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• How can one describe a rock-paper-scissors relationship between 3 items?

  - by Madara Uchiha

  Let's say I have the following structure: abstract class Hand {} class Rock extends Hand {} class Paper extends Hand {} class Scissors extends Hand {} The goal is to make a function (or a method) Hand::compareHands(Hand $hand1, Hand $hand2), which would return the winning hand in a rock-paper-scissors match. That would be very easy with a bunch of ifs, but the point is to have a more robust structure, that's relying on polymorphism rather than on procedural code. P.S. this is done in actual production code, if someone is asking. This isn't some sort of challenge or homework. (It's not really rock-paper-scissors, but you get the point).

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• changing restriction on simple type in extended complex type

  - by rotary_engine

  I am trying to create a schema that has 2 address types. The first AdressType requires an element Line 1 to have a value at least 10 characters. The second type OtherAdressType derives from this with the same elements, but does not require a value for Line 1. I've tried different ways but always get schema errors, this error is: Invalid particle derivation by restriction - 'Derived element '{namespace}:Line1' is not a valid restriction of base element '{namespace}:Line1' according to Elt:Elt -- NameAndTypeOK.'. If I add a type xs:string to OtherAdressType:Line1 then I get other errors. <xs:complexType name="AdressType"> <xs:sequence> <xs:element name="Line1" minOccurs="1" maxOccurs="1"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:minLength value="10" /> </xs:restriction> </xs:simpleType> </xs:element> <xs:element name="Line2" type="xs:string" minOccurs="1" maxOccurs="1" /> </xs:sequence> </xs:complexType> <xs:complexType name="OtherAdressType"> <xs:complexContent> <xs:restriction base="AdressType"> <xs:sequence> <xs:element name="Line1" nillable="true"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:minLength value="0" /> </xs:restriction> </xs:simpleType> </xs:element> <xs:element name="Line2" type="xs:string" minOccurs="1" maxOccurs="1" /> </xs:sequence> </xs:restriction> </xs:complexContent> </xs:complexType>

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• How to retrieve last primary Id from mdb's table?

  - by William

  I got table with next columns: Id, Name, Age, Class I am trying to insert new row in db like this: INSERT INTO MyTable (Name, Age, Class) VALUES (@name, @age, @class) And get an exeption: "Index or primary key cannot contain a Null value." The question is how to add a new row without knowing next primary Id, or maybe there is a way to get this Id from the table with the help of another query ?

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• Load iframe in html, only with jquery

  - by phpExe

  In this jquery code: $(document).ready(function(){ $list = $(".channeList li"); $list.click(function(){ var $this = $(this); var $mainDesc = $(".ply"); var iframe = $("a", $this).attr("rel"); $("iframe", $mainDesc).attr("src", iframe); } ); } ); There is a list o channels in left that iframe loads from a rel's. I want to load first iframe in <div class="ply"></div> In html, I dont want insert the first item. Can we do this without load first item in html and do this only with jquery? The php function channel() { if (is_numeric($_GET['kanalID'])) { $kanalID = $_GET['kanalID']; } if ($_GET['kanalID'] == "") { $kanalID = 1;} $channel = '<ul class="channeList">'; foreach ($tv as $id => $kanal) { $class = $kanalID == $id ? $class = "currentt": ''; $channel .= '<li> <a href="#" rel="http://mysite.com/index.php?id='.$id.'&w=500&h=320" >'.$kanal.'</a></li>'; } $channel .= '</ul>'; $channel .= '<div class="ply"><iframe frameborder=0 width="500" height="320"></iframe></div>'; return $channel; } Thanks in advance

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• What is Ruby's double-colon (::) all about?

  - by Meltemi

  I'd probably be able to answer this for myself if "::" wasn't so hard to Google. Didn't see anything on SO so thought I'd try my luck. What is this double-colon :: all about? I see it everywhere in Rails: class User < ActiveRecord::Base or… ActionController::Routing::Routes.draw do |map| I found a definition from this guy: The :: is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module. but that just leads to more questions. What good is scope (private, protected) if you can just use :: to expose anything?

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• Extending existing data structure in Scala.

  - by Lukasz Lew

  I have a normal tree defined in Scala. sealed abstract class Tree case class Node (...) extends Tree case class Leaf (...) extends Tree Now I want to add a member variable to all nodes and leaves in the tree. Is it possible with extend keyword or do I have to modify the tree classes by adding [T]?

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• How to limit setAccessible to only "legitimate" uses?

  - by polygenelubricants

  The more I learned about the power of setAccessible, the more astonished I am at what it can do. This is adapted from my answer to the question (Using reflection to change static final File.separatorChar for unit testing). import java.lang.reflect.*; public class EverythingIsTrue { static void setFinalStatic(Field field, Object newValue) throws Exception { field.setAccessible(true); Field modifiersField = Field.class.getDeclaredField("modifiers"); modifiersField.setAccessible(true); modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL); field.set(null, newValue); } public static void main(String args[]) throws Exception { setFinalStatic(Boolean.class.getField("FALSE"), true); System.out.format("Everything is %s", false); // "Everything is true" } } You can do truly outrageous stuff: public class UltimateAnswerToEverything { static Integer[] ultimateAnswer() { Integer[] ret = new Integer[256]; java.util.Arrays.fill(ret, 42); return ret; } public static void main(String args[]) throws Exception { EverythingIsTrue.setFinalStatic( Class.forName("java.lang.Integer$IntegerCache") .getDeclaredField("cache"), ultimateAnswer() ); System.out.format("6 * 9 = %d", 6 * 9); // "6 * 9 = 42" } } Presumably the API designers realize how abusable setAccessible can be, but must have conceded that it has legitimate uses to provide it. So my questions are: What are the truly legitimate uses for setAccessible? Could Java has been designed as to NOT have this need in the first place? What would the negative consequences (if any) of such design be? Can you restrict setAccessible to legitimate uses only? Is it only through SecurityManager? How does it work? Whitelist/blacklist, granularity, etc? Is it common to have to configure it in your applications?

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• Show Div When Radio Checked

  - by maniootek

  I tried to use this code: <script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js" type="text/javascript"></script> <style type="text/css"> div {display: none} </style> <script type="text/javascript"> $('.radio1').click(function () { $('.div1').show(); }); $('.radio2').click(function () { $('.div2').show(); }); </script> <label><input type="radio" name="group1" class="radio1"></label> <label><input type="radio" name="group1" class="radio2"></label> <div class="div1">Radio1 selected !</div> <div class="div2">Radio2 selected !</div> But when I check any radio then notthing happens. I tried with Fiddle: http://jsfiddle.net/Ac9c4/ and same no results Any idea?

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• How can I sync three classes?

  - by TheMachineCharmer

  class Foo { Bar b; List<Foo> Neighbours; } class Bar { Spam s; List<Bar> Neighbours; } class Spam { List<string> Neighbours; } Each of these classes have AddNeighbour,RemoveNeighbour methods. User can add/remove Neighbours from any of the class at random. I want these three objects to be in sync. How can I do this?

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• Android Notification with AlarmManager, Broadcast and Service

  - by user2435829

  this is my code for menage a single notification: myActivity.java public class myActivity extends Activity { protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.mylayout); cal = Calendar.getInstance(); // it is set to 10.30 cal.set(Calendar.HOUR, 10); cal.set(Calendar.MINUTE, 30); cal.set(Calendar.SECOND, 0); long start = cal.getTimeInMillis(); if(cal.before(Calendar.getInstance())) { start += AlarmManager.INTERVAL_FIFTEEN_MINUTES; } Intent mainIntent = new Intent(this, myReceiver.class); pIntent = PendingIntent.getBroadcast(this, 0, mainIntent, PendingIntent.FLAG_UPDATE_CURRENT); AlarmManager myAlarm = (AlarmManager)getSystemService(ALARM_SERVICE); myAlarm.setRepeating(AlarmManager.RTC_WAKEUP, start, AlarmManager.INTERVAL_FIFTEEN_MINUTES, pIntent); } } myReceiver.java public class myReceiver extends BroadcastReceiver { @Override public void onReceive(Context c, Intent i) { Intent myService1 = new Intent(c, myAlarmService.class); c.startService(myService1); } } myAlarmService.java public class myAlarmService extends Service { @Override public IBinder onBind(Intent arg0) { return null; } @Override public void onCreate() { super.onCreate(); } @SuppressWarnings("deprecation") @Override public void onStart(Intent intent, int startId) { super.onStart(intent, startId); displayNotification(); } @Override public void onDestroy() { super.onDestroy(); } public void displayNotification() { Intent mainIntent = new Intent(this, myActivity.class); PendingIntent pIntent = PendingIntent.getActivity(this, 0, mainIntent, PendingIntent.FLAG_UPDATE_CURRENT); NotificationManager nm = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE); Notification.Builder builder = new Notification.Builder(this); builder.setContentIntent(pIntent) .setAutoCancel(true) .setSmallIcon(R.drawable.ic_noti) .setTicker(getString(R.string.notifmsg)) .setContentTitle(getString(R.string.app_name)) .setContentText(getString(R.string.notifmsg)); nm.notify(0, builder.build()); } } AndroidManifest.xml <uses-permission android:name="android.permission.WAKE_LOCK" /> ... ... ... <service android:name=".myAlarmService" android:enabled="true" /> <receiver android:name=".myReceiver"/> IF the time has NOT past yet everything works perfectly. The notification appears when it must appear. BUT if the time HAS past (let's assume it is 10.31 AM) the notification fires every time... when I close and re-open the app, when I click on the notification... it has a really strange behavior. I can't figure out what's wrong in it. Can you help me please (and explain why, if you find a solution), thanks in advance :)

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• The Java interface doesn't declare any exception. How to manage checked exception of the implementat

  - by Frór

  Let's say I have the following Java interface that I may not modify: public interface MyInterface { public void doSomething(); } And now the class implementing it is like this: class MyImplementation implements MyInterface { public void doSomething() { try { // read file } catch (IOException e) { // what to do? } } } I can't recover from not reading the file. A subclass of RuntimeException can clearly help me, but I'm not sure if it's the right thing to do: the problem is that that exception would then not be documented in the class and a user of the class would possibly get that exception an know nothing about solving this. What can I do?

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• CSS overflow : list in a div

  - by Felicita

  I have an image gallery and I dont want give an extra class to third list item: <div class="row"> <ul class="rowUl"> <li>ssss</li> <li>ssss</li> <li>ssss</li> </ul> </div> and css .row { width: 620px; clear: both; overflow: hidden; } .rowUl { width: 645px; float: left; } .rowUl li { width: 220px; float: left; } but the third list item drop in other row. How can I solve this without extra class?

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• JPA entitylisteners and @embeddable

  - by seanizer

  I have a class hierarchy of JPA entities that all inherit from a BaseEntity class: @MappedSuperclass @EntityListeners( { ValidatorListener.class }) public abstract class BaseEntity implements Serializable { // other stuff } I want all entities that implement a given interface to be validated automatically on persist and/or update. Here's what I've got. My ValidatorListener: public class ValidatorListener { private enum Type { PERSIST, UPDATE } @PrePersist public void checkPersist(final Object entity) { if (entity instanceof Validateable) { this.check((Validateable) entity, Type.PERSIST); } } @PreUpdate public void checkUpdate(final Object entity) { if (entity instanceof Validateable) { this.check((Validateable) entity, Type.UPDATE); } } private void check(final Validateable entity, final Type persist) { switch (persist) { case PERSIST: if (entity instanceof Persist) { ((Persist) entity).persist(); } if (entity instanceof PersistOrUpdate) { ((PersistOrUpdate) entity).persistOrUpdate(); } break; case UPDATE: if (entity instanceof Update) { ((Update) entity).update(); } if (entity instanceof PersistOrUpdate) { ((PersistOrUpdate) entity).persistOrUpdate(); } break; default: break; } } } and here's my Validateable interface that it checks against (the outer interface is just a marker, the inner contain the methods): public interface Validateable { interface Persist extends Validateable { void persist(); } interface PersistOrUpdate extends Validateable { void persistOrUpdate(); } interface Update extends Validateable { void update(); } } All of this works, however I would like to extend this behavior to Embeddable classes. I know two solutions: call the validation method of the embeddable object manually from the entity validation method: public void persistOrUpdate(){ // validate my own properties first // then manually validate the embeddable property: myEmbeddable.persistOrUpdate(); // this works but I'd like something that I don't have to call manually } use reflection, checking all properties to see if their type is of one of their interface types. This would work, but it's not pretty. Is there a more elegant solution?

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• how to use listctrl in notebook wxPython

  - by ???

  I have one question.. wxPython listctrl in notebook I created 2 tab use notebook. I added button in first tab and added Listctrl in second tab. If i click the button, Add value in Listctrl to second tab. how to solve this problem? import wx class PageOne(wx.Panel): def __init__(self, parent): wx.Panel.__init__(self, parent) self.query_find_btn = wx.Button(self, 4, "BTN", (40,40)) self.Bind(wx.EVT_BUTTON, self.AddList, id = 4) def AddList(self, evt): self.list1.InsertStringItem(0,'Hello') class PageTwo(wx.Panel): def __init__(self, parent): wx.Panel.__init__(self, parent) self.list1 = wx.ListCtrl(self,-1,wx.Point(0,0),wx.Size(400,400),style=wx.LC_REPORT | wx.SUNKEN_BORDER) self.list1.InsertColumn(0,'values') class MyFrame(wx.Frame): def __init__(self, parent, id, title): wx.Frame.__init__(self,parent,id,title,size=(400,400),pos=wx.Point(100,100), style=wx.SYSTEM_MENU |wx.CAPTION ) p = wx.Panel(self) nb = wx.Notebook(p) MainFrame = PageOne(nb) SecondFrame = PageTwo(nb) nb.AddPage(MainFrame, "One") nb.AddPage(SecondFrame, "Two") sizer = wx.BoxSizer() sizer.Add(nb, 1, wx.EXPAND) p.SetSizer(sizer) class MyApp(wx.App): def OnInit(self): self.frame=MyFrame(None,-1,'Unknown.py') self.frame.Centre() self.frame.Show() return True if __name__ == '__main__': app = MyApp(False) app.MainLoop()

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• Loading Java applet from WEB-INF/classes by JSP

  - by Bruce

  Hi guys, Ive got a problem with loading an applet from WEB-INF/classes directory. The main class of an applet (MainApplet.class) is there in the package aaa, but when loading I got the exception java.lang.ClassNotFoundException. Where am I wrong? My jsp is in Web Pages dir. < jsp:plugin type="applet" code="aaa/MainApplet.class" jreversion="1.6" width="700" height="500" Thanks in advance for the reply!

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• Can JMX operations take interfaces as parameters?

  - by Thor84no

  I'm having problems with an MBean that takes a Map<String, Object> as a parameter. If I try to execute it via JMX using a proxy object, I get an Exception: Caused by: javax.management.ReflectionException at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:231) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) Caused by: java.lang.IllegalArgumentException: Unable to find operation updateProperties(java.util.HashMap) It appears that it attempts to use the actual implementation class rather than the interface, and doesn't check if this is a child of the required interface. The same thing happens for extended classes (for example declare HashMap, pass in LinkedHashMap). Does this mean it's impossible to use an interface for such methods? At the moment I'm getting around it by changing the method signature to accept a HashMap, but it seems odd that I wouldn't be able to use interfaces (or extended classes) in my MBeans. Edit: The proxy object is being created by an in-house utility class called JmxInvocationHandler. The (hopefully) relevant parts of it are as follows: public class JmxInvocationHandler implements InvocationHandler { ... public static <T> T createMBean(final Class<T> iface, SFSTestProperties properties, String mbean, int shHostID) { T newProxyInstance = (T) Proxy.newProxyInstance(iface.getClassLoader(), new Class[] { iface }, (InvocationHandler) new JmxInvocationHandler(properties, mbean, shHostID)); return newProxyInstance; } ... private JmxInvocationHandler(SFSTestProperties properties, String mbean, int shHostID) { this.mbeanName = mbean + MBEAN_SUFFIX + shHostID; msConfig = new MsConfiguration(properties.getHost(0), properties.getMSAdminPort(), properties.getMSUser(), properties.getMSPassword()); } ... public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if (management == null) { management = ManagementClientStore.getInstance().getManagementClient(msConfig.getHost(), msConfig.getAdminPort(), msConfig.getUser(), msConfig.getPassword(), false); } final Object result = management.methodCall(mbeanName, method.getName(), args == null? new Object[] {} : args); return result; } }

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• Effective Data Validation

  - by John Conde

  What's an effective way to handle data validation, say, from a form submission? Originally I had a bunch of if statements that checked each value and collected invalid values in an array for later retrieval (and listing). // Store errors here $errors = array(); // Hypothetical check if a string is alphanumeric if (!preg_match('/^[a-z\d]+$/i', $fieldvalue)) { $errors[$fieldname] = 'Please only use letters and numbers for your street address'; } // etc... What I did next was create a class that handles various data validation scenarios and store the results in an internal array. After data validation was complete I would check to see if any errors occurred and handle accordingly: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more methods here public function creditCard($cardNumber, $field, $msg = '') { // Validate credit card number } // more methods here public function hasErrors() { return count($this->errorList); } } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue1, $fieldname1, 'Please only use letters and numbers for your street address'); $validate->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Naturally it didn't take long before this class became bloated with the virtually unlimited types of data to be validated. What I'm doing now is using decorators to separate the different types of data into their own classes and call them only when needed leaving generic validations (i.e. isAlphaNumeric()) in the base class: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more generic methods here public function setError($field, $msg = '') { $this->errorList[$field] = $msg; } public function hasErrors() { return count($this->errorList); } } class ValidationCreditCard { protected $validate; public function __construct(Validation $validate) { $this->validate = $validate; } public function creditCard($cardNumber, $field, $msg = '') { // Do validation // ... // if there is an error $this->validate->setError($field, $msg); } // more methods here } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue, $fieldname, 'Please only use letters and numbers for your street address'); $validateCC = new ValidationCreditCard($validate); $validateCC->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Am I on the right track? Or did I just complicate data validation more then I needed to?

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• Best way to implement game loop without freezing UI thread

  - by Matt H

  I'm trying to make a simple 2D game in Java. So far I have a JFrame, with a menubar, and a class which extends JPanel and overrides it's paint method. Now, I need to get a game loop going, where I will update the position of images and so on. However, I'm stuck at how best to achieve this. Should I use multi-threading, because surely, if you put an infinite loop on the main thread, the UI (and thus my menu bar) will freeze up? Here's my code so far: import java.awt.Color; import java.awt.Graphics; import javax.swing.JPanel; @SuppressWarnings("serial") public class GameCanvas extends JPanel { public void paint(Graphics g) { while (true) { g.setColor(Color.DARK_GRAY); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } } import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; @SuppressWarnings("serial") public class Main extends JFrame { GameCanvas canvas = new GameCanvas(); final int FRAME_HEIGHT = 400; final int FRAME_WIDTH = 400; public static void main(String args[]) { new Main(); } public Main() { super("Game"); JMenuBar menuBar = new JMenuBar(); JMenu fileMenu = new JMenu("File"); JMenuItem startMenuItem = new JMenuItem("Pause"); menuBar.add(fileMenu); fileMenu.add(startMenuItem); super.add(canvas); super.setVisible(true); super.setSize(FRAME_WIDTH, FRAME_WIDTH); super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); super.setJMenuBar(menuBar); } } Any pointers/tips? Also, where should I put my loop? In my main class, or my GameCanvas class? Any help is appreciated, thanks.

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• Can I make PDOStatement->fetchObject not use non-member variables?

  - by threendib

  Lets say I have a class like this: Class User { var $id var $name; } And I run a query using PDO in php like so: $stm = $db->prepare('select * from users where id = :id'); $r = $stm->execute(array(':id' => $id)); $user = $r->fetchObject('User'); If I vardump my user object it has all kinds of other fields in it that I have not defined in the User class. Obviously I could make my query specific so that it only gives me back the fields I need/want. But if I don't want to do that is there any way to make this work the way I want it to? I like the idea of fetchObject, because it's one line of code to create this object and set member variables for me. I just don't want it to set variables I haven't defined in my class.

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• PHP if statement - select two different get variables?

  - by arsoneffect

  Below is my example script: <li><a <?php if ($_GET['page']=='photos' && $_GET['view']!=="projects"||!=="forsale") { echo ("href=\"#\" class=\"active\""); } else { echo ("href=\"/?page=photos\""); } ?>>Photos</a></li> <li><a <?php if ($_GET['view']=='projects') { echo ("href=\"#\" class=\"active\""); } else { echo ("href=\"/?page=photos&view=projects\""); } ?>>Projects</a></li> <li><a <?php if ($_GET['view']=='forsale') { echo ("href=\"#\" class=\"active\""); } else { echo ("href=\"/?page=photos&view=forsale\""); } ?>>For Sale</a></li> I want the PHP to echo the "href="#" class="active" only when it is not on the two pages: ?page=photos&view=forsale or ?page=photos&view=projects

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• jquery find() - how to exclude certain descendants, and their children?

  - by jammypeach

  I have markup similar to this: <div class='wrapper plugin'> //some content <div class='child-wrapper plugin'> //some more content <div> <ul> <li><div class='cliky'>clicky!</div></li> </ul> </div> </div> <div class='cliky'>clicky!</div> </div> I need to be able to select the first .clicky div only, not any .clicky divs inside a .plugin > .plugin div. The wrapper has .plugin class too - might seem counter-intuitive so another way to view it is this: I want to get the .clicky children of a given .plugin div, but not .plugin .plugin .clicky. Here's the problem - the depth of each .clicky element (or indeed, the number of them) is unknown and variable in relation to the wrappers. One could be immediately below the first wrapper, or inside 10 <ul>s. I've tried selectors like: $('.wrapper').find('.clicky').not('.plugin > .clicky'); But they still selected child .clicky. How would I be able to filter out .plugin and any children of .plugin from my selector before using find()?

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• Appropriate uses of Monad `fail` vs. MonadPlus `mzero`

  - by jberryman

  This is a question that has come up several times for me in the design code, especially libraries. There seems to be some interest in it so I thought it might make a good community wiki. The fail method in Monad is considered by some to be a wart; a somewhat arbitrary addition to the class that does not come from the original category theory. But of course in the current state of things, many Monad types have logical and useful fail instances. The MonadPlus class is a sub-class of Monad that provides an mzero method which logically encapsulates the idea of failure in a monad. So a library designer who wants to write some monadic code that does some sort of failure handling can choose to make his code use the fail method in Monad or restrict his code to the MonadPlus class, just so that he can feel good about using mzero, even though he doesn't care about the monoidal combining mplus operation at all. Some discussions on this subject are in this wiki page about proposals to reform the MonadPlus class. So I guess I have one specific question: What monad instances, if any, have a natural fail method, but cannot be instances of MonadPlus because they have no logical implementation for mplus? But I'm mostly interested in a discussion about this subject. Thanks! EDIT: One final thought occured to me. I recently learned (even though it's right there in the docs for fail) that monadic "do" notation is desugared in such a way that pattern match failures, as in (x:xs) <- return [] call the monad's fail. It seems like the language designers must have been strongly influenced by the prospect of some automatic failure handling built in to haskell's syntax in their inclusion of fail in Monad.

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• Compare Properties automatically

  - by juergen d

  I want to get the names of all properties that changed for matching objects. I have these (simplified) classes: public enum PersonType { Student, Professor, Employee } class Person { public string Name { get; set; } public PersonType Type { get; set; } } class Student : Person { public string MatriculationNumber { get; set; } } class Subject { public string Name { get; set; } public int WeeklyHours { get; set; } } class Professor : Person { public List<Subject> Subjects { get; set; } } Now I want to get the objects where the Property values differ: List<Person> oldPersonList = ... List<Person> newPersonList = ... List<Difference> = GetDifferences(oldPersonList, newPersonList); public List<Difference> GetDifferences(List<Person> oldP, List<Person> newP) { //how to check the properties without casting and checking //for each type and individual property?? //can this be done with Reflection even in Lists?? } In the end I would like to have a list of Differences like this: class Difference { public List<string> ChangedProperties { get; set; } public Person NewPerson { get; set; } public Person OldPerson { get; set; } } The ChangedProperties should contain the name of the changed properties.

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• Get Mail with PHP and IMAP in Gmail just loading

  - by Oscar Godson

  I'm not sure why. Ive tried a bunch of different code. Wrote it myself, and copied other people's tutorials but every bit of code it's loading forever and eventually stops due to script processing times on the server. Does anyone know why? Oh, and IMAP is turned on, i get IMAP / Exchange on my iPhone from this same account fine. And IMAP is turned on in my version of PHP (checked with phpinfo they all say enabled.) <?php /* connect to gmail */ $hostname = '{imap.gmail.com:993/imap/ssl}INBOX'; $username = '[email protected]'; $password = 'xxxxxx'; /* try to connect */ $inbox = imap_open($hostname,$username,$password) or die('Cannot connect to Gmail: ' . imap_last_error()); /* grab emails */ $emails = imap_search($inbox,'ALL'); /* if emails are returned, cycle through each... */ if($emails) { /* begin output var */ $output = ''; /* put the newest emails on top */ rsort($emails); /* for every email... */ foreach($emails as $email_number) { /* get information specific to this email */ $overview = imap_fetch_overview($inbox,$email_number,0); $message = imap_fetchbody($inbox,$email_number,2); /* output the email header information */ $output.= '<div class="toggler '.($overview[0]->seen ? 'read' : 'unread').'">'; $output.= '<span class="subject">'.$overview[0]->subject.'</span> '; $output.= '<span class="from">'.$overview[0]->from.'</span>'; $output.= '<span class="date">on '.$overview[0]->date.'</span>'; $output.= '</div>'; /* output the email body */ $output.= '<div class="body">'.$message.'</div>'; } echo $output; } /* close the connection */ imap_close($inbox); ?

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• How to make Event visible?

  - by eflles

  Inside a Silverlight library project I have a public event, which is not visible for other classes. How can I make the event visible? When I try the following code, I can not locate the event in the "ReceivingClass". .dll - file: Public Class MyClass Public Event MyEvent(ByVal sender As Object, ByVal e As EventArgs) Public Sub OnStart() RaiseEvent MyEvent(Me, new EventArgs) End Sub End Class Silverlight app: Imports MyClass Public Class ReceivingClass Public Sub New() Dim myClass As new MyClass AddHandler myClass.MyEvent, AddressOf Me.EventHandler End Sub Private Sub EventHandler(ByVal sender As Object, ByVal e As EventArgs) 'Handle Event End Sub End Class

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