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  • How to convert an existing callback interface to use boost signals & slots

    - by the_mandrill
    I've currently got a class that can notify a number of other objects via callbacks: class Callback { virtual NodulesChanged() =0; virtual TurkiesTwisted() =0; }; class Notifier { std::vector<Callback*> m_Callbacks; void AddCallback(Callback* cb) {m_Callbacks.push(cb); } ... void ChangeNodules() { for (iterator it=m_Callbacks.begin(); it!=m_Callbacks.end(); it++) { (*it)->NodulesChanged(); } } }; I'm considering changing this to use boost's signals and slots as it would be beneficial to reduce the likelihood of dangling pointers when the callee gets deleted, among other things. However, as it stands boost's signals seems more oriented towards dealing with function objects. What would be the best way of adapting my code to still use the callback interface but use signals and slots to deal with the connection and notification aspects?

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  • operator+ overload returning object causing memory leaks, C++

    - by lampshade
    The problem i think is with returing an object when i overload the + operator. I tried returning a reference to the object, but doing so does not fix the memory leak. I can comment out the two statements: dObj = dObj + dObj2; and cObj = cObj + cObj2; to free the program of memory leaks. Somehow, the problem is with returning an object after overloading the + operator. #include <iostream> #include <vld.h> using namespace std; class Animal { public : Animal() {}; virtual void eat() = 0 {}; virtual void walk() = 0 {}; }; class Dog : public Animal { public : Dog(const char * name, const char * gender, int age); Dog() : name(NULL), gender(NULL), age(0) {}; virtual ~Dog(); Dog operator+(const Dog &dObj); private : char * name; char * gender; int age; }; class MyClass { public : MyClass() : action(NULL) {}; void setInstance(Animal &newInstance); void doSomething(); private : Animal * action; }; Dog::Dog(const char * name, const char * gender, int age) : // allocating here, for data passed in ctor name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Dog::~Dog() { delete name; delete gender; age = 0; } Dog Dog::operator+(const Dog &dObj) { Dog d; d.age = age + dObj.age; return d; } void MyClass::setInstance(Animal &newInstance) { action = &newInstance; } void MyClass::doSomething() { action->walk(); action->eat(); } int main() { MyClass mObj; Dog dObj("Scruffy", "Male", 4); // passing data into ctor Dog dObj2("Scooby", "Male", 6); mObj.setInstance(dObj); // set the instance specific to the object. mObj.doSomething(); // something happens based on which object is passed in dObj = dObj + dObj2; // invoke the operator+ return 0; }

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  • What is the reverse of GetVirtualPath for asp.net routing?

    - by Fredou
    From a virtualpath, I need to get his name. How can I do this? Since people think that I'm talking about file system here an example of what I need. With asp.net routing you can associate a name to a virtual file linked to a physical file. For an example, I can give the name homeEn to http://mysite.com/home which is linked to the physical file ~/homepage.aspx. What I need is from the virtual file http://mysite.com/home to get back homeEn name.

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  • How do I improve the efficiency of the queries executed by this generic Linq-to-SQL data access clas

    - by Lee D
    Hi all, I have a class which provides generic access to LINQ to SQL entities, for example: class LinqProvider<T> //where T is a L2S entity class { DataContext context; public virtual IEnumerable<T> GetAll() { return context.GetTable<T>(); } public virtual T Single(Func<T, bool> condition) { return context.GetTable<T>().SingleOrDefault(condition); } } From the front end, both of these methods appear to work as you would expect. However, when I run a trace in SQL profiler, the Single method is executing what amounts to a SELECT * FROM [Table], and then returning the single entity that meets the given condition. Obviously this is inefficient, and is being caused by GetTable() returning all rows. My question is, how do I get the query executed by the Single() method to take the form SELECT * FROM [Table] WHERE [condition], rather than selecting all rows then filtering out all but one? Is it possible in this context? Any help appreciated, Lee

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  • Problem when trying to use simple Shaders + VBOs

    - by Mr.Gando
    Hello I'm trying to convert the following functions to a VBO based function for learning purposes, it displays a static texture on screen. I'm using OpenGL ES 2.0 with shaders on the iPhone (should be almost the same than regular OpenGL in this case), this is what I got working: //Works! - (void) drawAtPoint:(CGPoint)point depth:(CGFloat)depth { GLfloat coordinates[] = { 0, 1, 1, 1, 0, 0, 1, 0 }; GLfloat width = (GLfloat)_width * _maxS, height = (GLfloat)_height * _maxT; GLfloat vertices[] = { -width / 2 + point.x, -height / 2 + point.y, width / 2 + point.x, -height / 2 + point.y, -width / 2 + point.x, height / 2 + point.y, width / 2 + point.x, height / 2 + point.y, }; glBindTexture(GL_TEXTURE_2D, _name); //Attrib position and attrib_tex coord are handles for the shader attributes glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices); glEnableVertexAttribArray(ATTRIB_POSITION); glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, GL_FALSE, 0, coordinates); glEnableVertexAttribArray(ATTRIB_TEXCOORD); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } I tried to do this to convert to a VBO however I don't see anything displaying on-screen with this version: //Doesn't display anything - (void) drawAtPoint:(CGPoint)point depth:(CGFloat)depth { GLfloat width = (GLfloat)_width * _maxS, height = (GLfloat)_height * _maxT; GLfloat position[] = { -width / 2 + point.x, -height / 2 + point.y, width / 2 + point.x, -height / 2 + point.y, -width / 2 + point.x, height / 2 + point.y, width / 2 + point.x, height / 2 + point.y, }; //Texture on-screen position ( each vertex is x,y in on-screen coords ) GLfloat coordinates[] = { 0, 1, 1, 1, 0, 0, 1, 0 }; // Texture coords from 0 to 1 glBindVertexArrayOES(vao); glGenVertexArraysOES(1, &vao); glGenBuffers(2, vbo); //Buffer 1 glBindBuffer(GL_ARRAY_BUFFER, vbo[0]); glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), position, GL_STATIC_DRAW); glEnableVertexAttribArray(ATTRIB_POSITION); glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, position); //Buffer 2 glBindBuffer(GL_ARRAY_BUFFER, vbo[1]); glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), coordinates, GL_DYNAMIC_DRAW); glEnableVertexAttribArray(ATTRIB_TEXCOORD); glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, GL_FALSE, 0, coordinates); //Draw glBindVertexArrayOES(vao); glBindTexture(GL_TEXTURE_2D, _name); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } In both cases I'm using this simple Vertex Shader //Vertex Shader attribute vec2 position;//Bound to ATTRIB_POSITION attribute vec4 color; attribute vec2 texcoord;//Bound to ATTRIB_TEXCOORD varying vec2 texcoordVarying; uniform mat4 mvp; void main() { //You CAN'T use transpose before in glUniformMatrix4fv so... here it goes. gl_Position = mvp * vec4(position.x, position.y, 0.0, 1.0); texcoordVarying = texcoord; } The gl_Position is equal to product of mvp * vec4 because I'm simulating glOrthof in 2D with that mvp And this Fragment Shader //Fragment Shader uniform sampler2D sampler; varying mediump vec2 texcoordVarying; void main() { gl_FragColor = texture2D(sampler, texcoordVarying); } I really need help with this, maybe my shaders are wrong for the second case ? thanks in advance.

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  • xsl : getting specific node values from a table

    - by prashant rao
    My XML Code <DBE:Attribute name="Test1" type="Table"> <DBE:Table> <DBE:TableHeader> <DBE:TableColumn>t1</DBE:TableColumn> <DBE:TableColumn>t2</DBE:TableColumn> <DBE:TableColumn>t3</DBE:TableColumn> <DBE:TableColumn>t4</DBE:TableColumn> <DBE:TableColumn>t5</DBE:TableColumn> <DBE:TableColumn>t6</DBE:TableColumn> <DBE:TableColumn>t7</DBE:TableColumn> <DBE:TableColumn>t8</DBE:TableColumn> <DBE:TableColumn>t9</DBE:TableColumn> <DBE:TableColumn>t10</DBE:TableColumn> <DBE:TableColumn>t11</DBE:TableColumn> <DBE:TableColumn>t12</DBE:TableColumn> <DBE:TableColumn>t13</DBE:TableColumn> </DBE:TableHeader> <DBE:TableRow> <DBE:TableData>0300 </DBE:TableData> <DBE:TableData/> <DBE:TableData>25</DBE:TableData> <DBE:TableData>25</DBE:TableData> <DBE:TableData>2009/09/03</DBE:TableData> <DBE:TableData/> <DBE:TableData>BAG</DBE:TableData> <DBE:TableData>rrr</DBE:TableData> <DBE:TableData>Yes</DBE:TableData> <DBE:TableData>12</DBE:TableData> <DBE:TableData>2009/03/09</DBE:TableData> <DBE:TableData>GO</DBE:TableData> <DBE:TableData/> </DBE:TableRow> </DBE:Table> </DBE:Attribute> I would like my output to be - t7 t5 t1 t13 --> Header --------------------------------------------------------------- BAG 2009/09/03 0300 GO --> ROW1 .............................................................. --> ROW2 and so on My XSL code -- (for only selected values to be displayed) <xsl:for-each select="DBE:Attribute[@name='Test1']/DBE:Table/DBE:TableRow"> <tr bgcolor="white"> <xsl:for-each select="DBE:TableData"> <td> <xsl:value-of select="node()|*"> </xsl:value-of> </td> </xsl:for-each> </tr> </xsl:for-each>

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  • Fluent nHibernate and mapping IDictionary<DaysOfWeek,IDictionay<int, decimal>> how to?

    - by JS Future Software
    Hello, I have problem with making mapping of classes with propert of type Dictionary and value in it of type Dictionary too, like this: public class Class1 { public virtual int Id { get; set; } public virtual IDictionary<DayOfWeek, IDictionary<int, decimal>> Class1Dictionary { get; set; } } My mapping looks like this: Id(i => i.Id); HasMany(m => m.Class1Dictionary); This doesn't work. The important thing I want have everything in one table not in two. WHet I had maked class from this second IDictionary I heve bigger problem. But first I can try like it is now.

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  • Serializing WPF DataTemplates and {Binding Expressions} (from PowerShell?)

    - by Jaykul
    Ok, here's the deal: I have code that works in C#, but when I call it from PowerShell, it fails. I can't quite figure it out, but it's something specific to PowerShell. Here's the relevant code calling the library (assuming you've added a reference ahead of time) from C#: public class Test { [STAThread] public static void Main() { Console.WriteLine( PoshWpf.XamlHelper.RoundTripXaml( "<TextBlock Text=\"{Binding FullName}\" xmlns=\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\"/>" ) ); } } Compiled into an executable, that works fine ... but if you call that method from PowerShell, it returns with no {Binding FullName} for the Text! add-type -path .\PoshWpf.dll [PoshWpf.Test]::Main() I've pasted below the entire code for the library, all wrapped up in a PowerShell Add-Type call so you can just compile it by pasting it into PowerShell (you can leave off the first and last lines if you want to paste it into a new console app in Visual Studio. To output (from PowerShell 2) as an executable, just change the -OutputType parameter to ConsoleApplication and the -OutputAssembly to PoshWpf.exe (or something). Thus, you can see that running the SAME CODE from the executable gives you the correct output. But running the two lines as above or manually calling [PoshWpf.XamlHelper]::RoundTripXaml or [PoshWpf.XamlHelper]::ConvertToXaml from PowerShell just doesn't seem to work at all ... HELP?! Add-Type -TypeDefinition @" using System; using System.ComponentModel; using System.Globalization; using System.Linq; using System.Windows; using System.Windows.Data; using System.Windows.Markup; namespace PoshWpf { public class Test { [STAThread] public static void Main() { Console.WriteLine( PoshWpf.XamlHelper.RoundTripXaml( "<TextBlock Text=\"{Binding FullName}\" xmlns=\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\"/>" ) ); } } public class BindingTypeDescriptionProvider : TypeDescriptionProvider { private static readonly TypeDescriptionProvider _DEFAULT_TYPE_PROVIDER = TypeDescriptor.GetProvider(typeof(Binding)); public BindingTypeDescriptionProvider() : base(_DEFAULT_TYPE_PROVIDER) { } public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance) { ICustomTypeDescriptor defaultDescriptor = base.GetTypeDescriptor(objectType, instance); return instance == null ? defaultDescriptor : new BindingCustomTypeDescriptor(defaultDescriptor); } } public class BindingCustomTypeDescriptor : CustomTypeDescriptor { public BindingCustomTypeDescriptor(ICustomTypeDescriptor parent) : base(parent) { } public override PropertyDescriptorCollection GetProperties(Attribute[] attributes) { PropertyDescriptor pd; var pdc = new PropertyDescriptorCollection(base.GetProperties(attributes).Cast<PropertyDescriptor>().ToArray()); if ((pd = pdc.Find("Source", false)) != null) { pdc.Add(TypeDescriptor.CreateProperty(typeof(Binding), pd, new Attribute[] { new DefaultValueAttribute("null") })); pdc.Remove(pd); } return pdc; } } public class BindingConverter : ExpressionConverter { public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType) { return (destinationType == typeof(MarkupExtension)) ? true : false; } public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType) { if (destinationType == typeof(MarkupExtension)) { var bindingExpression = value as BindingExpression; if (bindingExpression == null) throw new Exception(); return bindingExpression.ParentBinding; } return base.ConvertTo(context, culture, value, destinationType); } } public static class XamlHelper { static XamlHelper() { // this is absolutely vital: TypeDescriptor.AddProvider(new BindingTypeDescriptionProvider(), typeof(Binding)); TypeDescriptor.AddAttributes(typeof(BindingExpression), new Attribute[] { new TypeConverterAttribute(typeof(BindingConverter)) }); } public static string RoundTripXaml(string xaml) { return XamlWriter.Save(XamlReader.Parse(xaml)); } public static string ConvertToXaml(object wpf) { return XamlWriter.Save(wpf); } } } "@ -language CSharpVersion3 -reference PresentationCore, PresentationFramework, WindowsBase -OutputType Library -OutputAssembly PoshWpf.dll Again, you can get an executable by just altering the last line like so: "@ -language CSharpVersion3 -reference PresentationCore, PresentationFramework, WindowsBase -OutputType ConsoleApplication -OutputAssembly PoshWpf.exe

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  • How to write a bison grammer for WDI?

    - by Rizo
    I need some help in bison grammar construction. From my another question: I'm trying to make a meta-language for writing markup code (such as xml and html) wich can be directly embedded into C/C++ code. Here is a simple sample written in this language, I call it WDI (Web Development Interface): /* * Simple wdi/html sample source code */ #include <mySite> string name = "myName"; string toCapital(string str); html { head { title { mySiteTitle; } link(rel="stylesheet", href="style.css"); } body(id="default") { // Page content wrapper div(id="wrapper", class="some_class") { h1 { "Hello, " + toCapital(name) + "!"; } // Lists post ul(id="post_list") { for(post in posts) { li { a(href=post.getID()) { post.tilte; } } } } } } } Basically it is a C source with a user-friendly interface for html. As you can see the traditional tag-based style is substituted by C-like, with blocks delimited by curly braces. I need to build an interpreter to translate this code to html and posteriorly insert it into C, so that it can be compiled. The C part stays intact. Inside the wdi source it is not necessary to use prints, every return statement will be used for output (in printf function). The program's output will be clean html code. So, for example a heading 1 tag would be transformed like this: h1 { "Hello, " + toCapital(name) + "!"; } // would become: printf("<h1>Hello, %s!</h1>", toCapital(name)); My main goal is to create an interpreter to translate wdi source to html like this: tag(attributes) {content} = <tag attributes>content</tag> Secondly, html code returned by the interpreter has to be inserted into C code with printfs. Variables and functions that occur inside wdi should also be sorted in order to use them as printf parameters (the case of toCapital(name) in sample source). Here are my flex/bison files: id [a-zA-Z_]([a-zA-Z0-9_])* number [0-9]+ string \".*\" %% {id} { yylval.string = strdup(yytext); return(ID); } {number} { yylval.number = atoi(yytext); return(NUMBER); } {string} { yylval.string = strdup(yytext); return(STRING); } "(" { return(LPAREN); } ")" { return(RPAREN); } "{" { return(LBRACE); } "}" { return(RBRACE); } "=" { return(ASSIGN); } "," { return(COMMA); } ";" { return(SEMICOLON); } \n|\r|\f { /* ignore EOL */ } [ \t]+ { /* ignore whitespace */ } . { /* return(CCODE); Find C source */ } %% %start wdi %token LPAREN RPAREN LBRACE RBRACE ASSIGN COMMA SEMICOLON CCODE QUOTE %union { int number; char *string; } %token <string> ID STRING %token <number> NUMBER %% wdi : /* empty */ | blocks ; blocks : block | blocks block ; block : head SEMICOLON | head body ; head : ID | ID attributes ; attributes : LPAREN RPAREN | LPAREN attribute_list RPAREN ; attribute_list : attribute | attribute COMMA attribute_list ; attribute : key ASSIGN value ; key : ID {$$=$1} ; value : STRING {$$=$1} /*| NUMBER*/ /*| CCODE*/ ; body : LBRACE content RBRACE ; content : /* */ | blocks | STRING SEMICOLON | NUMBER SEMICOLON | CCODE ; %% I am having difficulties on defining a proper grammar for the language, specially in splitting WDI and C code . I just started learning language processing techniques so I need some orientation. Could someone correct my code or give some examples of what is the right way to solve this problem?

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  • XSLT: a variation on the pagination problem

    - by MarcoS
    I must transform some XML data into a paginated list of fields. Here is an example. Input XML: <?xml version="1.0" encoding="UTF-8"?> <data> <books> <book title="t0"/> <book title="t1"/> <book title="t2"/> <book title="t3"/> <book title="t4"/> </books> <library name="my library"/> </data> Desired output: <?xml version="1.0" encoding="UTF-8"?> <pages> <page number="1"> <field name="library_name" value="my library"/> <field name="book_1" value="t0"/> <field name="book_2" value="t1"/> </page> <page number="2"> <field name="book_1" value="t2"/> <field name="book_2" value="t3"/> </page> <page number="3"> <field name="book_1" value="t4"/> </page> </pages> In the above example I assume that I want at most 2 fields named book_n (with n ranging between 1 and 2) per page. Tags <page> must have an attribute number. Finally, the field named library_name must appear only the first <page>. Here is my current solution using XSLT: <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0" exclude-result-prefixes="trx xs"> <xsl:output method="xml" indent="yes" omit-xml-declaration="no" /> <xsl:variable name="max" select="2"/> <xsl:template match="//books"> <xsl:for-each-group select="book" group-ending-with="*[position() mod $max = 0]"> <xsl:variable name="pageNum" select="position()"/> <page number="{$pageNum}"> <xsl:for-each select="current-group()"> <xsl:variable name="idx" select="if (position() mod $max = 0) then $max else position() mod $max"/> <field value="{@title}"> <xsl:attribute name="name">book_<xsl:value-of select="$idx"/> </xsl:attribute> </field> </xsl:for-each> <xsl:if test="$pageNum = 1"> <xsl:call-template name="templateFor_library"/> </xsl:if> </page> </xsl:for-each-group> </xsl:template> <xsl:template name="templateFor_library"> <xsl:for-each select="//library"> <field name="library_name" value="{@name}" /> </xsl:for-each> </xsl:template> </xsl:stylesheet> Is there a better/simpler way to perform this transformation?

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  • generated service mock: everything but RhinoMocks fails?

    - by hko
    I have the "quest" to search for the next Mocking Framework for my company, and basically it's down to NSubstitute (simplest syntax, but no strict mocks), FakeItEasy(best reviews, Roy Osherove bonus, and slightly better lib support than NSubstitute), Moq (best "other libs support", biggest featureset, downside: mock.Object). We definitely want to move on from RhinoMocks, e.g. because of the unusefull interactiontest error messages (it should tell me what the parameter was instead, when a verification fails). So I was pretty surprised the other day (that was yesterday) when I found out RhinoMocks could do a thing where every other mock framework fails at: Mocking an autogenerated SomethingService (a typical VS autogenerated service with a default construtor in a partial class). Please don't argue about the design.. I intend to write lightweight integration tests (and some unit tests), and I can't mess around with the service, the product is installed on too many customers system. See this code: // here the NSubstitute and FakeItEasy equivalents throw an exception.. see below TicketStoreService fakeTicketStoreService = MockRepository.GenerateMock<TicketStoreService>(); fakeTicketStoreService.Expect(service => service.DoSomething(Arg.Is(new Guid())).Return(new Guid()); fakeTicketStoreService.DoSomething(Arg.Is(new Guid())); fakeTicketStoreService.VerifyAllExpectations(); Note that DoSomething is a non-virtual methodcall in an autogenerated class. So it shouldn't work, according to common knowledge. But it does. Problem is that it's the only (non commercial) framework that can do this: Rhino.Mocks works, and verification works too FakeItEasy says it doesn't find a default constructor (probably just wrong exception message): No default constructor was found on the type SomeNamespace.TicketStoreService Moq gives something sane and understandable: Invalid setup on a non-virtual (overridable in VB) member: service=> service.DoSomething Nsubstitute gives a message System.NotSupportedException: Cannot serialize member System.ComponentModel.Component.Site of type System.ComponentModel.ISite because it is an interface. I'm really wondering what's going on here with the frameworks, except Moq. The "fancy new" frameworks seem to have an initial perf hit too, probably preparing some Type cache and serializing stuff, whilst RhinoMocks somehow manages to create a very "slim" mock without recursion. I have to admit I didn't like RhinoMocks very well, but here it shines.. unfortunately. So, is there a way to get that to work with newer (non-commercial!) mocking frameworks, or somehow get a sane error message out of Rhino.Mocks? And why can Rhino.Mocks achieve this, when clearly every Mocking framework states it can only work with virtual methods when given a concrete class? Let's not derail the discussion by talking about alternative approaches like Extract&Override or runtime-proxy Mocking frameworks like JustMock/TypeMock/Moles or the new Fakes framework, I know these, but that would be less ideal solutions, for reasons beyond this topic. Any help appreciated..

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  • Why is the this-pointer needed to access inherited attributes?

    - by Shadow
    Hi, assume the following class is given: class Base{ public: Base() {} Base( const Base& b) : base_attr(b.base_attr) {} void someBaseFunction() { .... } protected: SomeType base_attr; }; When I want a class to inherit from this one and include a new attribute for the derived class, I would write: class Derived: public Base { public: Derived() {} Derived( const Derived& d ) : derived_attr(d.derived_attr) { this->base_attr = d.base_attr; } void SomeDerivedFunction() { .... } private: SomeOtherType derived_attr; }; This works for me (let's ignore eventually missing semicolons or such please). However, when I remove the "this-" in the copy constructor of the derived class, the compiler complains that "'base_attr' was not declared in this scope". I thought that, when inheriting from a class, the protected attributes would then also be accessible directly. I did not know that the "this-" pointer was needed. I am now confused if it is actually correct what I am doing there, especially the copy-constructor of the Derived-class. Because each Derived object is supposed to have a base_attr and a derived_attr and they obviously need to be initialized/set correctly. And because Derived is inheriting from Base, I don't want to explicitly include an attribute named "base_attr" in the Derived-class. IMHO doing so would generally destroy the idea behind inheritance, as everything would have to be defined again. EDIT Thank you all for the quick answers. I completely forgot the fact that the classes actually are templates. Please, see the new examples below, which are actually compiling when including "this-" and are failing when omiting "this-" in the copy-constructor of the Derived-class: Base-class: #include <iostream> template<class T> class Base{ public: Base() : base_attr(0) {} Base( const Base& b) : base_attr(b.base_attr) {} void baseIncrement() { ++base_attr; } void printAttr() { std::cout << "Base Attribute: " << base_attr << std::endl; } protected: T base_attr; }; Derived-class: #include "base.hpp" template< class T > class Derived: public Base<T>{ public: Derived() : derived_attr(1) {} Derived( const Derived& d) : derived_attr(d.derived_attr) { this->base_attr = d.base_attr; } void derivedIncrement() { ++derived_attr; } protected: T derived_attr; }; and for completeness also the main function: #include "derived.hpp" int main() { Derived<int> d; d.printAttr(); d.baseIncrement(); d.printAttr(); Derived<int> d2(d); d2.printAttr(); return 0; }; I am using g++-4.3.4. Although I understood now that it seems to come from the fact that I use template-class definitions, I did not quite understand what is causing the problem when using templates and why it works when not using templates. Could someone please further clarify this?

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  • Is there a way to change the maximum width of a window without using the WM_GETMINMAXINFO message?

    - by David
    I want to change the imposed Windows maximum width that a window can be resized to, for an external application's window (not my C#/WinForms program's window). The documentation of GetSystemMetrics for SM_CXMAXTRACK says: "The default maximum width of a window that has a caption and sizing borders, in pixels. This metric refers to the entire desktop. The user cannot drag the window frame to a size larger than these dimensions. A window can override this value by processing the WM_GETMINMAXINFO message." Is there a way to modify this SM_CXMAXTRACK value (either system wide or for one particular window), without processing the WM_GETMINMAXINFO message? Maybe an undocumented function, a registry setting, etc.? (Or: The documentation for MINMAXINFO.ptMaxTrackSize says: "This value is based on the size of the virtual screen and can be obtained programmatically from the system metrics SM_CXMAXTRACK and SM_CYMAXTRACK." Maybe there is a way to change the size of the virtual screen?) Thank you

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  • Unresolved symbol when inheriting interface

    - by LeopardSkinPillBoxHat
    It's late at night here and I'm going crazy trying to solve a linker error. If I have the following abstract interface: class IArpPacketBuilder { public: IArpPacketBuilder(const DslPortId& aPortId); virtual ~IArpPacketBuilder(); // Other abstract (pure virtual methods) here... }; and I instantiate it like this: class DummyArpPacketBuilder : public IArpPacketBuilder { public: DummyArpPacketBuilder(const DslPortId& aPortId) : IArpPacketBuilder(aPortId) {} ~DummyArpPacketBuilder() {} }; why am I getting the following error when linking? Unresolved symbol references: IArpPacketBuilder::IArpPacketBuilder(DslPortId const&): ppc603_vxworks/_arpPacketQueue.o IArpPacketBuilder::~IArpPacketBuilder(): ppc603_vxworks/_arpPacketQueue.o typeinfo for IArpPacketBuilder: ppc603_vxworks/_arpPacketQueue.o *** Error code 1 IArpPacketBuilder is an abstract interface, so as long as I define the constructors and destructions in the concrete (derived) interface, I should be fine, no? Well it appears not.

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  • Adding two different Objects by overloading operator+ C++

    - by lampshade
    Hello, I've been trying to figure out how to add a private member from Object A, to a private member from Object B. Both Cat and Dog Class's inheriate from the base class Animal. I have a thrid class 'MyClass', that I want to inheriate the private members of the Cat and Dog class. So in MyClass, I have a friend function to overload the + operator. THe friend function is defined as follows: MyClass operator+(const Dog &dObj, const Cat &cObj); I want to access dObj.age and cObj.age within the above function, invoke by this statement in main: mObj = dObj + cObj; Here is the entire source for a complete reference into the class objects: #include <iostream> #include <vld.h> using namespace std; class Animal { public : Animal() {}; virtual void eat() = 0 {}; virtual void walk() = 0 {}; }; class Dog : public Animal { public : Dog(const char * name, const char * gender, int age); Dog() : name(NULL), gender(NULL), age(0) {}; virtual ~Dog(); void eat(); void bark(); void walk(); private : char * name; char * gender; int age; }; class Cat : public Animal { public : Cat(const char * name, const char * gender, int age); Cat() : name(NULL), gender(NULL), age(0) {}; virtual ~Cat(); void eat(); void meow(); void walk(); private : char * name; char * gender; int age; }; class MyClass : private Cat, private Dog { public : MyClass() : action(NULL) {}; void setInstance(Animal &newInstance); void doSomething(); friend MyClass operator+(const Dog &dObj, const Cat &cObj); private : Animal * action; }; Cat::Cat(const char * name, const char * gender, int age) : name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Cat::~Cat() { delete name; delete gender; age = 0; } void Cat::walk() { cout << name << " is walking now.. " << endl; } void Cat::eat() { cout << name << " is eating now.. " << endl; } void Cat::meow() { cout << name << " says meow.. " << endl; } Dog::Dog(const char * name, const char * gender, int age) : name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Dog::~Dog() { delete name; delete gender; age = 0; } void Dog::eat() { cout << name << " is eating now.. " << endl; } void Dog::bark() { cout << name << " says woof.. " << endl; } void Dog::walk() { cout << name << " is walking now.." << endl; } void MyClass::setInstance(Animal &newInstance) { action = &newInstance; } void MyClass::doSomething() { action->walk(); action->eat(); } MyClass operator+(const Dog &dObj, const Cat &cObj) { MyClass A; //dObj.age; //cObj.age; return A; } int main() { MyClass mObj; Dog dObj("B", "Male", 4); Cat cObj("C", "Female", 5); mObj.setInstance(dObj); // set the instance specific to the object. mObj.doSomething(); // something happens based on which object is passed in dObj.bark(); mObj.setInstance(cObj); mObj.doSomething(); cObj.meow(); mObj = dObj + cObj; return 0; }

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  • What causes my borderless C++/CLI app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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  • Returning a C++ reference in a const member functionasses

    - by Chris Kaminski
    A have a class hierarchy that looks somethign like this: class AbstractDataType { public: virtual int getInfo() = 0; }; class DataType: public AbstractDataType { public: virtual int getInfo() { }; } class Accessor { DataType data; public: const AbstractDataType& getData() const { return(data); } } Well, GCC 4.4 reports: In member function ‘const AbstractDataType& Accessor::getData() const’: error: invalid initialization of reference of type ‘const AbstractDataType&’ from expression of type ‘const DataType’ Where am I going wrong - is this a case where I MUST use a pointer?

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  • Oracle Professional Developer, Ver. 6.0.33 for MS-DOS

    - by Frank Developer
    Hi, I'm trying to install this fossil in DOS 6.22, which is running in Microsoft Virtual PC 2007. I'm hoping that some of you veteran Oracle developers have any recollection of in what order do these diskette images need to be loaded, since I don't have any documentation available for 6.0.33. A friend emailed me the following 720K diskette images: INSTALLE.IMG RDBMS1.IMG RDBMS2.IMG RDBMS3.IMG RSF.IMG SQLLDR1.IMG SQLLDR2.IMG UTIL1.IMG UTIL2.IMG UTIL3.IMG Within Virtual PC, I capture a diskette image, one at a time, into Drive A: VPC's floppy disk emulation supports FAT12, so the supported diskette formats can be: 720K or 1.44MB. If anyone happens to have documentation for this legacy version, I would greatly appreciate a copy of it! Thank You.

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  • C++ Class Inheritance architecture - preventing casting

    - by Some One
    I have a structure of base class and a couple of inherited classed. Base class should be pure virtual class, it should prevent instantiation. Inherited classes can be instantiated. Code example below: class BaseClass { public: BaseClass(void); virtual ~BaseClass(void) = 0; }; class InheritedClass : public BaseClass { public: InheritedClass1(void); ~InheritedClass1(void); }; class DifferentInheritedClass : public BaseClass { public: DifferentInheritedClass(void); ~DifferentInheritedClass(void); }; I want to prevent the following operations to happen: InheritedClass *inherited1 = new InheritedClass(); DifferentInheritedClass *inherited2 = new DifferentInheritedClass (); BaseClass *base_1 = inherited1; BaseClass *base_2 = inherited2; *base_1 = *base_2;

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  • android set hidden the keybord on press enter (in a EditText)

    - by user119333
    Hi, When my user press "ENTER" on the virtual android "user validate entry!" keybord my keybord stay visible ! (Why?) Here my Java code... private void initTextField() { entryUser = (EditText) findViewById(R.id.studentEntrySalary); entryUser.setOnKeyListener(new OnKeyListener() { public boolean onKey(View v, int keyCode, KeyEvent event) { if (event.getAction() == KeyEvent.ACTION_DOWN) { switch (keyCode) { case KeyEvent.KEYCODE_DPAD_CENTER: case KeyEvent.KEYCODE_ENTER: userValidateEntry(); return true; } } return true; } }); } private void userValidateEntry() { System.out.println("user validate entry!"); } ... here my View <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="wrap_content"> <EditText android:id="@+id/studentEntrySalary" android:text="Foo" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout> Maybe something wrong on my virtual device ?

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  • C++: warning: '...' declared with greater visibility than the type of its field '...::<anonymous>'

    - by Albert
    I'm getting these two warnings (with GCC 4.2 on MacOSX): /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154: warning: 'startMainLockDetector()::MainLockDetector' declared with greater visibility than the type of its field 'startMainLockDetector()::MainLockDetector::<anonymous' /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154: warning: 'startMainLockDetector()::MainLockDetector' declared with greater visibility than its base 'Action' In this code: struct Action { virtual ~Action() {} virtual int handle() = 0; }; static void startMainLockDetector() { /* ... */ struct MainLockDetector : Action { bool wait(Uint32 time) { /* ... */ } int handle() { /* ... */ } }; /* ... */ } I'm not exactly sure what these warnings mean (what visibility?) and how to fix them. (I really want the class MainLockDetector to be local for that function only.) I have already compiled the same code with a lot of other compilers (clang, GCC 3.*, GCC 4.0, GCC 4.4, etc) and never got any warning for this code.

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  • How to Sort List Collection

    - by Muhammad Akhtar
    I have class like public class ProgressBars { public ProgressBars() { } private Int32 _ID; private Int32 _Name; public virtual Int32 ID {get { return _ID; } set { _ID = value; } } public virtual Int32 Name { get { return _Name; } set { _Name = value; }} } here is List collection List<ProgressBars> progress; progress.Sort //I need to get sort here by Name how can I sort this collection? Thanks

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  • What causes my borderless C++ app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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