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-6
votes
5answers
140 views

Java constructor: I can't understand

I am learning Java and I have a problem understanding the concept of constructor for the field variables. What is the problem with the following code. It shows "null" as an output. public class ...
2
votes
3answers
178 views

C++ Virtual destructors used only when there are virtual functions

This is from Effective C++ (Meyers): Classes not designed to be base classes or not designed to be used polymorphically should not declare virtual destructors I don't understand why ...
1
vote
1answer
70 views

How do constructor parameters of a MVC Controller get set?

How does the construction injection work? I have the following code: public class AdvancedSearchController : Controller { private EmployeeController _employeeController; public ...
2
votes
0answers
18 views

What reasons would someone separate instantiation and data loading? [duplicate]

I was wondering what the purpose of separating the instantiation logic and the data loading logic of a class that loads data into memory if the class is a one time use. Here is an example of what I ...
14
votes
3answers
1k views

Legitimate “real work” in a constructor?

I am working on a design, but keep hitting a roadblock. I have a particular class (ModelDef) that is essentially the owner of a complex node tree built by parsing an XML schema (think DOM). I want to ...
5
votes
3answers
112 views

Stubbing Properties with private setters for tests

We have the object public class MyObject{ protected MyObject(){} public string Property1 {get;private set;} public string Property2 {get;private set;} public string Property3 ...
0
votes
1answer
66 views

Is it always better to use __construct() in CodeIgniter's Models and Views, even if it's not needed? [closed]

Sometimes we have Models and Controllers where the function __construct() just doesn't do anything, but is sitting on the top of all the methods in CodeIgniter's models and controllers. A lot of ...
7
votes
3answers
743 views

How to deal with constructors in large data classes [duplicate]

Several times now I have come across the situations where you have some kind of settings class that simply contains a mass of data. Often these classes are simply not valid without at least most of ...
0
votes
4answers
77 views

Public and Private Constructors with Equivalent Signatures

Here is the problem illustrated using an example of an immutable class. A Book must have at least one of a title and an ISBN. public class Book { private readonly string _title; private ...
3
votes
2answers
239 views

When to use Constructor and when to use Collection Initializer?

I am having a .Net class which has 10 properties like given below: [the datatypes of individual property is just a placeholder here and it can be anything from a primitive type to an object to a list ...
3
votes
2answers
79 views

How can I roll-back the execution of a constructor while building a complex data structure?

I'm building a complex tree of objects. There are a total of five types, A, B, C, D, and E. There is a single instance of A, which is the root node. A has one or more Bs as children, each B has one or ...
7
votes
1answer
200 views

Is a large static initializer a code smell?

I am extending SimpleExpandableListAdapter in Android. I don't think Android's adapter is implemented very well, in that its constructors have a large number of rather complicated arguments and it has ...
3
votes
4answers
469 views

Why can't I call a constructor in itself?

I am currently porting the class NumberRange from Java to C#. I am writing this constructor and I wonder whether I can call a constructor in itself. Something like this: public NumberRange(Double ...
1
vote
1answer
81 views

Pass data into a constructor or instead create virtual methods?

In an object oriented module describing a database, should I pass DB description data structures to the constructor in the constructors of derived classes, or should I instead create ("virtual" that ...
0
votes
1answer
92 views

Should I put the parameters in constructor or in method? (Python 3)

I have the following code: def __init__(self, vocable_file_path, xsd_file_path, word_list_file_path): self.vocable_file_path = vocable_file_path self.xsd_file_path = xsd_file_path ...
28
votes
5answers
3k views

Should I initialize C structs via parameter, or by return value? [closed]

The company I work at is initializing all of their data structures through an initialize function like so: //the structure typedef struct{ int a,b,c; } Foo; //the initialize function ...
7
votes
4answers
321 views

Can I make my constructors less repetitive?

I'm extending a class with 10 different constructors. The new subclass, SpecialImage, is used like this: SpecialImage specialImage = new SpecialImage(..); // Leverage the Rotate() method of ...
2
votes
2answers
251 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. ...
1
vote
2answers
138 views

Should constructors for API classes ever be public, or can a factory always be used? [closed]

I'm surprised this doesn't seem to have been asked before, or at least I can't find it anywhere. I know this is more of a philosophical question, but is there any particular reason not to use a ...
0
votes
2answers
140 views

Usage of objects in multiple containers in C++

In cases where there is a desire for objects to be "shared" between multiple containers, I would like to know what is the best practice in C++. For example, when implementing some path algorithms ...
-2
votes
1answer
215 views

pass a variable as parameter to constructor c# [closed]

pass a variable as parameter to constructor as i want to change the variable value with changeable value i'm new to c# so that i tries to implement one thing in many way i did what i want to do with ...
0
votes
1answer
227 views

C# Constructor and private LINQ to SQL members

I am extending an application I have developed so that it is more broadly useful for multiple jobs, rather than the single job I created it for. There are a number of tables that I get from SQL ...
0
votes
1answer
146 views

Multiple method calls in the constructor and dependency injection

I was asked to refactor some almost ureadable spaghetti code into object-oriented architecture. I have some doubts regarding a class that I designed. Here is the class' skeleton: require_once ...
0
votes
1answer
136 views

How can I condense a case class with ~20 constructor arguments into 5 or 6 arguments in Scala?

Let's say I have a case class with ~20 constructor arguments? This is obviously very clunky to type. What would be the best way to condense these arguments into maybe 5 or 6 arguments? There are some ...
14
votes
4answers
2k views

How does one keep argument counts low and still keep third party dependencies separate?

I use a third party library. They pass me a POJO that, for our intents and purposes, is probably implemented like this: public class OurData { private String foo; private String bar; private ...
-3
votes
1answer
119 views

How should I change in get method without calling getList() of Deque? [closed]

import java.util.List; import java.util.ArrayList; public class Test { /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { ...
2
votes
2answers
141 views

Initialize physical resources in constructor

Is it an acceptable practice to initialize physical/external resources from a constructor when the resource is needed for the object to do it's work? For instance, let's say I wanted to create an ...
1
vote
1answer
341 views

Constructor vs casting operator

I'm programming a library (so I have complete access to all the mentioned classes). Two classes (A and B) are essentially the same and differ only by their implementation, so they can be easily ...
0
votes
1answer
112 views

Query on usage of 'Window()' default constructor from java.awt

I had been through this query before asking this question. In class Window we have constructor with default direct access level package private but not private as shown below: Window() throws ...
1
vote
1answer
292 views

Patterns for subclass constructors that vary the parent class constructor slightly

So, my problem is in the context of an MVC-style approach. The code here is PHP, but I'm hoping this is a design issue independent of it. abstract class Controller { private $domain; private ...
51
votes
8answers
15k views

Why should I use a factory class instead of direct object construction?

I have seen the history of several С# and Java class library projects on GitHub and CodePlex, and I see a trend of switching to factory classes as opposed to direct object instantiation. Why should I ...
5
votes
1answer
405 views

Decoupling when constructors have non-contractual parameters

By non-contractual parameters, I mean parameters that are not interfaces or service dependencies, something like class Person(string name). I am writing a webpage scraping application, and so far ...
2
votes
2answers
199 views

Wrapping constructor arguments

Given a base class with around 25 or so subclasses, I have found that adding an argument to the base constructor is painful. protected AbstractController(Service1 s1, Service2 s2, Service3 s3){ ... } ...
0
votes
1answer
111 views

Constructors, Ignore Arguments

Is it possible to have a constructor in a class, that you can ignore certain arguments/parameters? For example, I have this constructor Car(color, make, model, wheels, type, doors) Could I call ...
14
votes
1answer
906 views

Is it fine to make a default constructor unusable?

Specifically asking about the default constructor Given that the constructor initializes all the data for an object, if I create a class that can't be used without proper initialization, is it not ...
18
votes
5answers
2k views

How can you decompose a constructor?

Lets say I have a Enemy class, and the constructor would look something like: public Enemy(String name, float width, float height, Vector2 position, float speed, int maxHp, int ...
5
votes
4answers
399 views

Where should an object in CQRS+ES be fully initialized: in the constructor, or when applying the first event?

There appears to be widespread agreement in the OOP community that the class constructor should not leave an object partly or even fully uninitialized. What do I mean by "initialization"? Roughly ...
8
votes
2answers
2k views

how complex a constructor should be

I am having a discussion with my co-worker on how much work a constructor can do. I have a class, B that internally requires another object A. Object A is one of a few members that class B needs to do ...
1
vote
3answers
763 views

Explicitly writing default empty constructor

Does it make sense to write default constructor when it has no arguments, empty body and no other constructors exist? The only benefit I can think of is reducing the risk of forgetting to add the ...
5
votes
2answers
345 views

Constructor Injection, Single Responsibility and List initialisation

Given the class: public class Foo : IFoo { private IBarRepository repository public Foo(IBarRepository repository) { this.repository = repository } public IList<IBar> Bars { ...
3
votes
1answer
1k views

Initializing properties that aren't parameters in a constructor: alternatives

A class loads properties from a file and uses those as it performs its duties. For testing purposes I want to be able to modify said properties directly without having to use a test properties file. ...
3
votes
3answers
877 views

Is it better to have constructors with or without parameters?

Is it better to have constructors with or without parameters and why? public NewClass( String a, String b, int c) throws IOException { //something } OR public NewClass() { //something } ...
1
vote
1answer
131 views

Writing arguments in constructors

When creating constructors with multiple arguments, is ok to use the generic String[] args or is it better to list the arguments? Does it really make any significant difference as the coding becomes ...
4
votes
5answers
563 views

Requring static class setter to be called before constructor, bad design?

I have a class, say Foo, and every instance of Foo will need and contain the same List object, myList. Since every class instance will share the same List Object, I thought it would be good to make ...
-4
votes
4answers
566 views

Why must a constructor's call to the superconstructor be the first call?

It is an error if you do anything in a constructor before calling the superconstructor. I remember that I had problems because of that. Yet, I do not see how this saves us from errors. It could save ...
3
votes
3answers
5k views

How to initialize all your references?

I have recently taken a project with another developer, and he has a certain way of initializing his references. class Player { private: Console &console; Armor &armor1, ...
3
votes
4answers
547 views

Separation of construction and initialization

I'm confused by this post by Mark Seeman. And his comment on IInitializable below: The problem with an Initialize method is the same as with Property Injection (A.K.A. Setter Injection): it ...
29
votes
3answers
2k views

Is a “start”, “run” or “execute” method a good practice?

I'm currently working on a code base that has many classes that implement a Start method. This seems like two-phase construction to me, which I had always considered a bad practice. I can't tell the ...
4
votes
6answers
1k views

Should all classes have a default constructor as part of good coding convention

From the texts I have read so far, the conventions talk about organizing constructors, starting with the default, if any. I am wondering, should all classes have a default constructor anyway. This ...
13
votes
4answers
9k views

C++ - Constructor or Initialize Method to Startup [duplicate]

Possible Duplicate: Avoid having an initialization method I want to determine when to do non-trivial initialization of a class. I see two times to do initialization: constructor and other ...