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  • What is the problem with my LinkedList class?

    - by user258367
    class LinkedList { private: int data; LinkedList *ptr; public: LinkedList(int i_data) { data = i_data; ptr = 0; { ~LinkedList() { delete ptr ; } void insert(LinkedList *node) { while(this->next != 0) this = this->next; this->next = node; } } I will be creating a head node like head = new LinkedList(4) and then will be calling like head->insert(new LinkedList(5)) and subsequently . Can you please tell me does above class represent a linkedlist . i think yes it has node which contain address of next node . Please correct me if i am wrong

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  • How can I type cast EventArgs to have a .point property in c#? [closed]

    - by Sean Smyth
    I'm working with a double click function in c#. the function takes an object and EventArgs as it's parameters: private void gvHL7_DoubleClick(object sender, EventArgs e){ . . . } However, I want to use the .Point property, and EventArgs doesn't have that property. I know that DevExpress.XtraGrid.Views.Grid.GridMenuEventArgs does, but it's saying that's an invalid casting. What type should I cast my EventArgs instance to if I wish to access the .Point property? Edit: The double click function I'm working with is provided by devexpress for their grids.

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  • RAII: Initializing data member in const method

    - by Thomas Matthews
    In RAII, resources are not initialized until they are accessed. However, many access methods are declared constant. I need to call a mutable (non-const) function to initialize a data member. Example: Loading from a data base struct MyClass { int get_value(void) const; private: void load_from_database(void); // Loads the data member from database. int m_value; }; int MyClass :: get_value(void) const { static bool value_initialized(false); if (!value_initialized) { // The compiler complains about this call because // the method is non-const and called from a const // method. load_from_database(); } return m_value; } My primitive solution is to declare the data member as mutable. I would rather not do this, because it suggests that other methods can change the member. How would I cast the load_from_database() statement to get rid of the compiler errors?

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  • Converting mxml Rect & SolidColor to actionscript

    - by touB
    I'm trying to learn how to use actionscript over mxml for flexibility. I have this simple block of mxml that I'm trying to convert to actionscript, but I'm stuck half way though <s:Rect id="theRect" x="0" y="50" width="15%" height="15%"> <s:fill> <s:SolidColor color="black" alpha="0.9" /> </s:fill> </s:Rect> I can convert the Rect no problem to private var theRect:Rect = new Rect(); theRect.x = 0; theRect.y = 50; theRect.width = "15%"; theRect.height = "15%"; then I'm stuck on the fill. What's the most efficient way to add the SolidColor in as few lines of code as possible.

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  • jsf icefaces basic problem with displaying value

    - by michal
    Hi All, I don't know what I'm doing wrong.I'm using icefaces and have basic controller: public class TestingController { private String name; public String submit() { setName("newName"); return null; } public void setName(String name) { this.name = name;} public String getName() { return name; } } --------and view: <ice:inputText id="inp" value="#{testController.name}" /> <br> <ice:commandButton id="submit" value="SUBMIT" action="#{testController.submit}" /> When I submit the form after first displaying the page..the input is set to newName, next I clear the inputText to "". and submit again but the name is not set to newName again as I would expect but it's empty. thank you in advance for you help.

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  • Relvance of 'public' contructor in abstract class.

    - by Amby
    Is there any relevance of a 'public' constructor in an abstract class? I can not think of any possible way to use it, in that case shouldn't it be treated as error by compiler (C#, not sure if other languages allow that). Sample Code: internal abstract class Vehicle { public Vehicle() { } } The C# compiler allows this code to compile, while there is no way i can call this contructor from the outside world. It can be called from derived classes only. So shouldn't it allow 'protected' and 'private' modifiers only. Please comment.

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  • Filter the datagridview column based on the current row of another column in C#

    - by user286546
    I have a datagridview that is populating columns from different table. I want to filter the column based on another column of the current row. I tried to use the cell enter event of the datagridview and then filtered the column by filtering the binding source on the column of the current row. private void lINKDataGridView_CellEnter(object sender, DataGridViewCellEventArgs e) { this.pROBLEMBindingSource.Filter = "item_id = " + this.lINKDataGridView.Rows[e.RowIndex].Cells[dataGridViewTextBoxColumn4.Index].Value + ""; } This is how I am filtering the "problem " binding source on the cell enter event of the datagridview . It is working fine but I am getting an error- being: System.ArgumentException: DataGridViewComboBoxCell value is not valid. Any suggestion

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  • how to modify a textbox using remoting

    - by danutz0119
    I am trying to modify a textBox found in the server Form using remoting from the client side. i have tried some solutions i found, but none of them work. the remoting part works propperly, the only thing that I am not able to figure out is this: this is what i have: client side: ... private void btn_b1_Click(object sender, EventArgs e) { ... myFunc.update(string s); ... } ... sharedLibs: public interface myInterf { void update(string s); } server side: here i have 2 classes in the same namespace class class1 : MarshalByRefObject, myInterf { public void update(string s) { //what do i write here to modify textBox1? } } public partial class class2 : Form { ... // here is the textBox i am trying to alter; }

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  • how to cout a vector of structs (that's a class member, using extraction operator)

    - by Julz
    hi, i'm trying to simply cout the elements of a vector using an overloaded extraction operator. the vector contians Point, which is just a struct containing two doubles. the vector is a private member of a class called Polygon, so heres my Point.h #ifndef POINT_H #define POINT_H #include <iostream> #include <string> #include <sstream> struct Point { double x; double y; //constructor Point() { x = 0.0; y = 0.0; } friend std::istream& operator >>(std::istream& stream, Point &p) { stream >> std::ws; stream >> p.x; stream >> p.y; return stream; } friend std::ostream& operator << (std::ostream& stream, Point &p) { stream << p.x << p.y; return stream; } }; #endif my Polygon.h #ifndef POLYGON_H #define POLYGON_H #include "Segment.h" #include <vector> class Polygon { //insertion operator needs work friend std::istream & operator >> (std::istream &inStream, Polygon &vertStr); // extraction operator friend std::ostream & operator << (std::ostream &outStream, const Polygon &vertStr); public: //Constructor Polygon(const std::vector<Point> &theVerts); //Default Constructor Polygon(); //Copy Constructor Polygon(const Polygon &polyCopy); //Accessor/Modifier methods inline std::vector<Point> getVector() const {return vertices;} //Return number of Vector elements inline int sizeOfVect() const {return vertices.size();} //add Point elements to vector inline void setVertices(const Point &theVerts){vertices.push_back (theVerts);} private: std::vector<Point> vertices; }; and Polygon.cc using namespace std; #include "Polygon.h" // Constructor Polygon::Polygon(const vector<Point> &theVerts) { vertices = theVerts; } //Default Constructor Polygon::Polygon(){} istream & operator >> (istream &inStream, Polygon::Polygon &vertStr) { inStream >> ws; inStream >> vertStr; return inStream; } // extraction operator ostream & operator << (ostream &outStream, const Polygon::Polygon &vertStr) { outStream << vertStr.vertices << endl; return outStream; } i figure my Point insertion/extraction is right, i can insert and cout using it and i figure i should be able to just...... cout << myPoly[i] << endl; in my driver? (in a loop) or even... cout << myPoly[0] << endl; without a loop? i've tried all sorts of myPoly.at[i]; myPoly.vertices[i]; etc etc also tried all veriations in my extraction function outStream << vertStr.vertices[i] << endl; within loops, etc etc. when i just create a... vector<Point> myVect; in my driver i can just... cout << myVect.at(i) << endl; no problems. tried to find an answer for days, really lost and not through lack of trying!!! thanks in advance for any help. please excuse my lack of comments and formatting also there's bits and pieces missing but i really just need an answer to this problem thanks again

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  • How to distinguish properties from constants if they both use PascalCasing for naming?

    - by Gishu
    As stated in the framework design guidelines and the WWW in general, the current guideline is to name your constants like this LastTemplateIndex as opposed to LAST_TEMPLATE_INDEX With the PascalCasing approach, how do you differentiate between a Property and a Constant. ErrorCodes.ServerDown is fine. But what about private constants within your class ? I use quite a lot of them for naming magic numbers.. or for expected values in my unit tests and so on. The ALL_CAPS style helps me know that it is a constant . _testApp.SelectTemplate(LAST_TEMPLATE_INDEX); *Disclosure: I have been using the SCREAMING_CAPS style for a while for constants + I find it more readable than squishedTogetherPascalCasedName. It actually STANDS_OUT in a block of text*

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  • How do I get client ip address using TcpClient?

    - by brendan
    I am using TcpClient to listen on a port for requests. When the requests come in from the client I want to know the client ip making the request. I've tried: Console.WriteLine(tcpClient.Client.RemoteEndPoint.ToString()); Console.WriteLine(tcpClient.Client.LocalEndPoint.ToString()); var networkStream = tcpClient.GetStream(); var pi = networkStream.GetType().GetProperty("Socket", BindingFlags.NonPublic | BindingFlags.Instance); var socketIp = ((Socket)pi.GetValue(networkStream, null)).RemoteEndPoint.ToString(); Console.WriteLine(socketIp); All of these addresses output 10.x.x.x addresses which are private addresses and are clearly not the address of the clients off my network making the requests. What can I do to get the public ip of the clients making the requests?

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  • problem in counting two fields in one query

    - by Mac Taylor
    hey guys i need to count new private messages and old one from a table so first thing come to mind is using mysql_num_rows and easy thing to do // check new pms $user_id = $userinfo['user_id']; $sql = "SELECT author_id FROM bb3privmsgs_to WHERE user_id='$user_id' AND (pm_new='1' OR pm_unread='1')"; $result = $db->sql_query($sql) ; $new_pms = $db->sql_numrows($result); $db->sql_freeresult($result); // check old pms $sql = "SELECT author_id FROM bb3privmsgs_to WHERE user_id='$user_id' AND (pm_new='0' OR pm_unread='0')"; $result = $db->sql_query($sql) ; $old_pms = $db->sql_numrows($result); $db->sql_freeresult($result); but how can i count these two fields just in one statement and shorter lines ?~

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  • RAW key generation in IOS with AES

    - by sudheer
    I am novice to the cryptography in ios . I got a requirement to convert android encryption code into IOS . Below is the android code part. I need that in IOS . Can any one please help me out in this . I need this below android code in IOS. private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance("AES"); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed(seed); kgen.init(256, sr); SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); return raw; }

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  • Referring to a non-final variable data inside an inner class

    - by shoaibmohammed
    Im doing a program in GWT. Here is the snippet where Im having problem private String[] populateRSSData() { 1==>> String[] data = null; try { new RequestBuilder(RequestBuilder.GET, "../database.php?action=populaterss").sendRequest(null, new RequestCallback() { @Override public void onResponseReceived(Request request, Response response) { 2==>> data=response.getText().split("~"); } @Override public void onError(Request request, Throwable exception) { Window.alert(exception.getMessage()); } }); } catch (RequestException e) { Window.alert(e.getMessage()); } return data; } Now the problem arises that I get an error that the variable 1==>> data should be declared final. But if I declare it as final then i cannot store the datas in 2==>> The error i get Cannot refer to a non-final variable data inside an inner class defined in a different method RSS_Manager.java Please suggest

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  • Administrator account: Where, when and how?

    - by Pickels
    Where, when and how to insert/create the administrator account for a website? Here are a few ways I encountered in other websites/webapplication. Installation wizard: You see this a lot in blog software or forums. When you install the application it will ask you to create an administrator user. Private webapplication will most likely not have this. Installation file: A file you run to install your application. This file will create the administrator account for you. Configuration files: A configuration file that holds the credentials for the administrator account. Manually insert it into a database: Manually insert the administrator info into the database.

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  • loading a file and getting its contents crashes on me.

    - by Richards
    private class Lytterklasse implements ActionListener{ public void actionPerformed(ActionEvent e) { JFileChooser chooser = new JFileChooser(); FileNameExtensionFilter filter = new FileNameExtensionFilter( "Sudoku Tekstfiler", "txt"); chooser.setFileFilter(filter); int returnVal = chooser.showOpenDialog(getParent()); String filnavn=chooser.getName(); In innfil=new In(filnavn); int type=innfil.inInt(); int lengdeBoks=innfil.inInt(); int breddeBoks=innfil.inInt(); for(int i=0;i } Why does this crash on me? I cant figure it out. Please help!

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  • Problem with passing parameters to SQL procedure using VBA

    - by Stefan Åstrand
    Hi, I am trying to pass @intDocumentNo and @intCustomerNo to a stored procedure using VBA but only @intCustomerNo is updated in dbo.tblOrderHead. I don't think the problem is with the procedure because if I enter the values manually it runs properly. What am I doing wrong? VBA Code: Private Sub intCustomerNo_Click() Dim cmdCommand As New ADODB.Command With cmdCommand .ActiveConnection = CurrentProject.Connection .CommandType = adCmdStoredProc .CommandText = "uspSelectCustomer" '@intDocumentNo .Parameters("@intDocumentNo").Value = Forms![frmSalesOrder].[IntOrderNo] '@intCustomerNo .Parameters("@intCustomerNo").Value = Me![intCustomerNo] .Execute End With DoCmd.Close Forms![frmSalesOrder].Requery End Sub Procedure: UPDATE dbo.tblOrderHead SET dbo.tblOrderHead.intCustomerNo = @intCustomerNo , dbo.tblOrderHead.intPaymentCode = dbo.tblCustomer.intPaymentCode, dbo.tblOrderHead.txtDeliveryCode = dbo.tblCustomer.txtDeliveryCode, dbo.tblOrderHead.txtRegionCode = dbo.tblCustomer.txtRegionCode, dbo.tblOrderHead.txtCurrencyCode = dbo.tblCustomer.txtCurrencyCode, dbo.tblOrderHead.txtLanguageCode = dbo.tblCustomer.txtLanguageCode FROM dbo.tblOrderHead INNER JOIN dbo.tblCustomer ON dbo.tblOrderHead.intCustomerNo = dbo.tblCustomer.intCustomerNo AND dbo.tblOrderHead.intOrderNo = @intDocumentNo

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  • Proper way to have an endless worker thread?

    - by Neil N
    I have an object that requires a lot of initialization (1-2 seconds on a beefy machine). Though once it is initialized it only takes about 20 miliseconds to do a typical "job" In order to prevent it from being re-initialized every time an app wants to use it (which could be 50 times a second or not at all for minutes in typical usage), I decided to give it a job que, and have it run on its own thread, checking to see if there is any work for it in the que. However I'm not entirely sure how to make a thread that runs indefinetly with or without work. Here's what I have so far, any critique is welcomed private void DoWork() { while (true) { if (JobQue.Count > 0) { // do work on JobQue.Pop() } else { System.Threading.Thread.Sleep(50); } } } After thought: I was thinking I may need to kill this thread gracefully insead of letting it run forever, so I think I will add a Job type that tells the thread to end. Any thoughts on how to end a thread like this also appreciated.

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  • any way to get sharepoint groups with a given site url

    - by standley-nguyen
    Hi all. I'm getting a stuck. Suppose that I create 5 sites. For each one, I create a few sharepoint groups. So, I create a dropdownlist control to bind 5 sites and when I click on any site there, I will get sharepoint groups created on it. But I always see the dropdownlist used to bind these groups still never change. I mean it only binds a few default groups in sahrepoint everytime. The new created groups is not. And I have confusion like this web.AssociatedGroups web.Groups web.SiteGroups which one we will use this case ? Please guide me Here my snippet code private void BindSPGroupsToDropDownList(DropDownList ddl, string siteUrl) { ddl.Items.Clear(); try { SPSecurity.RunWithElevatedPrivileges(delegate() { using (SPSite site = new SPSite(siteUrl)) { using (SPWeb web = site.OpenWeb()) { //web.SiteGroups foreach (SPGroup spGroup in web.Groups) { ddl.Items.Add(new ListItem(spGroup.Name.Trim(), spGroup.ID.ToString())); } } } }); } } thanks in advance

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  • Saving image from Gallery to db - Coursor IllegalStateException

    - by MyWay
    I want to save to db some strings with image. Image can be taken from gallery or user can set the sample one. In the other activity I have a listview which should present the rows with image and name. I'm facing so long this problem. It occurs when I wanna display listview with the image from gallery, If the sample image is saved in the row everything works ok. My problem is similar to this one: how to save image taken from camera and show it to listview - crashes with "IllegalStateException" but I can't find there the solution for me My table in db looks like this: public static final String KEY_ID = "_id"; public static final String ID_DETAILS = "INTEGER PRIMARY KEY AUTOINCREMENT"; public static final int ID_COLUMN = 0; public static final String KEY_NAME = "name"; public static final String NAME_DETAILS = "TEXT NOT NULL"; public static final int NAME_COLUMN = 1; public static final String KEY_DESCRIPTION = "description"; public static final String DESCRIPTION_DETAILS = "TEXT"; public static final int DESCRIPTION_COLUMN = 2; public static final String KEY_IMAGE ="image" ; public static final String IMAGE_DETAILS = "BLOP"; public static final int IMAGE_COLUMN = 3; //method which create our table private static final String CREATE_PRODUCTLIST_IN_DB = "CREATE TABLE " + DB_TABLE + "( " + KEY_ID + " " + ID_DETAILS + ", " + KEY_NAME + " " + NAME_DETAILS + ", " + KEY_DESCRIPTION + " " + DESCRIPTION_DETAILS + ", " + KEY_IMAGE +" " + IMAGE_DETAILS + ");"; inserting statement: public long insertToProductList(String name, String description, byte[] image) { ContentValues value = new ContentValues(); // get the id of column and value value.put(KEY_NAME, name); value.put(KEY_DESCRIPTION, description); value.put(KEY_IMAGE, image); // put into db return db.insert(DB_TABLE, null, value); } Button which add the picture and onActivityResult method which saves the image and put it into the imageview public void AddPicture(View v) { // creating specified intent which have to get data Intent intent = new Intent(Intent.ACTION_PICK); // From where we want choose our pictures intent.setType("image/*"); startActivityForResult(intent, PICK_IMAGE); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { // TODO Auto-generated method stub super.onActivityResult(requestCode, resultCode, data); // if identification code match to the intent, //if yes we know that is our picture, if(requestCode ==PICK_IMAGE ) { // check if the data comes with intent if(data!= null) { Uri chosenImage = data.getData(); String[] filePathColumn = {MediaStore.Images.Media.DATA}; Cursor cursor = getContentResolver().query(chosenImage, filePathColumn, null, null, null); cursor.moveToFirst(); int columnIndex = cursor.getColumnIndex(filePathColumn[0]); String filePat = cursor.getString(columnIndex); cursor.close(); ImageOfProduct = BitmapFactory.decodeFile(filePat); if(ImageOfProduct!=null) { picture.setImageBitmap(ImageOfProduct); } messageDisplayer("got picture, isn't null " + IdOfPicture); } } } Then the code which converts bitmap to byte[] public byte[] bitmapToByteConvert(Bitmap bit ) { // stream of data getted for compressed bitmap ByteArrayOutputStream gettedData = new ByteArrayOutputStream(); // compressing method bit.compress(CompressFormat.PNG, 0, gettedData); // our byte array return gettedData.toByteArray(); } The method which put data to the row: byte[] image=null; // if the name isn't put to the editView if(name.getText().toString().trim().length()== 0) { messageDisplayer("At least you need to type name of product if you want add it to the DB "); } else{ String desc = description.getText().toString(); if(description.getText().toString().trim().length()==0) { messageDisplayer("the description is set as none"); desc = "none"; } DB.open(); if(ImageOfProduct!= null){ image = bitmapToByteConvert(ImageOfProduct); messageDisplayer("image isn't null"); } else { BitmapDrawable drawable = (BitmapDrawable) picture.getDrawable(); image = bitmapToByteConvert(drawable.getBitmap()); } if(image.length>0 && image!=null) { messageDisplayer(Integer.toString(image.length)); } DB.insertToProductList(name.getText().toString(), desc, image ); DB.close(); messageDisplayer("well done you add the product"); finish(); You can see that I'm checking here the length of array to be sure that I don't send empty one. And here is the place where Error appears imo, this code is from activity which presents the listview with data taken from db private void LoadOurLayoutListWithInfo() { // firstly wee need to open connection with db db= new sqliteDB(getApplicationContext()); db.open(); // creating our custom adaprer, the specification of it will be typed // in our own class (MyArrayAdapter) which will be created below ArrayAdapter<ProductFromTable> customAdapter = new MyArrayAdapter(); //get the info from whole table tablecursor = db.getAllColumns(); if(tablecursor != null) { startManagingCursor(tablecursor); tablecursor.moveToFirst(); } // now we moving all info from tablecursor to ourlist if(tablecursor != null && tablecursor.moveToFirst()) { do{ // taking info from row in table int id = tablecursor.getInt(sqliteDB.ID_COLUMN); String name= tablecursor.getString(sqliteDB.NAME_COLUMN); String description= tablecursor.getString(sqliteDB.DESCRIPTION_COLUMN); byte[] image= tablecursor.getBlob(3); tablefromDB.add(new ProductFromTable(id,name,description,image)); // moving until we didn't find last row }while(tablecursor.moveToNext()); } listView = (ListView) findViewById(R.id.tagwriter_listoftags); //as description says // setAdapter = The ListAdapter which is responsible for maintaining //the data backing this list and for producing a view to represent //an item in that data set. listView.setAdapter(customAdapter); } I put the info from row tho objects which are stored in list. I read tones of question but I can't find any solution for me. Everything works when I put the sample image ( which is stored in app res folder ). Thx for any advice

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  • Custom Grid LINQ to SQL help

    - by user488361
    Following is my custome cotrol grid... public partial class LinqGrid : UserControl { object tmpDataTable = new object(); public LinqGrid() { InitializeComponent(); } public void Bind(System.Data.Linq.Table listSource) where T : class { Project.dbClassesDataContext dbc = new Project.dbClassesDataContext(); tmpDataTable = listSource; var query = (from c in listSource select c); dgvRecords.DataSource = query.Take(10).ToList(); } private void btnNext_Click(object sender, EventArgs e) { // now what i have to do here if i want next 10 records.....means how to retrive tmpDataTable object here... ??? i can't find Type of variable....?? plz help me.... } }

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  • C# Async call garbage collection

    - by Troy
    Hello. I am working on a Silverlight/WCF application and of course have numerous async calls throughout the Silverlight program. I was wondering on how is the best way to handle the creation of the client classes and subscribing. Specifically, if I subscribe to an event in a method, after it returns does it fall out of scope? internal MyClass { public void OnMyButtonClicked() { var wcfClient = new WcfClient(); wcfClient.SomeMethodFinished += OnMethodCompleted; wcfClient.SomeMethodAsync(); } private void OnMethodCompleted(object sender, EventArgs args) { //Do something with the result //After this method does the subscription to the event //fall out of scope for garbage collection? } } Will I run into problems if I call the function again and create another subscription? Thanks in advance to anyone who responds.

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  • Dynamically create and cast objects at runtime

    - by vaibhav bindroo
    Let's say we have 2 classes A and B public class A{ private int member1; A() { member1 = 10; } public getMember(){ return member1; } } Class B is also on the same lines except that its member variable is named member2 and gets intitialized to say 20 inside the constructor. My Requirement : At runtime , I get a string which contains a className ( could be A or B). I want to dynamically create an object of this class along with invoking the constructor. How can I achieve this . I don't want to use interfaces for common functionality of above classes Morever, later on I set the properties of this raw object using Propery Builder Bean Util class based on a list of columns . Class clazz = Class.forName("className"); Obj obj = clazz.newInstance(); How I can dynamically convert that obj to className object.

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  • How can I simulate the effects of an observable collection in this situation?

    - by MGSoto
    I am making a configuration editor for another application and am using reflection to pull editable fields from the configuration class. The following class is the base class for my various "DataTypeViewModels" and shows how I get and set the appropriate properties. public abstract class DataTypeViewModel<T> : ViewModelBase { Func<T> getFunction; Action<T> setAction; public const string ValuePropertyName = "Value"; public string Label { get; set; } public T Value { get { return getFunction.Invoke(); } set { if (getFunction.Invoke().Equals(value)) { return; } setAction.Invoke(value); // Update bindings, no broadcast RaisePropertyChanged(ValuePropertyName); } } /// <summary> /// Initializes a new instance of the StringViewModel class. /// </summary> public DataTypeViewModel(string sectionName, string label) { if (IsInDesignMode) { // Code runs in Blend --> create design time data. } else { Label = label; getFunction = new Func<T>(() => { return (T)Settings.Instance.GetType().GetProperty(sectionName).PropertyType. GetProperty(label).GetValue(Settings.Instance.GetType().GetProperty(sectionName).GetValue(Settings.Instance, null), null); }); setAction = new Action<T>(value => { Settings.Instance.GetType().GetProperty(sectionName).PropertyType.GetProperty(label). SetValue(Settings.Instance.GetType().GetProperty(sectionName).GetValue(Settings.Instance, null), value, null); }); } } } This part works the way I want it to, the next part is a sample DataTypeViewModel on a list of strings. public class StringListViewModel : DataTypeViewModel<ICollection<string>> { /// <summary> /// The <see cref="RemoveItemCommand" /> property's name. /// </summary> public const string RemoveItemCommandPropertyName = "RemoveItemCommand"; private RelayCommand<string> _removeItemCommand = null; public ObservableCollection<string> ObservableValue { get; set; } /// <summary> /// Gets the RemoveItemCommand property. /// TODO Update documentation: /// Changes to that property's value raise the PropertyChanged event. /// This property's value is broadcasted by the Messenger's default instance when it changes. /// </summary> public RelayCommand<string> RemoveItemCommand { get { return _removeItemCommand; } set { if (_removeItemCommand == value) { return; } var oldValue = _removeItemCommand; _removeItemCommand = value; // Update bindings, no broadcast RaisePropertyChanged(RemoveItemCommandPropertyName); } } /// <summary> /// The <see cref="AddItemCommand" /> property's name. /// </summary> public const string AddItemCommandPropertyName = "AddItemCommand"; private RelayCommand<string> _addItemCommand = null; /// <summary> /// Gets the AddItemCommand property. /// TODO Update documentation: /// Changes to that property's value raise the PropertyChanged event. /// This property's value is broadcasted by the Messenger's default instance when it changes. /// </summary> public RelayCommand<string> AddItemCommand { get { return _addItemCommand; } set { if (_addItemCommand == value) { return; } var oldValue = _addItemCommand; _addItemCommand = value; // Update bindings, no broadcast RaisePropertyChanged(AddItemCommandPropertyName); } } /// <summary> /// Initializes a new instance of the StringListViewModel class. /// </summary> public StringListViewModel(string sectionName, string label) : base(sectionName, label) { ObservableValue = new ObservableCollection<string>(Value); AddItemCommand = new RelayCommand<string>(param => { if (param != string.Empty) { Value.Add(param); ObservableValue.Add(param); } }); RemoveItemCommand = new RelayCommand<string>(param => { if (param != null) { Value.Remove(param); ObservableValue.Remove(param); } }); } } As you can see in the constructor, I currently have "Value" mirrored into a new ObservableCollection called "ObservableValue", which is then bound to by a ListView in the XAML. It works well this way, but cloning the List seems like such a hacky way to do this. While bound to Value, I've tried adding: RaisePropertyChanged("Value"); to the AddItemCommand and RemoveItemCommand, but this doesn't work, the ListView won't get updated. What is the proper way to do this?

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  • Singletons and other design issues

    - by Ahmed Saleh
    I have worked using different languages like C++/Java and currently AS3. Most applications were computer vision, and small 2D computer games. Most companies that I have worked for, they use Singletons in a language like AS3, to retrieve elements or classes in an easy way. Their problem is basically they needs some variables or to call other functions from other classes. In a language like AS3, there is no private constructor, and they write a hacky code to prevent new instances. In Java and C++ I also faced the situation that I need to use other classe's members or to call their functions in different classes. The question is, is there a better or another design, to let other classes interact with each others without using singletons? I feel that composition is the answer, but I need more detailed solutions or design suggestions.

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