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  • Extension methods on a null object instance – something you did not know

    - by nmarun
    Extension methods gave developers with a lot of bandwidth to do interesting (read ‘cool’) things. But there are a couple of things that we need to be aware of while using these extension methods. I have a StringUtil class that defines two extension methods: 1: public static class StringUtils 2: { 3: public static string Left( this string arg, int leftCharCount) 4: { 5: if (arg == null ) 6: { 7: throw new ArgumentNullException( "arg" ); 8: } 9: return arg.Substring(0, leftCharCount); 10...(read more)

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  • Get selected object from TreeView

    - by GoGoDo
    I've been working on a minor (first time) app with quickly and hit a hurdle - how do I get the selected row (the data) from a TreeView? The data to the TreeView is passed from a list of files in a directory, and I need to know which rows were selected (and thus which files were). What is the best way to do that? Here's the current code: self.treeview = self.builder.get_object("treeview") select = self.treeview.get_selection() select.connect("changed", self.on_tree_selection_changed) def on_tree_selection_changed(selection): model, treeiter = self.treeview.selection-get() if treeiter != None: print "You selected", model[treeiter][0]

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  • what is the Best way to learn object oriented principles

    - by Mike
    I am interesed in OOP principles and i found lots of documentations and books about it, for instance in C++, Java, .NET, PHP and so on, but if i only want to learn OOP principle, differences and not in language, what can i do? i want a good documentation, not just like a whole book about something except OOP :) specific answers, how it works, main features, pictures, or videos, or forum, or even stack... in every time I began studying i read a whole history of programming, computer science, software development and bla bla... i need specific answers, if it is possible i really need to learn, i need examples and exercises thanks in advance

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  • Hibernate object equality checking

    - by Sujee
    As far as I understand(correct me if I am wrong) Hibernate uses object reference to check the object equality. When Hibernate identifies that there are more than one objects attached to same DB record, it throws following exception. "a different object with the same identifier value was already associated with the session" My question is, does Hibernate use equal() method to check the object equality (The default equal method uses object reference)? If it is true, will overridden equal() method change the Hibernate behavior? Note: My question is not about the issues of implementing equal() or hashCode() methods in a Hibernate persisted object. Thank you.

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  • What's the fastest way to compare two objects in PHP?

    - by johnnietheblack
    Let's say I have an object - a User object in this case - and I'd like to be able to track changes to with a separate class. The User object should not have to change it's behavior in any way for this to happen. Therefore, my separate class creates a "clean" copy of it, stores it somewhere locally, and then later can compare the User object to the original version to see if anything changed during its lifespan. Is there a function, a pattern, or anything that can quickly compare the two versions of the User object? Option 1 Maybe I could serialize each version, and directly compare, or hash them and compare? Option 2 Maybe I should simply create a ReflectionClass, run through each of the properties of the class and see if the two versions have the same property values? Option 3 Maybe there is a simple native function like objects_are_equal($object1,$object2);? What's the fastest way to do this?

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  • C++ memory management of reference types

    - by Russel
    Hello, I'm still a fairly novice programmer and I have a question about c++ memory management with refence types. First of all, my understanding of reference types: A pointer is put on the stack and the actual data that the pointer points to is created and placed on the heap. Standard arrays and user defined classes are refence types. Is this correct? Second, my main question is do c and c++'s memory management mechanisms (malloc, free and new, delete) always handle this properly and free the memory that a class or array is pointing to? Does everything still work if those pointers get reassigned somehow to other objects of the same size/type on the heap? What if a class has a pointer member that points to another object? I am assuming that delete/freeing the class object doesn't free what it's member pointer points to, is that correct? Thanks all! -R

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  • Java Dragging an object from one area to another [on hold]

    - by user50369
    Hello I have a game where you drag bits of food around the screen. I want to be able to click on an ingredient and drag it to another part of the screen where I release the mouse. I am new to java so I do not really know how to do this please help me Here is me code. This is the class with the mouse listeners in it: public void mousePressed(MouseEvent e) { if (e.getButton() == MouseEvent.BUTTON1) { Comp.ml = true; // placing if (manager.title == true) { if (title.r.contains(Comp.mx, Comp.my)) { title.overview = true; } else if (title.r1.contains(Comp.mx, Comp.my)) { title.options = true; } else if (title.r2.contains(Comp.mx, Comp.my)) { System.exit(0); } } if (manager.option == true) { optionsMouse(e); } mouseinventory(e); } else if (e.getButton() == MouseEvent.BUTTON3) { Comp.mr = true; } } private void mouseinventory(MouseEvent e) { if (e.getButton() == MouseEvent.BUTTON1) { } else if (e.getButton() == MouseEvent.BUTTON1) { } } @Override public void mouseReleased(MouseEvent e) { if (e.getButton() == MouseEvent.BUTTON1) { Comp.ml = false; } else if (e.getButton() == MouseEvent.BUTTON3) { Comp.mr = false; } } @Override public void mouseDragged(MouseEvent e) { for(int i = 0; i < overview.im.ing.toArray().length; i ++){ if(overview.im.ing.get(i).r.contains(Comp.mx,Comp.my)){ overview.im.ing.get(i).newx = Comp.mx; overview.im.ing.get(i).newy = Comp.my; overview.im.ing.get(i).dragged = true; }else{ overview.im.ing.get(i).dragged = false; } } } @Override public void mouseMoved(MouseEvent e) { Comp.mx = e.getX(); Comp.my = e.getY(); // System.out.println("" + Comp.my); } This is the class called ingredient public abstract class Ingrediant { public int x,y,id,lastx,lasty,newx,newy; public boolean removed = false,dragged = false; public int width; public int height; public Rectangle r = new Rectangle(x,y,width,height); public Ingrediant(){ r = new Rectangle(x,y,width,height); } public abstract void tick(); public abstract void render(Graphics g); } and this is a class which extends ingredient called hagleave public class HagLeave extends Ingrediant { private Image img; public HagLeave(int x, int y, int id) { this.x = x; this.y = y; this.newx = x; this.newy = y; this.id = id; width = 75; height = 75; r = new Rectangle(x,y,width,height); } public void tick() { r = new Rectangle(x,y,width,height); if(!dragged){ x = newx; y = newy; } } public void render(Graphics g) { ImageIcon i2 = new ImageIcon("res/ingrediants/hagleave.png"); img = i2.getImage(); g.drawImage(img, x, y, null); g.setColor(Color.red); g.drawRect(r.x, r.y, r.width, r.height); } } The arraylist is in a class called ingrediantManager: public class IngrediantsManager { public ArrayList<Ingrediant> ing = new ArrayList<Ingrediant>(); public IngrediantsManager(){ ing.add(new HagLeave(100,200,1)); ing.add(new PigHair(70,300,2)); ing.add(new GiantsToe(100,400,3)); } public void tick(){ for(int i = 0; i < ing.toArray().length; i ++){ ing.get(i).tick(); if(ing.get(i).removed){ ing.remove(i); i--; } } } public void render(Graphics g){ for(int i = 0; i < ing.toArray().length; i ++){ ing.get(i).render(g); } } }

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  • Simple moving object jitters every couple of seconds [on hold]

    - by Liam
    I'm trying to get smooth movement in my game, right now every couple of seconds the moving square jitters. I'm using C++ with SDL2. I made a very simple project to test different methods so all that's happening is a box moves across the screen. Here's a pastebin of the code http://pastebin.com/7YxxSw0D Here's a link to a dropbox folder containing the 'game' https://www.dropbox.com/sh/0ygntl140qv8iv0/AABVuuk6khArOJmdBi1OaFlua?dl=0 Any input would be greatly appreciated, and let me know if you need any more info. Thanks!

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  • Declarative Data Load for Object Properties & .NET UI Controls

    This article details a new practice to prepare the .NET Business Objects using the data retrieved from the Database and binding them to .NET UI Controls dynamically using Reflection through centralized mapping between a typess Properties Vs Data-Columns Vs UI-Controls....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Multiple operations depending on the type of the object passed

    - by mixm
    Assuming I create a method which is passed an object and that method would perform an action depending on the object passed. How should I identify the object? I thought of using the class name to identify the object, but that may be impractical since I could easily change the class name of objects, and generate headaches during future development. Am I right? edit: for example, i have objects ball and bomb. if i have another object called wall, and the wall has the method to resolve collisions with the wall (e.g. the coordinates of the colliding ball and bomb) but have different logic depending on the colliding object (i.e. ball and bomb)

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  • Variable reference in a Groovy GString

    - by Maurits Rijk
    From the book "Groovy and Grails recipes" I'm using the following code snippet: String HelloLanguage = "def hello(language) {return \"Hello $language\"}" However, I get a compiler error "You attempted to reference a variable in the binding or an instance variable from a static context." because language can't be bound. What is wrong?

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  • Pushing reference of an object to array

    - by intacto
    As far as i can see in a situation like this: var x = []; var y = {}; y.someProp='asd'; This doesnt work: x.push(y); What I want to do is add a reference of y to x so that later if I will "delete y;" I want it also to be removed from the array x.

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  • SSIS web service task producing "object reference" error

    - by gfrizzle
    Our care management system uses a web service to import data. I've successfully executed one of its methods using soapUI, and now I want to replicate this with an SSIS 2008 web service task, but I'm running into a problem. I've created the "HTTP Connection Manager" successfully, and specified the location of the "WSDLFile", but when I go to the Input tab and select the Service from the dropdown (there is only one), I get an "Object reference not set to an instance of an object" error, and and the Method dropdown is empty. Any idea what this is trying to tell me?

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  • Getting an object from a 2d array inside of a class

    - by user36324
    I am have a class file that contains two classes, platform and platforms. platform holds the single platform information, and platforms has an 2d array of platforms. Im trying to render all of them in a for loop but it is not working. If you could kindly help me i would greatly appreciate. void Platforms::setUp() { for(int x = 0; x < tilesW; x++){ for(int y = 0; y < tilesH; y++){ Platform tempPlat(x,y,true,renderer,filename,tileSize/scaleW,tileSize/scaleH); platArray[x][y] = tempPlat; } } } void Platforms::show() { for(int x = 0; x < tilesW; x++){ for(int y = 0; y < tilesH; y++){ platArray[x][y].show(renderer,scaleW,scaleH); } } }

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  • how can I change object look point?

    - by jques
    I have tried to load image but system does not give permission. Please look image http://www.rps.net/gunslinger/scrnshot/gunslinger33.jpg I have two arm with two gun, I want to rotate these arm with mouse. For example, if I move mouse position to the left, arms with guns should be move also. Since this is hoby project, I am a bit confort to ask below question ; What should I do to achieve my wish ? some explanation: perspective view gun in viewing direction left click = trigger left gun perspective Feel free to change the title Thanks

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  • How to copy an object by value, not by reference

    - by Blankman
    I want to make a copy of an object, then after some logic, re-assign the original object the value of the copy. example: User userCopy = //make a copy foreach(...) { user.Age = 1; user.ID = -1; UserDao.Update(user) user = userCopy; } I don't want a copy by reference, it has to be a copy by value. The above is just a sample, not how I really want to use it but I need to learn how to copy by value.

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  • How to I reference a pointer from a different class

    - by Justagruvn
    Hey team of awesomeness!, (Iphone Objective-C question) First off, I despise singletons with a passion. Though I should probably be trying to use one, I just dont want to. I want to create a data class (that is instantiated only once by a view controller on loading), and then using a different class, message the crap out of that data instance until it is brimming with so much data, it smiles. So, how do i do that? I made a pointer to the instance of the data class when I instantiated it. I'm now over in a separate view controller, action occurs, and I want to update the initial data object. I think I need to reference that object by way of pointer, but I have no idea how to do that. yes I've set properties and getters and setters, which seem to work, but only in the initial view controller class. Peace Love applesauce.

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  • .rdlc reporting bound to Object Data Source in Three layer Application

    - by Saeedouv
    Hi, i have the following situation, i have a Reporting layer(stand alone) in asp.net application(NOT website, this means NO App_Code folder exists), and i want just to create Object Data Source to take an Object in a separate layer(lets say from Data Access Layer), and then to use that Object Data Source to create a report, i have spent my whole day working around that, tons of work around's and articles on the web, but does not mention what i really want to do, any answer is appriciated... just to make things more clear here, assume the following: i have a solution with the follwoing layers, UI Reporting(has NO Employees object) just a reference Business Logic Data Access Layer(Employees--GetEmployees(), all i need is as mentioned above, i want to create Object Data Source from Reporting layer, to take Employee object from DAL, and then use it's GetEmployees method to be added to report, i think its more clear now, since also Reporting layer has NO App_Code folder.

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  • Question regarding to value/reference type of events

    - by Petr
    Hi, On the MSDN, I have found following: public event EventHandler<MyEventArgs> SampleEvent; public void DemoEvent(string val) { // Copy to a temporary variable to be thread-safe. EventHandler<MyEventArgs> temp = SampleEvent; if (temp != null) temp(this, new MyEventArgs(val)); } I do not understand, "copy to temporary variable", isnt it reference type?

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