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69
votes
13answers
7k views

Do objects in OOP have to represent an entity?

Does an object have to represent an entity? By an entity I mean something like a Product, Motor, a ParkingLot etc, a physical, or a conceptual object, something that is well defined, with some core ...
39
votes
6answers
5k views

How do I prove or disprove “god” objects are wrong?

Problem Summary: Long story short, I inherited a code base and a development team I am not allowed to replace and the use of God Objects is a big issue. Going forward, I want to have us re-factor ...
28
votes
6answers
4k views

Can you implement “object-oriented” programming without the class keyword?

Say we want to provide an abstraction of an "account" in a bank. Here's one approach, using a function object in Python: def account(): """Return a dispatch dictionary representing a bank ...
17
votes
11answers
4k views

When would you want two references to the same object?

In Java specifically, but likely in other languages as well: when would it be useful to have two references to the same object? Example: Dog a = new Dog(); Dob b = a; Is there a situation where ...
15
votes
5answers
2k views

Why am I seeing so many instantiable classes without state?

I'm seeing a lot of instantiable classes in the C++ and Java world that don't have any state. I really can't figure out why people do that, they could just use a namespace with free functions in C++, ...
14
votes
3answers
3k views

How many strings are created in memory when concatenating strings in Java?

I was asked about immutable strings in Java. I was tasked with writing a function that concatenated a number of "a"s to a string. What I wrote: public String foo(int n) { String s = ""; for ...
12
votes
1answer
22k views

Design pattern for object conversion (java)

I don't use design patterns very often, besides an occasional factory and MVC, and I want to start using them more. I have a concrete case at hand that I would like your opinion on the use of design ...
8
votes
3answers
248 views

Is a single object to be preferred over multiple variables?

It was quite hard to put what I meant into a title, but it's easy to put into code. C++ Is this int offset_x = 10; int offset_y = 40; ... element.move(offset_x, offset_y); To be preferred over ...
8
votes
4answers
187 views

When in your language classes are objects too, does the Liskov substitution principle apply to their interfaces?

According to Wikipedia the Liskov substitution principle states that objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program ...
7
votes
6answers
5k views

Is it called class or object instance?

I have a wording / precision question. Sometimes I write "object instance" sometimes "class instance". Isn't it that an object is always an instance of a class? Therefore "object instance" is not the ...
6
votes
2answers
474 views

Is there a standard, formal name for an object or class that behaves as if it is a given object?

I have an app in Django that expects to get a record with the fields email, first_name, and last_name. However, sometimes I want to be able to send it something that isn't actually a record but ...
6
votes
0answers
368 views

Object Constraint Language (OCL) for Stack in java.util package

I have an exam coming up and I'm looking at past papers to get some ideas of what to expect. I'm a bit stuck on the following one and would really appreciate if someone could give some example ...
5
votes
2answers
2k views

What is the process of determining which method in a class hierarchy should execute known as?

I thought I understood inheritance and polymorphism, but I was given this question, and I can't, for the life of me, figure out what the proper answer is or what they're trying to get at: The ...
5
votes
2answers
4k views

Why multiple calls to same classes' Constructor from within a Constructor wouldn't work?

Please have a look at following snippet: public class Foo { int digit; String name; Foo (int d, String n) { this(d); // cannot do following. //compile-time error: Constructor call must ...
5
votes
1answer
178 views

Is it called an instance in Javascript?

Say I have a function. function foo(){ //do stuff } And then I create an object of that function. var fooObj = new foo(); What is fooObj called? An instance, An object instance, or something ...
4
votes
5answers
2k views

Why is there no deterministic object destruction in Java? [duplicate]

I understand and enjoy the benefits of the Garbage Collection in Java. However I don't understand why there is no way in Java to explicitly (and quickly) destroy an object. Surely this could be useful ...
4
votes
3answers
180 views

Better way of manipulating large objects

I am doing a lot of work with SOAP Api in PHP and the objects that are returned are quite big. I am then updating the objects from local db changes and pushing them back. So more often than not I ...
4
votes
5answers
1k views

Config Class/Struct: Pattern or Anti-Pattern? Alternatives?

If you add new configuration options to a program, it can often have tons of ripple effects in terms of getting the options to where they need to be acted upon. There are three basic ways to deal ...
4
votes
1answer
435 views

Modelling Login and Authentication on an iOS mobile client

I'm about to start working on a V2 of a mobile application and I'd like to adopt a more object-centric approach. Primarily because I think it makes for more maintainable code, but a secondary ...
3
votes
6answers
775 views

How assertive should I be in handling exceptions in objects?

I have been writing in C# 4.0 a lot lately and trying to write as lean as possible. As such, I have not been using the classic try/catch blocks and using statements as often. I understand the general ...
3
votes
4answers
4k views

Returning multiple values in Javascript

Often I am writing a function that returns multiple values, such as a pair of coordinates: function get_coords() { return ???; } If I was using a language like Python, I would use a tuple: ...
3
votes
3answers
2k views

Arrays vs Objects in view template

I am wondering, in view templates, what would contribute to me choosing between using arrays or objects for getting things printed out in arrays {{$user->zip_code}} vs {{$user['zip_code']}} I'm ...
3
votes
1answer
91 views

PHP OOP, structuring my objects properly

I have an architecture similar to this: User (Name, Email, ID...) ---- Studios (Name, Location, Description...) ---------- Videos (Title, Description, URL, Length, Views...) Simply put, a user can ...
3
votes
1answer
226 views

How do I design a Javascript Object to not use any public properties?

I have been playing with the Object creation outlined by Douglas Crockford in his new talk "The Better Parts" function constructor(spec){ var that = otherConstructor(spec), member, ...
3
votes
1answer
207 views

Class instance clustering in object reference graph for multi-entries serialization

My question is on the best way to cluster a graph of class instances around specifically marked objects (objects are the graph nodes and the references to each other are the directed edges of the ...
2
votes
2answers
253 views

interpretation of the statement in java

I am confused over the interpretation of the following statement Fruit x= new Fruit(); My interpretation is that the new operator along with Fruit(); creates a new object somewhere in the memory. ...
2
votes
2answers
81 views

Advantages of extending the default Exception class

I've seen that it's possible to extend the default Exception class in PHP, enabling one to throw an IncorrectParameterTypeException exception, or a ValueOutOfRangeException exception (maybe these are ...
2
votes
2answers
321 views

Three variants of circular references between objects: how to choose?

I'm designing an object dependency graph of my program and one ambiguity between design variants appears from time to time. Imagine two objects having a reference to each other. Obviously, at least ...
2
votes
1answer
1k views

Analogy of a class being a cookie cutter and objects being cookies

I came across the analogy of the class being a cookie cutter and the cookies being objects while reading Code Complete. I fail to see why this analogy was drawn.How is it related to the concept of ...
2
votes
2answers
188 views

Where is the class itself stored at runtime to be used as a reference

In C# or Java we find that the objects are stored on heap and their reference vars are stored on stack. But at run time where is the class definition stored to be used as a template for creating ...
2
votes
1answer
85 views

How to decouple SELF as a special word within Rebol objects?

Rebol has no keywords. It's a concept that forms a part of what makes the language so versatile—any word can be reassigned, any word can be assigned the value of a 'built-in' function—and one that in ...
1
vote
5answers
330 views

Understanding basics of object declaration in Java

Is there a case when an object is declared without a call to the constructor? as in, for example: ArrayList<Integer> grades; Or is it always the case that ArrayList<Integer> grades (as ...
1
vote
4answers
4k views

What are the differences between class variables and instance variables in Java? [closed]

I'm very new to Java and want to be difference between class variables and instance variables. For example: class Bicycle { int cadence = 0; int speed = 0; int gear = 1; } How are ...
1
vote
2answers
839 views

Instantiating objects in Java [closed]

I'm learning now Java from scratch and when I started to learn about instantiating objects, I don't understand - in which cases do I need to instantiate objects? For example I'm studying from TutsPlus ...
1
vote
5answers
287 views

Clarification about Polymorphism / Inheritance

I am trying to better my understanding of polymorphism. Say I have a base class called baseClass with one method called foo() and I have three derived classes called derived1 , derived2 and derived3 ...
1
vote
1answer
162 views

Destructing an object of a class correctly

I have a scenario, where I draw multiple graphs in same applications and each graph is an object of graph class. I want to delete the graph using event handling (button click event) and the event ...
1
vote
1answer
204 views

Under what cirumstances would type 'System.Object' qualify for serialization?

I'm in charge of a comprehensive serialization format with support to serialize runtime objects (any derived type of Object). I can't find a sane scenario where one would choose to serialize an ...
1
vote
1answer
201 views

javascript - would you consider 'prototype' to be the same as 'parent'

I'm learning javascript. I see that with an object, I can use .prototype, is it fair to say that, in a class/tree hierarchy I am effectively using the 'parent' (or 'ancestor' perhaps) by doing that? ...
1
vote
1answer
371 views

Using class like an object in Python

I am learning from Learn Python the hard way where I have come across a study drill where they want to know that whether a class can be used like an object. As I have experimented: class A(object): ...
1
vote
1answer
235 views

Loose typing not applied to objects

I have very little experience working with classes and object. I work in a loosely typed language, PHP. I was working with a SimpleXML object and ran into a problem where I was trying to do math with ...
1
vote
1answer
66 views

Object Storage where Object Type is variable

From time to time, we come across a problem where we must store an object, but we don't know in advance what kind of object we're going to store. I'm going to give a very simple example. Requirement: ...
1
vote
1answer
126 views

Replaceable parameter syntax meaning

Replaceable parameter syntax for the console object in C#. I am taking the O'Reilly C# Course 1 and it is asking for a replaceable parameter syntax and it is not very clear on what that means. ...
1
vote
1answer
114 views

create function of object prototype

I am reading "Javascript : The good Parts" to improve my Javascript bases and knowledge. I was reading stuff about prototype and I encountered in this function : var stooge = { ... } if(typeof ...
1
vote
1answer
120 views

When to use trait components, objects, package objects in Scala

When I am adding dependencies in Scala, I tend to use mixin trait components for those that are inherit to the class itself. For example, DaoGenerator extends Generator However, for trait components ...
1
vote
0answers
264 views

Why is deep plucking a bad idea?

Both underscore and lodash refuse to implement deep plucking, despite many requests from users and gists or modules that implement the feature. ...
1
vote
2answers
393 views

What is the purpose of creating a member function with the same type as its class?

I'm sure I'll botch some of the specific terminology, but what is the difference between object and object2 in this implementation? Is the only purpose of the first method (prototyping the class's ...
0
votes
4answers
250 views

Is collection object better being immutable? [closed]

As per this link, it is an advice that: A good object should never change his encapsulated state. Remember, an object is a representative of a real-life entity, and this entity should stay the ...
0
votes
3answers
655 views

Overriding equals() method in Java

Short question: Why does Java allow overriding equals(), why is it not final? I am reading Effective Java 2nd edition by Joshua Bloch. I am a bit baffled by the conclusion that There is no way to ...
0
votes
1answer
141 views

Should an object query its owner?

I have a World class World: def __init__(self): self.size = 10 self.n_busStops = 10 self.busStopMatrix = SpatialGraph(self.size, self.n_busStops, 1.0) self.buses ...
0
votes
1answer
86 views

Object oriented programming - subobject vs globals (use case) [closed]

I am developing a nethack-like game, and I would like an advice how to approach the design part. For now I got class like Location, Npc, Item etc. But I've got a problem how to easily access parts of ...