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  • Why wasn't C# designed with 'const' for variables and methods?

    - by spoulson
    I suspect const was simplified for the C# spec for general language simplicity. Was there a specific reason we can't declare variable references or methods as const like we can with C++? e.g.: const MyObject o = new MyObject(); // Want const cast referenece of MyObject o.SomeMethod(); // Theoretically legal because SomeMethod is const o.ChangeStuff(); // Theoretically illegal because ChangeStuff is not const class MyObject { public int val = 0; public void SomeMethod() const { // Do stuff, but can't mutate due to const declaration. } public void ChangeStuff() { // Code mutates this instance. Can't call with const reference. val++; } }

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  • Best ways to write a method that updates two objects in a multithreaded java environment?

    - by DanielHonig
    Suppose we have a class called AccountService that manages the state of accounts. AccountService is defined as interface AccountService{ public void debit(account); public void credit(account); public void transfer(Account account, Account account1); } Given this definition, what is the best way to implement transfer() so that you can guarantee that transfer is an atomic operation. I'm interested in answers that reference Java 1.4 code as well as answers that might use resources from java.util.concurrent in Java 5

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  • Use variables to decide which object in an array gets an attribute?

    - by DavidR
    I have a web app which has two text areas. When one text area receives a mousedown event, a variable "side" is set, either "left" or "right." When a user selects some text in a text area, three strings are made. One for the text before the beginning of the selection, the selection itself, and the text after the selection to the end. A function is set to return these like this: return { head: head_text, tail: tail_text, sel: sel_text, side: text_side } Now, I have created an array, and I want it to appear in such a way that we get, text.left({"head":"four score", "selection":"and seven", "tail":"years ago."}) I am assuming I would do this by text.side = getSelection(), but how do I get it to evaluate the variable "side" instead of thinking of it as an object within "text"? EDIT: Ok, just to clarify, I might be completely wrong in my ideas in how this works, but here it goes. I want to make it so that a function can look at "text" see within text two objects, "left" and "right," and then evaluate the head, sel, and tail of each object. Would it be easier for me to use two objects?

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  • Why doesn't Rails' "errors.full_messages" replace attribute and message variables?

    - by tybro0103
    Having a strange problem with a rails model I just created. Here are my validations: validates_presence_of :from_name, :message => 'Please provide a from name.' validates_presence_of :from_email validates_presence_of :giftition_plan_id I'm having issues using errors.full_messages as well as f.error_messages in my form: g = Giftition.create g.errors.first => ["from_name", "Please provide a from name."] >> g.errors.full_messages => ["{{attribute}} {{message}}", "{{attribute}} {{message}}", "{{attribute}} {{message}}"] I'm just getting "{{attribute}} {{message}}". Any ideas? UPDATE: I've uninstalled rails 3 and all the gems that were installed with it and that made the problem go away. It's not a fix though... I would still like to have rails 3 installed.

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  • Is it possible to use the ScalaTest BDD syntax in a JUnit environment?

    - by ebruchez
    I would like to describe tests in BDD style e.g. with FlatSpec but keep JUnit as a test runner. The ScalaTest Quick Start does not seem to show any example of this: http://www.scalatest.org/getting_started_with_junit_4 I first tried naively to write tests within @Test methods, but that doesn't work and the assertion is never tested: @Test def foobarBDDStyle { "The first name control" must "be valid" in { assert(isValid("name·1")) } // etc. } Is there any way to achieve this? It would be even better if regular tests can be mixed and matched with BDD-style tests.

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  • Javascript style variables with "-" in their name aren't able to be changed?

    - by William
    Okay, so this bug has cost me quite a bit of time and embarrassment. It seems that any style variable with a - in it's name can't be modified by javascript. As seen here: <!DOCTYPE html> <html lang="en"> <head> <title>Class Test</title> <meta charset="utf-8" /> <style> body { text-align: center; background-color: #ffffff;} #box { position: absolute; left: 610px; top: 80px; height: 50px; width: 50px; background-color: #ff0000; color: #000000;} </style> <script type="text/javascript"> var box = 0; </script> </head> <body> <div id="box" ></div> <script type="text/javascript"> box = document.getElementById('box'); box.style.background-color = "#0000ff"; </script> </body> </html> The box in said example will just remain red. So how do I change a style variable with a - in it's name?

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  • Is there a way to access Joomla 1.5 user variables (like user id) from a Flex 4 application using a PHP Data Service?

    - by Zachary G. Schroeder
    I have written a script (in two files) that correctly displays a Joomla user id, like this: //this is testy.php define( '_JEXEC', 1 ); define('JPATH_BASE', dirname(FILE)); define( 'DS', DIRECTORY_SEPARATOR ); require_once ( JPATH_BASE .DS.'includes'.DS.'defines.php' ); require_once ( JPATH_BASE .DS.'includes'.DS.'framework.php' ); $mainframe =& JFactory::getApplication('site'); $id = JFactory::getUser()-id; The above file is located in the Joomla root folder. The other file is in a different directory and is as follows: //this is testid.php include '../../joomla/testy.php'; echo $id; However, and here is the rub, when I change the "echo" to a "return" and put the second code snippet inside my Flex 4 Data Service script file, like this... function getUserId() { include '../../joomla/testy.php'; return $id; } ...I get a Flex error that says this: Fatal error: Class 'JRequest' not found in /var/www/html/joomla/libraries/joomla/import.php on line 33 I am extremely confused by this error and would appreciate any suggestions that the stackoverflow community may have. Thanks so much! Zach

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  • restrict the scope of variables in a mysql query? with brackets?

    - by Haroldo
    I can't remember what the method is meant to be for ensuring the scope of a variable in a query is restricted to prevent mysql injection. where should i put brackets in the following examples? UPDATE table SET col_1 = '$var', col_2 = '$var2' WHERE col_1 = '$var3' and SELECT * FROM table WHERE WHERE col_1 >= '$var1' (Obviously looking for answers not using PDO!)

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  • How to pass variables to slot methods in QT?

    - by Neko
    Hi. I'm making a little chat messenger program, which needs a list of chat channels the user has joined. To represent this list graphically, I have made a list of QPushButtons, which all represent a different channel. These buttons are made with the following method, and that's where my problem kicks in: void Messenger::addToActivePanels(std::string& channel) { activePanelsContents = this->findChild<QWidget *>(QString("activePanelsContents")); pushButton = new QPushButton(activePanelsContents); pushButton->setObjectName("pushButton"); pushButton->setGeometry(QRect(0, 0, 60, 60)); pushButton->setText(""); pushButton->setToolTip(QString(channel.c_str())); pushButton->setCheckable(true); pushButton->setChecked(false); connect(pushButton, SIGNAL(clicked()), this, SLOT(switchTab(channel))); } (activePanelContents is a QWidget that holds the list.) The point is that each button should call the switchTab(string& tabname) method when clicked, including the specific channel's name as variable. This implementation doesn't work though, and I haven't been able to find out how to properly do this, even after reading several pages on it on the internet. Can anybody please tell me how to do this? It'd be greatly appreciated, as always. :)

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  • Can g++ fill uninitialized POD variables with known values?

    - by Bob Lied
    I know that Visual Studio under debugging options will fill memory with a known value. Does g++ (any version, but gcc 4.1.2 is most interesting) have any options that would fill an uninitialized local POD structure with recognizable values? struct something{ int a; int b; }; void foo() { something uninitialized; bar(uninitialized.b); } I expect uninitialized.b to be unpredictable randomness; clearly a bug and easily found if optimization and warnings are turned on. But compiled with -g only, no warning. A colleague had a case where code similar to this worked because it coincidentally had a valid value; when the compiler upgraded, it started failing. He thought it was because the new compiler was inserting known values into the structure (much the way that VS fills 0xCC). In my own experience, it was just different random values that didn't happen to be valid. But now I'm curious -- is there any setting of g++ that would make it fill memory that the standard would otherwise say should be uninitialized?

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  • how to add a variables which comes from dataset in for loop Collection array in c#?

    - by leventkalay1986
    I have a collection of RSS items protected Collection<Rss.Items> list = new Collection<Rss.Items>(); The class RSS.Items includes properties such as Link, Text, Description, etc. But when I try to read the XML and set these properties: for (int i = 0; i < dt.Rows.Count; i++) { row = dt.Rows[i]; list[i].Link.Equals(row[0].ToString()); list[i].Description.Equals( row[1].ToString()); list[i].Title.Equals( row[2].ToString()); list[i].Date.Equals( Convert.ToDateTime(row[3])); } I get a null reference exception on the line list[i].Link.Equals(row[0].ToString()); What am I doing wrong?

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  • How would you update 100+ variables if something is changed in a different class?

    - by N. Lucas
    I have a class Grid which produces a graph paper like grid on in the drawing area. I then have 5 other classes for different shapes to draw with; Line, Polygon, Ellipse, Curve, Arc Now, these 5 classes use an instance of Grid because Grid has a resolution and a scale. Inside Grid I have: public function set resolution(x:Number):void { _gap = (modBy10(x) / 10); _scale = (modBy10(x) / (this.resolution * _scale)); draw(); } public function get resolution():Number { return (_gap * 10); } public function set scale(x:Number):void { _scale = (this.resolution / x); } public function get scale():Number { return _scale; } /**/ public function scaleLength(x:Number):Number { return (x * this.scale); } public function scaleLengthDown(x:Number):Number { return (x / this.scale); } public function scaleArea(x:Number):Number { return (x / Math.pow(this.scale, 2)); } I'm just lost for a solution on how to update every instance of my 5 drawing classes when Grid is changed. For instance, Polygon is made up of multiple instances of Line, Line(length, angle) where "length" is in either in, ft, cm, or m. If the user wishes to change the scale from say 10ft per 100px resolution.. Is there an easier way than re-drawing every Line inside Polygon?

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  • Can I install Whizzy for Emacs on a Mac (is Mac OS X a unix environment)?

    - by Vivi
    I think my question is pretty stupid, but here it goes: I am using Aquamacs, and I want to install the Whizzy mode. The website for Whizzy says that "it is designed for Unix platforms". I read that Mac OS X is unix certified, but does that mean I can install Whizzy on my mac? If yes, can I install and use it with Aquamacs or do I have to use the Emacs running from the terminal? PS: I don't know whether this question should be posted here or on SuperUser, but as Emacs users seem to hang out here more often, this is the place I chose.

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  • How can I efficiently retrieve a large number of database settings as PHP variables?

    - by Steven
    Currently all of my script's settings are located in a PHP file which I 'include'. I'm in the process of moving these settings (about 100) to a database table called 'settings'. However I'm struggling to find an efficient way of retrieving all of them into the file. The settings table has 3 columns: ID (autoincrements) name value Two example rows might be: 1 admin_user john 2 admin_email_address [email protected] The only way I can think of retrieving each setting is like this: $result = mysql_query("SELECT value FROM settings WHERE name = 'admin_user'"); $row = mysql_fetch_array($result); $admin_user = $row['value']; $result = mysql_query("SELECT value FROM settings WHERE name = 'admin_email_address'"); $row = mysql_fetch_array($result); $admin_email_address = $row['value']; etc etc Doing it this way will take up a lot of code and will likely be slow. Is there a better way? Thanks.

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  • Any way to define getters for lazy variables in Javascript arrays?

    - by LLer
    I'm trying to add elements to an array that are lazy-evaluated. This means that the value for them will not be calculated or known until they are accessed. This is like a previous question I asked but for objects. What I ended up doing for objects was Object.prototype.lazy = function(var_name, value_function) { this.__defineGetter__(var_name, function() { var saved_value = value_function(); this.__defineGetter__(var_name, function() { return saved_value; }); return saved_value; }); } lazy('exampleField', function() { // the code that returns the value I want }); But I haven't figured out a way to do it for real Arrays. Arrays don't have setters like that. You could push a function to an array, but you'd have to call it as a function for it to return the object you really want. What I'm doing right now is I created an object that I treat as an array. Object.prototype.lazy_push = function(value_function) { if(!this.length) this.length = 0; this.lazy(this.length++, value_function); } So what I want to know is, is there a way to do this while still doing it on an array and not a fake array?

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