Calling Protected Function From Derived Friend Function
A friend function is a non member function which has access to private members of a class. But you still have to provide the object details for accessing data members. The usage of eat function must be similar to object_name.eat() in the feed function....
Is dynamic_casting through inheritance hierarchy bad practice?
There are a lot of questions on dynamic_cast here on SO. I read only a few and also don't use that method often in my own code, so my answer reflects my opinion on this subject rather than my experience. Watch out. (1.) Why is casting up/down considered bad design,...
Am I violating the Object-Oriented encapsulation principle? [closed]
Encapsulation principle is about restricting some parts of an object (e.g. internal operations or fields that shouldn't be available from outside of the object). Common understanding is also using accessors to access fields. Javascript doesn't offer any mechanism that allow restricting access to fields or methods. However, it is possible...
base class pointer, invoke method based on derived type
c++,oop,inheritance,polymorphism
The easiest way is probably to just make method() a virtual member function on foo: class base { public: virtual void method() const = 0; }; class foo : public base { public: void method() const override { } }; int main(){ foo f; base* b = &f; b->method(); }...
Why metaclass's __call__ method called on class, but native class's __call__ not?
When you create a class instance, the metaclass's (whose instance the class is) __call__ is called. # Instantiate class. StandardClass() # StandardClass.__call__ is not called! When you create a class instance and then "call" the instance, then the class's __call__ is called. I don't think decorating __call__ with classmethod will...
Why there isn't library of design patterns?
Design patterns are solutions to programming problems that automatically implement good design techniques. Someone has already faced the issues you’re facing, solved them, and is willing to show you what the best techniques are. Answer to your question is - Design patterns are higher level than libraries. Design patterns tell...
PHP Data Objetcs (PDO) example
It looks alright for a basic implementation, beside that you shouldn't echo something inside a class. If you want see a well implemented solution, have a look into eloquent created by taylor otwell. That should give you heaps of ideas how to improve your code. https://github.com/laravel/framework/blob/4.2/src/Illuminate/Database/Connection.php...
Find method contents from a method in superclass? (Java/Eclipse)
No, it isn't possible in Java. Because, you can not modify the return type of a function you override. The Java Tutorials Overriding and Hiding Methods says (in part) An instance method in a subclass with the same signature (name, plus the number and the type of its parameters) and...
Object Oriented Python - rectangle using classes and functions
python,function,class,oop,methods
Not sure I got your question right, but you may want to try: def getStats(self): return "width: %s\nheight: %s\narea: %s\nperimeter: %s" % (self.width, self.height, self.area(), self.perimeter()) To satisfy requirements 4 and 6, I would suggest something like: class Shape(object): def area(self): raise NotImplementedError def perimeter(self): raise NotImplementedError class Rectangle(Shape): def...
Understanding difference in Swift properties for structs and classes in assignment
Whenever a method in a struct modifies one of its own properties, you have to use the mutating keyword. I believe that if you write: mutating func intializeAllDataPoints() { ... } it should work for you. This article gives a little more background information....
missing 1 required positional argument: 'key'
You probably meant: class Keys(): def __init__(self): self.key_list = {1:"one", 2:"two", 3:"three"} def get_name(self, key): self.ddd = key key1 = Keys() key1.get_name(1) Note the use of parenthesis: key1 = Keys()...
Can adhering to the JavaBeans naming standard aid in achieving encapsulation?
java,oop,inheritance,coupling,cohesion
No. Naming standards don't do, open or restrict anything. For encapsulation you will of course need access modifiers. Best is to use both. That helps understanding your code even if you didn't look at it for some time or if you indend to share it.
My simple php class not working [closed]
You can't use type hints with scalar values ( in you case string - check the docs) Change your constructor in this way: public function __construct($scheme, $hostname, $www) { $this->scheme = $scheme; $this->hostname = $hostname; $this->www = $www; } and it should work...
Calling a method on array iteration, from an object - PHP
How about this <?php class MyClass { public $myArray=array(); public $htm = NULL; public function __construct(&$format=NULL) { //.. //Mysql query as $stmt //.. $this->myArray=$stmt->fetchAll(PDO::FETCH_ASSOC); $i=0; foreach($this->myArray as $row) { switch ($format) { case 'Page1' : $this->htm .= $this->format1($row); break; case 'Page2' : $this->htm .= $this->format2($row); break; default: $this->htm .= $this->format_default($row);...
How to extract variable from one function into another in same class in php
<?php abstract class abc { protected $te; } class test extends abc { public function __construct() { $this->te = 5; } public function team() { $this->te += 100; } public function tee() { return $this->te; } } $obj = new test(); $obj->team(); echo $obj->tee(); -- edit: to make at least...
Function pointer to singleton class instance function
Simply create a normal class without static methods, ditch the singleton pattern aside, and create an instance. The burden of singleton pattern usually outweigh any benefit....
How access member function from arrayobject in a loop
Use array_object[i]->get_data(); instead of array_object[i].get_data();. The DOT(.) operator is used when an object try to access its class member functions/variables whereas Arrow(->) operator is used if the object is a pointer. Now, you declared Matrix *array_object[100]; Which means array_object is an array of Matrix pointers. Hence you need to use...
How to avoid anemic data model? Can repositories be injected into entities?
java,oop,design,domain-driven-design
For a system-wide password expiration policy your approach is not that bad, as long as your UserPasswordService is a domain service, not an application service. Embedding the password expiration policy within User would be a violation of the SRP IMHO, which is not much better. You could also consider something...
Javascript: Access function within deep object on parse
Because scope in which function2 is defined does not contain definition of object1. Then when you try to access object1.object2 it throws error because object1 is not defined
How to reuse this ViewController code in an object oriented way?
It is a very good idea to refactor this code; it is an example of DRY. The best way in this case would be to use inheritance: write all common code in the ViewController class, e.g. ViewController.h @interface ViewController : UIViewController { // Variables which are declared here can also...
Why does Instagram's pagination return the same page over and over?
php,wordpress,oop,pagination,instagram
I've added the following lines of code to the try block of my try...catch statement to return several successive pages at a time: while ( count( $this->data["photos"] ) < 160 ) { $this-> api_request( $this->data["next_page"] ); } This essentially tells api_request to call itself until my $this->data["next_page"] array is populated...
Add key and value (as argument via function) to array
Modify your addError function: public function addError($error, $key=false){ if($key){ self::$_errors[$key] = $error; }else{ self::$_errors[] = $error; } } Then it will go like this: if(strlen($value) < $rule_value){ $this->addError("More than {$rule_value} characters are needed as {$item}.", 'min_notmet'); } If you don't provide $key parameter, it will just add the element as...
How Do I Architect Out This Relationship
You can do this with a self referential parent. Table Business [BusinessID, BusinessLevelID, ParentBusinessID] Table BusinessLevel [BusinessLevelID, Description ]{eg. business, division, dept } ...
Passing variable data between classes OO Javascript
Maybe can put contactsAppModel.init(); on the first line of your contactsApp.init() method.
Python class design: explicit keyword arguments vs. **kwargs vs. @property
Without really knowing the particulars of your situation, the classic answer is this: if your class initializer requires a whole bunch of arguments, then it is probably doing too much, and it should be factored into several classes. Take a Car class defined as such: class Car: def __init__(self, tire_size,...
Class fields as method parameters
Assuming your EntityQuery.groovy ( model )looks like : private String typeName private Order order Assuming you have Order.groovy ( model ) that looks like : private String fieldName; private String orderType; private String orderName; use these model chain as a parameter, I think that is still strongly-typed (correct me). Your...
JavaScript Functional Classes [closed]
Answer: None of the above. Try something like this: function Car(loc) { this.loc = loc; } Car.prototype.move = function () { this.loc++; }; var obj = new Car(someLoc); obj.move(); This uses object prototyping which is JavaScript's implementation of object-oriented programming. You can read more about prototypes and inheritance here on...
C# Code design / Seperate classes for each TabControl
c#,oop,architecture,software-design,code-design
Place a UserControl on each tab.
Where is the defination of rails validators?
These are Rails methods: You can find valid? here and its code on Github. Likewise with new_record?, you can find a description and its source code here. Also, here is a link to the Rails repository on Github. These methods are not defined in the project, they are defined in...
Can i use only _ (underscore) for the name of the class?
Yes, you can use only underscore for the class name. class _{ function __construct(){ echo 'It works!'; } } new _(); Output: It works! DEMO...
Moving all fields info from one object to another
As @OliverCharlesworth points out, it can't be done directly. You will either have to resort to reflection (though I wouldn't recommend it!) or a series of field-by-field assignments. Another option though, would be to switch from inheritance to composition: public class BetterThing implements IBetterObject { Thing delegate; public BetterThing(Thing t)...
program that creates one main object and creates a pet for each of them [closed]
Here is an example of a swift program that deals with pets. I found it on here. It has a protocol Animal that defines parts to an animal, with int legs, and boolean domesticated. protocol Animal { var legs: Int { get set } var domesticated: Bool { get }...
What is the default value of internal [[prototype]] property in JavaScript?
By default its an instance of global Object constructor. By default, the last object in each prototype chain is Object.prototype. It's actually not an instance of Object: > Object.prototype instanceof Object false simply because Object.prototype doesn't have a prototype itself. does JavaScript have a reserved instance of Object which...
TypeScript project organization, compile into a single JS file?
Yes, you want to use gulp or grunt. I suggest gulp, but that's a personal preference. You can use this to inject your scripts in a particular order based on your file naming convention.
“Undefined method PDO::execute()” despite using prepare
Create a variable to store your prepared statement then execute that. $connection = MYSQLDatabase::getInstance()->getConnection(); $statement = $connection->prepare("INSERT INTO users etc etc......."); $insertArray = $statement->execute(array( ":username" => $_POST["username"] )); ...
Fatal error: Using $this when not in object context in E:\xampp\htdocs\
$role = userrole::get_premium_subscritpion(1); I notice that you are trying to call a non-static function in a static way You may either change the function to static or change the way you call this function public static function get_premium_subscritpion { or $obj = new userrole(); $role = $obj->get_premium_subscritpion(1); ...
JavaScript oop: Designing classes correctly
javascript,oop,closures,prototype
Mi question are: what is exactly the difference in using the Box prototype or not? is any approach better for any reason(cost, legibility, standard...)? Functions (and other properties) on the prototype are shared between instances; if you create them in your constructor function, each instance gets its own copy...
Javascript, Array of Objects?
javascript,oop,jquery-mobile,mobile
It honestly depends what you want to do with this array If you are going to send it via an XMLHTTPRequest then I'd say you should use JSON format. var arr_of_objs = [{},{}]; //fill it up however you need it If this array is going to consist of objects with...
Nested pointer instead of inheritance
Your source code and documentation contradict each other (although each one might make some sense on its own). The is-a relationship in (runtime) C++ is through inheritance alone (see the Liskov Substitution Principle). In this case, the relationship is has-a, or implemented-in-terms-of. Making the composition through pointers might make sense...
Switching Classes during __construct()
php,class,oop,constructor,magic-methods
You can of do this by introducing another class (lets call it user) and using the __call magic method in php and call_user_func_array for calling the methods. The logic is something like this - Create a user class that has no method except check_user_level. It checks proper details and assigns...
Is array of primitives assigned to variable as an Object (by reference) or by value?
on one hand, x and y are arrays of primitive so the array is partial considered as primitive so it may copy the values to a new array, like normal int: You are correct in "arrays of primitive" but not in "partial considered as primitive". Array is an array,...
Extending a method in PHP
You dont need to add two function to do same work all you need to do is pass parameter to function public function getResultsByID($userID = null,$flag){ $sqlParams = array(); if (!$userID) { throw new Exception("No User ID Provided"); } $sqlParams['userID'] = $userID; if($flag=value1){ $sql = "SELECT t.user_id,t.owner_id,t.store_id FROM users t...
PHP extend existing class for table insertion/update
Well it doesn't really make sense for the new class (let's call it ProductPrice) to extend the Product class because logically the Product class contains a ProductPrice. So ideally you would add a ProductPrice member variable to the Product class and do something like this: class Product () { /**...
Serial modification of objects in R
I would create a list of all your matrices using mget and ls (and some regex expression according to the names of your matrices) and then modify them all at once using lapply and colnames<- and rownames<- replacement functions. Something among these lines l <- mget(ls(patter = "m\\d+.m")) lapply(l, function(x)...
Symfony : is it better to use a trait or an intermediary class to complete Controller one?
Using a trait depends on 2 things : Do you want to use RestController methods for some classes that doesn't depend on Controller ? Since you will surely use some Controller methods to write RestController, I think the answer is no. Do you plan to create others classes that you...
calling a method to restart if a condition is met without using a loop
java,user-interface,oop,jtextfield,jtextarea
You're almost there. Move the section of code where you clear your JTextFields before the section of code where you check hours worked are within range. Then return just after you show your error message. That way execution of the method does not continue. //Clears JTextFields before checking the error...
PHP classes - is it preferable to use normal variables instead of properties?
It's somewhat vague what you're asking, but if valueToUseHere is not used outside of doStuff, then don't make it a property! class someClass { public function doStuff() { $valueToUseHere = 60; // Do more stuff here... } } If there's no reason to share that value with other methods of...
Is bootstrap file a controller?
php,oop,model-view-controller,controller
No, bootstrap file is for initialization. A controller is resoponsible for handling user input (requests in a web environment) and providing him an output (responses in a web environment). A front controller is just a centralized point for handling incomming requests. None of these compoments should have the responsibility of...
What is the proper way to use inheritance when combined with factory method?
I would create a base Asset class and have AssetA and AssetB inherit from it. The factory class should be a separate class - AssetFactory - with just one single responsibility - it should create new Asset object based on some conditions.
Is it bad practice to have a static class that does not instantiate objects
I would say that in object oriented programming the use of statics should me minimized, but they do have a place. It takes a bit of time to develop a good sense for when static methods/variable are appropriate, so I would start out only using them in a small set...
Actual class of object reference
java,oop,inheritance,polymorphism,instanceof
Since this is clearly a homework exercise, it is not appropriate for me to provide an answer directly. Instead, I have written a little program for you to demonstrate what the question means, and running it will provide an answer. You can try this out for yourself: public class Main...
Why has java kept length field in the jvm public
A bigger question is; why is there no class file for int[]? Without such a class file there is no where to put such a method, so it is purely a language feature. It looks like a field of int[] but it not. They could have made it look like...
Interfaces in UML component diagram
There is actually no real difference between both. You can realize an interface with a class as well as with a component. Also you can show the realization in both cases with the socket/lollipop notation. Components are not much different to classes. You can think of a component as a...
Using $_GET in class
You can pass $_GET in the constructor from your class: Class GetClass { public $action; public function __construct($get){ $this->action = isset($get['action']) ? $get['action'] : null; $this->db = new Db(); $this->Select($this->action); } private function Select($action){ if (strtolower($action) == 'delete') { echo "Here"; } } } $getClass = new GetClass($_GET); ...
Why is 1_2_3_4 a valid integer literal in java? [duplicate]
java,oop,inheritance,integer,literals
Numeric literals are specified in JLS 3.10.1. A decimal numeral is either the single ASCII digit 0, representing the integer zero, or consists of an ASCII digit from 1 to 9 optionally followed by one or more ASCII digits from 0 to 9 interspersed with underscores, representing a positive integer....
What is this thing called in Java?
java,oop,object,inheritance,immutability
They are called enumarations. You can find detailed info here they are defined as: public enum Day { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY } and used as: public class EnumTest { Day day; public EnumTest(Day day) { this.day = day; } public void tellItLikeItIs() { switch (day) {...
mysqli_query() expects parameter 1 to be mysqli, i cant use a variable?
In db.php class dbConnect { protected $connection; function __construct() { require_once('config.php'); } function Connect() { $this->connection = mysqli_connect(hostname, username, password); if ($this->connection === FALSE) { die('Could not connect to the database because: ' .mysqli_connect_error()); } mysqli_select_db($this->connection, database); return $this->connection; } public function Close() { mysqli_close($this->connect); } } In class.User.php: protected...
Validation within Get/Set Methods Java
java,oop,boolean,encapsulation
A boolean value is a primitive data type and is thus passed by value only. Only objects are passed by reference. So there are two options for you. Either make your primitive boolean value a Boolean object (as this will be passed by reference). Or have the method return a...
Creating attribute defaults by calling a wrapped object
You can use $attr where your question marks are because it is still in scope when you declare the attributes. foreach my $attr (@getDefaultsFromWrappers) { has $attr => ( is => 'rw', default => sub { shift->wrapped->$attr() }, lazy => 1, ); } The following is a possible alternative, which...
Global function or function with no name java for factory pattern
Thanks to Sotirios Delimanolis for Help: this is possible with defining the static method and import it statically in every where you want. package factorypakcage; public class firstFactory{ public static factoryFunction(String className){ //switch case for class creation } } Using like this import static factorypakcage.firstFactory.factoryFunction; ... MyClass MyObj = factoryFunction("Class...
(Java) What kind of argument is this? With a [duplicate]
Varargs (Variable Arguments) Varargs (introduced in Java SE 5) allows you to pass 0, 1, or more params to a method's vararg param. They let you pass any number of objects of a specific type.This reduces the need for overloading methods that do the similar things. For example, public static...
Java Design Issue: Enforce method call sequence
We commonly use StopWatch from Apache Commons StopWatch check the pattern how they've provided. IllegalStateException is thrown when the stop watch state is wrong. public void stop() Stop the stopwatch. This method ends a new timing session, allowing the time to be retrieved. Throws: IllegalStateException - if the StopWatch is...
Avoiding type checking when interface method parameters are abstract
In my opinion, the interface should use generics, so you can rely on the implementation of the interface. I would suggest something like this: public interface UserHandler<TRequest, TResponse> where TRequest : CheckUsernameRequest where TResponse : CheckUsernameResponse { } Then FooHandler would become: public class FooHandler : UserHandler<FooRequest, FooResponse> { }...
Force a child class to initialise a parent property after computation
d4Rk's answer was very close, however you should try not call virtual methods from a constructor as bad things can happen. However if you use a combination of Lazy loading tricks and ISupportInitialize you can defer the creation of the plugin till after the constructor is finished. public abstract class...
Bound mismatch: The type is not a valid substitute for the bounded parameter
The definition of your BinarySearchTree is: public class BinarySearchTree<Element> extends Tree<Element, Node<Element>> Here, Element is a type-parameter, but not the actual type Element. It's pretty much the same, as you did: public class BinarySearchTree<T> extends Tree<T, Node<T>> Now the error you're getting makes more sense: The type T is not...
Python: I'm getting an error when using self.name
You are trying to print print witch.enemy_name But the attribute is self.name = enemy_name So you should be calling print witch.name ...
Nested objects in Python
Your classes would be as follows, note that there is no notion of public vs private so you do not need setters and getters class Foo: def __init__(self, fooName): self.fooName = fooName class Bar: def __init__(self, barName, foo): self.barName = barName self.foo = foo As an example >>> f =...
Calling an add on a list from a getter of an object does not work as expected
Your posted sample code has syntax errors. Fix those and the code does what you're wanting. public class Customers { private List<String> names; public Customers(List<String> names) { this.names = names; } public List<String> getNames() { return names; } @Override public String toString() { StringBuilder sb = new StringBuilder(); for (String...
Loop by Object inside another Object in Java
This will solve the problem, seasonMap contains values in the order you need (assuming classes implement Comparable) Map<Season, Map<Building, List<Info>>> seasonMap = new TreeMap<>(); for (Building building : buildings) { for (Map.Entry<Season, List<Info>> e : building.infosBySeason.entrySet()) { Season season = e.getKey(); List<Info> infos = e.getValue(); if (!seasonMap.containsKey(season)) { seasonMap.put(season, new...
Multidimensional array in class C++
c++,arrays,oop,multidimensional-array
char *levelchargement[][]= new char [widthmap][heightmap]; is not a valid declaration or allocation for a multi-dimentional array. Since you are dynamically allocating the array at runtime, you need to move the allocation into the class constructor and use this syntax instead: class Map{ public: Map(); Map(const Map&); ~Map(); ... char **levelchargement;...
How to get rid of duplicate code in derived classes?
You could make B's children override a different function: class B : public A { protected: void update_current() override final { do_something_important(); do_something_important_later(); }; virtual void do_something_important_later() = 0; }; With: class C2 : public B { protected: void do_something_important_later() override { do_something_very_important_2(); }; }; ...
Is Django For A Suitable For A Procedure Orientad Programming Lover? [closed]
Django isn't particularly object-orientated. The main place where you need to use classes is in defining and querying models; if you understand the basics of defining a class and creating an instance of it, you'll probably have enough to get started with. All the rest of the functionality - eg...
Why does the “this” keyword refer to the subclass too?
Generally speaking, since this refers to the current instance, how is it possible that Fireball.onChat(PlayerChatEvent) is registered too? Because when you're constructing an instance of Fireball, this refers to the Fireball being constructed at execution time. The compile-time type of this is Spell, but if you print out this.getClass()...
creating multiple objects with browserify
With CommonJS (Browserify), what you export will be what you get when you call require (however, be careful with assuming what you export is a singleton, it's not always the case from my experience). So in this case, you want to export the Human class directly. Then in each file...
Call to a member function query() on a non-object in PHP when trying to access parent constructor in php
You're doing it wrong First thing is that PHP4-style constructors are deprecated, use __construct method to define a costructor. Second is that you must not return from constructor but rather keep the connection object inside class as instance property. Third is that you must call parent methods using parent keyword....
Rails modeling headache
It depends on whether you have many fields specific to agenda (not to month). If you do, it's better to have one separate model for agenda. BTW, It seems user and agenda are many-to-many relationship. In this case, you need one intermediate model between user and agenda. ...
How to get the name of child class from base class when an object of child class is created
You can use get_class() passing it the current object reference, like so: class Base_class { function __construct() { $calledClassName = get_class($this); } } Edit: You can find more info on get_class() in the PHP manual http://php.net/manual/en/function.get-class.php...
PDO FETCH_CLASS multiple rows into array of objects
Instead of building a class to create the booking objects, it would be advisable to either create a standalone function, or a function within a parent class to achieve this. The issue I run in to with using fetchAll() with the FETCH_CLASS parameter, is that the objects do not automatically...
PHP mysqli_fetch_array() OOP style
You're doing two conflicting things $con= new mysqli('localhost','root','','afiliate'); $query="SELECT * FROM product WHERE ID=? "; $stmt->bind_param("i",$ID); /* $ID has a value, it's ok */ $stmt->execute(); So at this point $stmt is a mysql_stmt object. If you have mysqlnd installed you can do this $result = $stmt->get_result(); while($row=$result->fetch_row()){ echo $row['name']; }...
Calling an object and its method from another object class method
javascript,class,oop,object,methods
Welcome to the world of javascript where you are not using it to just paint and moves boxes :) Coming to your question: //Initialize objects var spaceButton = new Navigation('#spaceWarp'); var stars1 = new Stars('#stars1'); var stars2 = new Stars('#stars2'); var stars3 = new Stars('#stars3'); The initialization of your objects...
Getting ArgumenError while trying to create instance of a ruby class
ruby,oop,encapsulation,argument-error
I'd say, that the error of number of arguments (1 for 0) is caused by your set_first_name and set_last_name methods, which are declared not to accept any arguments: class EncapsulatedPerson # ... def set_first_name @first_name = name end def set_last_name @last_name = name end end Try updating them, so they...
Interface for Child Class that Inherits from parent class without reimplementing parent class
If I understand you correctly, you're saying that you want an inheritance hierarchy in your interfaces as well as your classes. This is how you'd achieve such a thing: public interface IBase { // Defines members for the base implementations } public interface IDerived : IBase { // Implementors will...
Solving a java riddle
The class B should be as follows: public class B extends A{ public String foo(String s){ return s+s; } public A getA(boolean flag){ if (flag){ A a = new A(); return(a); } else{ B b = new B(); return (b); } } } ...
Having issues with methods
You calling getUserChoice() in the pickWinner method. It should be the userChoice method parameter you should be checking. public String pickWinner(String userChoice, String cpuChoice) { String result = " "; if (userChoice.equalsIgnoreCase("rock")) { if (cpuChoice.equalsIgnoreCase("rock")){ result = "tie"; } else if (cpuChoice.equalsIgnoreCase("paper")){ result = "Computer"; } else if (cpuChoice.equalsIgnoreCase("scissors")){ result...
How to transform a method call pattern found in multiple methods into a simpler OO mechanism?
You could do that by implementing the magic method __call(). However, I would strongly recommend against it. Using magic methods is a lot slower, and it's harder for IDEs to display code insight information. Also, you would still wind up with almost as much code, unless you pass everything on...
How to implement repeated behavior when inheritance isn't an option
Your solution is perfectly valid for Java. You are actually using the design pattern Use Composition Over Inheritance. As @Naruto_Biju_Mode says in a comment, if you are using Java 8, you can move the implementation to a default method of Transformable however you would have to make the helper class...
Check if object has given properties
You can use at least three ways to do it: property_exists() isset() ReflectionClass::hasProperty() All of these are demonstrated below: <?php class myClass { public $a=1; public $b=2; public $c=3; } $myObj = new myClass(); $reflectionClass = new ReflectionClass($myObj); foreach (['a', 'b', 'c', 'd'] as $property) { printf("Checking if %s exists:...
How to check if objectB used instance of objectA from objectA using private variables
Use Getters and Setters. The below code will let the $mesh_name property be read, but not written by external code. class MyObject { protected $mesh_name = 'foo'; protected $accessible = ['mesh_name']; protected $writable = []; public function __get($name) { if( in_array($name, $this->accessible) ) [ return $this->name; } else { //...
Downcasting doesn't work and functions called from object own class instead of where the function is (Java)
java,class,oop,methods,casting
When using inheritance within classes, overriding a method will ALWAYS call the child method regardless of casting. You can never change the type of an object, so a RockMusician - although it is an extension of Musician - is still a RockMusician and will be called by its type, not...
JS: Is it possible “something(arg)” and “something.my_method(arg)” at same time
javascript,function,oop,methods
Well, this is javacript, and there are many ways to do it. edit: I actually thought about this, and tried to imagine other way to do the same thing, and actually I cannot find any. There's @elcodedocle which I thought about but is close but not what you ask, or...
Python method that can be called on a list of objects
The only way to do exactly what you're asking for is to subclass python build-in class list. This should help....
Python 2.7 @property usage results in error “global name '_c__pro' is not defined”
python,python-2.7,oop,properties,encapsulation
You need to use self. when accessing member variables: def __init__(self): self.__pro = 1 @property def pro(self): return self.__pro *10 ...
Calling on an implemented method automatically?
This is called "dynamic binding" in Java. You can read this on details here, for example http://www.studytonight.com/java/dynamic-method-dispatch.php
Why can't I call a method I define in a field? [duplicate]
lorem is a method of an anonymous sub-class of B. Therefore you can't call it by using a reference of class B, and since it's anonymous, you can't cast b to a type that contains lorem.
Laravel5: Access public variable in another class
php,class,oop,laravel,laravel-5
That's simple php stuff. Set the attribute as static and access it with ::. class LanguageMiddleware { public static $languages = ['en','es','fr','de','pt','pl','zh','ja']; } @foreach (App\Http\Middleware\LanguageMiddleware::$languages as $lang) ... @endforeach You should not have that in a middleware though. You'd better add a configuration (i.e in /config/app.php) with that array, and...
Making list of objects of class with function overloading
I think the problem is in this line: currentNodePtr->data = &new_car; of the function void StringOfCar::push(Car & new_car). That should be currentNodePtr->data = currentCarPtr; ...
Class variables in OOP
The basic idea is that you add each instance of a car to the dealership, but note that I changed car_inventory to be an instance member of Dealer. This is because you want each new dealership you make to have its own car_inventory. If you left it as a class...
Automatic cast to subclass in getter/setter
If you don't mind pulling Node out into an abstract class you can specify the type as part of the generic signature like so: public abstract class AbstractNode<T, U extends AbstractNode<T, U>> { ... public U getLeft() { ... } ... } // inherited getLeft() will return Node<T> public class...