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  • Add class to elements which already have a class

    - by bwstud
    I have a group of divs which I'm dynamically generating when a button is clicked with the class, "brick". This gives them dimension and starting position of top: 0. I'm trying to get them to animate to the bottom of the view using a css transition with a second class assignment which gives them a bottom position: 0;. Can't figure out the syntax for adding a second class to elements with a pre-existing class. On inspection they only show the original class of, "brick". HTML <!DOCTYPE html> <html> <head> <script src="http://code.jquery.com/jquery-2.1.0.min.js"></script> <meta charset="utf-8"> <title>JS Bin</title> </head> <body> <div id="container"> <div id="button" >Click Me</div> </div> </body> </html> CSS #container { width: 100%; height: 100vh; padding: 10vmax; } #button { position: fixed; } .brick { position: relative; top: 0; height: 10vmax; width: 20vmax; background: white; margin: 0; padding: 0; transition: all 1s; } .drop { transition: all 1s; bottom 0; } The offending JS: var brickCount = function() { var count = prompt("How many boxes you lookin' for?"); for(var i=0; i < count; i++) { var newBrick = document.createElement("div"); newBrick.className="brick"; document.querySelector("#container") .appendChild(newBrick); } }; var getBricks = function(){ document.getElementByClass("brick"); }; var changeColor = function(){ getBricks.style.backgroundColor = '#'+Math.floor(Math.random()*16777215).toString(16); }; var addDrop = function() { getBricks.brick = "getBricks.brick" + " drop"; }; var multiple = function() { brickCount(); getBricks(); changeColor(); addDrop(); }; document.getElementById("button").onclick = function() {multiple();}; Thanks!

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  • PHP Changing Class Variables Outside of Class

    - by Jamie Bicknell
    Apologies for the wording on this question, I'm having difficulties explaining what I'm after, but hopefully it makes sense. Let's say I have a class, and I wish to pass a variable through one of it's methods, then I have another method which outputs this variable. That's all fine, but what I'm after is that if I update the variable which was originally passed, and do this outside the class methods, it should be reflected in the class. I've created a very basic example: class Test { private $var = ''; function setVar($input) { $this->var = $input; } function getVar() { echo 'Var = ' . $this->var . '<br />'; } } If I run $test = new Test(); $string = 'Howdy'; $test->setVar($string); $test->getVar(); I get Var = Howdy However, this is the flow I would like: $test = new Test(); $test->setVar($string); $string = 'Hello'; $test->getVar(); $string = 'Goodbye'; $test->getVar(); Expected output to be Var = Hello Var = Goodbye I don't know what the correct naming of this would be, and I've tried using references to the original variable but no luck. I've come across this in the past, with the PDO prepared statements, see Example #2 $stmt = $dbh->prepare("INSERT INTO REGISTRY (name, value) VALUES (?, ?)"); $stmt->bindParam(1, $name); $stmt->bindParam(2, $value); // insert one row $name = 'one'; $value = 1; $stmt->execute(); // insert another row with different values $name = 'two'; $value = 2; $stmt->execute(); I know I can change the variable to public and do the following, but it isn't quite the same as how the PDO class handles it, and I'm really looking to mimic that behaviour. $test = new Test(); $test->setVar($string); $test->var = 'Hello'; $test->getVar(); $test->var = 'Goodbye'; $test->getVar(); Any help, ideas, pointers, or advice would be greatly appreciated, thanks.

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  • Singleton Pattern Implementation Issues?

    - by locky28
    Hi I am revising for an exam and need to know some implementation issues with the singleton pattern. they do not need to be too complex just basic things that would affect a developers decision to include them, Thanks P.S. Could any code examples be given in Java thanks.

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  • Singleton rule questions (do not allow to create copy and deserialization)

    - by Petr
    Hi, Reading some article about singleton, I stopped at the point saying: "Do not allow to crate copy of existing instance". I realized that I do not know how would I do that! Could you tell me, please, how could I copy existing instance of class? And the second one: deserializaition. How it could be dangerous? And for both - how to deny creating copies or deserialization? Thanks

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  • How bad is it to have two methods with the same name but different signatures in two classes?

    - by Super User
    I have a design problem related to a public interface, the names of methods, and the understanding of my API and code. I have two classes like this: class A: ... function collision(self): .... ... class B: .... function _collision(self, another_object, l, r, t, b): .... The first class has one public method named collision, and the second has one private method called _collision. The two methods differs in argument type and number. As an example let's say that _collision checks if the object is colliding with another object with certain conditions l, r, t, b (collide on the left side, right side, etc) and returns true or false. The public collision method, on the other hand, resolves all the collisions of the object with other objects. The two methods have the same name because I think it's better to avoid overloading the design with different names for methods that do almost the same thing, but in distinct contexts and classes. Is this clear enough to the reader or I should change the method's name?

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  • How bad it's have two methods with the same name but differents signatures in two classes?

    - by Super User
    I have a design problem relationated with the public interface, the names of methods and the understanding of my API and my code. I have two classes like this: class A: ... function collision(self): .... ... class B: .... function _collision(self, another_object, l, r, t, b): .... The first class have one public method named collision and the second have one private method called _collision. The two methods differs in arguments type and number. In the API _m method is private. For the example let's say that the _collision method checks if the object is colliding with another_ object with certain conditions l, r, t, b (for example, collide the left side, the right side, etc) and returns true or false according to the case. The collision method, on the other hand, resolves all the collisions of the object with other objects. The two methods have the same name because I think is better avoid overload the design with different names for methods who do almost the same think, but in distinct contexts and classes. This is clear enough to the reader or I should change the method's name?

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  • private class calling a method from its outer class

    - by oxinabox.ucc.asn.au
    Ok, so I have a class for a "Advanced Data Structure" (in this case a kinda tree) SO I implimented a Iterator as a private class with in it. So the iterator needs to implement a remove function to remove the last retuirned element. now my ADT already impliments a remove function, and in this case there is very little (thinking about it, i think nothing) to be gain by implimenting a different remove function for the iterator. so how do I go about calling the remove from my ADT sketch of my struture: public class ADT { ... private class ADT_Iterator impliments java.util.Itorator{ ... public void remove(){ //where I want to call the ADT's remove function from } ... public void remove( Object paramFoo ) { ... } ... } So just calling remove(FooInstance) won't work (will it?) and this.remove(FooInstance) is the same thing. what do i call? (and changign the name of the ADT's remove function is not an option, as that AD T has to meet an Interace wich I am note at liberty to change) I could make both of them call a removeHelper functon, I guess...

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  • passing reference of class to another class android error

    - by prolink007
    I recently asked the precursor to this question and had a great reply. However, when i was working this into my android application i am getting an unexpected error and was wondering if everyone could take a look at my code and help me see what i am doing wrong. Link to the initial question: passing reference of class to another class My ERROR: "The constructor ConnectDevice(new View.OnClickListener(){}) is undefined" The above is an error detected by eclipse. Thanks in advance! Below are My code snippets: public class SmartApp extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.intro); final Button connectDeviceButton = (Button) findViewById(R.id.connectDeviceButton); connectDeviceButton.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { Thread cThread = new Thread(new ConnectDevice(this)); cThread.start(); } }); } } public class ConnectDevice implements Runnable { private boolean connected; private SmartApp smartAppRef; private ObjectInputStream ois; public ConnectDevice(SmartApp smartAppRef) { this.smartAppRef = smartAppRef; } }

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  • C++ Problem: Class Promotion using derived class

    - by Michael Fitzpatrick
    I have a class for Float32 that is derived from Float32_base class Float32_base { public: // Constructors Float32_base(float x) : value(x) {}; Float32_base(void) : value(0) {}; operator float32(void) {return value;}; Float32_base operator =(float x) {value = x; return *this;}; Float32_base operator +(float x) const { return value + x;}; protected: float value; } class Float32 : public Float32_base { public: float Tad() { return value + .01; } } int main() { Float32 x, y, z; x = 1; y = 2; // WILL NOT COMPILE! z = (x + y).Tad(); // COMPILES OK z = ((Float32)(x + y)).Tad(); } The issue is that the + operator returns a Float32_base and Tad() is not in that class. But 'x' and 'y' are Float32's. Is there a way that I can get the code in the first line to compile without having to resort to a typecast like I did on the next line?

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  • How do I find out if the variable is declared in Python?

    - by golergka
    I want to use a module as a singleton referenced in other modules. It looks something like this (that's not actually a code I'm working on, but I simplified it to throw away all unrelated stuff): main.py import singleton import printer def main(): singleton.Init(1,2) printer.Print() if __name__ == '__main__': pass singleton.py variable1 = '' variable2 = '' def Init(var1, var2) variable1 = var1 variable2 = var2 printer.py import singleton def Print() print singleton.variable1 print singleton.variable2 I expect to get output 1/2, but instead get empty space. I understand that after I imported singleton to the print.py module the variables got initialized again. So I think that I must check if they were intialized before in singleton.py: if not (variable1): variable1 = '' if not (variable2) variable2 = '' But I don't know how to do that. Or there is a better way to use singleton modules in python that I'm not aware of :)

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  • Class or Dictionary

    - by user2038134
    I want to create a immutable Scale class in C#. public sealed class Scale { string _Name; string _Description; SomeOrderedCollection _ScaleValueDefinitions; Unit _Unit // properties .... // methods ContainsValue(double value) .... // constructors // all parameters except scalevaluedefinitions are optional // for a Scale to be useful atleast 1 ScaleValueDefinition should exist public Scale(string name, string description, SomeOrderedCollection scaleValueDefinitions, unit) { /* initialize */} } so first a ScaleValueDefinition should be represented by to values: Value (double) Definition (string) these values are known before the Scale class is created and should be unique. so what is the best approach. create a immutable class ScaleValueDefinition with value and definition as properties and use it in a list. use a dictionary. use another way i didn't think of... and how to implement it. for option 1. i can use params ScaleValueDefinition[] ValueDefinitions in the constructor, but how to do it for the other options? and as last at what amount of value's (properties) should i choose one option over the other?

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  • PHP class data implementation

    - by Bakanyaka
    I'm studying OOP PHP and have watched two tutorials that implement user login\registration system as an example. But implementation varies. Which way will be more correct one to work with data such as this? Load all data retrieved from database as array into a property called something like _data on class creation and further methods operate with this property Create separate properties for each field retrieved from database, on class creation load all data fields into respective properties and operate with that properties separately? Then let's say I want to create a method that returns a list of all users with their data. Which way is better? Method that returns just an array of userdata like this: Array([0]=>array([id] => 1, [username] => 'John', ...), [1]=>array([id] => 2, [username] => 'Jack', ...), ...) Method that creates a new instance of it's class for each user and returns an array of objects

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  • How to create a manager class without global variables nor singletons?

    - by Omega
    I would like to implement some kind of manager class in my application. It will be in charge of loading textures, processing them, distributing them etc... At first, I wanted to make a global variable that simply contains an instance of my manager class. I found this question: http://stackoverflow.com/questions/4646577/global-variables-in-java. However, the users there seem to recommend to never use global variables. Fine then, I once heard about Singletons, so I though I could use that instead. I mean, creating just one instance of my manager class sounds good. However, I found this other question: When is Singleton appropriate?, which basically tells me that Singletons are, in most scenarios, some kind of anti-pattern. Now I am a bit lost - what other approach can I take to create my manager class, whose only requirement is to be accessible from anywhere?

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  • How To Create Per-Request Singleton in Pylons?

    - by dave mankoff
    In our Pylons based web-app, we're creating a class that essentially provides some logging functionality. We need a new instance of this class for each http request that comes in, but only one per request. What is the proper way to go about this? Should we just create the object in middleware and store in in request.environ? Is there a more appropriate way to go about this?

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  • Access static class variable of parent class in Python

    - by fuenfundachtzig
    I have someting like this class A: __a = 0 def __init__(self): A.__a = A.__a + 1 def a(self): return A.__a class B(A): def __init__(self): # how can I access / modify A.__a here? A.__a = A.__a + 1 # does not work def a(self): return A.__a Can I access the __astatic variable in B? It's possible writing a instead of __a, is this the only way? (I guess the answer might be rather short: yes :)

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  • Rails 3 Abstract Class vs Inherited Class

    - by R. Yanchuleff
    In my rails 3 model, I have two classes: Product, Service. I want both to be of type InventoryItem because I have another model called Store and Store has_many :InventoryItems This is what I'm trying to get to, but I'm not sure how to model this in my InventoryItem model and my Product and Service models. Should InventoryItem just be a parent class that Product and Service inherit from, or should InventoryItem be modeled as a class abstract of which Product and Service extend from. Thanks in advance for the advice!

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  • General question about Ruby Eigenclass/Singleton

    - by Dex
    module MyModule def my_method; 'hello'; end end class MyClass class << self include MyModule end end MyClass.my_method # => "hello I'm unsure why "include MyModule" needs to be in the eigenclass in order to be called using just MyClass. Why can't I go: X = MyClass.new X.my_method How is this type of pattern useful if I can't call it from an instance?

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  • Setting attributes of a class during construction from **kwargs

    - by Carson Myers
    Python noob here, Currently I'm working with SQLAlchemy, and I have this: from __init__ import Base from sqlalchemy.schema import Column, ForeignKey from sqlalchemy.types import Integer, String from sqlalchemy.orm import relationship class User(Base): __tablename__ = "users" id = Column(Integer, primary_key=True) username = Column(String, unique=True) email = Column(String) password = Column(String) salt = Column(String) openids = relationship("OpenID", backref="users") User.__table__.create(checkfirst=True) #snip definition of OpenID class def create(**kwargs): user = User() if "username" in kwargs.keys(): user.username = kwargs['username'] if "email" in kwargs.keys(): user.username = kwargs['email'] if "password" in kwargs.keys(): user.password = kwargs['password'] return user This is in /db/users.py, so it would be used like: from db import users new_user = users.create(username="Carson", password="1234") new_user.email = "[email protected]" users.add(new_user) #this function obviously not defined yet but the code in create() is a little stupid, and I'm wondering if there's a better way to do it that doesn't require an if ladder, and that will fail if any keys are added that aren't in the User object already. Like: for attribute in kwargs.keys(): if attribute in User: user.__attribute__[attribute] = kwargs[attribute] else: raise Exception("blah") that way I could put this in its own function (unless one hopefully already exists?) So I wouldn't have to do the if ladder again and again, and so I could change the table structure without modifying this code. Any suggestions?

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  • Boost C++ Singleton error LNK2001: unresolved external symbol "private: static long Nsp::HL::flag" (

    - by Soós Roland
    I try to create a multi-threaded singleton pattern class. Header: class HL{ public: static HL* getInstance(); ......... private: static HL* instance; static boost::once_flag flag; HL(); static void initOnce(); } CPP: HL* HL::instance = NULL; HL* HL::getInstance(){ if(instance == NULL){ boost::call_once(flag, initOnce); } return instance; } void HL::initOnce(){ instance = new HL(); } I get this error: error LNK2001: unresolved external symbol "private: static long Nsp::HL::flag" (?flag@HL@Nsp@@0JA) What's wrong?

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  • Singleton pattern and broken double checked locking in real world java application

    - by saugata
    I was reading the article Double-checked locking and the Singleton pattern, on how double checked locking is broken, and some related questions here on stackoverflow. I have used this pattern/idiom several times without any issues. Since I have been using Java 5, my first thought was that this has been rectified in Java 5 memory model. However the article says This article refers to the Java Memory Model before it was revised for Java 5.0; statements about memory ordering may no longer be correct. However, the double-checked locking idiom is still broken under the new memory model. I'm wondering if anyone has actually run into this problem in any application and under what conditions.

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  • some confusions to singleton pattern in PHP

    - by SpawnCxy
    Hi all, In my team I've been told to write resource class like this style: class MemcacheService { private static $instance = null; private function __construct() { } public static function getInstance($fortest = false) { if (self::$instance == null) { self::$instance = new Memcached(); if ($fortest) { self::$instance->addServer(MEMTEST_HOST, MEMTEST_PORT); } else { self::$instance->addServer(MEM_HOST, MEM_PORT); } } return self::$instance; } } But I think in PHP resource handles will be released and initialized again every time after a request over. That means MemcacheService::getInstance() is totally equal new Memcached() which cannot be called singleton pattern at all. Please correct me if I'm wrong. Regards

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