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• C# Anyway to detect if an object is locked.

  - by scope-creep

  Hi, Is their anyway to determine if a object is locked in c#. I have the unenviable position, through design where i'm reading from a queue inside a class, and I need to dump the contents into a collection in the class. But that collection is also read/write from an interface outside the class. So obviously their may be a case when the collection is being written to, as the same time i want to write to it. I could program round it, say using delegate but it would be ugly. Bob.

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• What's the difference between => , ()=>, and Unit=>

  - by Malvolio

  I'm trying to represent a function that takes no arguments and returns no value (I'm simulating the setTimeout function in JavaScript, if you must know.) case class Scheduled(time : Int, callback : => Unit) doesn't compile, saying " `val' parameters may not be call-by-name" case class Scheduled(time : Int, callback : () => Unit) compiles, but has to be invoked strangely, instead of Scheduled(40, { println("x") } ) I have to do this Scheduled(40, { () => println("x") } ) What also works is class Scheduled(time : Int, callback : Unit => Unit) but is invoked in an even-less-sensible way Scheduled(40, { x : Unit => println("x") } ) (What would a variable of type Unit be?) What I want of course is a constructor that can be invoke the way I would invoke it if it were an ordinary function: Scheduled(40, println("x") ) Give baby his bottle!

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• GCC compiler -- bug or unspecified behavior?

  - by Jared P

  When I have conflicting definitions of the ivars of a class in objective-c (not redeclaring the class in the same file, but rather naming the same class with diff ivars, no warnings or better yet errors are issued by the compiler. However, both sets of ivars are useable by the appropriate methods in the respective files. For instance Foo.m: @interface foo { int a; } - (int)method; @end @implementation foo - (int)method { return a; } @end Bar.m: @interface foo { float baz; } @end @implementation foo (category) - (float)blah { return baz; } @end compiles without warnings or errors. Is this intentional? Is this an unchecked error? (for the record, a and baz are actually the same memory location.)

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• TPageControl tab area OnMouseEnter OnMouseLeave events

  - by daemon_x

  Hello, I need to catch the "OnMouseEnter" and "0nMouseLeave" for a certain area of the TPageControl component. With that specific area I mean the whole "tab header" rectangle. The problem is, that the page control doesn't catch the messages (I'm catching internal control messages CM_MOUSEENTER and CM_MOUSELEAVE) in the "empty" space. The aim for me is to draw a small arrow in the right empty side when user hovers in the red framed area (and drawing is just piece of cake) and erase it when leaves this area. And I'm don't care about the overflow of the tabs (which causes to draw scrolling double button) - that will never happen.

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• How do you like to define your module-wide variables in drupal 6?

  - by sprugman

  I'm in my module file. I want to define some complex variables for use throughout the module. For simple things, I'm doing this: function mymodule_init() { define('SOME_CONSTANT', 'foo bar'); } But that won't work for more complex structures. Here are some ideas that I've thought of: global: function mymodule_init() { $GLOBALS['mymodule_var'] = array('foo' => 'bar'); } variable_set: function mymodule_init() { variable_set('mymodule_var', array('foo' => 'bar')); } property of a module class: class MyModule { static $var = array('foo' => 'bar'); } Variable_set/_get seems like the most "drupal" way, but I'm drawn toward the class setup. Are there any drawbacks to that? Any other approaches out there?

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• Accessing primitive properties from objects stored in a NSDictionary

  - by ChrisS

  Apologies if this is a basic question, I am just starting with Objective-C and trying to wrap things around in my head! I have a simple class of the form: @interface Whatever : NSObject { int somePrimitive; SomeObject* someObject; } @property (nonatomic) int somePrimitive; @property (nonatomic, retain) SomeObject* someObject; The class is more involved that this, but this illustrates the purpose. When I store instances of this class in a NSMutableDictionary: Whatever *whatever = [[Whatever alloc] init]; whatever.somePrimitive = 1; whatever.someObject = ...; [myDictionary setObject:whatever forKey:@"someKey"]; and then try to retrieve the object later: Whatever *result = [myDictionary valueForKey:@"someKey"]; then, result.someObject is ok to reference but, result.somePrimitive crashes. Does the NSDictionary not copy over the primitives of the object? Is the rule that the object stored in a dictionary should only contain objects?

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• What pattern is this? php

  - by user151841

  I have several classes that are basically interfaces to database rows. Since the class assumes that a row already exists ( __construct expects a field value ), there is a public static function that allows creation of the row and returns an instance of the class. Here's an example ( without the actual database inserts ): class selfStarter { public $type; public function __construct( $type ) { $this->type = $type; } public static function create( $type ) { if ( ! empty($type) ) { $starter = & new selfStarter($type); return $starter; } } } $obj1 = selfStarter::create( "apple" ); $obj2 = & new selfStarter( "banana" ); What is this pattern called?

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• PHP variable question

  - by Kyle Parisi

  This works: $customerBox = mysql_query("MY SQL STATEMENT HERE"); $boxRow = mysql_fetch_array($customerBox); $customerBox = mysql_query("MY SQL STATEMENT AGAIN"); while($item = mysql_fetch_assoc($customerBox)) { foreach ($item as $columnName = $value) { if (empty($value)) { print $columnName; } } } This does not: $customerBox = mysql_query("MY SQL STATEMENT HERE"); $boxRow = mysql_fetch_array($customerBox); while($item = mysql_fetch_assoc($customerBox)) { foreach ($item as $columnName = $value) { if (empty($value)) { print $columnName; } } } Why? I guess I don't understand how variables work yet.

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• C++ and virtual methods overriding

  - by silent

  Sorry for this stupid question, but I can't find an answer by myself, I'm too new in C++ :( class DBObject : public QObject { ... protected: virtual QString tableName() { return ""; }; }; class DBUserObject : public DBObject { ... protected: virtual QString tableName() { return "profiles"; }; }; And I have this code in parent: bool DBObject::load(quint32 id) { QString query = QString("select %1 from %2 where id = :id") .arg(fieldList().join(",")) .arg(tableName()); <--- here is trouble ... } So I'm trying to execute: DBUserObject user; user.load(3); But in result I have a query with empty table name cause tableName() method returns empty string. Why not "profiles"?

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• Word Counter Implementation

  - by kenny

  Is there a better way than the following brute foce implementation of a c# word counting class? UPDATED CODE: Sorry! /// <summary> /// A word counting class. /// </summary> public class WordCounter { Dictionary<string, int> dictTest = new Dictionary<string, int> (); /// <summary> /// Enters a word and returns the current number of times that word was found. /// </summary> /// <param name="word">The word or string found.</param> /// <returns>Count of times Found() was called with provided word.</returns> public int Found ( string word ) { int count = 1; return dictTest.TryGetValue ( word, out count ) ? ++dictTest[word] : dictTest[word] = 1; } }

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• How do I print the method body reflectively?

  - by kunjaan

  Right now I have private static void getMethods(Class<? extends Object> clazz) { Method[] declaredMethods = clazz.getDeclaredMethods(); for (Method aMethod : declaredMethods) { aMethod.setAccessible(true); // Print the declaration System.out.print(Modifier.toString(aMethod.getModifiers()) + " " + aMethod.getReturnType().getSimpleName() + " " + aMethod.getName()); // Get Parameter Types getParameters(aMethod); //Empty Body System.out.println("{}\n"); } } Which prints most information reflectively but creates an empty body. How do I add to the reflective nature of Java to print the method body?

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• Mysql with innodb and serializable transaction does not (always) lock rows

  - by Tobias G.

  Hello, I have a transaction with a SELECT and possible INSERT. For concurrency reasons, I added FOR UPDATE to the SELECT. To prevent phantom rows, I'm using the SERIALIZABLE transaction isolation level. This all works fine when there are any rows in the table, but not if the table is empty. When the table is empty, the SELECT FOR UPDATE does not do any (exclusive) locking and a concurrent thread/process can issue the same SELECT FOR UPDATE without being locked. CREATE TABLE t ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, display_order INT ) ENGINE = InnoDB; SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; START TRANSACTION; SELECT COALESCE(MAX(display_order), 0) + 1 from t FOR UPDATE; .. This concept works as expected with SQL Server, but not with MySQL. Any ideas on what I'm doing wrong? EDIT Adding an index on display_order does not change the behavior.

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• DataContext Doesn't Exist in Dynamic Data Project?

  - by davemackey

  This is really annoying...and I know it is something extremely simple... 1. I create a new Dynamic Data project. 2. I add a LINQ-to-SQL class and drag and drop some tables onto the class. 3. I open the global.asax.vb and uncomment the line: DefaultModel.RegisterContext(GetType(YourDataContext), New ContextConfiguration() With {.ScaffoldAllTables = True}) I remove YourDataContext and replace it with the DataContext from my LINQ-to-SQL class: DefaultModel.RegisterContext(GetType(NorthwindDataContext), New ContextConfiguration() With {.ScaffoldAllTables = True}) I then try to debug/build/etc. and receive the following error: Type 'NorthwindDataContext' is not defined Why is it not defined? It seems like its not recognizing I created the DBML file.

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• jQuery: Scroll the window then addClass() - how to callback

  - by carillonator

  Inside a jQuery event handler, I would like to scroll the window and then add a class to something. This is my code: $('#foo').click(function() { window.scrollTo(y); $('#bar').addClass('active'); }); $(window).scroll(function() { $('#bar').removeClass('active'); }); Notice I have another handler to remove that same class whenever the window is scrolled. The scrolling part works fine, but seems to run asynchronously, so removeClass() happens after addClass() but before the scrolling is finished. I don't know how to do this in plain javascript. I know there is a jQuery scrollTop() function that does the same thing (but seems to have cross-browser issues), but it doesn't accept a callback. What I really need is a callback to add the class after the scrolling is finished. thanks!

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• Why doesn't list.get(0).equals(null) work?

  - by Jessy

  The first index is set to null (empty), but it doesn't print the right output, why? //set the first index as null and the rest as "High" String a []= {null,"High","High","High","High","High"}; //add array to arraylist ArrayList<Object> choice = new ArrayList<Object>(Arrays.asList(a)); for(int i=0; i<choice.size(); i++){ if(i==0){ if(choice.get(0).equals(null)) System.out.println("I am empty"); //it doesn't print this output } }

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• KindError: Property r must be an instance of SecondModel, why ?

  - by zjm1126

  class FirstModel(db.Model): p = db.StringProperty() r=db.ReferenceProperty(SecondModel) class SecondModel(db.Model): r = db.ReferenceProperty(FirstModel) class sss(webapp.RequestHandler): def get(self): a=FirstModel() a.p='sss' a.put() b=SecondModel() b.r=a b.put() a.r=b a.put() self.response.out.write(str(b.r.p)) the error is : Traceback (most recent call last): File "D:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 511, in __call__ handler.get(*groups) File "D:\zjm_code\helloworld\a.py", line 158, in get a.r=b File "D:\Program Files\Google\google_appengine\google\appengine\ext\db\__init__.py", line 3009, in __set__ value = self.validate(value) File "D:\Program Files\Google\google_appengine\google\appengine\ext\db\__init__.py", line 3048, in validate (self.name, self.reference_class.kind())) KindError: Property r must be an instance of SecondModel thanks

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• Why the data binding in this validation example works in WPF?

  - by MartyIX

  I'm wondering how exactly the XAML sample (MSDN sample) works: <Style x:Key="textBoxInError" TargetType="{x:Type TextBox}"> <Style.Triggers> <Trigger Property="Validation.HasError" Value="true"> <Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors)[0].ErrorContent}"/> </Trigger> </Style.Triggers> </Style> Questions: (Validation.Errors)[0].ErrorContent - Is this code somehow checked by WPF? Because Validation.Errors may be an empty collection and in ordinary C# code this code may throw an exception. If this data-binding returns null for valid input - the null value is then casted to empty string (in a text control for example)? The index 0 corresponds to the first error message. How can I return more error messages from Validate method? Thank you for responses!

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• How to use multiple restrictions in C# Generics properly?

  - by plouh

  I am attempting to bind c# generics to a class and an interface like this: public class WizardPage<T> where T : UserControl, IWizardControl { private T page; public WizardPage( T page ) { this.page = page; } } And use it with this: public MyControl : UserControl, IWizardControl { //... } Somehow C# doesn't seem to be able to decide that MyControl is a proper instance of T as public class Wizard<T> where T : UserControl, IWizardControl { private WizardPage<T> Page1; public Wizard( MyControl control ) { this.Page1 = new WizardPage(control); } } fails with error The best overloaded method match for 'Controls.WizardPage.WizardPage(T)' has some invalid arguments Am I doing something wrong or is this just not going to work?

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• start intent without onCreate {}

  - by melvintcs

  i create a class extend Gallery and there is no onCreate, and i having a problem to run my intent. this is my sample code: this.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View v, int position, long id) { Intent intent = new Intent(v.getContext(), ClassName.class); startActivity(intent); }} i also tried below code to run, failed me also: Intent intent = new Intent(ThisClassName.this, ClassName.class); startActivity(intent); Please advice me what should i do :)

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• How can I simulate a click event via script?

  - by Scott B

  I have a jquery accordion style menu that I'd like to add some shortcut links to across the top. When one of these shortcuts is clicked, it should have the same effect as if the user clicked the corresponding a tag that serves as that panel's header... Here's some code... <div> Application Shortcuts > <a href="" onclick="simulateAclick("generalSettings")>Open General Settings</a> </div> <ul class="menu collapsible"> <li class='header'><a href='#' id="generalSettings">General Settings</a> <ul class='acitem'>...stuff goes here... In the example above, clicking on "Open General Settings" toggles the "acitem" UL's child elements visible. I'd just like to simulate a click on that element, from a link at the top of my app...

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• NoMethodError when using .where (eager fetching)

  - by Ethan Leroy

  I have the following model classes... class Image < ActiveRecord::Base attr_accessible :description, :title has_many :imageTags has_many :tags, :through => :imageTags end class Tag < ActiveRecord::Base attr_accessible :name has_many :imageTags has_many :images, :through => :imageTags end class ImageTag < ActiveRecord::Base attr_accessible :position belongs_to :image belongs_to :tag end And when I use find for getting the Tag with the id 1 t = Tag.find(1); @images = t.images; But when I do the same with where, I get a NoMethodError, with the description undefined method 'images': t = Tag.where(:name => "foo"); @images = t.images; I also tried adding .includes(:images) before the .where statement, but that doesn't work too. So, how can I get all Images that belong to a Tag?

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• EntityFramework 4.0: can you return different types depending on data in the database?

  - by user200341

  I have a Media table in the database. I also have an IMedia interface. I have two different media types that implements the same interface: 1) AudioMedia 2) PictureMedia What I wonder here, is if I can use EntityFramework (I'm using an EDMX file but I have my models in a separate library, with automatic code generation turned off), and depending on the data in the database, select what type to get (AutioMedia or PictureMedia). Since they are both implementing the same interface (could be changed to an abstract class if needed I suppose), I'm thinking that somewhere along the way you could specify what class it should be. I should perhaps point out that I have a class that inherits from ObjectContext to access the objects. Perhaps there is something that that can be done?

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• SQL Server 2003: how can I assign a name to the SUM column ?

  - by Patrick

  hi, how can I assign a column name to the SUM column ? i.e. select OwnerUserId, SUM(PostScore) INTO Experts from ... I get this error: An object or column name is missing or empty. For SELECT INTO statements, verify each column has a name. For other statements, look for empty alias names. Aliases defined as "" or [] are not allowed. Change the alias to a valid name. I guess because the column containing the results of SUM has not name. thanks

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• Return an opaque object to the caller without violating type-safety

  - by JS Bangs

  I have a method which should return a snapshot of the current state, and another method which restores that state. public class MachineModel { public Snapshot CurrentSnapshot { get; } public void RestoreSnapshot (Snapshot saved) { /* etc */ }; } The state Snapshot class should be completely opaque to the caller--no visible methods or properties--but its properties have to be visible within the MachineModel class. I could obviously do this by downcasting, i.e. have CurrentSnapshot return an object, and have RestoreSnapshot accept an object argument which it casts back to a Snapshot. But forced casting like that makes me feel dirty. What's the best alternate design that allows me to be both type-safe and opaque?

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• Switching from php to python

  - by ts

  Hello I am trying to make a list of things which can be difficult/surprising to someone who is changing language from PHP to Python. so far i have rather short list: forget require / include, learn import (this was most difficult to me - to understand package - module - class - object hierarchy and its mapping to filesystem) you can't just upload file on server to have webpage (-mod_python, wsgi etc) learn the python way for use variable class names (new $class() vs import + getattr) / operator in python 2.x and all float-related horrors those were difficult to me, it takes few days before mind adapts a new paradigm after i found that there is few other areas which could be challenging for someone with (too) many years of php: everything is an object you have to live with exceptions array vs list, set, dictionary, tuple ... learn (effective) list comprehensions learn generators any other ideas / personal experiences ?

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