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  • Refactoring Singleton Overuse

    - by drharris
    Today I had an epiphany, and it was that I was doing everything wrong. Some history: I inherited a C# application, which was really just a collection of static methods, a completely procedural mess of C# code. I refactored this the best I knew at the time, bringing in lots of post-college OOP knowledge. To make a long story short, many of the entities in code have turned out to be Singletons. Today I realized I needed 3 new classes, which would each follow the same Singleton pattern to match the rest of the software. If I keep tumbling down this slippery slope, eventually every class in my application will be Singleton, which will really be no logically different from the original group of static methods. I need help on rethinking this. I know about Dependency Injection, and that would generally be the strategy to use in breaking the Singleton curse. However, I have a few specific questions related to this refactoring, and all about best practices for doing so. How acceptable is the use of static variables to encapsulate configuration information? I have a brain block on using static, and I think it is due to an early OO class in college where the professor said static was bad. But, should I have to reconfigure the class every time I access it? When accessing hardware, is it ok to leave a static pointer to the addresses and variables needed, or should I continually perform Open() and Close() operations? Right now I have a single method acting as the controller. Specifically, I continually poll several external instruments (via hardware drivers) for data. Should this type of controller be the way to go, or should I spawn separate threads for each instrument at the program's startup? If the latter, how do I make this object oriented? Should I create classes called InstrumentAListener and InstrumentBListener? Or is there some standard way to approach this? Is there a better way to do global configuration? Right now I simply have Configuration.Instance.Foo sprinkled liberally throughout the code. Almost every class uses it, so perhaps keeping it as a Singleton makes sense. Any thoughts? A lot of my classes are things like SerialPortWriter or DataFileWriter, which must sit around waiting for this data to stream in. Since they are active the entire time, how should I arrange these in order to listen for the events generated when data comes in? Any other resources, books, or comments about how to get away from Singletons and other pattern overuse would be helpful.

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  • Automark model names/attributes for translation

    - by Saosin
    Is there any way one could automatically mark all model names and attributes for translation, without specifying verbose_name/_plural on each one of them? Doesn't feel very DRY to do this every time: class Profile(models.Model): length = models.IntegerField(_('length')) weight = models.IntegerField(_('weight')) favorite_movies = models.CharField(_('favorite movies'), max_length=100) favorite_quote = models.CharField(_('favorite quote'), max_length=30) religious_views = models.CharField(_('religious views'), max_length=30) political_views = models.CharField(_('political views'), max_length=30) class Meta: verbose_name = _('profile') verbose_name_plural = _('profiles')

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  • Error with python decorator

    - by Timmy
    I get this error object has no attribute 'im_func' with this class Test(object): def __init__(self, f): self.func = f def __call__( self, *args ): return self.func(*args) pylons code: class TestController(BaseController): @Test def index(self): return 'hello world'

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  • Simple Java to XML example

    - by Tom Brito
    I've read a time ago about generate xml from Java using annotations, but I'm not finding a simple example now. If I want to make a xml file like: <x:element uid="asdf">value</x:element> from my java class: public class Element { private String uid = "asdf"; } Which annotations I should use to perform that? (I have a xml-schema, if this helps the generation)

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  • Variable scope and the 'using' statement in .NET

    - by pete the pagan-gerbil
    If a variable is at class level (ie, private MyDataAccessClass _dataAccess;, can it be used as part of a using statement within the methods of that class to dispose of it correctly? Is it wise to use this method, or is it better to always declare a new variable with a using statement (ie, using (MyDataAccessClass dataAccess = new MyDataAccessClass()) instead of using (_dataAccess = new MyDataAccessClass()))?

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  • How do I determine if a property was overriden?

    - by Benjamin
    Hello I am doing a project that where I need to register all the properties, because of the system being so huge it would require a lot of work to register all the properties that i want to be dependent for the purpose of Xaml. The goal is to find all properties that are on the top of the tree. so basically public class A{ public int Property1 { get; set; } } public class B : A{ public int Property2 { get; set; } public virtual int Property3 { get; set; } } public class C : B{ public override int Property3 { get; set; } public int Property4 { get; set; } public int Property5 { get; set; } } The end result would be something like this A.Prorperty1 B.Property2 B.Property3 C.Property4 C.Property5 If you notice I don't want to accept overridden properties because of the way I search for the properties if I do something like this C.Property3 for example and it cannot find it it will check C's basetype and there it will find it. This is what I have so far. public static void RegisterType( Type type ) { PropertyInfo[] properties = type.GetProperties( BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly | BindingFlags.GetProperty | BindingFlags.SetProperty ); if ( properties != null && properties.Length > 0 ) { foreach ( PropertyInfo property in properties ) { // if the property is an indexers then we ignore them if ( property.Name == "Item" && property.GetIndexParameters().Length > 0 ) continue; // We don't want Arrays or Generic Property Types if ( (property.PropertyType.IsArray || property.PropertyType.IsGenericType) ) continue; // Register Property } } } What I want are the following: Public properties, that are not overridden, not static, not private Either get and set properties are allowed They are not an array or a generic type They are the top of the tree ie C class in the example is the highest (The property list example is exactly what I am looking for) They are not an indexer property ( this[index] ) Any help will be much appreciated =).

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  • adding a property to an EventArgs

    - by aleroot
    I have extended the standard FileSystemWatcher class by adding a string property (fileToTest), now i need to extend also the FileSystemEventArgs to add this property how can i do this ? my extend FileSystemWatcher : class AleFileSystemWatcher : FileSystemWatcher { public string fileToTest { get; set; } } The FileSystemEventArgs fileToTest property should be the same of AleFileSystemWatcher fileToTest . Can i do this ?

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  • DataContractJsonSerializer generating Ghost string to JSON keys?

    - by Anil Namde
    DataContractJsonSerializer this is nice class added in the .net framework which can be used to serialize/desirealize object into JSON. Now following is the example i am trying [Serializable] class User { public string name; public string userId; } Now following is the output generated Output : Notice structure where only "name" is expected instead of k__BackingField Now this is the problem after digging so much i am not sure from where < and _BackingField is coming ? { "<name>k__BackingField":"test user", "<userId>k__BackingField":100001}

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  • How to reorder type members with Resharper?

    - by AngryHacker
    Typical scenario: a class that a lot of people have worked on. I'd like to sort methods, properties, etc... in alphabetical order. I'd like to be able to do this within the region or globally in the class. I see the feature in Resharper to do it, but it does not seem to do anything.

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  • Flex: Constant strings in metadata

    - by Daniel Engmann
    I have something like public class Controller { [Observer("fetchEmployeesEvent")] public function fetchEmployees() : void { //doSomething } } and I want something like public class Controller { public static const FETCH_EMPLOYEES_EVENT : String = "fetchEmployeesEvent"; [Observer(FETCH_EMPLOYEES_EVENT)] public function fetchEmployees() : void { //doSomething } } My problem is that only the first code snippet works. Flex seems to ignore the constant FETCH_EMPLOYEES_EVENT in the metadata-tag. My question is: Is it somehow possible to use constant strings in metadata?

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  • display:none and scrolling text

    - by small
    There is a conflict between display:none and scrolling text. What can I use instead of using display:none? <div id="side_forums_pane" class="side_pane" style=" height:350px;width:260px"> <div class="jscroller2_up jscroller2_speed-19 jscroller2_mousemove" style="height:250px;width:260px;"> </div> </div>

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  • variables reference value of string

    - by xdevel2000
    How can I get the reference value of a string object? If I hava a class like class T() { } T t = new T(); System.out.println( t); print out T@a3455467 that is the reference value inside t but for string? maybe with method hashCode()??

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  • Django form and User data

    - by Dean
    I have a model that looks like this: class Client(models.Model): name = models.CharField(max_length=100, primary_key=True) user = models.ForeignKey(User) class Contract(models.Model): title = models.CharField(max_length=100, primary_key=True) start_date = models.DateField() end_date = models.DateField() description = models.TextField() client = models.ForeignKey(Client) user = models.ForeignKey(User) How can i configure a django form so that only clients associated with that user show in the field in the form? My initial thought was this in my forms.py: client = forms.ModelChoiceField(queryset=Client.objects.filter(user__username = User.username)) But it didn't work. So how else would I go about it?

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  • Java homework help, Error <identifier> expected

    - by user2900126
    Help with java homework this is my assignment that I have, this assignment code I've tried. But when I try to compile it I keep getting errors which I cant seem to find soloutions too: Error says <identifier> expected for Line 67 public static void () Assignment brief To write a simple java classMobile that models a mobile phone. Details the information stored about each mobile phone will include • Its type e.g. “Sony ericsson x90” or “Samsung Galaxy S”; • Its screen size in inches; You may assume that this a whole number from the scale 3 to 5 inclusive. • Its memory card capacity in gigabytes You may assume that this a whole number • The name of its present service provider You may assume this is a single line of text. • The type of contract with service provider You may assume this is a single line of text. • Its camera resolution in megapixels; You should not assume that this a whole number; • The percentage of charge left on the phone e.g. a fully charged phone will have a charge of 100. You may assume that this a whole number • Whether the phone has GPS or not. Your class will have fields corresponding to these attributes . Start by opening BlueJ, creating a new project called myMobile which has a classMobile and set up the fields that you need, Next you will need to write a Constructor for the class. Assume that each phone is manufactured by creating an object and specifying its type, its screen size, its memory card capacity, its camera resolution and whether it has GPS or not. Therefore you will need a constructor that allows you to pass arguments to initialise these five attributes. Other fields should be set to appropriate default values. You may assume that a new phone comes fully charged. When the phone is sold to its owner, you will need to set the service provider and type of contract with that provider so you will need mutator methods • setProvider () - - to set service provider. • setContractType - - to set the type of contract These methods will be used when the phones provider is changed. You should also write a mutator method ChargeUp () which simulates fully charging the phone. To obtain information about your mobile object you should write • accessor methods corresponding to four of its fields: • getType () – which returns the type of mobile; • getProvider () – which returns the present service provider; • getContractType () – which returns its type of contract; • getCharge () – which returns its remaining charge. An accessor method to printDetails () to print, to the terminal window, a report about the phone e.g. This mobile phone is a sony Erricsson X90 with Service provider BigAl and type of contract PAYG. At present it has 30% of its battery charge remaining. Check that the new method works correctly by for example, • creating a Mobile object and setting its fields; • calling printDetails () and t=checking the report corresponds to the details you have just given the mobile; • changing the service provider and contract type by calling setprovider () and setContractType (); • calling printDetails () and checking the report now prints out the new details. Challenging excercises • write a mutator methodswitchedOnFor () =which simulates using the phone for a specified period. You may assume the phone loses 1% of its charge for each hour that it is switched on . • write an accessor method checkcharge () whichg checks the phone remaing charge. If this charge has a value less than 25%, then this method returns a string containg the message Be aware that you will soon need to re-charge your phone, otherwise it returns a string your phone charge is sufficient. • Write a method changeProvider () which simulates changing the provider (and presumably also the type of service contract). Finally you may add up to four additional fields, with appropriate methods, that might be required in a more detailed model. above is my assignment that I have, this assignment code I've tried. But when I try to oompile it I keep getting errors which I cant seem to find soloutions too: Error says <identifier> expected for Line 67 public static void () /** * to write a simple java class Mobile that models a mobile phone. * * @author (Lewis Burte-Clarke) * @version (14/10/13) */ public class Mobile { // type of phone private String phonetype; // size of screen in inches private int screensize; // menory card capacity private int memorycardcapacity; // name of present service provider private String serviceprovider; // type of contract with service provider private int typeofcontract; // camera resolution in megapixels private int cameraresolution; // the percentage of charge left on the phone private int checkcharge; // wether the phone has GPS or not private String GPS; // instance variables - replace the example below with your own private int x; // The constructor method public Mobile(String mobilephonetype, int mobilescreensize, int mobilememorycardcapacity,int mobilecameraresolution,String mobileGPS, String newserviceprovider) { this.phonetype = mobilephonetype; this.screensize = mobilescreensize; this.memorycardcapacity = mobilememorycardcapacity; this.cameraresolution = mobilecameraresolution; this.GPS = mobileGPS; // you do not use this ones during instantiation,you can remove them if you do not need or assign them some default values //this.serviceprovider = newserviceprovider; //this.typeofcontract = 12; //this.checkcharge = checkcharge; Mobile samsungPhone = new Mobile("Samsung", "1024", "2", "verizon", "8", "GPS"); 1024 = screensize; 2 = memorycardcapacity; 8 = resolution; GPS = gps; "verizon"=serviceprovider; //typeofcontract = 12; //checkcharge = checkcharge; } // A method to display the state of the object to the screen public void displayMobileDetails() { System.out.println("phonetype: " + phonetype); System.out.println("screensize: " + screensize); System.out.println("memorycardcapacity: " + memorycardcapacity); System.out.println("cameraresolution: " + cameraresolution); System.out.println("GPS: " + GPS); System.out.println("serviceprovider: " + serviceprovider); System.out.println("typeofcontract: " + typeofcontract); } /** * The mymobile class implements an application that * simply displays "new Mobile!" to the standard output. */ public class mymobile { public static void main(String[] args) { System.out.println("new Mobile!"); //Display the string. } } public static void buildPhones(){ Mobile Samsung = new Mobile("Samsung", "3.0", "4gb", "8mega pixels", "GPS"); Mobile Blackberry = new Mobile("Blackberry", "3.0", "4gb", "8mega pixels", "GPS"); Samsung.displayMobileDetails(); Blackberry.displayMobileDetails(); } public static void main(String[] args) { buildPhones(); } } any answers.replies and help would be greatly appreciated as I really lost!

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  • Why cant we use UIFont or UIcolor in the method which we unit test?

    - by PrithviRaj
    Hi all, I have an method in the tableview controller class. It consists few of the UIColor and UIFont class names. I am unit testing that metohd. But when i build that test target i am getting this error: "/Developer/Tools/RunPlatformUnitTests.include:451:0 Test rig '/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator3.0.sdk/Developer/usr/bin/otest' exited abnormally with code 133 (it may have crashed)." Any idea about this? Thanks in advance.

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  • Html Agility Pack: Setting an HtmlNode's Attribute Value isn't reflected in the HtmlDocument.

    - by Avi
    In Html Agility Pack, when I set an attribute of an HtmlNode, should I see this in the HtmlDocument from which the node was selected? Lets say that htmlDocument is an HtmlDocument. So the simplified code looks like this: HtmlNode documentNode = htmlDocument.DocumentNode; HtmlNodeCollection nodeCollection = documentNode.SelectNodes(someXPath); foreach(var node in nodeCollection) if(SomeCondition(node)) node.SetAttributeValue("class","something"); Now, I see the class attribte of node change, but I don't see this change reflected in the htmlDocument's html.

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  • How can i make projects bound to eachother in eclipse?

    - by ikky
    Hi! I have 3 projects in Eclipse that are bound to eachother. With bound i mean this: Everytime i add a class in one of the projects, the other projects also updates themselves and add the class Now i want to add another project to these, but i don't know how to bind it together with the other projects. Any suggestions? Thanks in advance!

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  • Eclipse "Add unimplemented methods" method ordering

    - by Steve Kuo
    Eclipse has a feature "Add unimplemented methods" that adds the unimplemented methods for a class (such as when implementing an interface). When Eclipse adds the methods it adds them in alphabetical order. Is there a way to configure Eclipse to add them in the order that they appear in the interface (or abstract class)?

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  • c# Lambda Expression built with LinqKit does not compile

    - by Frank Michael Kraft
    This lambda does not compile, but I do not understand why. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions; using LinqKit; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { var barModel = new BarModel(); string id = "some"; Console.WriteLine(barModel.subFor(id).ToString()); // output: m => (True AndAlso (m.key == value(ConsoleApplication2.Bar`1+<>c__DisplayClass0[ConsoleApplication2.Model]).id)) Console.ReadKey(); var subworkitems = barModel.list.Where(barModel.subFor(id).Compile()); // Exception {"variable 'm' of type 'ConsoleApplication2.Model' referenced from scope '', but it is not defined"} Console.WriteLine(subworkitems.ToString()); Console.ReadKey(); } } class Bar<TModel> { public Bar(Expression<Func<TModel, string>> foreignKeyExpression) { _foreignKeyExpression = foreignKeyExpression; } private Expression<Func<TModel, string>> _foreignKeyExpression { get; set; } public Expression<Func<TModel, bool>> subFor(string id) { var ex = forTargetId(id); return ex; } public Expression<Func<TModel, bool>> forTargetId(String id) { var fc = _foreignKeyExpression; Expression<Func<TModel, bool>> predicate = m => true; var result = predicate.And(m => fc.Invoke(m) == id).Expand(); return result; } } class Model { public string key; public string value; } class BarModel : Bar<Model> { public List<Model> list; public BarModel() : base(m => m.key) { list = new List<Model>(); } } }

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  • Handle property change event listeners (lots of them) more elegantly (dictionary?)

    - by no9
    hELLO ! Here i have a simple class example with three fields of type class B and some other stuff. As you can see im listening on every child object change. Since i could need alot of properties of type class B i wonder if there is a way of shrinking the code. Creating a listener + a method for each seems like i will have ALOT of code. How would i fix this ... using a dictionary or something similar? I have been told that IoC could fix this, but im not sure where to start. public class A : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; public int _id; public int Id { get { return _id; } set { if (_id == value) { return; } _id = value; OnPropertyChanged("Id"); } } public string _name; public string Name { get { return _name; } set { if (_name == value) { return; } _name = value; OnPropertyChanged("Name"); } } public B _firstB; public B FirstB { get { return _firstB; } set { if (_firstB == value) { return; } if (_firstB != null) { FirstB.PropertyChanged -= firstObjectB_Listener; } _firstB = value; if (_firstB != null) FirstB.PropertyChanged += new PropertyChangedEventHandler(firstObjectB_Listener); OnPropertyChanged("FirstB"); } } public B _secondB; public B SecondB { get { return _secondB; } set { if (_secondB == value) { return; } if (_secondB != null) { FirstB.PropertyChanged -= secondObjectB_Listener; } _secondB = value; if (_secondB != null) SecondB.PropertyChanged += new PropertyChangedEventHandler(secondObjectB_Listener); OnPropertyChanged("FirstB"); } } public B _thirdB; public B ThirdB { get { return _thirdB; } set { if (_thirdB == value) { return; } if (_thirdB != null) { ThirdB.PropertyChanged -= thirdObjectB_Listener; } _thirdB = value; if (_thirdB != null) ThirdB.PropertyChanged += new PropertyChangedEventHandler(thirdObjectB_Listener); OnPropertyChanged("ThirdB"); } } protected void OnPropertyChanged(string name) { PropertyChangedEventHandler handler = PropertyChanged; if (handler != null) { handler(this, new PropertyChangedEventArgs(name)); } } void firstObjectB_Listener(object sender, PropertyChangedEventArgs e) { Console.WriteLine("Object A has found a change of " + e.PropertyName + " on first object B"); } void secondObjectB_Listener(object sender, PropertyChangedEventArgs e) { Console.WriteLine("Object A has found a change of " + e.PropertyName + " on second object B"); } void thirdObjectB_Listener(object sender, PropertyChangedEventArgs e) { Console.WriteLine("Object A has found a change of " + e.PropertyName + " on third object B"); } }

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  • How do I hide the text links over a toggleable horizontal list with background images.

    - by Sivakanesh
    I'm trying to create a UL/LI horizontal list with background images only, with no text link visible. The reason for this is so that when I over over a list item, the background would rollover and when I click on it the current item would toggle. basically it is a horizontal menu with background images that can be toggled; mimicking the job of a radio button. I have done it like this; <div id="options"> <ul id="list"> <li class="active"><a href="#" class="option1 active" id="link1"><span>XXXXX</span></a></li> <li><a href="#" class="option2" id="link2"><span>XXXXX</span></a></li> <li><a href="#" class="option3" id="link3"><span>XXXXX</span></a></li> </ul> </div> The CSS for option1, option2 and option3 simply define the background image. #options LI{list-style-type: none; display : inline} a.option1{ background:url('../images/option1.png') no-repeat;} a.option2{ background:url('../images/option2.png') no-repeat;} a.option3{ background:url('../images/option3.png') no-repeat;} a.option1, a.option2, a.option3{ background-position:top; display:inline; width:230px; height:40px; } And the hover & active css part simply sets the background position like so- a.option1:hover, a.option2:hover, a.option3:hover{ background-position:bottom; } a.active{ background-position:bottom !important; } This works fine, however on top of the background I get the words "XXXXX" as text links and I'm struggling to hide them. They are interfering with the hover action and preventing rollover (even if I replace XXXXX with a period or something short). I can't just remove the text from the link as it would hide the whole LI element. I have tried to use display:none; or text-indent:-999px but then the whole UI element becomes invisible. I can't understand what I'm doing wrong. Are you able to help? Thanks

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