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• How do I take the advantage of the variable column key/value structure of Cassandra

  - by icejade

  If I have to predefine all the columns, how do I take the advantage of the variable column key/value structure of cassandra? If I use update table command, it will insert null for all the rows which don't have that column. This is same as relational DB. For example, for contact column family, I have name, phone, email. I have 100 contacts have all 3 field. Then number 101 contact has skype id which I want to add. If I use insert statement, it won't let me add skypeid since it's not defined in the CF. So I have to run alter statement to change the CF, then all the first 100 contacts will have a null field for each of them.

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• How do I avoid boxing/unboxing when extending System.Object?

  - by Robert H.

  I'm working on an extension method that's only applicable to reference types. I think, however, it's currently boxing and unboxing the the value. How can I avoid this? namespace System { public static class SystemExtensions { public static TResult GetOrDefaultIfNull<T, TResult>(this T obj, Func<T, TResult> getValue, TResult defaultValue) { if (obj == null) return defaultValue; return getValue(obj); } } } Example usage: public class Foo { public int Bar { get; set; } } In some method: Foo aFooObject = new Foo { Bar = 1 }; Foo nullReference = null; Console.WriteLine(aFooObject.GetOrDefaultIfNull((o) => o.Bar, 0)); // results: 1 Console.WriteLine(nullReference.GetOrDefaultIfNull((o) => o.Bar, 0)); // results: 0

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• List<string> doesn't update the UI when change occurs [WPF]

  - by Hard Turner

  <ListBox x:Name="MainList" HorizontalAlignment="Left" Height="468" Margin="10,10,0,0" VerticalAlignment="Top" Width="100" ItemsSource="{Binding Items,Mode=TwoWay}" DisplayMemberPath="Name"/> [Serializable()] public class MYcontainer : INotifyPropertyChanged,ISerializable { private List<MYClass> _items = new List<MYClass>(); public List<MYClass> Items { get{ return _items;} set { this._items =value; OnPropertyChanged("Items"); } public event PropertyChangedEventHandler PropertyChanged; public void OnPropertyChanged(string propertyName = null) { var eventHandler = this.PropertyChanged; if (eventHandler != null) eventHandler(this, new PropertyChangedEventArgs(propertyName)); } } when i add an item to "Items" the UI doesnt update, the binding is working fine, since if i closed the window and opened it again, the new items appear correctly what am i doing wrong? i know if i used observablecollection it will work fine, but shouldn't it work with List<? , i already have in another window a string[] property and it update fine

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• "more" as a target of piped command breaks bash

  - by xavier

  Consider following source, reduced for simplicity int main() { int d[2]; pipe(d); if(fork()) { close(1); dup(d[1]); execlp("ls", "ls", NULL); } else { close(0); dup(d[0]); execlp("cat", "cat", NULL); } } So it creates a pipe and redirects the output from ls to cat. It works perfectly fine, no problems. But change cat to more and bash breaks. The symptoms are: you don't see anything you type pressing "enter" shows up a new prompt, but not in a new line, but in the same one you can execute any command and see the output reset helps fixing things up. So there is a problem with input from keyboard, it is there, but is not visible. Why is that?

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• Is it possible to use JavaScript to submit an unnamed form from outside an iFrame?

  - by Scott

  I know that may sound silly, but I'm trying to submit a form on a page inside an iFrame, from the parent site. Here's an example of the form: <form action="/add_email" method="post"> <div class="field"> <label for="newEmailAddress" style="width: auto">Add new email address</label> <input type="text" id="newEmailAddress" name="email" value="null" class="text-field" /> <input type="hidden" name="__app_key" value="null"/> <input type="submit" value="Add address and send activation email"> </div> </form> As you can see, the Submit button, and the form itself both lack a proper name or id, this is not something I have control over. (It's on an external website.) Any suggestions?

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• Are protected constructors considered good practice?

  - by Álvaro G. Vicario

  I'm writing some little helper classes to handle trees. Basically, I have a node and a special root node that represents the tree. I want to keep it generic and simple. This is part of the code: <?php class Tree extends TreeNode{ public function addById($node_id, $parent_id, $generic_content){ if( $parent = $this->findNodeById($parent_id) ){ $parent->addChildById($node_id, $generic_content); } } } class TreeNode{ public function __construct($node_id, $parent_id, $generic_content){ // ... } protected function addChildById($node_id, $generic_content){ $this->children[] = new TreeNode($this->node_id, $node_id, $generic_content); } } $Categories = new Tree; $Categories->addById(1, NULL, $foo); $Categories->addById(2, NULL, $bar); $Categories->addById(3, 1, $gee); ?> My questions: Is it sensible to force TreeNode instances to be created through TreeNode::addById()? If it's so, would it be good practise to declare TreeNode::__construct() as private/protected?

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• Unable to get nodeValue using DOMDocument class in PHP

  - by Harish

  I am Parsing a HTML document using DOMDocument Class in PHP, i wanted to get the nodeValue of a div element, but it is giving me null, <div id="summary"> Hi, my name is <span>ABC</span> <br/> address is here at stackoverflow... <span>.... .... <div> want to get the value inside the div, and the code i wrote wass $div_node=$dom->getElementById("summary"); $node_value=$div_node->nodeValue; but it is giving me a null value, please help.

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• Why this java application print "true"?

  - by user292084

  This is my first Class Hello.java public class Hello { String name = ""; } This is my second Class Test1.java public class Test1 { public static void main(String[] args) { Hello h = new Hello(); Test1 t = new Test1(); t.build(h); System.out.println((h.name)); } void build(Hello h){ h.name = "me"; } } When I run Test1.java, it prints "me". I think I understand, because of "reference transfer". This is my third Class Test2.java public class Test2 { public static void main(String[] args) { Hello h = null; Test2 t = new Test2(); t.build(h); System.out.println(((h == null))); } void build(Hello h){ h = new Hello(); } } When I run Test2.java, it prints "true", why ? Is it "reference transfer" no longer? I am confused.

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• Does NavigationHandler.handleNavigation() clear the flash?

  - by kgrad

  I am using JSF2.0 Mojarra 2.0.2. I have a method that logs out a user and puts a logout message in the flash, forwards to the login page (which has a div that prints out the flash). However, when I use navigationHandlers handleNavigation method for some reason the flash is not being displayed. I have a similar method that forwards a user to the login page if he/she isn't logged in. If I handle the navigation through an h:link and just call the logout method directly, the flash is displayed as normal, but if I use the handleNavigation() method, the flash is cleared for some reason. The code in question is: public void performLogout() { getFacesContext().getExternalContext().invalidateSession(); setCurrentUser(null); getFlash().put("notice", "Successfully logged out."); super.getFacesContext().getApplication().getNavigationHandler() .handleNavigation(getFacesContext(), null, "login"); } Is there some way I can keep the flash when navigating like this? thanks.

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• how to update multiple tables in oracle DB?

  - by murali

  hi, i am using two tables in my oracle 10g. the first table having the keyword,count,id(primary key) and my second table having id, timestamp.. but i am doing any chages in the first table(keyword,count) it will reflect on the my second table timestamp.. i am using id as reference for both the tables... table1: CREATE TABLE Searchable_Keywords (KEYWORD_ID NUMBER(18) PRIMARY KEY, KEYWORD VARCHAR2(255) NOT NULL, COUNT NUMBER(18) NOT NULL, CONSTRAINT Searchable_Keywords_unique UNIQUE(KEYWORD) ); table2: CREATE TABLE Keywords_Tracking_Report (KEYWORD_ID NUMBER(18), PROCESS_TIMESTAMP TIMESTAMP(8) ); how can update one table with reference of another table.. help me plz...

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• Linked List Inserting in sorted format

  - by user2738718

  package practise; public class Node { public int data; public Node next; public Node (int data, Node next) { this.data = data; this.next = next; } public int size (Node list) { int count = 0; while(list != null){ list = list.next; count++; } return count; } public static Node insert(Node head, int value) { Node T; if (head == null || head.data <= value) { T = new Node(value,head); return T; } else { head.next = insert(head.next, value); return head; } } } This work fine for all data values less than the first or the head. anything greater than than doesn't get added to the list.please explain in simple terms thanks.

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• Obtaining kerning information

  - by chadb

  How can I obtain kerning information for GDI to then use in GetKerningPairs? The documentation states that The number of pairs in the lpkrnpair array. If the font has more than nNumPairs kerning pairs, the function returns an error. However, I do not know how many pairs to pass in, and I don't see a way to query for it. EDIT I tried to do the following, however, it still gave me 0. Font* myFont = new Font(L"Times New Roman", 10); Bitmap* bitmap = new Bitmap(256, 256, PixelFormat32bppARGB); Graphics* g = new Graphics(bitmap); SelectObject(g->GetHDC(), myFont); //DWORD numberOfKerningPairs = GetKerningPairs( g->GetHDC(), -1, NULL ); DWORD numberOfKerningPairs = GetKerningPairs( g->GetHDC(), INT_MAX, NULL );

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• How do you override operator == when using interfaces instead of actual types?

  - by RickL

  I have some code like this: How should I implement the operator == so that it will be called when the variables are of interface IMyClass? public class MyClass : IMyClass { public static bool operator ==(MyClass a, MyClass b) { if (ReferenceEquals(a, b)) return true; if ((Object)a == null || (Object)b == null) return false; return false; } public static bool operator !=(MyClass a, MyClass b) { return !(a == b); } } class Program { static void Main(string[] args) { IMyClass m1 = new MyClass(); IMyClass m2 = new MyClass(); MyClass m3 = new MyClass(); MyClass m4 = new MyClass(); Console.WriteLine(m1 == m2); // does not go into custom == function. why not? Console.WriteLine(m3 == m4); // DOES go into custom == function } }

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• Managing log4j.properties with lein

  - by erikcw

  I'm trying to figure out how I can manage my log4j.properties file with leiningen. I'd like to be able to automatically include the file in the jars that lein creates as well as have the properties file be accessible to "lein swank" (and lein repl). Right now I have the file in my project "root", but I get this error when I using logging from swank [null] log4j:WARN No appenders could be found for logger (com.dev). [null] log4j:WARN Please initialize the log4j system properly. Thanks!

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• Bug in Programming Interviews Exposed?

  - by Sam

  Hi, I could not find an errata for the 2nd edition of this book. My question concerns the if-statement in the following piece of code. void removeHead (Node ** head) { Node * temp; if (!(*head)) { temp = (*head)->next; delete *head; *head = temp; } } So I understand that the point of the if-statement is to check if the Node is null. However by adding an additional "!" to the evaluation, wouldn't this negate the false value of null? Would it be correct to change it to something like: if (*head) { ... } Also if anyone knows where I can find an official errata for the 2nd edition that would be great. Thanks, Sam

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• Tooltip Support For ASP.NET Image Controls v2010 vol 1

  Tooltip property has been added to DevExpress ASP.NET image controls! Starting with DXperience v2010.1, all DevExpress ASP.NET image controls like the ASPxImage have a new property called: Tooltip. Whats a tooltip? Wikipedia defines it as: The tooltip is a common graphical user interface element. It is used in conjunction with a cursor, usually a mouse pointer. The user hovers the cursor over an item, without clicking it, and a tooltip may appear a small "hover box" with information...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Codeigniter + ajax(jQuery) session problem

  - by faya

  Hello, I have a problem in server side retrieving session with using ajax post request. Here is my sample code: JavaScript: $(function() { $('.jid_hidden_data').submit(function() { var serialized = $(this).serialize(); var sUrl = "http://localhost/stuff"; $.ajax({ url: sUrl, type: "POST", data: serialized, success: function(data) { alert(data); } }) return false; }); }); CodeIngiter(PHP) side: function stuff() { $post_stuff = $this->input->post('my_stuff'); // WORKS PERFECTLY $user_id = $this->session->userdata('user_id'); // RETURNS NULL } Where commented returns NULL it should return users session data, because it really exists. What is the problem? Method post doesn't get cookies or what? Thanks for any help!

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• SQL Server 2000 - Filter by String Length

  - by user208662

  Hello, I have a database on a SQL Server 2000 server. This database has a table called "Person" that has a field call "FullName" that is a VARCHAR(100). I am trying to write a query that will allow me to get all records that have a name. Records that do not have a name have a FullName value of either null or an empty string. How do I get all of the Person records have a FullName? In other words, I want to ignore the records that do not have a FullName. Currently I am trying the following: SELECT * FROM Person p WHERE p.FullName IS NOT NULL AND LEN(p.FullName) > 0 Thank you

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• findNode in binary search tree

  - by Weadadada Awda

  Does this look right? I mean I am trying to implement the delete function. Node* BST::findNode(int tofind) { Node* node = new Node; node = root; while (node != NULL) { if (node->val == tofind) { return node; } else if (tofind < node->val) { node = node->left; } else { node = node->right; } } } Here is the delete, it's not even close to done but, void BST::Delete(int todelete) { // bool found = false; Node* toDelete = new Node(); toDelete=findNode(todelete); if(toDelete->val!=NULL) { cout << toDelete->val << endl; } } This causes a segmentation fault just running that, any ideas?

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• Overriding setter on domain class in grails 1.1.2

  - by Pavel P

  I have following two domain classes in Grails 1.1.2: class A implements Serializable { MyEnumType myField Date fieldChanged void setMyField(MyEnumType val) { if (myField != null && myField != val) { myField = val fieldChanged = new Date() } } } class B extends A { List children void setMyField(MyEnumType val) { if (myField != null && myField != val) { myField = val fieldChanged = new Date() children.each { child -> child.myField = val } } } When I set B instance's myField, I get the setter into the cycle... myField = val line calls setter again instead of assiging the new value. Any hint how to override the setter correctly? Thanks

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• how to get count column

  - by soclose

  Hi I'd like to get the value of Count column from cursor. public Cursor getRCount(String iplace) throws SQLException { try { String strSql = "SELECT COUNT(_id) AS RCount FROM tbName WHERE place= '" + iplace + "'"; return db.rawQuery(strSql, null); } catch (SQLException e) { Log.e("Exception on query", e.toString()); return null; } } I tried to get this count column value from cursor like below Cursor cR = mDbHelper.getRCount(cplace);if (cR.getCount() > 0){long lCount = cR.getLong(0);}cR.close();} I got the debug error. How to get it?

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• Split string in C every white space

  - by redsolja

  I want to write a program in C that displays each word of a whole sentence (taken as input) at a seperate line. This is what i have done so far: void manipulate(char *buffer); int get_words(char *buffer); int main(){ char buff[100]; printf("sizeof %d\nstrlen %d\n", sizeof(buff), strlen(buff)); // Debugging reasons bzero(buff, sizeof(buff)); printf("Give me the text:\n"); fgets(buff, sizeof(buff), stdin); manipulate(buff); return 0; } int get_words(char *buffer){ // Function that gets the word count, by counting the spaces. int count; int wordcount = 0; char ch; for (count = 0; count < strlen(buffer); count ++){ ch = buffer[count]; if((isblank(ch)) || (buffer[count] == '\0')){ // if the character is blank, or null byte add 1 to the wordcounter wordcount += 1; } } printf("%d\n\n", wordcount); return wordcount; } void manipulate(char *buffer){ int words = get_words(buffer); char *newbuff[words]; char *ptr; int count = 0; int count2 = 0; char ch = '\n'; ptr = buffer; bzero(newbuff, sizeof(newbuff)); for (count = 0; count < 100; count ++){ ch = buffer[count]; if (isblank(ch) || buffer[count] == '\0'){ buffer[count] = '\0'; if((newbuff[count2] = (char *)malloc(strlen(buffer))) == NULL) { printf("MALLOC ERROR!\n"); exit(-1); } strcpy(newbuff[count2], ptr); printf("\n%s\n",newbuff[count2]); ptr = &buffer[count + 1]; count2 ++; } } } Although the output is what i want, i have really many black spaces after the final word displayed, and the malloc() returns NULL so the MALLOC ERROR! is displayed in the end. I can understand that there is a mistake at my malloc() implementation but i do not know what it is. Is there another more elegant - generally better way to do it? Thanks in advance.

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• Safely dereferencing FirstOrDefault call in Linq c#

  - by samy

  For brevity's sake in my code, i'd like to be able to do the following: having a collection, find the first element matching a lambda expression; if it exists, return the value of a property or function. If it doesn't exist, return null. var stuff = {"I", "am", "many", "strings", "obviously"}; var UpperValueOfAString = stuff.FirstOrDefault(s => s.contains("bvi")).ToUpper(); // would return "OBVIOUSLY" var UpperValueOfAStringWannabe = stuff.FirstOrDefault(s => s.contains("unknown token")).ToUpper(); // would return null Is it possible with some linq-syntax-fu or do i have to check explicitly for the return value before proceeding?

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• ASP.Net mysterious behaviour

  - by kalan

  Does anyone have any idea why this works (expression in the if-clause) if (!(childNode.Roles != null && !Helper.HasEqualElements((string[])childNode.Roles, System.Web.Security.Roles.GetRolesForUser()))) AddNode(childNode, parentNode); And this doesn't if (childNode.Roles == null || Helper.HasEqualElements((string[])childNode.Roles, System.Web.Security.Roles.GetRolesForUser())) AddNode(childNode, parentNode); The problem is that the second if-clause sometimes doesn't work. Though it always works in debug mode, but it sometimes fails while running. And the strange thing is that these two pieces of code seems absolutely equal for me.

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• Why is TargetInvocationException treated as uncaught by the IDE?

  - by Jason Coyne

  I have some code that is using reflection to pull property values from an object. In some cases the properties may throw exceptions, because they have null references etc. try { child.Target = propertyInfo.GetValue(target, null); } catch (TargetInvocationException ex) { child.Target = ex.InnerException.Message; } catch (Exception ex) { child.Target = ex.Message; } Ultimately the code works correctly, however when I am running under the debugger : When the property throws an exception, the IDE drops into the debugger as if the exception was uncaught. If I just hit run, the program flows through and the exception comes out as a TargetInvocationException with the real exception in the InnerException property. How can I stop this from happening?

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