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  • Does this simple cache class need thread synchronization?

    - by DayOne
    Does this simple cache class need thread synchronization ... if I remove the lock _syncLock statement will encounter any problems? I think i can remove the locks as the references should be updated correctly right? ... BUt i'm think whar happens if client code is iterating over the GetMyDataStructure method and it get replaced? Thanks! public sealed class Cache { private readonly object _syncLock = new object(); private IDictionary<int, MyDataStructure> _cache; public Cache() { Refresh(); } public void Refresh() { lock (_syncLock) { _cache = DAL.GetMyDataStructure(); } } public IDictionary<int, MyDataStructure> **GetMyDataStructure**() { lock (_syncLock) { return _cache; } } }

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  • Thread-safe use of a singleton's members

    - by Anthony Mastrean
    I have a C# singleton class that multiple classes use. Is access through Instance to the Toggle() method thread-safe? If yes, by what assumptions, rules, etc. If no, why and how can I fix it? public class MyClass { private static readonly MyClass instance = new MyClass(); public static MyClass Instance { get { return instance; } } private int value = 0; public int Toggle() { if(value == 0) { value = 1; } else if(value == 1) { value = 0; } return value; } }

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  • Multiple windows services in a single project = mystery

    - by Remoh
    I'm having a bizarre issue that I haven't seen before and I'm thinking it MUST be something simple that I'm not seeing in my code. I have a project with 2 windows services defined. One I've called DataSyncService, the other SubscriptionService. Both are added to the same project installer. Both use a timer control from System.Timers. If I start both services together, they seem to work fine. The timers elapse at the appropriate time and everything looks okay. However, if I start either service individually, leaving the other stopped, everything goes haywire. The timer elapses constantly and on the wrong service. In other words, if I start the DataSyncService, the SubscriptionService timer elapses over and over. ...which is obviously strange. The setup is similar to what I've done in the past so I'm really stumped. I even tried deleting both service and starting over but it doesn't seem to make a difference. At this point, I'm thinking I've made a simple error in the way I'm defining the services and my brain just won't let me see it. It must be creating some sort of threading issue that causes one service to race when the other is stopped. Here the code.... From Program.cs: static void Main() { ServiceBase[] ServicesToRun; ServicesToRun = new ServiceBase[] { new DataSyncService(), new SubscriptionService() }; ServiceBase.Run(ServicesToRun); } From ProjectInstaller.designer.cs: private void InitializeComponent() { this.serviceProcessInstaller1 = new System.ServiceProcess.ServiceProcessInstaller(); this.dataSyncInstaller = new System.ServiceProcess.ServiceInstaller(); this.subscriptionInstaller = new System.ServiceProcess.ServiceInstaller(); // // serviceProcessInstaller1 // this.serviceProcessInstaller1.Account = System.ServiceProcess.ServiceAccount.LocalSystem; this.serviceProcessInstaller1.Password = null; this.serviceProcessInstaller1.Username = null; // // dataSyncInstaller // this.dataSyncInstaller.DisplayName = "Data Sync Service"; this.dataSyncInstaller.ServiceName = "DataSyncService"; this.dataSyncInstaller.StartType = System.ServiceProcess.ServiceStartMode.Automatic; // // subscriptionInstaller // this.subscriptionInstaller.DisplayName = "Subscription Service"; this.subscriptionInstaller.ServiceName = "SubscriptionService"; this.subscriptionInstaller.StartType = System.ServiceProcess.ServiceStartMode.Automatic; // // ProjectInstaller // this.Installers.AddRange(new System.Configuration.Install.Installer[] { this.serviceProcessInstaller1, this.dataSyncInstaller, this.subscriptionInstaller}); } private System.ServiceProcess.ServiceProcessInstaller serviceProcessInstaller1; private System.ServiceProcess.ServiceInstaller dataSyncInstaller; private System.ServiceProcess.ServiceInstaller subscriptionInstaller; From DataSyncService.cs: public static readonly int _defaultInterval = 43200000; //log4net.ILog log; public DataSyncService() { InitializeComponent(); //log = LogFactory.Instance.GetLogger(this); } protected override void OnStart(string[] args) { timer1.Interval = _defaultInterval; //GetInterval(); timer1.Enabled = true; EventLog.WriteEntry("MyProj", "Data Sync Service Started", EventLogEntryType.Information); //log.Info("Data Sync Service Started"); } private void timer1_Elapsed(object sender, System.Timers.ElapsedEventArgs e) { EventLog.WriteEntry("MyProj", "Data Sync Timer Elapsed.", EventLogEntryType.Information); } private void InitializeComponent() { this.timer1 = new System.Timers.Timer(); ((System.ComponentModel.ISupportInitialize)(this.timer1)).BeginInit(); // // timer1 // this.timer1.Enabled = true; this.timer1.Elapsed += new System.Timers.ElapsedEventHandler(this.timer1_Elapsed); // // DataSyncService // this.ServiceName = "DataSyncService"; ((System.ComponentModel.ISupportInitialize)(this.timer1)).EndInit(); } From SubscriptionService: public static readonly int _defaultInterval = 300000; //log4net.ILog log; public SubscriptionService() { InitializeComponent(); } protected override void OnStart(string[] args) { timer1.Interval = _defaultInterval; //GetInterval(); timer1.Enabled = true; EventLog.WriteEntry("MyProj", "Subscription Service Started", EventLogEntryType.Information); //log.Info("Subscription Service Started"); } private void timer1_Elapsed(object sender, System.Timers.ElapsedEventArgs e) { EventLog.WriteEntry("MyProj", "Subscription Service Time Elapsed", EventLogEntryType.Information); } private void InitializeComponent() //in designer { this.timer1 = new System.Timers.Timer(); ((System.ComponentModel.ISupportInitialize)(this.timer1)).BeginInit(); // // timer1 // this.timer1.Enabled = true; this.timer1.Elapsed += new System.Timers.ElapsedEventHandler(this.timer1_Elapsed); // // SubscriptionService // this.ServiceName = "SubscriptionService"; ((System.ComponentModel.ISupportInitialize)(this.timer1)).EndInit(); } Again, the problem is that the timer1_elapsed handler runs constantly when only one of the services is started. And it's the handler on the OPPOSITE service. Anybody see anything?

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  • SimpleInjector - Register a type for all it's interfaces

    - by Karl Cassar
    Is it possible to register a type for all it's implementing interfaces? E.g, I have a: public class Bow : IWeapon { #region IWeapon Members public string Attack() { return "Shooted with a bow"; } #endregion } public class HumanFighter { private readonly IWeapon weapon = null; public HumanFighter(IWeapon weapon) { this.weapon = weapon; } public string Fight() { return this.weapon.Attack(); } } [Test] public void Test2b() { Container container = new Container(); container.RegisterSingle<Bow>(); container.RegisterSingle<HumanFighter>(); // this would match the IWeapon to the Bow, as it // is implemented by Bow var humanFighter1 = container.GetInstance<HumanFighter>(); string s = humanFighter1.Fight(); }

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  • How should i be handling string Interning on deserialization?

    - by DayOne
    In the example below I am interning the string in the constructor which is fine. However when i deserialise the object from the binary formatter I don't think the string will be interned as the constructor should be called. How should I be ensuring the _name string is interned? ... or will it be interned ok? Thanks [Serializable] class City { private readonly string _name; public City(string t) { _name = string.Intern(t); } public string Name { get { return _name; } } public override string ToString() { return _name; } }

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  • Explain the code: c# locking feature and threads

    - by Mendy
    I used this pattern in a few projects, (this snipped of code is from CodeCampServer), I understand what it does, but I'm really interesting in an explanation about this pattern. Specifically: Why is the double check of _dependenciesRegistered. Why to use lock (Lock){}. Thanks. public class DependencyRegistrarModule : IHttpModule { private static bool _dependenciesRegistered; private static readonly object Lock = new object(); public void Init(HttpApplication context) { context.BeginRequest += context_BeginRequest; } public void Dispose() { } private static void context_BeginRequest(object sender, EventArgs e) { EnsureDependenciesRegistered(); } private static void EnsureDependenciesRegistered() { if (!_dependenciesRegistered) { lock (Lock) { if (!_dependenciesRegistered) { new DependencyRegistrar().ConfigureOnStartup(); _dependenciesRegistered = true; } } } } }

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  • Using locks inside a loop

    - by Xaqron
    // Member Variable private readonly object _syncLock = new object(); // Now inside a static method foreach (var lazyObject in plugins) { if ((string)lazyObject.Metadata["key"] = "something") { lock (_syncLock) { if (!lazyObject.IsValueCreated) lazyObject.value.DoSomething(); } return lazyObject.value; } } Here I need synchronized access per loop. There are many threads iterating this loop and based on the key they are looking for, a lazy instance is created and returned. lazyObject should not be created more that one time. Although Lazy class is for doing so and despite of the used lock, under high threading I have more than one instance created (I track this with a Interlocked.Increment on a volatile shared int and log it somewhere). The problem is I don't have access to definition of Lazy and MEF defines how the Lazy class create objects. My questions: 1) Why the lock doesn't work ? 2) Should I use an array of locks instead of one lock for performance improvement ?

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  • In WPF XAML how can I concatenate 2 constants so I can use pre-define paths?

    - by toaster24
    I'm new to XAML, so presume I'm missing something simple. I want to replace the path part of the source path with a c# constant for easier path management, for example I have: <Image Source="/Images/Themes/Buttons/MyPicture.png" /> and in another class I have my constant defined: public static readonly string UriImagesButtons = "/Images/Big/PNG/"; I want to have something along the lines of: <Image Source="{static:UriImagesButtons + MyPicture.png}" /> This means that I can change the path globally at a stroke if the need arises. What's the syntax to do this?

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  • GridView CheckBox Disable

    - by zxc
    I have a gridview populated by checkbox using the code below Data Source Result: Branch,101,102,103,104,105,106,107,108,109,110 00001,null,null,null,null,null,null,null,null,null,null 00016,1,1,1,1,1,0,0,0,0,0 00244,1,1,1,1,1,1,1,1,1,1 <asp:TemplateField HeaderText="101"> <ItemTemplate> <asp:CheckBox runat="server" id="cb101" Checked='<%# Eval("101").ToString().Equals("1") %>' /> </ItemTemplate> </asp:TemplateField>... and so on It is properly working for checkbox if if the column is 0 and 1. Now what I need to do is if the column is null the checkbox should be disabled/readonly

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  • Will lock() statement block all threads in the proccess/appdomain?

    - by MikeJ
    Maybe the question sounds silly, but I don't understand 'something about threads and locking and I would like to get a confirmation (here's why I ask). So, if I have 10 servers and 10 request in the same time come to each server, that's 100 request across the farm. Without locking, thats 100 request to the database. If I do something like this: private static readonly object myLockHolder = new object(); if (Cache[key] == null) { lock(myLockHolder) { if (Cache[key] == null) { Cache[key] = LengthyDatabaseCall(); } } } How many database requests will I do? 10? 100? Or as much as I have threads?

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  • ASP.NET GridView - how to enable validation declaratively

    - by Joe
    It it possible to enable validation in an ASP.NET GridView purely declaratively? What I've tried: A GridView bound to an ObjectDataSource with SelectMethod and UpdateMethod defined The GridView contains some ReadOnly BoundField columns and a TemplateField whose EditTemplate contains a TextBox and a RegularExpressionValidator that only allows numeric input in the TextBox. The GridView also contains a CommandField with ShowEditButton=true and CausesValidation=true. If I click on Edit, enter an invalid value, then click on Save, there is a PostBack, and an exception is thrown in the server (Input string was not in a correct format). I can of course avoid this by adding validation code to the RowUpdating event handler on the server (see below), but is there any declarative way to force the validation to be done without adding this code? protected void MyGridView_RowUpdating(object sender, GridViewUpdateEventArgs e) { Page.Validate("MyValidationGroup"); if (!Page.IsValid) { e.Cancel = true; } }

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  • How to create DataSource dependency property on a wpf User Control

    - by Michael Hedgpeth
    I have a user control that wraps a grid. I want to be able to set the underlying grid's data source, but through the user control, like this: <my:CustomGrid DataSource="{Binding Path=CollectionView}" /> I have set this up in the grid like this: private static readonly DependencyProperty DataSourceProperty = DependencyProperty.Register("DataSource", typeof(IEnumerable), typeof(CustomGrid)); public IEnumerable DataSource { get { return (IEnumerable)GetValue(DataSourceProperty); } set { SetValue(DataSourceProperty, value); underlyingGrid.DataSource = value; } } But this doesn't work (it doesn't give me an error either). The data source is never set. What am I missing?

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  • Class design question (Disposable and singleton behavior)

    - by user137348
    The Repository class has singleton behavior and the _db implements the disposable pattern. As excepted the _db object gets disposed after the first call and because of the singleton behavior any other call of _db will crash. [ServiceBehavior(InstanceContextMode=InstanceContextMode.Single)] public class Repository : IRepository { private readonly DataBase _db; public Repository(DataBase db) { _db = db; } public int GetCount() { using(_db) { return _db.Menus.Count(); } } public Item GetItem(int id) { using(_db) { return _db.Menus.FirstOrDefault(x=>x.Id == id); } } } My question is, is there any way to design this class to work properly without removing the singleton behavior? The Repositoryclass will be serving big amount of requests.

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  • Objective-C property getter

    - by Daniel
    What is technically wrong with the following: @property(nonatomic, assign) NSUInteger timestamp; @property(nonatomic, readonly, getter = timestamp) NSUInteger startTime; @property(nonatomic, assign) NSUInteger endTime; I am sure I can find a better way to organise this, but this is what I ended up with at one point in my project and I noticed that accessing the startTime property always returned 0, even when the timestamp property was set to a correct timestamp. It seems having set the getter of startTime to an existing property (timestamp), it is not forwarding the value of timestamp when I do: event.startTime => 0 event.timestamp => 1340920893 All these are timestamps by the way. Just a reminder, I know the above should have happened in my project but I don't understand why accessing startTime doesn't forward onto timestamp property. UPDATE In my implementation I am synthesising all of these properties: @synthesize timestamp, endTime, startTime; Please check an example object to use that demonstrates this at my gist on GitHub: https://gist.github.com/3013951

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  • how to get the value entered in combobox that is binded to datagridview

    - by Ranjana
    i have dynamically added combobox to datagridview. in this gridview i need to enter the values to combobox. but it is not allowing me to enter the value. code: if (strtype.Contains("ComboBox")) { checkcmbColumn.Name = strControlName; checkcmbColumn.HeaderText = strColumnName; checkcmbColumn.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter; checkcmbColumn.Width = 100; checkcmbColumn.ReadOnly = false; checkcmbColumn.Items.Add("1"); checkcmbColumn.Items.Add("2"); GrdViewDetails.Columns.Add(checkcmbColumn); }

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  • Unit tests logged (or run) multiple times

    - by HeavyWave
    I have this simple test: protected readonly ILog logger = LogManager.GetLogger(MethodBase.GetCurrentMethod().ReflectedType); private static int count = 0; [Test] public void TestConfiguredSuccessfully() { logger.Debug("in test method" + count++); } log4net is set up like this: [TestFixtureSetUp] public void SetUp() { log4net.Config.BasicConfigurator.Configure(); } The problem is, that if I run this test in nUnit once, I get the output (as expected): 1742 [TestRunnerThread] DEBUG Tests.TestSomthing (null) - in test method0 But if I press RUN in nUnit.exe again (or more) I get the following: 1742 [TestRunnerThread] DEBUG Tests.TestSomthing (null) - in test method1 1742 [TestRunnerThread] DEBUG Tests.TestSomthing (null) - in test method1 And so on (if I run it 5 times, I'll get 5 repeating lines). Now, if I run the same test alone from reSharper the output is fine and does not repeat. However, if I run this test along side 2 other tests in the same class, the output is repeated three times. I am totally confused. What the hell is going on here?

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  • Why is the Dependency Property not returning its value?

    - by B-Rad
    I have a MyUserControl with the following Xaml: <TextBox Text="{Binding InputValueProperty}" /> In the MyUserControl.xaml.cs I have: public string InputValue { get { return (string)GetValue(InputValueProperty); } set { SetValue(InputValueProperty, value); } } public static readonly DependencyProperty InputValueProperty = DependencyProperty.Register("InputValueProperty", typeof(string), typeof(MyUserControl)); In my MainWindow.xaml I create a user control: <local:MyUserControl InputValue="My Input" /> Later on in my MainWindow.xaml.cs I am trying to access this string. All instances of MyUserControl are contained in a List and I access them with a foreach. string temp = userControl.InputValue; This is always null. In my MainWindow.xaml I can see the "My Input" in the text box of the user control but I can't ever seem to get it out of there.

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  • VB.NET Abstract Property

    - by ElPresidente
    I have an abstract "GridBase" class with two types of derived classes "DetailGrid" and "HeaderGrid". Respectively, one is comprised of "DetailRow" objects and the other "HeaderRow" objects. Both of those inherit from a "RowBase" abstract class. What I am trying to do is the following: Public MustInherit Class GridBase Private pRows As List(Of RowBase) Public ReadOnly Property Rows As List(Of RowBase) Get Return pRows End Get End Property End Class Public Class DetailGrid Inherits GridBase End Class In this scenario, I want DetailGrid.Rows to return a list of DetailRow. I want HeaderRow.Rows to return a list of HeaderRow. Am I on the right track with this or should the Rows property not be included in the GridBase class?

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  • How do I link (dependency) properties in my ViewModel?

    - by mos
    Simplified example: I have an object that models a user. Users have a first name and a last name. The UserViewModel has a dependency property for my Models.User object. In the declaration of the UserView's xaml, I want to bind a couple of TextBlocks to the first and last name properties. What is the correct way to do this? Should I have readonly DependencyProperties for the name fields, and when the dependency property User is set, update them? Can the name fields be regular C# properties instead? Or, should I bind like this: <TextBlock Text="{Binding User.FirstName}" />

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  • Is it possible to inspect the contents of a Table Value Parameter via the debugger?

    - by Stephen Edmonds
    Does anyone know if it is possible to use the Visual Studio / SQL Server Management Studio debugger to inspect the contents of a Table Value Parameter passed to a stored procedure? To give a trivial example: CREATE TYPE [dbo].[ControllerId] AS TABLE( [id] [nvarchar](max) NOT NULL ) GO CREATE PROCEDURE [dbo].[test] @controllerData [dbo].[ControllerId] READONLY AS BEGIN SELECT COUNT(*) FROM @controllerData; END DECLARE @SampleData as [dbo].[ControllerId]; INSERT INTO @SampleData ([id]) VALUES ('test'), ('test2'); exec [dbo].[test] @SampleData; Using the above with a break point on the exec statement, I am able to step into the stored procedure without any trouble. The debugger shows that the @controllerData local has a value of '(table)' but I have not found any tool that would allow me to actual view the rows that make up that table.

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  • Disable Adding Item to Collection

    - by Wonko the Sane
    Hi All, I'm sure there's an "easy" answer to this, but for the moment it escapes me. In an MVVM application, I have a property that is a ObservableCollection, used for displaying some set of elements on the view. private readonly ObservableCollection<MyType> mMyCollection = new ObservableCollection<MyType>(); public ObservableCollection<MyType> MyCollection { get { return mMyCollection; } } I want to restrict consumers of this collection from simply using the property to add to the collection (i.e. I want to prevent this from the view): viewModel.MyCollection.Add(newThing); // want to prevent this! Instead, I want to force the use of a method to add items, because there may be another thread using that collection, and I don't want to modify the collection while that thread is processing it. public void AddToMyCollection(MyType newItem) { // Do some thread/task stuff here } Thanks, wTs

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  • wp7 and dependency property : onChanged and onRead?

    - by user233150
    hi here's my question : well I want build a wp7 control,so I write it and all go well, but the problem is that I can intercept on write(see onItemsSourcePropertyChanged)but not on read I would like explain better: public static readonly DependencyProperty ItemsSourceProperty= DependencyProperty.Register( "ItemsSource", typeof(ObservableCollection<ObjWithDesc>), typeof(HorizontalListBox), new PropertyMetadata(OnItemsSourcePropertyChanged) ); static void OnItemsSourcePropertyChanged(DependencyObject obj,DependencyPropertyChangedEventArgs e) { ((HorizontalListBox) obj).OnItemsSourcePropertyChanged(e); } OnItemsSourcePropertyChanged is called when I use SetValue(dp,..) but there isn't onItemsSourcePropertyRead ? that is called when I Use GetValue()? thanks

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  • Select a Dictionary<T1, T2> with LINQ

    - by Rich
    I have used the "select" keyword and extension method to return an IEnumerable<T> with LINQ, but I have a need to return a generic Dictionary<T1, T2> and can't figure it out. The example I learned this from used something in a form similar to the following: IEnumerable<T> coll = from x in y select new SomeClass{ prop1 = value1, prop2 = value2 }; I've also done the same thing with extension methods. I assumed that since the items in a Dictionary<T1, T2> can be iterated as KeyValuePair<T1, T2> that I could just replace "SomeClass" in the above example with "new KeyValuePair<T1, T2> { ...", but that didn't work (Key and Value were marked as readonly, so I could not compile this code). Is this possible, or do I need to do this in multiple steps? Thanks.

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  • Checking for a session variable... returns (Object reference not set to an instance of an object.)

    - by Chocol8
    In the Session_Start i have Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs) Session("login") = False End Sub and in a custom .aspx page i included the following... Public ReadOnly Property GetLoginState() As Boolean Get If Current.Session("login") Is Nothing Then Current.Session("login") = False End If Return Current.Session("login") End Get End Property Why i am getting error the error Object reference not set to an instance of an object. at line If Current.Session("login") Is Nothing Then while checking for the login state as follows? If GetLogin = False Then 'Do something End if I mean i have already created the instance on the Session_Start... Haven't i? What am i doing wrong here?

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  • onclick from an Object's button doesn't work

    - by 730
    I instantiate an object, with an argument which is a button. When the button of an instance is clicked, it should run a function, but it doesn't. In the full version of the code, Chrome gives this message in the console: "Uncaught TypeError: Cannot read property 'onclick' of undefined" HTML: <textarea id='txt' readonly rows='5' cols='40'></textarea> <button id='btn' type='button'>click</button> JS: var btn = document.getElementById('btn'); var txt = document.getElementById('txt'); var foo = new Foo(btn); function Foo(btn) { this.button = btn; } Foo.prototype.buy = function() { txt.value = 'Foo Bar'; }; Foo.button.onclick = function() { foo.buy(); }; Fiddle

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