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• Designing a "Grid" like object that contains game objects

  - by liortal

  I am working on a 2D game, where there's a game "board" on which other game objects are placed. This this is 2D, my starting point was to design a class that will internally use a 2d array for the actual stored game objects. This class could be simply accessed by 2 indices: (i, j) to get game objects on it. My problem is that i have no idea how to make the game "board" "propagate" its data onto its children. Design questions i ran into are: Should the children placed on the board have display properties such as size, screen position? Should the board itself dictate this information? How to update children in case the board changes some of its properties? (position, etc). Should the board be aware of the types of objects stored in it ? I have no idea how similar things such as WPF or other UI frameworks go about organizing a "container like" object that can arrange or apply certain UI properties to its children.

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• Ruby - when to use instance variables vs parameters between methods?

  - by Michael Durrant

  I'm writing several methods that call other methods. To pass the information I have a couple of choices: Pass the information as parameters Set instance variables so that other methods can access them When should I choose one option over the other? It seems that the first option is good as it is very specific about what is being passed. the downside seems to be that a lot of values are being passed around. The second method doesn't require passing all the values around but seems to lead to a lot of magic where methods set instance variables 'somewhere' Should I always be very explicit about gets passed to other methods in the class? Are there exceptions so this?

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• Is having 'Util' classes a cause for concern? [closed]

  - by Matt Fenwick

  I sometimes create 'Util' classes which primarily serve to hold methods and values that don't really seem to belong elsewhere. But every time I create one of these classes, I think "uh-oh, I'm gonna regret this later ...", because I read somewhere that it's bad. But on the other hand, there seem to be two compelling (at least for me) cases for them: implementation secrets that are used in multiple classes within a package providing useful functionality to augment a class, without cluttering its interface Am I on the way to destruction? What you say !! Should I refactor?

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• Setting up ASP.NET structure for code

  - by user1175327

  I've always coded in C# MVC3 when developing web applications. But now i wanted to learn a bit more about developing web sites with just ASP.NET. But now i'm wondering what a good setup for my code would be. For me, an MVC like pattern seems to be a good way to go. But obviously ASP.NET doesn't have any router and controller classes. So i guess people have a different way of setting up their code when they do ASP.NET. So i'm looking for more information on how to get started with this. So not really the basics of ASP.NET, but something that focuses on a good code setup. Any good tutorials/information about this/?

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• Learning OO for a C Programmer

  - by Holysmoke

  I've been programming professionally in C, and only C, for around 10 years in a variety of roles. As would be normal to expect, I understand the idioms of the language fairly well and beyond that also some of the design nuances - which APIs to make public, who calls what, who does what, what is supposed to reentrant and so on. I grew up reading 'Writing Solid Code', it's early C edition, not the one based on C++. However, I've never ever programmed in an OO language. Now, I want to migrate to writing applications for iPhone (maybe android), so want to learn to use Objective-C and use it with a degree of competence fitting a professional programmer. How do I wrap my head around the OO stuff? What would be your smallest reading list suggestion to me. Is there a book that carries some sort of relatively real world example OO design Objective-C? Besides, the reading what source code would you recommend me to go through. How to learn OO paradigm using Objective-C?

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• Breaking up classes and methods into smaller units

  - by micahhoover

  During code reviews a couple devs have recommended I break up my methods into smaller methods. Their justification was (1) increased readability and (2) the back trace that comes back from production showing the method name is more specific to the line of code that failed. There may have also been some colorful words about functional programming. Additionally I think I may have failed an interview a while back because I didn't give an acceptable answer about when to break things up. My inclination is that when I see a bunch of methods in a class or across a bunch of files, it isn't clear to me how they flow together, and how many times each one gets called. I don't really have a good feel for the linearity of it as quickly just by eye-balling it. The other thing is a lot of people seem to place a premium of organization over content (e.g. 'Look at how organized my sock drawer is!' Me: 'Overall, I think I can get to my socks faster if you count the time it took to organize them'). Our business requirements are not very stable. I'm afraid that if the classes/methods are very granular it will take longer to refactor to requirement changes. I'm not sure how much of a factor this should be. Anyway, computer science is part art / part science, but I'm not sure how much this applies to this issue.

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• Defining formula through user interface in user form

  - by BriskLabs Pakistan

  I am a student and developing a simple assignment - windows form application in visual studio 2010. The application is suppose to construct formulas as per user requirement. The process: It has to pick data from columns of Microsoft Access database and the user should be able to pick the data by column name like we do in a drop down menu. and create reusable formulas in it ( configure it once and can change it again). followings are column titles from database that can be picked for example. e.g Col -1 : Marks in Maths Col -2 : Total Marks in Maths Col -3 : Marks in science Col -4 : Total marks in science Finally we should be able to construct any formula in the UI like (Col 1 + Col 3 ) / ( col 2 + col 4) = Formula 1 once this is formula is set saved and a name is assigned to it by user. he/she can use the formula and results shall appear in a window below. i.e He would be able to calculate his desired figures (formula) by only manipulating underlying data on the UI layer....choose the data for a period and apply the formula and get the answer Problem: It looks like I have to create an app where rules are set through UI....... this means no stored procedures are required in SQL.... please suggest the right approach.

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• Why setter method when getter method enough in PHP OOP

  - by phphunger

  I am practicing OOP with PHP, and I am struck at setter and getter methods. I can directly access the class properties and methods with getter method then what's the use of setter method? See my example. <?php class MyClass{ public $classVar = "Its a class variable"; public function Getter(){ return $this -> classVar; } } $obj = new MyClass; echo $obj -> Getter(); ?>

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• Cookie access within a HTTP Class

  - by James Jeffery

  I have a HTTP class that has a Get, and Post, method. It's a simple class I created to encapsulate Post and Get requests so I don't have to repeat the get/post code throughout the application. In C#: class HTTP { private CookieContainer cookieJar; private String userAgent = "..."; public HTTP() { this.cookieJar = new CookieContainer(); } public String get(String url) { // Make get request. Return the JSON } public String post(String url, String postData) { // Make post request. Return the JSON } } I've made the CookieJar a property because I want to preserve the cookie values throughout the session. If the user is logged into Twitter with my application, each request I make (be it get or post) I want to use the cookies so they remain logged in. That's the basics of it anyway. But, I don't want to return a string in all instances. Sometimes I may want the cookie, or a header value, or something else from the request. Ideally I'd like to be able to do this in my code: Cookie cookie = http.get("http://google.com").cookie("g_user"); String g_user = cookie.value; or String source = http.get("http://google.com").body; My question - To do this, would I need to have a Get class, and a Post class, that are included within the HTTP class and are accessible via accessors? Within the Get and Post class I would then have the Cookie method, and the body property, and whatever else is needed. Should I also use an interface, or create a Request class and have Post and Get extend it so that common methods and properties are available to both classes? Or, am I thinking totally wrong?

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• Rails: The Law of Demeter [duplicate]

  - by user2158382

  This question already has an answer here: Rails: Law of Demeter Confusion 4 answers I am reading a book called Rails AntiPatterns and they talk about using delegation to to avoid breaking the Law of Demeter. Here is their prime example: They believe that calling something like this in the controller is bad (and I agree) @street = @invoice.customer.address.street Their proposed solution is to do the following: class Customer has_one :address belongs_to :invoice def street address.street end end class Invoice has_one :customer def customer_street customer.street end end @street = @invoice.customer_street They are stating that since you only use one dot, you are not breaking the Law of Demeter here. I think this is incorrect, because you are still going through customer to go through address to get the invoice's street. I primarily got this idea from a blog post I read: http://www.dan-manges.com/blog/37 In the blog post the prime example is class Wallet attr_accessor :cash end class Customer has_one :wallet # attribute delegation def cash @wallet.cash end end class Paperboy def collect_money(customer, due_amount) if customer.cash < due_ammount raise InsufficientFundsError else customer.cash -= due_amount @collected_amount += due_amount end end end The blog post states that although there is only one dot customer.cash instead of customer.wallet.cash, this code still violates the Law of Demeter. Now in the Paperboy collect_money method, we don't have two dots, we just have one in "customer.cash". Has this delegation solved our problem? Not at all. If we look at the behavior, a paperboy is still reaching directly into a customer's wallet to get cash out. EDIT I completely understand and agree that this is still a violation and I need to create a method in Wallet called withdraw that handles the payment for me and that I should call that method inside the Customer class. What I don't get is that according to this process, my first example still violates the Law of Demeter because Invoice is still reaching directly into Customer to get the street. Can somebody help me clear the confusion. I have been searching for the past 2 days trying to let this topic sink in, but it is still confusing.

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• correct way to implement auth/acl in mvc

  - by WiseStrawberry

  I am looking into making a correctly laid out MVC auth/acl system. I think I want the authentication of a user (and the session handling) to be seperate from the ACL system. (I don't know why but this seems a good idea from the things I've read) What does mvc have to do with this question you ask? Because I wish for the application to be well integrated with my acl. An example of a controller (CodeIgniter) <?php class forums extends MX_Controller { $allowed = array('users', 'admin'); $need_login = true; function __construct() { //example of checking if logged in. if($this->auth->logged_in() && $this->auth->is_admin()) { echo "you're logged in!"; } } public function add_topic() { if($this->auth->allowed('add_topic') { //some add topic things. } else { echo 'not allowed to add topic'; } } } ?> My thoughts $this->auth would be autoloaded in the system. I would like to check the $allowed array against the user currently (not) logged in and react accordingly. Is this a good way of doing things? I haven't seen much literature on mvc integration and auth. I want to make things as easy as possible.

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• is 'protected' ever reasonable outside of virtual methods and destructors?

  - by notallama

  so, suppose you have some fields and methods marked protected (non-virtual). presumably, you did this because you didn't mark them public because you don't want some nincompoop to accidentally call them in the wrong order or pass in invalid parameters, or you don't want people to rely on behaviour that you're going to change later. so, why is it okay for that nincompoop to use those fields and methods from a subclass? as far as i can tell, they can still screw up in the same ways, and the same compatibility issues still exist if you change the implementation. the cases for protected i can think of are: non-virtual destructors, so you can't break things by deleting the base class. virtual methods, so you can override 'private' methods called by the base class. constructors in c++. in java/c# marking the class as abstract will do basically the same. any other use cases?

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• PHP OOP: Am i following right way?

  - by sineverba

  I'm learning OOP (PHP). I've realized my own CRUD Class, that performs some kind of queries SQL. Btw, a Gasoline asked us to realize a smart, simple web-app where he can update prices of his gasoline (gasoline, diesel, lpg) and via an API i could recall them and display in his site. So, I did create a new Class Gasoline but it perform some methods of CRUD Class public function getPrezzoBenzina($id) { $prezzo_benzina = $this->distributore->sql('SELECT prezzo_benzina FROM prezzi WHERE id = '.$id); return $prezzo_benzina } And so on (code is pseudocode, just to explain). I could perform all my code only with help of Crud Class... without necessity of Class Gasoline. So, what I'm missing about OOP? Where am I wrong?

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• Semantic coupling vs. large class

  - by user106587

  I have hardware I communicate with via TCP. This hardware accepts ~40 different commands/requests with about 20 different responses. I've created a HardwareProxy class which has a TcpClient to send and receive data. I didn't like the idea of having 40 different methods to send the commands/requests, so I started down the path of having a single SendCommand method which takes an ICommand and returns an IResponse, this results in 40 different SpecificCommand classes. The problem is this requires semantic coupling, i.e. the method that invokes SendCommand receives an IResponse which it has to downcast to SpecificResponse, I use a future map which I believe ensures the appropriate SpecificResponse, but I get the impression this code smells. Besides the semantic coupling, ICommand and IResponse are essentially empty abstract classes (Marker Interfaces) and this seems suspicious to me. If I go with the 40 methods I don't think I have broken the single responisbility principle as the responsibility of the HardwareProxy class is to act as the hardware, which has all of these commands. This route is just ugly, plus I'd like to have Asynchronous versions, so there'd be about 80 methods. Is it better to bite the bullet and have a large class, accept the coupling and MarkerInterfaces for a smaller soultuion, or am I missing a better way? Thanks.

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• Should all, none, or some overriden methods call Super?

  - by JoJo

  When designing a class, how do you decide when all overridden methods should call super or when none of the overridden methods should call super? Also, is it considered bad practice if your code logic requires a mixture of supered and non-supered methods like the Javascript example below? ChildClass = new Class.create(ParentClass, { /** * @Override */ initialize: function($super) { $super(); this.foo = 99; }, /** * @Override */ methodOne: function($super) { $super(); this.foo++; }, /** * @Override */ methodTwo: function($super) { this.foo--; } }); After delving into the iPhone and Android SDKs, I noticed that super must be called on every overridden method, or else the program will crash because something wouldn't get initialized. When deriving from a template/delegate, none of the methods are supered (obviously). So what exactly are these "je ne sais quoi" qualities that determine whether a all, none, or some overriden methods should call super?

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• Rotate object Up/Down/Left/Right in any orientation

  - by George Duckett

  I'm rendering model at the origin with a fixed camera looking at it positioned on the z axis. I want to be able to rotate the model up/down and left/right. Currently I have 2 variables, HorizontalRotation and VerticalRotation. When calculating the world matrix I rotate about the Y axis by HorizontalRotation and about the X axis by VerticalRotation. The ..Rotation variables are controlled by pressing up/down/left/right arrow keys. The problem I'm having is that the rotations are happening relative to the object. Lets say it's a model of the world. Pressing Up a bit would let me look at the north pole. Currently when i press right the earth spins infront of the camera on its axis; I'm still looking at the north pole. How can i get it so that no matter what rotations are currently applied i can always rotate my model relative to the camera/world axis?

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• Class Versus Struct

  - by Prometheus87

  In C++ and other influenced languages there is a construct called Structure (struct) and we all know the class. Both are capable of holding functions and variables. some differences are 1. Class is given memory in heap and struct is given memory in stack 2. in class variable are private by default and in struct thy are public My question is that struct was somehow abandoned for Class. Why? other that abstraction, a struct can do all the same stuff a class does. Then why abandon it?

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• What is the order of diagram drawing in a design?

  - by Manuel Malagon

  I'm new with OOP and UML and I have some confusion here. I'd like to know where to start, I mean, somebody comes to you and ask you to do something (involves software design of course), once you have determined what has to be done, what is the order in which you have to start the software architecture? I mean, is it first the use case diagram or the class diagram? or should I draw some diagrams in parallel? But basically, where should I start? and what UML diagram goes first? Thanks for helping!!

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• What books/references are recommended on the subject of planning and developing efficient web sites [closed]

  - by Shakil

  Once I visited a site containing videos; a well-known web developer creating a site from scratch via planning(paper, software), management, designing then development. I bookmarked the site but unable to find it now. My question is : How to do web-development effectively? What books or videos are recommended ???(I tried google but unable to find useful books or videos). I want to learn how people does it. Can you share resources(books, videos, links) about this... Thanks in advance.. Note: I created a job site for my university project. It gave me huge pain. Thats why I want to learn efficient way. I know html, css, javascript, jquery, php[learning(mvc and framework not yet completed)], phpmyadmin.

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• Am I violating LSP if the condition can be checked?

  - by William

  This base class for some shapes I have in my game looks like this. Some of the shapes can be resized, some of them can not. private Shape shape; public virtual void SetSizeOfShape(int x, int y) { if (CanResize()){ shape.Width = x; shape.Height = y; } else { throw new Exception("You cannot resize this shape"); } } public virtual bool CanResize() { return true; } In a sub class of a shape that I don't ever want to resize I am overriding the CanResize() method so a piece of client code can check before calling the SetSizeOfShape() method. public override bool CanResize() { return false; } Here's how it might look in my client code: public void DoSomething(Shape s) { if(s.CanResize()){ s.SetSizeOfShape(50, 70); } } Is this violating LSP?

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• Python simulation-scripts architecture

  - by Beastcraft

  Situation: I've some scripts that simulate user-activity on desktop. Therefore I've defined a few cases (workflows) and implemented them in Python. I've also written some classes for interacting with the users' software (e.g. web browser etc.). Problem: I'm a total beginner in software design / architecture (coding isn't a problem). How could I structure what I described above? Providing a library which contains all the workflows as functions, or a separate class/module etc. for each workflow? I want to keep the the workflows simple. The complexity should be hidden in the classes for interacting with the users' software. Are there any papers / books I could read about this, or could you provide some tips? Kind regards, B

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• Read an object from compressed file generated from ActionScript 3

  - by Last Chance

  I have made a simple game Map Editor and I want to save a array that contain map tile info to a file, as below: var arr:Array = [.....2d tile info in it...]; var ba:ByteArray = new ByteArray(); ba.writeObject(arr); ba.compress(); var file:File = new File(); file.save(ba); I had successfully saved a compressed object to a file. Now the problem is my server side need to read this file and decompress the array out from the file, then convert it to a Python list. Is that possible?

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• A better alternative to incompatible implementations for the same interface?

  - by glenatron

  I am working on a piece of code which performs a set task in several parallel environments where the behaviour of the different components in the task are similar but quite different. This means that my implementations are quite different but they are all based on the relationships between the same interfaces, something like this: IDataReader -> ContinuousDataReader -> ChunkedDataReader IDataProcessor -> ContinuousDataProcessor -> ChunkedDataProcessor IDataWriter -> ContinuousDataWriter -> ChunkedDataWriter So that in either environment we have an IDataReader, IDataProcessor and IDataWriter and then we can use Dependency Injection to ensure that we have the correct one of each for the current environment, so if we are working with data in chunks we use the ChunkedDataReader, ChunkedDataProcessor and ChunkedDataWriter and if we have continuous data we have the continuous versions. However the behaviour of these classes is quite different internally and one could certainly not go from a ContinuousDataReader to the ChunkedDataReader even though they are both IDataProcessors. This feels to me as though it is incorrect ( possibly an LSP violation? ) and certainly not a theoretically correct way of working. It is almost as though the "real" interface here is the combination of all three classes. Unfortunately in the project I am working on with the deadlines we are working to, we're pretty much stuck with this design, but if we had a little more elbow room, what would be a better design approach in this kind of scenario?

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• Are injectable classes allowed to have constructor parameters in DI?

  - by Songo

  Given the following code: class ClientClass{ public function print(){ //some code to calculate $inputString $parser= new Parser($inputString); $result= $parser->parse(); } } class Parser{ private $inputString; public __construct($inputString){ $this->inputString=$inputString; } public function parse(){ //some code } } Now the ClientClass has dependency on class Parser. However, if I wanted to use Dependency Injection for unit testing it would cause a problem because now I can't send the input string to the parser constructor like before as its calculated inside ClientCalss itself: class ClientClass{ private $parser; public __construct(Parser $parser){ $this->parser=$parser; } public function print(){ //some code to calculate $inputString $result= $this->parser->parse(); //--> will throw an exception since no string was provided } } The only solution I found was to modify all my classes that took parameters in their constructors to utilize Setters instead (example: setInputString()). However, I think there might be a better solution than this because sometimes modifying existing classes can cause much harm than benefit. So, Are injectable classes not allowed to have input parameters? If a class must take input parameters in its constructor, what would be the way to inject it properly? UPDATE Just for clarification, the problem happens when in my production code I decide to do this: $clientClass= new ClientClass(new Parser($inputString));//--->I have no way to predict $inputString as it is calculated inside `ClientClass` itself. UPDATE 2 Again for clarification, I'm trying to find a general solution to the problem not for this example code only because some of my classes have 2, 3 or 4 parameters in their constructors not only one.

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• Should all, none, or some overridden methods call Super?

  - by JoJo

  When designing a class, how do you decide when all overridden methods should call super or when none of the overridden methods should call super? Also, is it considered bad practice if your code logic requires a mixture of supered and non-supered methods like the Javascript example below? ChildClass = new Class.create(ParentClass, { /** * @Override */ initialize: function($super) { $super(); this.foo = 99; }, /** * @Override */ methodOne: function($super) { $super(); this.foo++; }, /** * @Override */ methodTwo: function($super) { this.foo--; } }); After delving into the iPhone and Android SDKs, I noticed that super must be called on every overridden method, or else the program will crash because something wouldn't get initialized. When deriving from a template/delegate, none of the methods are supered (obviously). So what exactly are these "je ne sais quoi" qualities that determine whether a all, none, or some overriden methods should call super?

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