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• How can I use a prefix for the fields in my strongly typed View?

  - by deadtime

  Hi, I have an EditProfile action in my PersonController, that finds a Person object by ID and does return View(person). The EditProfile view has a bunch of fields that should be filled in with the information from the Person object. One of the fields is named "Person.FirstName", and is not filled in automatically when the View is rendered. However, if I rename the textbox to "FirstName", it gets filled in. My question is: How can I specify to the view that it should use the "Person" prefix when filling in the information from the Person object? The reason I want to do this is because of consistency - in some of my views I allow the user to edit more than one object at the same time, and use prefixes in order to bind these correctly.

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• Custom Sorting (IComparer on three fields)

  - by Kave

  I have a person class with three fields, Title, Name, Gender and I would like to create a Custom Sort for it to sort it first by Title, then by Name and then by Gender ascending: public class SortPerson : IComparer { public int Compare(object x, object y) { (…) } } I know how to do this for only one variable to compare against: But How would I have to proceed with three? public class SortPerson : IComparer { int IComparer.Compare(object a, object b) { Person p1=(Person)a; Person p2=(Person)b; if (p1.Title > p2.Title) return 1; if (p1.Title < p2.Title) return -1; else return 0; } } Many Thanks,

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• silverlight and windows workflow foundation

  - by wissem

  private void btnUpdate_Click(object sender, RoutedEventArgs e) { xxxxxxx.Workflow1_WebServiceSoapClient zer = new xxxxx.Workflow1_WebServiceSoapClient(); zer.demanderSubmitReportCompleted += new EventHandler<xxxxxxxxxxxxxxx.demanderSubmitReportCompletedEventArgs>(service2); zer.demanderSubmitReportAsync("zzz", 20000); } public void service2(object sender, xxxxx.demanderSubmitReportCompletedEventArgs e) { string a = e.Result; } I'm trying to call a windows workflow foundation published as a web service from a Silverlight project. When I call it from a console application it works fine because I can add a web reference then I just make an instance of that webservice then I invoke the method I want. The problem is in the silverlight project cause i can just add a service reference so I find myself working with soap stuff that doesn't work at all, and here is the code error: here is the code:i change it a litle bit in english Error in exécution Microsoft JScript: Unhandled Error in Silverlight Application exception happened in the operation, résult not valide. Consult InnerException for more information. in System.ComponentModel.AsyncCompletedEventArgs.RaiseExceptionIfNecessary() in AEDSilverlightIntegrated.ServiceReference2.demanderSubmitReportCompletedEventArgs.get_Result() in AEDSilverlightIntegrated.SilverEntryAedHeaderNew.mmm_demanderSubmitReportCompleted(Object sender, demanderSubmitReportCompletedEventArgs e) in AEDSilverlightIntegrated.ServiceReference2.Workflow1_WebServiceSoapClient.OndemanderSubmitReportCompleted(Object state)

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• How to fire off a asych thread in a web application, and gaurantee only 1 thread fires?

  - by Blankman

  I want to cache a object in memory. Regenerating the object when the cache expires is fairly expensive, so I want to do the following: When the cache is "about" to expire, I want to fire off a asychronous thread that will go and rebuild the object and then reset the cache. One thing I am worry about is multiple threads firing to fetch the object to cache, I only want a single thread doing this, realizing many people will be hitting the website. This might not be the best use case to do this, but I want to know how to do this sort of thing.

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• How to manage large amounts of delegates and usercallbacks in C# async http library

  - by Tyler

  I'm coding a .NET library in C# for communicating with XBMC via its JSON RPC interface using HTTP. I coded and released a preliminary version but everything is done synchronously. I then recoded the library to be asynchronous for my own purposes as I was/am building an XBMC remote for WP7. I now want to release the new async library but want to make sure it's nice and tidy before I do. Due to the async nature a user initiates a request, supplies a callback method that matches my delegate and then handles the response once it's been received. The problem I have is that within the library I track a RequestState object for the lifetime of the request, it contains the http request/response as well as the user callback etc. as member variables, this would be fine if only one type of object was coming back but depending on what the user calls they may be returned a list of songs or a list of movies etc. My implementation at the moment uses a single delegate ResponseDataRecieved which has a single parameter which is a simple Object - As this has only be used by me I know which methods return what and when I handle the response I cast said object to the type I know it really is - List, List etc. A third party shouldn't have to do this though - The delegate signature should contain the correct type of object. So then I need a delegate for every type of response data that can be returned to the third party - The specific problem is, how do I handle this gracefully internally - Do I have a bunch of different RequestState objects that each have a different member variable for the different delegates? That doesn't "feel" right. I just don't know how to do this gracefully and cleanly.

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• String Sharing/Reference issue with objects in Delphi

  - by jenakai123

  My application builds many objects in memory based on filenames (among other string based information). I was hoping to optimise memory usage by storing the path and filename separately, and then sharing the path between objects in the same path. I wasn't trying to look at using a string pool or anything, basically my objects are sorted so if I have 10 objects with the same path I want objects 2-10 to have their path "pointed" at object 1's path (eg object[2].Path=object[1].Path); I have a problem though, I don't believe that my objects are in fact sharing a reference to the same string after I think I am telling them to (by the object[2].Path=object[1].Path assignment). When I do an experiment with a string list and set all the values to point to the first value in the list I can see the "memory conservation" in action, but when I use objects I see absolutely no change at all, admittedly I am only using task manager (private working set) to watch for memory use changes. Here's a contrived example, I hope this makes sense. I have an object: TfileObject=class(Tobject) FpathPart: string; FfilePart: string; end; Now I create 1,000,000 instances of the object, using a new string for each one: var x: integer; MyFilePath: string; fo: TfileObject; begin for x := 1 to 1000000 do begin // create a new string for every iteration of the loop MyFilePath:=ExtractFilePath(Application.ExeName); fo:=TfileObject.Create; fo.FpathPart:=MyFilePath; FobjectList.Add(fo); end; end; Run this up and task manager says I am using 68MB of memory or something. (Note that if I allocated MyFilePath outside of the loop then I do save memory because of 1 instance of the string, but this is a contrived example and not actually how it would happen in the app). Now I want to "optimise" my memory usage by making all objects share the same instance of the path string, since it's the same value: var x: integer; begin for x:=1 to FobjectList.Count-1 do begin TfileObject(FobjectList[x]).FpathPart:=TfileObject(FobjectList[0]).FpathPart; end; end; Task Manager shows absouletly no change. However if I do something similar with a TstringList: var x: integer; begin for x := 1 to 1000000 do begin FstringList.Add(ExtractFilePath(Application.ExeName)); end; end; Task Manager says 60MB memory use. Now optimise with: var x: integer; begin for x := 1 to FstringList.Count - 1 do FstringList[x]:=FstringList[0]; end; Task Manager shows the drop in memory usage that I would expect, now 10MB. So I seem to be able to share strings in a string list, but not in objects. I am obviously missing something conceptually, in code or both! I hope this makes sense, I can really see the ability to conserve memory using this technique as I have a lot of objects all with lots of string information, that data is sorted in many different ways and I would like to be able to iterate over this data once it is loaded into memory and free some of that memory back up again by sharing strings in this way. Thanks in advance for any assistance you can offer.

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• Indirect property notification

  - by Carlo

  Hello, this question might look a little trivial, but it might not be. I'm just wondering which of the following two cases is better for indirect property notification, or perhaps there is an even better way. The scenario: I have two properties, the first one is an object called HoldingObject, the second one is a boolean called IsHoldingObject, which is false if HoldingObject == null, otherwise it's true. I'm just wondering what is the best notification mechanism for IsHoldingObject: Case (A) - Notify IsHoldingObject changed from the HoldingObject proeperty: public class NotifyingClass1 : INotifyPropertyChanged { private object _holdingObject; public object HoldingObject { get { return _holdingObject; } set { if (_holdingObject != value) { _holdingObject = value; NotifyPropertyChanged("HoldingObject"); // Notify from the property that is being checked NotifyPropertyChanged("IsHoldingObject"); } } } public bool IsHoldingObject { get { return this.HoldingObject == null; } } #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(string propertyName) { if (this.PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } #endregion } Case (B) - Notify IsHoldingObject changed from the IsHoldingObject directly, by setting it to false or true from HoldingObject property: public class NotifyingClass2 : INotifyPropertyChanged { private object _holdingObject; public object HoldingObject { get { return _holdingObject; } set { if (_holdingObject != value) { _holdingObject = value; NotifyPropertyChanged("HoldingObject"); // 1) Set the property here this.IsHoldingObject = _holdingObject != null; } } } private bool _isHoldingObject; public bool IsHoldingObject { get { return _isHoldingObject; } set { if (_isHoldingObject != value) { _isHoldingObject = value; // 2) Notify directly from the property NotifyPropertyChanged("IsHoldingObject"); } } } #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(string propertyName) { if (this.PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } #endregion } I personally lean to the first one because it requires less code, but I'm not sure how recommendable it is to do that. Let me know if there is another (better) way. Thanks!

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• Delphi / MySql : Problems escpaing strings

  - by mawg

  N00b here, having problems escaping strings. I used the QuotedStr() function - shouldn't that be enough. Unfortunately, the string that I am trying to quote is rather messy, but I will post it here in case anyone wants to paste it into WinMerge or KDiff3, etc. I am trying to store an entire Delphi form into the database, rather than into a .DFM file. It has only one field, a TEdit edit box. The debugger shows the form as text as 'object Form1: TScriptForm'#$D#$A' Left = 0'#$D#$A' Top = 0'#$D#$A' Align = alClient'#$D#$A' BorderStyle = bsNone'#$D#$A' ClientHeight = 517'#$D#$A' ClientWidth = 993'#$D#$A' Color = clBtnFace'#$D#$A' Font.Charset = DEFAULT_CHARSET'#$D#$A' Font.Color = clWindowText'#$D#$A' Font.Height = -11'#$D#$A' Font.Name = 'MS Sans Serif''#$D#$A' Font.Style = []'#$D#$A' OldCreateOrder = False'#$D#$A' SaveProps.Strings = ('#$D#$A' 'Visible=False')'#$D#$A' PixelsPerInch = 96'#$D#$A' TextHeight = 13'#$D#$A' object Edit1: TEdit'#$D#$A' Left = 192'#$D#$A' Top = 64'#$D#$A' Width = 121'#$D#$A' Height = 21'#$D#$A' TabOrder = 8'#$D#$A' end'#$D#$A'end'#$D#$A before calling QuotedStr() and ''object Form1: TScriptForm'#$D#$A' Left = 0'#$D#$A' Top = 0'#$D#$A' Align = alClient'#$D#$A' BorderStyle = bsNone'#$D#$A' ClientHeight = 517'#$D#$A' ClientWidth = 993'#$D#$A' Color = clBtnFace'#$D#$A' Font.Charset = DEFAULT_CHARSET'#$D#$A' Font.Color = clWindowText'#$D#$A' Font.Height = -11'#$D#$A' Font.Name = ''MS Sans Serif'''#$D#$A' Font.Style = []'#$D#$A' OldCreateOrder = False'#$D#$A' SaveProps.Strings = ('#$D#$A' ''Visible=False'')'#$D#$A' PixelsPerInch = 96'#$D#$A' TextHeight = 13'#$D#$A' object Edit1: TEdit'#$D#$A' Left = 192'#$D#$A' Top = 64'#$D#$A' Width = 121'#$D#$A' Height = 21'#$D#$A' TabOrder = 8'#$D#$A' end'#$D#$A'end'#$D#$A''' afterwards. The strange thing is that my complete command 'INSERT INTO designerFormDfm(designerFormDfmText) VALUES ("'object Form1: TScriptForm'#$D#$A' Left = 0'#$D#$A' Top = 0'#$D#$A' Align = alClient'#$D#$A' BorderStyle = bsNone'#$D#$A' ClientHeight = 517'#$D#$A' ClientWidth = 993'#$D#$A' Color = clBtnFace'#$D#$A' Font.Charset = DEFAULT_CHARSET'#$D#$A' Font.Color = clWindowText'#$D#$A' Font.Height = -11'#$D#$A' Font.Name = ''MS Sans Serif'''#$D#$A' Font.Style = []'#$D#$A' OldCreateOrder = False'#$D#$A' SaveProps.Strings = ('#$D#$A' ''Visible=False'')'#$D#$A' PixelsPerInch = 96'#$D#$A' TextHeight = 13'#$D#$A' object Edit1: TEdit'#$D#$A' Left = 192'#$D#$A' Top = 64'#$D#$A' Width = 121'#$D#$A' Height = 21'#$D#$A' TabOrder = 8'#$D#$A' end'#$D#$A'end'#$D#$A''");' executes in a MySql console, but not from Delphi, where I pass that command as parameter command to a function which ADOCommand.CommandText := command; ADOCommand.CommandType := cmdText; ADOCommand.Execute(); I can only assume that I am having problems escpaing sequences which contain single quotes (and QuotedStr() doesn't seem to escape backslahes(?!)) What am I doing that is obviously, glaringly wrong?

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• Thread Question

  - by Polaris

  I have method which create background thread to make some action. In this background thread I create object. But this object while creating in runtime give me an exception : The calling thread must be STA, because many UI components require this. I know that I must use Dispatcher to make reflect something to UI. But in this case I just create an object and dont iteract with UI. This is my code: public void SomeMethod() { BackgroundWorker worker = new BackgroundWorker(); worker.DoWork += new DoWorkEventHandler(Background_Method); worker.RunWorkerAsync(); } void Background_Method(object sender, DoWorkEventArgs e) { TreeView tv = new TreeView(); } How can I create objects in background thread? I use WPF application

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• How do I suppress this output?

  - by David

  I have a code chunk in an R Markdown file. ```{r} library(UsingR) ``` Using knitHTML to compile causes the following output, which never happened before I updated to the latest versions of R and RStudio: ## Loading required package: MASS ## Loading required package: HistData ## Loading required package: Hmisc ## Loading required package: grid ## Loading required package: lattice ## Loading required package: survival ## Loading required package: splines ## Loading required package: Formula ## ## Attaching package: 'Hmisc' ## ## The following objects are masked from 'package:base': ## ## format.pval, round.POSIXt, trunc.POSIXt, units ## ## Loading required package: aplpack ## Loading required package: tcltk ## Loading required package: quantreg ## Loading required package: SparseM ## ## Attaching package: 'SparseM' ## ## The following object is masked from 'package:base': ## ## backsolve ## ## ## Attaching package: 'quantreg' ## ## The following object is masked from 'package:Hmisc': ## ## latex ## ## The following object is masked from 'package:survival': ## ## untangle.specials ## ## ## Attaching package: 'UsingR' ## ## The following object is masked from 'package:survival': ## ## cancer How can I suppress this output? Note: echo=FALSE did not work.

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• Sqlite3 and PDO problem with ORDER BY

  - by Maenny

  Hi, I try to use the SQL statement SELECT * FROM table ORDER BY column via an PDO-Object in PHP. Problem is, that I always get an error (Call to a member function fetchall() on a non-object - that means, the query did not return a PDO-object) when using the names of all columnname EXCEPT for ID. When I query SELECT * FROM table ORDER BY ID it works. ID is the PRIMARY INTEGER KEY, all other columns are TEXT or NUMERIC, neither of them would works with the ORDER BY clause. Any ideas?

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• GAE transaction exception suggestion

  - by bach

  Hi, The current situation encourages the design of the system to split object fields to seperate objects in order to reduce the chance of the JDOCanRetryException to be thrown. If we could have the fields that were changed by the other client who changed the object in the exception content itself we could deside whether to re-retrieve the object or ignore...

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• How i solve memory leak problem?

  - by RRB

  Hi, I developing an simple application in which design or make code in which i creating and instance object of UIImage. When i swip on Ipad screen it make up an image of the sreen and that image i render into UIImage object after that this image i set into UIImageView object and UIimage object is released. Every time i swipe on the screen and above process is does again and again. But it give me leak in renderImage = [[UIImage alloc] init];. Code, _renderImage = [[UIImage alloc] init]; _textImageV = [[UIImageView alloc] init]; [self renderIntoImage]; -(void)renderIntoImage { UIGraphicsBeginImageContext(bgTableView.bounds.size); [self.view.layer renderInContext:UIGraphicsGetCurrentContext()]; _renderImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); } _textImageV.image = _renderImage; [_renderImage release]; after completing the process of swipe i also releasing _textImageV. How i solve the memory leak problem in UIImage *_renderImage?

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• How to sort data in a table data structure in Java?

  - by rgksugan

  I need to sort data based on the third column of the table data structure. I tried based on the answers for the following question. But my sorting does not work. Please help me in this. Here goes my code. Object[] data = new Object[y]; rst.beforeFirst(); while (rst.next()) { int p_id = Integer.parseInt(rst.getString(1)); String sw2 = "select sum(quantity) from tbl_order_detail where product_id=" + p_id; rst1 = stmt1.executeQuery(sw2); rst1.next(); String sw3 = "select max(order_date) from tbl_order where tbl_order.`Order_ID` in (select tbl_order_detail.`Order_ID` from tbl_order_detail where product_id=" + p_id + ")"; rst2 = stmt2.executeQuery(sw3); rst2.next(); data[i] = new Object[]{new String(rst.getString(2)), new String(rst.getString(3)), new Integer(rst1.getString(1)), new String(rst2.getString(1))}; i++; } ColumnComparator cc = new ColumnComparator(2); Arrays.sort(data, cc); if (i == 0) { table.addCell(""); table.addCell(""); table.addCell(""); table.addCell(""); } else { for (int j = 0; j < y; j++) { Object[] theRow = (Object[]) data[j]; table.addCell((String) theRow[0]); table.addCell((String) theRow[1]); table.addCell((String) theRow[2]); table.addCell((String) theRow[3]); }

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• multiple move operations and data processes in work thread

  - by younevertell

  main thread-- start workthread--StartStage(get list of positions for data process) -- move to one position -- data sampling*strong text*-- data collection--data analysis------data sampling*strong text* basically, work thread does the data sampling*strong text*-- data collection--data analysis------data sampling*strong text* loop for one positioin until press stop or target is obtained. my questions: After work thread finishs the loop for one positioin, it would end itself. now how to make the work thread moves to the next position to do the data process loop after work thread finish one position work, would not end itself until data process for all the positions are done? Thanks in advance!

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• List<T> paging asp.net

  - by user1397978

  Using a three-tier architecture, I have a list of objects List<object> careerList = new List<object>(); ModuleDTO module = new ModuleDTO(); careerList = module.getDegreeCodeByQualification(qualificationCode); which I then add to a gridview like so: gridViewMaster.DataSource = careerList; gridViewMaster.DataBind(); What I'd like to do is then enable paging on the gridview. My gridview so far is: <asp:GridView ID="gridViewMaster" runat="server" AutoGenerateColumns="False" GridLines="None" BorderWidth="1px" CellPadding="2" DataKeyNames="Grouping" ForeColor="Black" onrowdatabound="gridViewMaster_RowDataBound" CssClass="mGrid" PagerStyle-CssClass="pgr" AlternatingRowStyle-CssClass="alt" OnPageIndexChanging="gridView_PageIndexChanging" AllowPaging="True" > Is it possible to do enable paging on a list's without having to change that list to a Datatable or Dataview? If there is a way, this would help a lot. So far my events are as follows: protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e) { gridViewMaster.PageIndex = e.NewPageIndex; List<object> careerList = new List<object>(); ModuleDTO module = new ModuleDTO(); careerList = module.getDegreeCodeByQualification(qualificationCode); ModalProgress.Show(); System.Threading.Thread.Sleep(1000); JobPanel.Visible = true; gridViewMaster.DataSource = careerList.Distinct(); gridViewMaster.DataBind(); } Someone PLEASE HELP ME!!! Thank you

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• Shared/Static Variable Should Be Nothing but Isn't - what gives?

  - by Denis

  I have the following code: Public Class TestClass Public Sub Test() If theGlobal IsNot Nothing Then Throw New Exception("What gives!") End Sub Private Shared theGlobal As Object = Nothing Private Shared ReadOnly Property Global Get If theGlobal Is Nothing Then theGlobal = New Object() End If Return theGlobal End Get End Property End Class Am stumped... Why is theGlobal object NOT Nothing?

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• Is It Possible To Cast A Range

  - by Brad Rhoads

  I'd like to do something like this: def results = Item.findAll("from Item c, Tag b, ItemTag a where c = a.item and b = a.tag and (b.tag like :q or c.uri like :q) " + ob,[q:q]) def items = (Item) results[0..1][0] but I get Cannot cast object '[Ljava.lang.Object;@1e224a5' with class '[Ljava.lang.Object;' to class 'org.maflt.ibidem.Item' I can get what I need with this, but it doesn't seem like it's the best solution: def items = [] as Set def cnt = results.size() for (i=0;i<cnt-1;i++) { items << results[i][0] } items = items as List

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• Validates presence of each other in two associated models

  - by Sergey Alekseev

  I have the following two models: class Parent < ActiveRecord::Base has_one :child, dependent: :destroy validates :child, presence: true end class Child < ActiveRecord::Base belongs_to :parent validates :parent, presence: true end I want to create Parent object. If I do the following: Parent.create! or Factory(:parent) Exception raises: ActiveRecord::RecordInvalid: Validation failed: Child can't be blank But I can't create Child object without Parent object for the same reason - I need to create Parent object first in order to pass presence validation. As it appears I have some kind of infinite recursion here. How to solve it?

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• rvalues and temporary objects in the FCD

  - by FredOverflow

  It took me quite some time to understand the difference between an rvalue and a temporary object. But now the final committee draft states on page 75: An rvalue [...] is an xvalue, a temporary object or subobject thereof, or a value that is not associated with an object. I can't believe my eyes. This must be an error, right?

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• Javascript: 'this' changes when assigning a property?

  - by Pickels

  I know 'this' can be a problem when you don't understand Javascript well but this one got me a little puzzled. var ControlTypes = { TextBox: function () { console.log(this); this.Name = "TextBox"; console.log(this); } } ControlTypes.TextBox(); Firebug gives the following result: Object {} Object { Name="TextBox"} The first object is ControlTypes and the second one is Textbox. Could anybody explain the behavior behind this?

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• JavaScript - Inheritance in Constructors

  - by j0ker

  For a JavaScript project we want to introduce object inheritance to decrease code duplication. However, I cannot quite get it working the way I want and need some help. We use the module pattern. Suppose there is a super element: a.namespace('a.elements.Element'); a.elements.Element = (function() { // public API -- constructor Element = function(properties) { this.id = properties.id; }; // public API -- prototype Element.prototype = { getID: function() { return this.id; } }; return Element; }()); And an element inheriting from this super element: a.namespace('a.elements.SubElement'); a.elements.SubElement = (function() { // public API -- constructor SubElement = function(properties) { // inheritance happens here // ??? this.color = properties.color; this.bogus = this.id + 1; }; // public API -- prototype SubElement.prototype = { getColor: function() { return this.color; } }; return SubElement; }()); You will notice that I'm not quite sure how to implement the inheritance itself. In the constructor I have to be able to pass the parameter to the super object constructor and create a super element that is then used to create the inherited one. I need a (comfortable) possibility to access the properties of the super object within the constructor of the new object. Ideally I could operate on the super object as if it was part of the new object. I also want to be able to create a new SubElement and call getID() on it. What I want to accomplish seems like the traditional class based inheritance. However, I'd like to do it using prototypal inheritance since that's the JavaScript way. Is that even doable? Thanks in advance! EDIT: Fixed usage of private variables as suggested in the comments. EDIT2: Another change of the code: It's important that id is accessible from the constructor of SubElement.

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• Why Is the sender type null when dealing with events

  - by ChloeRadshaw

  From C# Via CLR: Note A lot of people wonder why the event pattern requires the sender parameter to always be of type Object After all, since the MailManager will be the only type raising an event with a NewMail EventArgs object, it makes more sense for the callback method to be prototyped like this: void MethodName(Mai l Manager sender, NewMail EventArgs e); The pattern requires the sender parameter to be of type Object mostly because of inheritance What if Mai lManager were used as a base class for SmtpMailManager? In this case, the callback method should have the sender parameter prototyped as SmtpMailManager instead of Mail Manager, but this can’t happen because SmtpMai lManager just inherited the NewMai l event So the code that was expecting SmtpMail Manager to raise the event must still have to cast the sender argument to SmtpMailManager In other words, the cast is still required, so the sender parameter might as well be typed as Obj ect The next reason for typing the sender parameter as Obj ect is just fexibility It allows the delegate to be used by multiple types that offer an event that passes a NewMail EventArgs object For example, a PopMai lManager class could use the delegate even if this class were not derived from Mail Manager I just simply cannot understand why the sender is an object - Why can it not be generified? so most of the time we do not need to do generic casts

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• Is it any loose coupling mechanism in Objective-C + Cocoa like C# delegates or C++Qt signals+slots?

  - by Eye of Hell

  Hello. For a large programs, the standard way to chalenge a complexity is to divide a program code into small objects. Most of the actual programming languages offer this functionality via classes, so is Objective-C. But after source code is separated into small object, the second challenge is to somehow connect them with each over. Standard approaches, supported by most languages are compositon (one object is a member field of another), inheritance, templates (generics) and callbacks. More cryptic techniques include method-level delagates (C#) and signals+slots (C++Qt). I like the delegates / signals idea, since while connecting two objects i can connect individual methods with each over, without objects knowing anything of each over. For C#, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); object1.SomethingHappened += object2.HandleSomething; In this code, is object1 calls it's SomethingHappened delegate (like a normal method call) the HandleSomething method of object2 will be called. For C++Qt, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); connect( object1, SIGNAL(SomethingHappened()), object2, SLOT(HandleSomething()) ); The result will be exactly the same. This technique has some advantages and disadvantages, but generally i like it more than interfaces since if program code base grows i can change connections and add new ones without creating tons of interfaces. After examination of Objective-C i havn't found any way to use this technique i like :(. It seems that Objective-C supports message passing perfectly well, but it requres for object1 to have a pointer to object2 in order to pass it a message. If some object needs to be connected to lots of other objects, in Objective-C i will be forced to give him pointers to each of the objects it must be connected. So, the question :). Is it any approach in Objective-C programming that will closely resemble delegate / signal+slot types of connection, not a 'give first object an entire pointer to second object so it can pass a message to it'. Method-level connections are a bit more preferable to me than object-level connection ^_^.

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• C# Casting system.__comobject to class type

  - by ijrufus

  I have an Excel Add-In that I'm currently trying to set up a unit test framework for. For the unit tests I've followed this guide: http://blogs.msdn.com/b/varsha/archive/2010/08/17/writing-automated-test-cases-for-vsto-application.aspx It seems to work fine, until I want to return a class object from my interface. Specifying the class object as the return type throws a "return argument has an invalid type" exception when calling the method. Changing the return type from the class to an object allows me to call the method and get the object, but now I'm unable to cast it as the class and use it as intended, getting this exception message when I try: > Unable to cast COM object of type 'System.__ComObject' to class type > 'anaplan.Utility.XYCoordinates'. Instances of types that represent COM > components cannot be cast to types that do not represent COM > components; however they can be cast to interfaces as long as the > underlying COM component supports QueryInterface calls for the IID of > the interface. I've retrieved the Type name using VisualBasic.Information.TypeName and it's showing it as the class I expect. Is there any way to get the comobject cast back to the class? Or another way to access the properties it has? Or am I just being a bit stupid here?

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