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  • What Getters and Setters should and shouldn't do.

    - by cyclotis04
    I've run into a lot of differing opinions on Getters and Setters lately, so I figured I should make it into it's own question. A previous question of mine received an immediate comment (later deleted) that stated setters shouldn't have any side effects, and a SetProperty method would be a better choice. Indeed, this seems to be Microsoft's opinion as well. However, their properties often raise events, such as Resized when a form's Width or Height property is set. OwenP also states "you shouldn't let a property throw exceptions, properties shouldn't have side effects, order shouldn't matter, and properties should return relatively quickly." Yet Michael Stum states that exceptions should be thrown while validating data within a setter. If your setter doesn't throw an exception, how could you effectively validate data, as so many of the answers to this question suggest? What about when you need to raise an event, like nearly all of Microsoft's Control's do? Aren't you then at the mercy of whomever subscribed to your event? If their handler performs a massive amount of information, or throws an error itself, what happens to your setter? Finally, what about lazy loading within the getter? This too could violate the previous guidelines. What is acceptable to place in a getter or setter, and what should be kept in only accessor methods?

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  • When are Getters and Setters Justified

    - by Winston Ewert
    Getters and setters are often criticized as being not proper OO. On the other hand most OO code I've seen has extensive getters and setters. When are getters and setters justified? Do you try to avoid using them? Are they overused in general? If your favorite language has properties (mine does) then such things are also considered getters and setters for this question. They are same thing from an OO methodology perspective. They just have nicer syntax. Sources for Getter/Setter Criticism (some taken from comments to give them better visibility): http://www.javaworld.com/javaworld/jw-09-2003/jw-0905-toolbox.html http://typicalprogrammer.com/?p=23 http://c2.com/cgi/wiki?AccessorsAreEvil http://www.darronschall.com/weblog/2005/03/no-brain-getter-and-setters.cfm http://www.adam-bien.com/roller/abien/entry/encapsulation_violation_with_getters_and To state the criticism simply: Getters and Setters allow you to manipulate the internal state of objects from outside of the object. This violates encapsulation. Only the object itself should care about its internal state. And an example Procedural version of code. struct Fridge { int cheese; } void go_shopping(Fridge fridge) { fridge.cheese += 5; } Mutator version of code: class Fridge { int cheese; void set_cheese(int _cheese) { cheese = _cheese; } int get_cheese() { return cheese; } } void go_shopping(Fridge fridge) { fridge.set_cheese(fridge.get_cheese() + 5); } The getters and setters made the code much more complicated without affording proper encapsulation. Because the internal state is accessible to other objects we don't gain a whole lot by adding these getters and setters. The question has been previously discussed on Stack Overflow: http://stackoverflow.com/questions/565095/java-are-getters-and-setters-evil http://stackoverflow.com/questions/996179

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  • Java Interface Usage Guidelines -- Are getters and setters in an interface bad?

    - by user68759
    What do people think of the best guidelines to use in an interface? What should and shouldn't go into an interface? I've heard people say that, as a general rule, an interface must only define behavior and not state. Does this mean that an interface shouldn't contain getters and setters? My opinion: Maybe not so for setters, but sometimes I think that getters are valid to be placed in an interface. This is merely to enforce the implementation classes to implement those getters and so to indicate that the clients are able to call those getters to check on something, for example.

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  • Data classes: getters and setters or different method design

    - by Frog
    I've been trying to design an interface for a data class I'm writing. This class stores styles for characters, for example whether the character is bold, italic or underlined. But also the font-size and the font-family. So it has different types of member variables. The easiest way to implement this would be to add getters and setters for every member variable, but this just feels wrong to me. It feels way more logical (and more OOP) to call style.format(BOLD, true) instead of style.setBold(true). So to use logical methods insteads of getters/setters. But I am facing two problems while implementing these methods: I would need a big switch statement with all member variables, since you can't access a variable by the contents of a string in C++. Moreover, you can't overload by return type, which means you can't write one getter like style.getFormatting(BOLD) (I know there are some tricks to do this, but these don't allow for parameters, which I would obviously need). However, if I would implement getters and setters, there are also issues. I would have to duplicate quite some code because styles can also have a parent styles, which means the getters have to look not only at the member variables of this style, but also at the variables of the parent styles. Because I wasn't able to figure out how to do this, I decided to ask a question a couple of weeks ago. See Object Oriented Programming: getters/setters or logical names. But in that question I didn't stress it would be just a data object and that I'm not making a text rendering engine, which was the reason one of the people that answered suggested I ask another question while making that clear (because his solution, the decorator pattern, isn't suitable for my problem). So please note that I'm not creating my own text rendering engine, I just use these classes to store data. Because I still haven't been able to find a solution to this problem I'd like to ask this question again: how would you design a styles class like this? And why would you do that? Thanks on forehand!

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  • Java - Should private instance variables be accessed in constructors through getters and setters met

    - by Yatendra Goel
    I know that private instance variables are accessed through their public getters and setters method. But when I generate constructors with the help of IDE, it initializes instance variables directly instead of initializing them through their setter methods. Q1. So should I change the IDE generated code for constructors to initialize those instance variables through their setter methods. Q2. If yes, then why IDE don't generate constructors code in that way?

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  • [PHP] Difference between normal and magic setters and getters

    - by Saif Bechan
    I am using a magic getter/setter class for my session variables, but I don't see any difference between normal setters and getters. The code: class session { public function __set($name, $value) { $_SESSION[$name] = $value; } public function __unset($name) { unset($_SESSION[$name]); } public function __get($name) { if(isset($_SESSION[$name])) { return $_SESSION[$name]; } } } Now the first thing I noticed is that I have to call $session->_unset('var_name') to remove the variable, nothing 'magical' about that. Secondly when I try to use $session->some_var this does not work. I can only get the session variable using $_SESSION['some_var']. I have looked at the PHP manual but the functions look the same as mine. Am I doing something wrong, or is there not really anything magic about these functions.

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  • Difference between normal and magic setters and getters

    - by Saif Bechan
    I am using a magic getter/setter class for my session variables, but I don't see any difference between normal setters and getters. The code: class session { public function __set($name, $value) { $_SESSION[$name] = $value; } public function __unset($name) { unset($_SESSION[$name]); } public function __get($name) { if(isset($_SESSION[$name])) { return $_SESSION[$name]; } } } Now the first thing I noticed is that I have to call $session->_unset('var_name') to remove the variable, nothing 'magical' about that. Secondly when I try to use $session->some_var this does not work. I can only get the session variable using $_SESSION['some_var']. I have looked at the PHP manual but the functions look the same as mine. Am I doing something wrong, or is there not really anything magic about these functions.

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  • Javascript setters/getters

    - by Martin Hansen
    var author = { firstname: 'Martin', lastname: 'Hansen' } function settersGetters(propStr) { for (var i = 0; i < propStr.length; i++) { author['_'+ propStr[i]] = null; author.__defineGetter__(propStr[i], function() { return author['_'+ propStr[i]]; }); author.__defineSetter__(propStr[i], function(val) { author['_'+ propStr[i]] = val; }); }; } The above code would hopefully generate setters/getters for any supplied properties (in an array) for the object author. But when I call the below code Both firstname and lastname is olsen.. What am I doing wrong? settersGetters(['firstname', 'lastname']); author.firstname = 'per'; author.lastname = 'olsen'; console.log(author.firstname); console.log(author.lastname);

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  • Naming conventions for complex getters in Java

    - by Simon
    Hi there! I was reading this C# article about the usage of properties and methods. It points out why and when to use properties or methods. Properties are meant to be used like fields, meaning that properties should not be computationally complex or produce side effects I was asking myself how you could express this difference in Java, where you only use getters for the retrieval of data. What is your opinion?

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  • TDD, DDD and the No-getters principle

    - by Justin
    Hi all, After several years of following the bad practice handed down from 'architects' at my place of work and thinking that there must be a better way, I've recently been reading up around TDD and DDD and I think the principles and practices would be a great fit for the complexity of the software we write. However, many of the TDD samples I have seen call a method on the domain object and then test properties of the object to ensure the behaviour executed correctly. On the other hand, several respected people in the industry (Greg Young most noticeably so) advocate the "no-getters" principle on our domain objects. My question therefore is: How does one test the functionality of a domain object if it is forbidden to retrieve its state? I believe I am missing something fundamental so please feel free to call me an idiot and enlighten me - any guidance would be greatly appreciated.

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  • Java design: too many getters

    - by dege
    After writing a few lesser programs when learning Java the way I've designed the programs is with Model-View-Control. With using MVC I have a plethora of getter methods in the model for the view to use. It feels that while I gain on using MVC, for every new value added I have to add two new methods in the model which quickly get all cluttered with getter & setters. So I was thinking, maybe I should use the notifyObserver method that takes an argument. But wouldn't feel very smart to send every value by itself either so I figured, maybe if I send a kind of container with all the values, preferably only those that actually changed. What this would accomplish would be that instead of having a whole lot of getter methods I could just have one method in the model which put all relevant values in the container. Then in the view I would have a method called from the update which extracted the values from the container and assigning them to the correct fields. I have two questions concerning this. First: is this actually a viable way to do this. Would you recommend me doing something along these lines? Secondly: if I do use this plan and I don't want to keep sending fields that didn't actually change. How would I handle that without having to have if statements to check if the value is not null for every single value?

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  • What should be allowed inside getters and setters?

    - by Botond Balázs
    I got into an interesting internet argument about getter and setter methods and encapsulation. Someone said that all they should do is an assignment (setters) or a variable access (getters) to keep them "pure" and ensure encapsulation. Am I right that this would completely defeat the purpose of having getters and setters in the first place and validation and other logic (without strange side-effects of course) should be allowed? When should validation happen? When setting the value, inside the setter (to protect the object from ever entering an invalid state - my opinion) Before setting the value, outside the setter Inside the object, before each time the value is used Is a setter allowed to change the value (maybe convert a valid value to some canonical internal representation)?

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  • Why can't I initialize a class through a setter?

    - by Rob emenaker
    If I have a custom class called Tires: #import <Foundation/Foundation.h> @interface Tires : NSObject { @private NSString *brand; int size; } @property (nonatomic,copy) NSString *brand; @property int size; - (id)init; - (void)dealloc; @end ============================================= #import "Tires.h" @implementation Tires @synthesize brand, size; - (id)init { if (self = [super init]) { [self setBrand:[[NSString alloc] initWithString:@""]]; [self setSize:0]; } return self; } - (void)dealloc { [super dealloc]; [brand release]; } @end And I synthesize a setter and getter in my View Controller: #import <UIKit/UIKit.h> #import "Tires.h" @interface testViewController : UIViewController { Tires *frontLeft, *frontRight, *backleft, *backRight; } @property (nonatomic,copy) Tires *frontLeft, *frontRight, *backleft, *backRight; @end ==================================== #import "testViewController.h" @implementation testViewController @synthesize frontLeft, frontRight, backleft, backRight; - (void)viewDidLoad { [super viewDidLoad]; [self setFrontLeft:[[Tires alloc] init]]; } - (void)dealloc { [super dealloc]; } @end It dies after [self setFrontLeft:[[Tires alloc] init]] comes back. It compiles just fine and when I run the debugger it actually gets all the way through the init method on Tires, but once it comes back it just dies and the view never appears. However if I change the viewDidLoad method to: - (void)viewDidLoad { [super viewDidLoad]; frontLeft = [[Tires alloc] init]; } It works just fine. I could just ditch the setter and access the frontLeft variable directly, but I was under the impression I should use setters and getters as much as possible and logically it seems like the setFrontLeft method should work. This brings up an additional question that my coworkers keep asking in these regards (we are all new to Objective-C); why use a setter and getter at all if you are in the same class as those setters and getters.

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  • SEO Professional Can Add the Required Magical Touch

    When you decide to get your business listed under a suitable search engine then you need to make sure that you get in touch with the SEO consultancy so that they help in sketching out a proper layout for the journey from then on. The SEO consultancy has professionals who take the charge and guide the innumerable entrepreneurs in getting the goal met with proper benefits and gains, in fact these professionals are the once who add that extra touch and enhance them even more. Realising that the role of the SEO professional is so important, it is...

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  • Ambiguous reference when getter/setter have different visibilities

    - by Warren Seine
    The following code raises an ambiguous reference to value at compile time: import flash.display.Sprite; public class Main extends Sprite { private var _value : Number = 0.; public function get value() : Number { return _value; } private function set value(v : Number) : void { _value = v; } public function Main() : void { value = 42.; } } I suspect some kind of bug in the compiler, though I didn't actually read the ECMA standard. Before someone asks those questions: Private setters do make sense. The ambiguity also exists with custom namespaces (which is the problem I'm facing).

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  • DI and hypothetical readonly setters in C#

    - by Luis Ferrao
    Sometimes I would like to declare a property like this: public string Name { get; readonly set; } I am wondering if anyone sees a reason why such a syntax shouldn't exist. I believe that because it is a subset of "get; private set;", it could only make code more robust. My feeling is that such setters would be extremely DI friendly, but of course I'm more interested in hearing your opinions than my own, so what do you think? I am aware of 'public readonly' fields, but those are not interface friendly so I don't even consider them. That said, I don't mind if you bring them up into the discussion Edit I realize reading the comments that perhaps my idea is a little confusing. The ultimate purpose of this new syntax would be to have an automatic property syntax that specifies that the backing private field should be readonly. Basically declaring a property using my hypothetical syntax public string Name { get; readonly set; } would be interpreted by C# as: private readonly string name; public string Name { get { return this.name; } } And the reason I say this would be DI friendly is because when we rely heavily on constructor injection, I believe it is good practice to declare our constructor injected fields as readonly.

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  • What is array portability?

    - by bobo
    From this page: http://www.doctrine-project.org/documentation/manual/1_2/en/working-with-models#dealing-with-relations:creating-related-records You can see that it says $obj['property']; is the recommended way of referring to an object's property in Doctrine for array portability purposes. I never heard about this term before and google did not come up with useful result. What is that?

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  • Change field access to getter / setter method access

    - by Chris Dennett
    Hi everyone, is it possible to change external class field accesses in Java to getter / setter calls automatically, and also hide the exposed fields? I'm using Javabeans and I want change notifications when a field property changes (this is important). I've found cglib which can automatically insert the property change call to the PropertyChangeSupport field. I'd like this question to be a discussion of the issues posed and their solutions. I know about Project Lombok, but this appears to modify the source code, and additionally doesn't support field access modification. Perhaps with modifications to Lombok, this could be supported, or are there other solutions? Cheers and thanks in advance, Chris

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  • What is a good practice to access class attributes in class methods?

    - by Clem
    I always wonder about the best way to access a class attribute from a class method in Java. Could you quickly convince me about which one of the 3 solutions below (or a totally different one :P) is a good practice? public class Test { String a; public String getA(){ return this.a; } public setA(String a){ this.a = a; } // Using Getter public void display(){ // Solution 1 System.out.println(this.a); // Solution 2 System.out.println(getA()); // Solution 3 System.out.println(this.getA()); } // Using Setter public void myMethod(String b, String c){ // Solution 1 this.a = b + c; // Solution 2 setA(b + c); // Solution 3 this.setA(b + c); } }

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  • The use of getters and setters for different programming languages [closed]

    - by leonhart88
    So I know there are a lot of questions on getters and setters in general, but I couldn't find something exactly like my question. I was wondering if people change the use of get/set depending on different languages. I started learning with C++ and was taught to use getters and setters. This is what I understand: In C++ (and Java?), a variable can either be public or private, but we cannot have a mix. For example, I can't have a read-only variable that can still be changed inside the class. It's either all public (can read and change it), or all private (can't read and can only change inside the class). Because of this (and possibly other reasons), we use getters and setters. In MATLAB, I can control the "setaccess" and "getaccess" properties of variables, so that I can make things read-only (can directly access the property, but can't overwrite it). In this case, I don't feel like I need a getter because I can just do class.property. Also, in Python it is considered "Pythonic" to not use getters/setters and to only put things into properties if needed. I don't really understand why its OK to have all public variables in Python, because that's opposite of what I learned when I started with C++. I'm just curious what other people's thoughts are on this. Would you use getters and setters for all languages? Would you only use it for C++/Java and do direct access in MATLAB and Python (which is what I am currently doing)? Is the second option considered bad? For my purposes, I am only referring to simple getters and setters (just return/set the value and do not do anything else). Thanks!

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