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  • How to use Object.GetHashCode() on a type that overrides GetHashCode()

    - by Jimmy
    Hi, I have a class A that implements IEquatable<, using its fields (say, A.b and A.c) for implementing/overriding Equals() and overriding GetHashCode(), and everything works fine, 99% of the time. Class A is part of a hierarchy (class B, C) that all inherit from interface D; they can all be stored together in a dictionary Dictionary, thus it's convenient when they all carry their own default Equals()/GetHashCode(). However, while constructing A I sometime need to do some work to get the values for A.b and A.c; while that's happening, I want to store a reference to the instance that's being built. In that case, I don't want to use the default Equals()/GetHashCode() overrides provided by A. Thus, I was thinking of implementing a ReferenceEqualityComparer, that's meant to force the use of Object's Equals()/GetHashCode(): private class ReferenceEqualityComparer<T> : IEqualityComparer<T> { #region IEqualityComparer<T> Members public bool Equals(T x, T y) { return System.Object.ReferenceEquals(x, y); } public int GetHashCode(T obj) { // what goes here? I want to do something like System.Object.GetHashCode(obj); } #endregion } The question is, since A overrides Object.GetHashCode(), how can I (outside of A) call Object.GetHashCode() for an instance of A? One way of course would be for A to not implement IEquatable< and always supply an IEqualityComparer< to any dictionary that I create, but I'm hoping for a different answer. Thanks

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  • Convert sqlalchemy row object to python dict

    - by Anurag Uniyal
    or a simple way to iterate over columnName, value pairs? My version of sqlalchemy is 0.5.6 Here is the sample code where I tried using dict(row), but it throws exception , TypeError: 'User' object is not iterable import sqlalchemy from sqlalchemy import * from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.orm import sessionmaker print "sqlalchemy version:",sqlalchemy.__version__ engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() users_table = Table('users', metadata, Column('id', Integer, primary_key=True), Column('name', String), ) metadata.create_all(engine) class User(declarative_base()): __tablename__ = 'users' id = Column(Integer, primary_key=True) name = Column(String) def __init__(self, name): self.name = name Session = sessionmaker(bind=engine) session = Session() user1 = User("anurag") session.add(user1) session.commit() # uncommenting next line throws exception 'TypeError: 'User' object is not iterable' #print dict(user1) # this one also throws 'TypeError: 'User' object is not iterable' for u in session.query(User).all(): print dict(u) Running this code on my system outputs: sqlalchemy version: 0.5.6 Traceback (most recent call last): File "untitled-1.py", line 37, in <module> print dict(u) TypeError: 'User' object is not iterable

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  • How to test COM object integrity automatically?

    - by sharptooth
    Every COM object must have integrity. In simplified terms this means that if an object implements 3 interfaces - A, B and C and I have A* pointer to the object I must be able to successfully QueryInterface() both B and C and having B I must be able to retrieve A and C and having C I must be able to retrieve A and B. Now my object implements 5 interfaces and I want to test its integrity. Writing checks for all of the above myself will require a substantial effort. Is there a tool or some easily tweakable code or a code pattern that would do it?

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  • When writing a game, should you make objects/enemies/etc. have unique ID numbers?

    - by SLC
    I have recently encountered some issues with merely passing references to objects/enemies in a game I am making, and am wondering if I am using the wrong approach. The main issue I have is disposing of enemies and objects, when other enemies or players may still have links to them. For example, if you have a Rabbit, and a Wolf, the Wolf may have selected the Rabbit to be its target. What I am doing, is the wolf has a GameObject Target = null; and when it decides it is hungry, the Target becomes the Rabbit. If the Rabbit then dies, such as another wolf killing it, it cannot be removed from the game properly because this wolf still has a reference to it. In addition, if you are using a decoupled approach, the rabbit could hit by lightning, reducing its health to below zero. When it next updates itself, it realises it has died, and is removed from the game... but there is no way to update everything that is interested in it. If you gave every enemy a unique ID, you could simply use references to that instead, and use a central lookup class that handled it. If the monster died, the lookup class could remove it from its own index, and subsequently anything trying to access it would be informed that it's dead, and then they could act accordingly. Any thoughts on this?

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  • Suggestions for Single-Page Web Application Design?

    - by DaveDev
    My view is that unless you need to change the basic structure of the user interface, you should not have to reload the page at all for any user interactions. I'd like to approach my next ASP.NET MVC project with this in mind. Can anyone suggest any principles, patterns or practices* I should consider? Excellent book, btw. Still trying to wrap my head around some of the concepts though. I thought a question like this would help link the theory to a practical design. Thanks

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  • How to troubleshoot deallocation of object in uitableview?

    - by 4thSpace
    I have a table view with tall cells. About 300 in height. The cells are custom and have an associated nib. In cellForRowAtIndexPath, I access an object in an array using indexPath.row. The object has properties, which I assign to labels on the custom cell. This works fine for the first two cells. Once I scroll enough for the third cell to get created, the app crashes. I have NSZombieEnabled set and here is the output: 2010-04-19 21:48:13.360 MyApp[54463:207] *** -[CALayer release]: message sent to deallocated instance 0xfc4e50 (gdb) continue 2010-04-19 21:48:18.382 MyApp[54463:207] *** NSInvocation: warning: object 0xfc4e50 of class '_NSZombie_CALayer' does not implement methodSignatureForSelector: -- trouble ahead 2010-04-19 21:48:18.383 MyApp[54463:207] *** NSInvocation: warning: object 0xfc4e50 of class '_NSZombie_CALayer' does not implement doesNotRecognizeSelector: -- abort (gdb) continue Program received signal: “EXC_BAD_ACCESS”. (gdb) I'm not sure what is deallocated. How can I trace this to the source?

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  • Disassemble Microsoft Visual Studio 2003 compiler output

    - by Carl Norum
    I'm seeing what I think is strange behaviour from object files output by the Microsoft Visual Studio 2003 tools. The file utility tells me: asmfile.obj: 80386 COFF executable not stripped - version 30821 For objects created by the assembler, but for objects coming from C files, I get just: cfile.obj: data Using Microsoft's dumpbin utility and the objdump I got from cygwin, I can disassemble the assembly-built file, but I get no useful results from either utility for the C-built files. I have a couple of questions related to this difference: What is the object file format generated by the MSVC2003 compiler? How can I disassemble that object file? I am particularly interested in getting the disassembly in AT&T syntax - I'm doing a port of a large source base to make it work with GCC, and I would like to use this method as a shortcut for some of the inline assembly routines in the project. Thanks!

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  • ASIHTTPRequest code design

    - by nico
    I'm using ASIHTTPRequest to communicate with the server asynchronously. It works great, but I'm doing requests in different controllers and now duplicated methods are in all those controllers. What is the best way to abstract that code (requests) in a single class, so I can easily re-use the code, so I can keep the controllers more simple. I can put it in a singleton (or in the app delegate), but I don't think that's a good approach. Or maybe make my own protocol for it with delegate callback. Any advice on a good design approach would be helpful. Thanks.

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  • How to structure a Genetic Algorithm class hierarchy?

    - by MahlerFive
    I'm doing some work with Genetic Algorithms and want to write my own GA classes. Since a GA can have different ways of doing selection, mutation, cross-over, generating an initial population, calculating fitness, and terminating the algorithm, I need a way to plug in different combinations of these. My initial approach was to have an abstract class that had all of these methods defined as pure virtual, and any concrete class would have to implement them. If I want to try out two GAs that are the same but with different cross-over methods for example, I would have to make an abstract class that inherits from GeneticAlgorithm and implements all the methods except the cross-over method, then two concrete classes that inherit from this class and only implement the cross-over method. The downside to this is that every time I want to swap out a method or two to try out something new I have to make one or more new classes. Is there another approach that might apply better to this problem?

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  • iPhone JSON Object

    - by Cosizzle
    Hello, I'm trying to create a application that will retrieve JSON data from an HTTP request, send it to a the application main controller as a JSON object then from there do further processing with it. Where I'm stick is actually creating a class that will serve as a JSON class in which will take a URL, grab the data, and return that object. Alone, im able to make this class work, however I can not get the class to store the object for my main controller to retrieve it. Because im fairly new to Objective-C itself, my thoughts are that im messing up within my init call: -initWithURL:(NSString *) value { responseData = [[NSMutableData data] retain]; NSString *theURL = value; NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:theURL]]; [[NSURLConnection alloc] initWithRequest:request delegate:self]; return self; } The processing of the JSON object takes place here: - (void)connectionDidFinishLoading:(NSURLConnection *)connection { [connection release]; NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; [responseData release]; NSError *jsonError; SBJSON *json = [[SBJSON new] autorelease]; NSDictionary *parsedJSON = [json objectWithString:responseString error:&jsonError]; // NSArray object. listings = [parsedJSON objectForKey:@"posts"]; NSEnumerator *enumerator = [listings objectEnumerator]; NSDictionary* item; // to prove that it does work. while (item = (NSDictionary*)[enumerator nextObject]) { NSLog(@"posts:id = %@", [item objectForKey:@"id"]); NSLog(@"posts:address = %@", [item objectForKey:@"address"]); NSLog(@"posts:lat = %@", [item objectForKey:@"lat"]); NSLog(@"posts:lng = %@", [item objectForKey:@"lng"]); } [responseString release]; } Now when calling the object within the main controller I have this bit of code in the viewDidLoad method call: - (void)viewDidLoad { [super viewDidLoad]; JSON_model *jsonObj = [[JSON_model alloc] initWithURL:@"http://localhost/json/faith_json.php?user=1&format=json"]; NSEnumerator *enumerator = [[jsonObj listings] objectEnumerator]; NSDictionary* item; // while (item = (NSDictionary*)[enumerator nextObject]) { NSLog(@"posts:id = %@", [item objectForKey:@"id"]); NSLog(@"posts:address = %@", [item objectForKey:@"address"]); NSLog(@"posts:lat = %@", [item objectForKey:@"lat"]); NSLog(@"posts:lng = %@", [item objectForKey:@"lng"]); } }

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  • Persist an object that is not marked as serializable

    - by lasseeskildsen
    Hi, I need to persist an object that is not marked with the serializable attribute. The object is from a 3rd party library which I cannot change. I need to store it in a persist place, like for example the file system, so the optimal solution would be to serialize the object to a file, but since it isn't marked as serializable, that is not a straight forward solution. It's a pretty complex object, which also holds a collection of other objects. Do you guys have any input on how to solve this? The code will never run in a production environment, so I'm ok with almost any solution and performance.

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  • Accessing the Private Constructor

    - by harigm
    I am java developer, went for an interview. I have been asked a question about the Private constructor 1) Can I access a Private Constructor of a Class and Instantiate the class. I was thinking and gave the answer directly--- "NO" But its wrong, can any one help Why NO? and How we can achieve this

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  • Can't find how to import as one object or how to merge

    - by Aaron
    I need write a script in blender that creates some birds which fly around some obstacles. The problem is that I need to import a pretty large Collada model (a building) which consists of multiple objects. The import works fine, but the the building is not seen as 1 object. I need to resize and move this building, but I can only get the last object in the building (which is a camera)... Does anyone know how to merge this building in 1 object, group, variable... so I can resize and move it correctly? Part of the code I used: bpy.ops.wm.collada_import(filepath="C:\\Users\\me\\building.dae") building= bpy.context.object building.scale = (100, 100, 100) building.name = "building"

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  • Wrappers/law of demeter seems to be an anti-pattern...

    - by Robert Fraser
    I've been reading up on this "Law of Demeter" thing, and it (and pure "wrapper" classes in general) seem to generally be anti patterns. Consider an implementation class: class Foo { void doSomething() { /* whatever */ } } Now consider two different implementations of another class: class Bar1 { private static Foo _foo = new Foo(); public static Foo getFoo() { return _foo; } } class Bar2 { private static Foo _foo = new Foo(); public static void doSomething() { _foo.doSomething(); } } And the ways to call said methods: callingMethod() { Bar1.getFoo().doSomething(); // Version 1 Bar2.doSomething(); // Version 2 } At first blush, version 1 seems a bit simpler, and follows the "rule of Demeter", hide Foo's implementation, etc, etc. But this ties any changes in Foo to Bar. For example, if a parameter is added to doSomething, then we have: class Foo { void doSomething(int x) { /* whatever */ } } class Bar1 { private static Foo _foo = new Foo(); public static Foo getFoo() { return _foo; } } class Bar2 { private static Foo _foo = new Foo(); public static void doSomething(int x) { _foo.doSomething(x); } } callingMethod() { Bar1.getFoo().doSomething(5); // Version 1 Bar2.doSomething(5); // Version 2 } In both versions, Foo and callingMethod need to be changed, but in Version 2, Bar also needs to be changed. Can someone explain the advantage of having a wrapper/facade (with the exception of adapters or wrapping an external API or exposing an internal one).

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  • Collaboration Diagrams: how to represent setting a variable's and attribute's value to a specified v

    - by devoured elysium
    Let's assume I have a class called MyClass with an attribute called MyAttribute and a method called MyMethod(). Inside that method I'd like to have a variable called MyVariable. I'd like to set the value of MyVariable to "MyVariable" and MyAttribute to "MyAttribute" inside the call to MyMethod(). How can I do this in a Collaboration Diagram? I can't find any info of this kind on the internet and the book I'm studying from (Applying UML and Patterns) is very vague in the details. Thanks

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  • looking for automated modeling tool for ASP.Net class diagramming

    - by alchemical
    I'm walking into a project with 500+ classes, and am wondering if anyone has had good experiences with automated modeling tools that can import from ASP.Net /C#? It would be a bonus if I could get an automated model based on all the objects called to completely load a single ASP.Net page, with relationships indicating which objects are calling out to which other ones, etc. Thanks for sharing your thoughts or recomendations.

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  • Example with Visitor Pattern

    - by devoured elysium
    public class Song { public string Genre { get; protected set; } public string Name { get; protected set; } public string Band { get; protected set; } public Song(string name, string band, string genre) { Name = name; Genre = genre; Band = band; } } public interface IMusicVisistor { void Visit(List<Song> items); } public class MusicLibrary { List<Song> _songs = new List<Song> { ...songs ... }; public void Accept(IMusicVisitor visitor) { visitor.Visit(_songs); } } and now here's one Visitor I made: public class RockMusicVisitor : IMusicVisitor { public List<Song> Songs { get; protected set; } public void Visit(List<Song> items) { Songs = items.Where(x => x.Genre == "Rock").ToList(); } } Why is this any better than just putting a public property Songs and then letting any kind of class do with it anything that it wants to? This example comes from this post.

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  • How to use a viewstate'd object as a datasource for controls on a user control

    - by user557325
    I've got a listview on a control. Each row comprises a checkbox and another listview. The outer listview is bound to a property on the control (via a method call, can't set a property as a SelectMethod on an ObjectDataSource it would appear) which is lazy loaded suchly: Public ReadOnly Property ProductLineChargeDetails() As List(Of WebServiceProductLineChargeDetail) Get If ViewState("WSProductLineChargeDetails") Is Nothing Then ViewState("WSProductLineChargeDetails") = GetWebServiceProductLineChargeDetails() End If Return DirectCast(ViewState("WSProductLineChargeDetails"), Global.System.Collections.Generic.List(Of Global.MI.Open.WebServiceProductLineChargeDetail)) End Get End Property The shape of the object referenced by the data source is something like this: (psuedocode) Product { bool Licenced; List<Charge> charges; } Charge { int property1; string property2; bool property3 . . . } The reason for the use of viewstate is this: When an one of the checkboxes on one of the outer list view rows is checked or unchecked I want to modify the object that the ODS represents (for example I'll add a couple of Charge objects to the relevant Product object) and then rebind. The problem I'm getting is that after every postback (specifically after checking or unchecking one of the rows' checkbox) my viewstate is empty. Thiss means that any changes I make to my viewstate'd object is lost. Now, I've worked out (after much googling and reading, amongst many others, Scott Mitchel's excellent bit on ViewState) that during initial databinding IsTrackingViewState is set to false. That means, I think, that assigning the return from GetWebServiceProductLineChargeDetails() to the ViewState item in my Property Get during the initial databind won't work. Mind you, even when the IsTrackingViewState is true and I call the Property Get, come the next postback, the viewstate is empty. So do you chaps have any ideas on how I keep the object referenced by the ObjectDataSource in ViewState between postbacks and update it and get those changes to stay in ViewState? This has been going on for a couple of days now and I'm getting fed up! Cheers in advance Steve

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  • WPF - How do I get an object that is bound to a ListBoxItem back

    - by JonBlumfeld
    Hi there here is what I would like to do. I get a List of objects from a database and bind this list to a ListBox Control. The ListBoxItems consist of a textbox and a button. Here is what I came up with. Up to this point it works as intended. The object has a number of Properties like ID, Name. If I click on the button in the ListBoxItem the Item should be erased from the ListBox and also from the database... <ListBox x:Name="taglistBox"> <ListBox.ItemContainerStyle> <Style TargetType="{x:Type ListBoxItem}"> <Setter Property="HorizontalAlignment" Value="Stretch"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ListBoxItem"> <ContentPresenter HorizontalAlignment="Stretch"/> </ControlTemplate> </Setter.Value> </Setter> <Setter Property="Tag" Value="{Binding TagSelf}"></Setter> </Style> </ListBox.ItemContainerStyle> <ListBox.ItemTemplate> <DataTemplate> <Grid HorizontalAlignment="Stretch"> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto"/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Button Grid.Column="0" Name="btTag" VerticalAlignment="Center" Click="btTag_Click" HorizontalAlignment="Left"> <Image Width="16" Height="16" Source="/WpfApplication1;component/Resources/104.png"/> </Button> <TextBlock Name="tbtagBoxTagItem" Margin="5" Grid.Column="1" Text="{Binding Name}" VerticalAlignment="Center" /> </Grid> </DataTemplate> </ListBox.ItemTemplate> </ListBox> The Textblock.Text is bound to object.Name and the ListBoxItem.Tag to object.TagSelf (which is just a copy of the object itself). Now my questions If I click the button in the listboxItem how do I get the listboxitem and the object bound to it back. In order to delete the object from the database I have to retrieve it somehow. I tried something like ListBoxItem lbi1 = (ListBoxItem)(taglistBox.ItemContainerGenerator.ContainerFromItem(taglistBox.Items.CurrentItem)); ObjectInQuestion t = (ObjectInQuestion) lbi1.Tag; Is there a way to automatically update the contents of the ListBox if the Itemssource changes? Right now I'm achieving that by taglistBox.ItemsSource = null; taglistBox.ItemsSource = ObjectInQuestion; I'd appreciate any help you can give :D Thanks in advance

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  • Does NSArray:lastObject return an autoreleased object?

    - by Kyle
    I'm working on an iPhone project where I would like to retrieve an object from an NSMutableArray, remove the object from the array and then use it later. The code looks something like this: NSMutableArray * array; // fill the array NSObject * obj = [array lastObject]; [array removeLastObject]; // do something with obj (in the same function) array is the only entity with a retain on the object that is being accessed. Is this safe to do? I would assume that this would only work if lastObject autoreleased the object which is something that I can't figure out if it does.

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  • Preserving multi-byte characters in Flex XML object

    - by Dan Petker
    I'm having an issue with the Flex XML object type mangling multi-byte characters (such as Japanese or Chinese characters). The basic setup is this. I'm getting an XML-formatted string from the server, and in that string there can be multi-byte characters. A lot of the time, these characters are in attributes, for example: <example id="foo" name="[some multi-byte characters]"/> Now, when I examine the raw string, the multi-byte characters display just fine. However, as soon as I convert the string to an XML object using the top-level XML() function, all the multi-byte characters become mangled. I've tried setting the XML's encoding by including an <?xml version="1.0" encoding="utf-8"?> element in the XML-formatted string, but this doesn't seem to have any effect on the resulting XML object. Is there a way to get the XML object to respect the encoding of the XML-formatted string and prevent the multi-byte characters from being mangled?

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