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Questions tagged [class]

A template for declaring a type of object.

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3
votes
2answers
456 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 ...
1
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3answers
3k views

What is the difference between proxy class and delegation in Python?

Wiki: A proxy, in its most general form, is a class functioning as an interface to something else. The proxy could interface to anything: a network connection, a large object in memory, a file, or ...
0
votes
1answer
112 views

Should I document expected call-sequences when call-order matters?

In dynamically and weakly-typed languages*, I often find myself with structures like the following pseudocode: class Stateful: # [ various datamembers / attributes / properties / fields / etc. ] ...
1
vote
3answers
556 views

Should I create a class for functions that uses of the database?

I have a PHP application which is pretty simple: It allows the user to create, edit and read a post. Basic stuff. I have a Database class which handles the connection and the queries execution. The ...
0
votes
1answer
573 views

Function or class design in library API for efficient object reuse

I am currently building a library in C++11, where I spent a lot of time trying to design a good interface. After some small redesigns along the way, I've ended up with a design that I am happy with. ...
14
votes
4answers
4k views

Singleton or instantiate everytime I use? [duplicate]

I use a class that just extracts data from one known object, and distributes it to other known objects. No persistent configuration or such is needed in that class instance. How should I decide ...
3
votes
1answer
154 views

CharSequence to represent a named object

I always followed the opinion to not abuse interfaces in case of decomposition. Usually I only implement them if I am absolutely sure to have a "is-a"-relation and avoid implementing them if there is ...
2
votes
2answers
1k views

Is it OK to use (WTF) forms to validate against stuff from DB?

Form classes are intended (IMO) for submitted data against rules. For example: are passwords equal, is end date later than start date. submitted data--->|Form| Is it okay for Form classes to ...
3
votes
1answer
71 views

Should I be taking these as arguments or define them in a sub class?

So I am making a mario clone in pygame and I have a base class Character and two sub classes, Mario and Luigi. The methods that the Character class defines require a significant amount of attributes ...
15
votes
4answers
202k views

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

I'm very new to Java and want to understand the difference between class variables and instance variables. For example: class Bicycle { static int cadence = 0; int speed = 0; int gear ...
2
votes
1answer
10k views

Good practice to hold Constants in their own file? [duplicate]

I've noticed some projects like to store constants in their own file, i.e constants used globally and in the main program loop might clutter the main file so perhaps they look to place them elsewhere ...
82
votes
13answers
12k 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 even a clear-cut non-physical conceptual object -- something that ...
2
votes
1answer
384 views

Python Classes and Design Questions

What is the best way to design a class to see if an update occurs on a property? I have a whole bunch of classes, and current am going through a re-design of the python package I created. ...
0
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0answers
831 views

Class design for Token, TokenType and regex constants

For use in a lexer class a have a class Token which represents a token of a specific type and its value, while the types are defined by the enum TokenType in which every token holds its own regular ...
4
votes
3answers
163 views

Unit of Design Versus Unit of Re-use. What is the difference?

Contemporary object-oriented programming languages employ the class as the unit of reuse. At the same time, the class is also the unit of design. This implies that to reuse a class, the design of ...
1
vote
4answers
367 views

Why I need to make method of my class private, If I need to access it throughout my application?

I am going through the beginners tutorial for C# from a website http://www.homeandlearn.co.uk/csharp/csharp_s10p1.html On chapter of classes, it makes the method of class private and then use ...
6
votes
2answers
2k views

Nested classes via a getter (to emulate namespacing)

So, we all know that ES6's introduced syntax is definitely sugar over what we've been doing, previously. That being said, we still don't have namespaces (which would be nice...) The problem that I'm ...
0
votes
1answer
798 views

Setting up folders and importing modules in Python

I'm building an app to automate some processes that are annoying to do by hand (looking in a file, taking certain information out of a file, building another file with that information). My project ...
3
votes
2answers
122 views

What's the best way to store class/type info in a plugin system in your software?

There are lots of applications like 3ds Max, Maya, etc that allows you to use plugins, where even the default nodes are created as plugins. This is all good but if the developer changes the class/...
1
vote
2answers
272 views

Are any side effects not concrete side effects?

In Chapter 23 of "Object Oriented Software Construction" (1988), Betrand Meyer makes a distinction between side effects, concrete side effects, and abstract side effects. Meyer defines a side effect ...
0
votes
1answer
252 views

Best OOP practice for object vs dataservice [duplicate]

I am working on a new project and am curious as to how I should go about doing something properly. Lets say I have a table called "leads" in my database. This clearly means that a single "lead" would ...
0
votes
0answers
52 views

Internal class variables convention

When I see some open source projects, specifically classes, I see that its variables starts with a 'm' minuscule. What does it mean? What means the 'm'?
3
votes
1answer
709 views

Static properties and implicit “self” property in structures and enumerations vs classes in Swift

I am currently reading the Swift language documentation and came across these sentences in the chapter about methods: Similarly, type methods on structures and enumerations can access static ...
1
vote
5answers
2k views

Are there too many parameters in this constructor? [duplicate]

Check this out: public function __construct( \Magento\Framework\Model\Context $context, \Magento\Framework\View\DesignInterface $design, \Magento\Framework\Registry $registry, ...
1
vote
3answers
905 views

OOP implementation doubts with databases

I was starting a project today and after designing the database structure and how the data would be stored etc, I started the implementation. I am doing this on php, but the language isn't really ...
4
votes
2answers
275 views

Should I use properties for the properties of properties?

Sometimes I use some indirect properties to set or get some other sub-properties, I give an example class Page { public string MainText { set { MainParagraph.Text = value; } get { return ...
2
votes
1answer
2k views

Should I prefer classes or singletons in JavaScript/Node?

This question applies especially to Node.js, but also to JavaScript in general. I started working on a simple web app in Node.js. I'm relatively new to Node and JavaScript, and come mainly from C# ...
19
votes
4answers
11k views

“Use map instead of class to represent data” -Rich Hickey

In this video by Rich Hickey, the Clojure creator, he advises to use map to represent data instead of using a class to represent it, as done in Java. I don't understand how it can be better, since how ...
4
votes
1answer
1k views

When to use nested classes and when to use namespaces?

I have really never made use of namespaces, and am considering them at the moment. My situation. I have a class Reverb. It contains as members instances of other classes, declared in the same header ...
0
votes
1answer
86 views

Comments for a class that isn't an entity

According to Java's commenting conventions, classes comments should describe a "thing", rather than "actions". It is easy when the class IS a thing (ex. a Clown), but what if it isn't? In this case, ...
0
votes
1answer
152 views

Why is it said that a class represents an abstraction? [closed]

I think that abstraction represents only the essential things needed for the purpose as there are so many unnecessary properties. So why is it said that a class represents an abstraction?
9
votes
5answers
2k views

class in OOP language and type

In programming language theory, a type is a set of values. E.g. the type "int" is the set of all integer values. In OOP languages, a class is a type, is it? When a class is defined with more than ...
1
vote
2answers
835 views

Class as resource handle & Bad Copy

I am reading Bjarne Stroustrup's book titled "A tour of C++". The following section is confusing to me: When a class is a resource handle – that is, when the class is responsible for an object ...
1
vote
1answer
1k views

Splitting single Class into multiple Classes

I am writing automated test scripts with Selenium Webdriver (Python) and I try to follow the correct programming practices, specifically the Object Oriented methodologies, where possible. At the ...
1
vote
1answer
474 views

How to represent “class” data type in C or any low level language? [closed]

I'm writing a simple language compiler,currently it's support functional programming only. I want to support OOP concept, but I don't know how exactly I can represent an object ? just where to start ....
4
votes
4answers
2k views

Refactoring: When to add a new class in the project?

When do you feel that you need a new class (maybe when you are developing or after development for refactoring purpose)? Maybe I can start from my existing variables and think how I can reorganize ...
3
votes
1answer
3k views

How to store/deal with data available to other classes

I'm writing a CAD program. Let's say I have in input class, this class reads various data from a text file and creates lots of lists/dictionaries and .... These data need to be accessed by other ...
1
vote
2answers
2k views

Is using multiple static classes with maximum one public method is a good idea

I'm writing a structural detailing (CAD) software for concrete buildings in C#. I have defined like hundreds of static classes each with one public method and if needed some private methods. Each one ...
2
votes
2answers
1k views

Confusion about associations in UML class diagram

--------------------- ---------------------- | FLIGHT | | STEWARD | --------------------- ---------------------- | Arrival time | | Steward ID | | ...
4
votes
2answers
448 views

In Python, is there any difference (apart from a few listed exceptions) between classes and dictionaries?

My logic goes like this: def A(val): return {'a':val} print(A(7)['a']) is the same as class A: def __init__(self, val): self.a = val print(A(7).a) Obviously, there are problems ...
2
votes
2answers
986 views

Will there be a memory or processing time difference between a class member function and a global function

I'm writing a neuron network simulation program and every operation or additional byte per neuron scales insanely. I prefer C++ as a language over the others, but now I'm wondering if the class ...
0
votes
1answer
132 views

Storing Form Data in a class

I have a form that writes to a database. Other than creating a class handle an external API, this project is done. However, the processing script is your standard procedural calling of queries using ...
2
votes
2answers
1k 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 ...
1
vote
2answers
633 views

Decide the type of an object during runtime

I try to implement a PriorityQueue with C#: public class PriorityQueue<T> : Heap<T> where T : IComparable<T> { ... } The Heap is abstract. I have MinHeap and MaxHeap that are ...
8
votes
5answers
53k views

Why is there no default constructor generated if you define an explicit constructor?

class Employee{ String name; int id; //No explicit constructors } Now I can invoke the following statement: Employee e1 = new Employee(); With the above code, the compiler will provide ...
15
votes
6answers
18k views

Unit test private method in c++ using a friend class

I know that this is a debated practice, but let's suppose that this is the best option for me. I am wondering about what is the actual technique to do this. The approach that I see is this: 1) Make a ...
1
vote
2answers
628 views

When should I refactor a private class into a package-private class?

When I began implementing a class in my system (let's call it A), I realized I needed some kind of object that does something. So I needed a new class (let's call it B), but I made it a private static ...
0
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0answers
62 views

c++ coding practice class vs. “free” functions [duplicate]

I am currently writing my first bigger project in c++. Its basic linear algebra. I am aware that boost libraries and others exist, but for various reasons I need to write my own. Purpose of the ...
2
votes
1answer
413 views

class hierarchy with structurally different subclasses

I want to implement a protocol layer which sits on top of the TCP/IP stack. There is a limited set of PDUs that can be sent and for each PDU there is a class which represents it in a structured form. ...
3
votes
2answers
153 views

How specific should be an interface about its implementation details?

Perhaps I should have picked a better title, but anyway... Basically what to do with two or more implementations that have the same public interface, but they are meant for slightly different ...