPYGameMode* >( GetLocalDict()[newgameplay]() ); However when i try and convert the Alpha class back to its base class (last line above) i get an boost error: TypeError: No registered converter was able to extract a C++ pointer to type class CGEPYGameMode from this Python object of type Alpha I have done alot of searching on the net but cant work out how to convert the Alpha object into its base class pointer. I could leave it as an object but rather have it as a pointer so some non python aware code can use it. Any ideas?

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  • Library to write javascript code

    - by Melursus
    Is there a c# library that can help to write and indent Javascript code. It's because I'm writing some c# code that generated some Javascript code. Something like this : js += "<script type=\"text/javascript\">\n"; js += " function()...\n"; And I find that generated a lot of ugly code. So, I thought that maybe a existing library can help me doing that ?

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  • what functions are called when passing value to function

    - by Tim
    In C++, if an object of a class is passed as a parameter into a function, the copy constructor of the class will be called. I was wondering if the object is of nonclass type, what function will be called? Similarly in C, what function is called when passing values or address of variables into a function? Thanks and regards!

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  • How does google swirl work?

    - by Karthik
    I have seen this type of effect on a visual thesaurus. Is there any open source code for this. I don't care about the algorithm to match similar objects. I only am wondering about the effects.

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  • http transfer file from server to server

    - by qualle
    Hi, with html forms we can upload a file from a client to a server with enctype="multipart/form-data", input type="file" and so on. Is there a way to have a file already ON the server and transfer it to another server the same way? Thanks for hints.

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  • Adding Transparency/alpha to Embedded Font

    - by Shubhra Bhushan
    Hi guys, I have embedded a font type in my application. Its working fine inside a text area. Now i need to add 60% transparency to it. In fact I need multiple transparency levels. Like - 60 % transparency for TextARea 70% for WindowShade Header etc. How do I add alpha values to it?

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  • Looping on a closed range

    - by AProgrammer
    How would you fix this code? template <typename T> void closed_range(T begin, T end) { for (T i = begin; i <= end; ++i) { // do something } } T is constrained to be an integer type, can be the wider of such types and can be signed or unsigned begin can be numeric_limits<T>::min() end can be numeric_limits<T>::max() (in which case ++i will overflow in the above code) I've several ways, but none I really like.

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  • Improving MVP in Scala

    - by Alexey Romanov
    The classical strongly typed MVP pattern looks like this in Scala: trait IView { } trait Presenter[View <: IView] { // or have it as an abstract type member val view : View } case class View1(...) extends IView { ... } case object Presenter1 extends Presenter[View1] { val view = View1(...) } Now, I wonder if there is any nice way to improve on it which I am missing...

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  • Multi-Column Primary Key in MySQL 5

    - by Kaji
    I'm trying to learn how to use keys and to break the habit of necessarily having SERIAL type IDs for all rows in all my tables. At the same time, I'm also doing many-to-many relationships, and so requiring unique values on either column of the tables that coordinate the relationships would hamper that. How can I define a primary key on a table such that any given value can be repeated in any column, so long as the combination of values across all columns is never repeated exactly?

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  • Node.js A Good authentication module ? or whats the proper way to authenticate users?

    - by Mohamed Ahmed
    I'm learning Node.js and looking forward to create a simple web application which will be based on Express and I was thinking of something like creating user groups and each group has its own users and each group has its own permissions (Just like ACL in Cakephp) So can anyone recommend a good module or whatever to do so ? Also I'm a little curious about security and how these passwords are going to be saved and what type of encryption the passwords will be encrypted in. Thanks :)

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  • how to disable a javascipt hyperlink?

    - by user320946
    Hi everyone, I just get a script from a website to put it on my own, but it has a hyperlink on it and I want to disable that, here is the script: <script language="javascript" src="http://www.parstools.net/calendar/?type=2"> </script> thanks.

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  • How can an object not be compared to null?

    - by ProfK
    I have an 'optional' parameter on a method that is a KeyValuePair. I wanted an overload that passes null to the core method for this parameter, but in the core method, when I want to check if the KeyValuePair is null, I get the following error: Operator '!=' cannot be applied to operands of type System.Collections.Generic.KeyValuePair<string,object>' and '<null>. How can I not be allowed to check if an object is null?

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  • How are iterators and pointers related?

    - by sharptooth
    Code with iterators looks pretty much like code with pointers. Iterators are of some obscure type (like std::vector<int>::iterator for example). What I don't get is how iterators and pointer are related to each other - is an iterator a wrapper around a pointer with overloaded operations to advance to adjacent elements or is it something else?

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  • Can you make an incrementing compiler constant?

    - by Keith Nicholas
    While sounding nonsensical..... I want a Contant where every time you use it it will increment by 1 int x; int y; x = INCREMENTING_CONSTNAT; y = INCREMENTING_CONSTNAT; where x == 1; and y == 2 Note I don't want y = INCREMENTING_CONSTNAT+1 type solutions. Basically I want to use it as a compile time unique ID ( generally it wouldn't be used in code like the example but inside another macro)

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  • immplementing security with session variables, how it is insecure

    - by haansi
    Hello, I am doing web based projects in dotnet. Currently I am implementing security using session variables. I keep current user id and user type in session and authenticate user from these session variables (say Session["UserId"],Session["UserName"] and Session["UserType"]) I do authentications. Please guide me how it is insecure ? I heard such security can be broken and applications can be hacked very easily, like it is possible to get session id and directly connect to that session id etc. Please guide me on this thanks

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