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  • fluent interface program in Ruby

    - by intern
    we have made the following code and trying to run it. class Numeric def gram self end alias_method :grams, :gram def of(name) ingredient = Ingredient.new(name) ingredient.quantity=self return ingredient end end class Ingredient def initialize(n) @@name= n end def quantity=(o) @@quantity = o return @@quantity end def name return @@name end def quantity return @@quantity end end e= 42.grams.of("Test") a= Ingredient.new("Testjio") puts e.quantity a.quantity=90 puts a.quantity puts e.quantity the problem which we are facing in it is that the output of puts a.quantity puts e.quantity is same even when the objects are different. what we observed is that second object i.e 'a' is replacing the value of the first object i.e. 'e'. the output is coming out to be 42 90 90 but the output required is 42 90 42 can anyone suggest why is it happening? it is not replacing the object as object id's are different..only the values of the objects are replaced.

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  • Is it good practice to put private API in the .m files and public API in .h files in Cocoa?

    - by Paperflyer
    Many of my classes in my current project have several properties and methods that are only ever called from within the class itself. Also, they might mess with the working of the class depending on the current state of the class. Currently, all these interfaces are defined in the main interface declaration in the .h files. Is it considered good practice to put the “private” methods and properties at the top of the .m files? This won't ever affect anything since I am very likely the only person ever to look at this source code, but of course it would be interesting to know for future projects.

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  • Is there any ready-made calendar control for iPhone apps?

    - by chester
    I am building an applicaiton for the iPhone that will display upcoming and past events. I settled for a list view, but then I realized that a calendar (just like the one displayed in the "month" view in the built-in Calendar application) would be a best match (that is, this one). However, the iPhone Human Interface Guidelines just mentions the Date Picker, not the calendar, so I believe there is nothing like that out of the box. Is that true? If so, does anyone know of a third-party control that could be used? (I could write one myself, but I'd rather pick up something ready, since this is a departure on the original project plans). Thank you all for your attention.

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  • MCV/MVP Patterns and Applications that interface with Hardware (DAQ/PLC/etc)

    - by Ryan
    I've been reading a lot about the MCV and MVP patterns for use with UI and it seems like a really nice powerful way to handle user interfaces. I am - however - having a difficult time deciding how this could integrate into a system where data in the model is created from a Data Acquisition System or Serial/Ethernet devices. There is also the added step that 70% of application interaction is performed by a PLC instead of a live user. It seems that for apps that just read/write & manipulate information from a database this works great, but how does does hardware and automation fit into these patterns? Is it as simple as another controller (for lack of a better term) that interacts with hardware that manipulates data and writes to a model? Maybe I am over thinking this or thinking too simply, so any advice would be great. I'm not quite sure where I'm going with this, so if something doesn't make sense or I was too vague leave me a comment. Thanks!

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  • EF 4.0 Code only assocation from abstract to derived

    - by Jeroen
    Using EF 4.0 Code only i want to make an assocation between an abstract and normal class. I have class 'Item', 'ContentBase' and 'Test'. 'ContentBase' is abstract and 'Test' derives from it. 'ContentBase' has a property 'Item' that links to an instance of 'Item'. So that 'Test.Item' or any class that derives from 'ContentBase' has an 'Item' navigation property. In my DB every record for Test has a matching record for Item. public class Item { public int Id { get; set;} } public abstract class ContentBase { public int ContentId { get; set;} public int Id { get; set;} public Item Item { get; set;} } public class Test : ContentBase { public string Name { get; set;} } now some init code public void SomeInitFunction() { var itemConfig = new EntityConfiguration<Item>(); itemConfig.HasKey(p => p.Id); itemConfig.Property(p => p.Id).IsIdentity(); this.ContextBuilder.Configurations.Add(itemConfig); var testConfig = new EntityConfiguration<Test>(); testConfig.HasKey(p => p.ContentId); testConfig.Property(p => p.ContentId).IsIdentity(); // the problem testConfig.Relationship(p => p.Item).HasConstraint((p, q) => p.Id == q.Id); this.ContextBuilder.Configurations.Add(testConfig); } This gives an error: A key is registered for the derived type 'Test'. Keys must be registered for the root type 'ContentBase'. anyway i try i get an error. What am i a doing wrong?

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  • Sorting NSTableColumn contents

    - by Yahoo
    Hey, I have a problem with sorting NSTableColumn contents. In my NSTableView there are three columns: File, Size, Path. The contents are stored in NSMutableArray. Each object in this array is a NSDictionary containing three keys: file, size and path - value for each is a NSString. In Interface Builder, in each Table Column's attributes I can choose sorting options: Selector: IB entered "compare:" which I think is ok, because I compare NSStrings. Sort Key - and that's the problem I think - I don't know what to enter here. Any clues? If you've got questions about my code, please ask.

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  • Maven POM: how to insist property is not overridden

    - by Joe Thomas
    I have a parent POM that uses a gmaven script to do some stuff: <plugin> <groupId>org.codehaus.gmaven</groupId> <artifactId>gmaven-plugin</artifactId> <version>1.4</version> <configuration combine.children="override"> <providerSelection>2.0</providerSelection> <scriptPath>${basedir}/build/groovy</scriptPath> </configuration> <executions> <execution> <id>groovy-properties-script</id> <phase>validate</phase> <goals> <goal>execute</goal> </goals> <configuration> <source>computeProperties.groovy</source> </configuration> </execution> <!-- ... --> All of the children are supposed to run this script as well, but they try to resolve the scriptpath based on their OWN basedir. Usually this is exactly what you want with properties, but here it doesn't work, and I can't figure out any way around it.

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  • Using member variables inherited from a templated base class (C++)

    - by Aaron Becker
    I'm trying to use member variables of a templated base class in a derived class, as in this example: template <class dtype> struct A { int x; }; template <class dtype> struct B : public A<dtype> { void test() { int id1 = this->x; // always works int id2 = A<dtype>::x; // always works int id3 = B::x; // always works int id4 = x; // fails in gcc & clang, works in icc and xlc } }; gcc and clang are both very picky about using this variable, and require either an explicit scope or the explicit use of "this". With some other compilers (xlc and icc), things work as I would expect. Is this a case of xlc and icc allowing code that's not standard, or a bug in gcc and clang?

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  • Having a base class function depend on its child class C#

    - by Junk Junk
    I have a Base class with a method that a child class will almost always override. However, instead of replacing the base class' method entirely, I would like for whatever is derived in the child class to be added to what is already in the base class. For Example: class BaseClass public string str() { var string = "Hello my name is" ; } class ChildClass : BaseClass public override string str(){ var string = "Sam"; } The point is that if I want to access the str() method by creating an instance of the ChildClass, the string will print out as "Hello, my name is Sam". I've been looking around and all I have been finding is that this should NOT happen, as the base class shouldn't even know that it is being inherited. So, if the design is false, how would I go about doing this? Keep in mind that there will be multiple child classes inheriting from BaseClass. Thank you

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  • Different return value of an overridden class

    - by Samer Afach
    I have a simple but confusing question here. Is it legal to have a different return value type for overridden methods than the abstact ones defined in the base class?? I did that and the compiler didn't complain... could someone please explain? class MyBaseClass { int value; public: virtual int getValue() = 0; }; class MyClass : public MyBaseClass { double value; public: virtual double getValue(); // here!!! return is double, not int }; double MyClass::getValue() { return this->value; } The compiler totally accepted something similar (MSVC und MinGW)... could anyone please exaplain to what extent this is legal?

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  • Java method get the inheriting type

    - by DrDro
    I have several classes that extend C and I would need a method that accepts any argument of type C. But in this method I would like to know if I'm dealing with A or B. * public A extends C public B extends C public void goForIt(C c)() If I cast how can I retrieve the type in a clean way (I just read using getClass or instanceof is often not the best way). PS: Fell free to edit an explicit title. *Sorry but I can't type closing braces

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  • Best way to insert items from a Derived class's constructor into a Base class's private std::vector?

    - by Will
    I have these classes: class Base { ... private: std::vector<X> v; }; class Derived { Derived(X*, int n); } where the constructor of Derived is passed an array of item Xs, which I need to insert into my vector v in the Base class. (X is a smart pointer) Currently I see two ways to do this: 1) Create a function in Base: InsertItem(X*) that will insert an item into the vector. 2) Create a vector in Derived that contains the full list, then get it into Base by moving the entire vector. I dont see any advantages to #2, but was wondering if #1 was a good solution, or if there are better ways to do this. Thanks!

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  • printing using one '\n'

    - by Alex
    I am pretty sure all of you are familiar with the concept of the Big4, and I have several stuffs to do print in each of the constructor, assignment, destructor, and copy constructor. The restriction is this: I CAN'T use more than one newline (e.g., ƒn or std::endl) in any method I can have a method called print, so I am guessing print is where I will put that precious one and only '\n', my problem is that how can the method print which prints different things on each of the element I want to print in each of the Big4? Any idea? Maybe overloading the Big4?

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  • Java generics question

    - by user247866
    So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = methodCall(); // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void someMethod(List<A> a) However, when I do: C c = new C(); c.someMethod(b); I get an error that some-method is not applicable for the argument List<B>, instead it's expecting to get List<A>. Is there a good way to fix this problem? Many thanks!

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  • User interface for messaging app for WP7

    - by ArtWorkAD
    I have a Message.xaml file that should display a recipient field and a message field like this: The user can add multiple recipients, so the TextBox should be flexible in height. I managed this with following code: <TextBox FontSize="24" Margin="0,0,80,532" Name="absenderField" AcceptsReturn="True" TextWrapping="Wrap" Height="auto" MinHeight="30" MaxWidth="375"> </TextBox> Now the recipient field is growing in height when text is added that does not fit into it. The other TextBox is for the message. The markup is the same as for the recipient field, just the height is different. The first problem is, that when the recipient field growes it goes over the message field but the message field should be aligned at the bottom of the recipient field and move down. how can I achieve that? Now the other problem. When I enter a lot of text to make the message field grow, the recipient field will grow too. This is very strange. Why does this happen? Is it possible to make the text scroll inside the text box? Whole xaml: http://pastebin.com/xPg7rV9e

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  • How to implement image map type interface for a game board in Java 6

    - by Billy
    My group project at school is to implement a style of monopoly in which students can buy courses and land on various squares and move around the board. This is not a regular square board so we were wondering if anyone had any ideas on how we would implement an image map or something like it to create many clickable regions not in a perfect square. I have attached the image of the game board. Just a way to start is needed, not lots of code or anything as we all know java pretty well. If anyone has any ideas that would be great. Image of board is here. http://imgur.com/fH5WC.png

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  • Where in the standard is forwarding to a base class required in these situations?

    - by pgast
    Maybe even better is: Why does the standard require forwarding to a base class in these situations? (yeah yeah yeah - Why? - Because.) class B1 { public: virtual void f()=0; }; class B2 { public: virtual void f(){} }; class D : public B1,public B2{ }; class D2 : public B1,public B2{ public: using B2::f; }; class D3 : public B1,public B2{ public: void f(){ B2::f(); } }; D d; D2 d2; D3 d3; EDG gives: sourceFile.cpp sourceFile.cpp(24) : error C2259: 'D' : cannot instantiate abstract class due to following members: 'void B1::f(void)' : is abstract sourceFile.cpp(6) : see declaration of 'B1::f' sourceFile.cpp(25) : error C2259: 'D2' : cannot instantiate abstract class due to following members: 'void B1::f(void)' : is abstract sourceFile.cpp(6) : see declaration of 'B and similarly for the MS compiler. I might buy the first case,D. But in D2 - f is unambiguously defined by the using declaration, why is that not enough for the compiler to be required to fill out the vtable? Where in the standard is this situation defined?

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  • C++ function overloading and dynamic binding compile problem

    - by Olorin
    #include <iostream> using namespace std; class A { public: virtual void foo(void) const { cout << "A::foo(void)" << endl; } virtual void foo(int i) const { cout << i << endl; } virtual ~A() {} }; class B : public A { public: void foo(int i) const { this->foo(); cout << i << endl; } }; class C : public B { public: void foo(void) const { cout << "C::foo(void)" << endl; } }; int main(int argc, char ** argv) { C test; test.foo(45); return 0; } The above code does not compile with: $>g++ test.cpp -o test.exe test.cpp: In member function 'virtual void B::foo(int) const': test.cpp:17: error: no matching function for call to 'B::foo() const' test.cpp:17: note: candidates are: virtual void B::foo(int) const test.cpp: In function 'int main(int, char**)': test.cpp:31: error: no matching function for call to 'C::foo(int)' test.cpp:23: note: candidates are: virtual void C::foo() const It compiles if method "foo(void)" is changed to "goo(void)". Why is this so? Is it possible to compile the code without changing the method name of "foo(void)"? Thanks.

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  • A question about entities, roles and interfaces in Entity Framework 4.

    - by mvole
    Hi, I am an experienced .NET developer but new to EF - so please bear with me. I will use an example of a college application to illustrate my problem. I have these user roles: Lecturer, Student, Administrator. In my code I envisage working with these entities as distinct classes so e.g. a Lecturer teaches a collection of Students. And work with 'is Student' 'TypeOf' etc. Each of these entities share lots of common properties/methods e.g. they can all log onto the system and do stuff related to their role. In EF designer I can create a base entity Person (or User...) and have Lecturer, Student and Administrator all inherit from that. The difficulty I have is that a Lecturer can be an Administrator - and in fact on occasion a Student can be a Lecturer. If I were to add other entities such as Employee and Warden then this gets even more of an issue. I could presumably work with Interfaces so a person could implement ILecturer and IStudent, however I do not see how this fits within EF. I would like to work within the EF designer if possible and I'm working model-first (coding in C#). So any help and advice/samples would be very welcome and much appreciated. Thanks

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  • Why can't I expose an interface in a .NET asmx web service?

    - by mcliedtk
    I have a .NET web service (using asmx...have not upgraded to WCF yet) that exposes the following: public class WidgetVersion1 : IWidget {} public class WidgetVersion2 : IWidget {} When I attempt to bind to the web service, I get the following serialization error: Cannot serialize member WidgetVersion1 of type IWidget because it is an interface. I have tried adding various attributes to the IWidget interface (XmlIgnore, SoapIgnore, NonSerialized), but they are not valid on an interface. Does anyone know why I am unable to expose the interface? I assume WSDL does not support interfaces, but couldn't .NET get around this by simply not serializing the interface? Are there any ways around this apart from removing the IWidget interface from the WidgetVersion1 and WidgetVersion2 class definitions?

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  • PyQt - QLabel inheriting

    - by Ockonal
    Hello, i wanna inherit QLabel to add there click event processing. I'm trying this code: class NewLabel(QtGui.QLabel): def __init__(self, parent): QtGui.QLabel.__init__(self, parent) def clickEvent(self, event): print 'Label clicked!' But after clicking I have no line 'Label clicked!' EDIT: Okay, now I'm using not 'clickEvent' but 'mousePressEvent'. And I still have a question. How can i know what exactly label was clicked? For example, i have 2 edit box and 2 labels. Labels content are pixmaps. So there aren't any text in labels, so i can't discern difference between labels. How can i do that? EDIT2: I made this code: class NewLabel(QtGui.QLabel): def __init__(self, firstLabel): QtGui.QLabel.__init__(self, firstLabel) def mousePressEvent(self, event): print 'Clicked' #myLabel = self.sender() # None =) self.emit(QtCore.SIGNAL('clicked()'), "Label pressed") In another class: self.FirstLang = NewLabel(Form) QtCore.QObject.connect(self.FirstLang, QtCore.SIGNAL('clicked()'), self.labelPressed) Slot in the same class: def labelPressed(self): print 'in labelPressed' print self.sender() But there isn't sender object in self. What i did wrong?

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