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  • Interface extension

    - by user877329
    Suppose that I have an input stream interface, which defines a method for reading data. I also have a seekable interface which defines a method for seeking. A natural way of defining a input file is then to implement both input stream and seekable. I want to construct a data decoder from the input stream interface so I can read data from a file or from another stream. The problem is that I also want to implement seek functionality to the data decoder, since I want to be able to step individual records not raw bytes. This is not possible if I only provide an input stream, which does not have the bytewise seek method. Should I skip the seekable interface and add the seek method to input stream instead and force all streams to at least leave it as a nop.

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  • Making a class pseudo-immutable by setting a flag

    - by scott_fakename
    I have a java project that involves building some pretty complex objects. There are quite a lot (dozens) of different ones and some of them have a HUGE number of parameters. They also need to be immutable. So I was thinking the builder pattern would work, but it ends up require a lot of boilerplate. Another potential solution I thought of was to make a mutable class, but give it a "frozen" flag, a-la ruby. Here is a simple example: public class EqualRule extends Rule { private boolean frozen; private int target; public EqualRule() { frozen = false; } public void setTarget(int i) { if (frozen) throw new IllegalStateException( "Can't change frozen rule."); target = i; } public int getTarget() { return target; } public void freeze() { frozen = true; } @Override public boolean checkRule(int i) { return (target == i); } } and "Rule" is just an abstract class that has an abstract "checkRule" method. This cuts way down on the number of objects I need to write, while also giving me an object that becomes immutable for all intents and purposes. This kind of act like the object was its own Builder... But not quite. I'm not too excited, however, about having an immutable being disguised as a bean however. So I had two questions: 1. Before I go too far down this path, are there any huge problems that anyone sees right off the bat? For what it's worth, it is planned that this behavior will be well documented... 2. If so, is there a better solution? Thanks

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  • Consistency vs. Usability?

    - by dsimcha
    When designing an API, consistency often aids usability. However, sometimes they conflict where an extra API feature can be added to streamline a common case. It seems like there's somewhat of a divide over what to do here. Some designs (the Java standard library come to mind) favor consistency even if it makes common cases more verbose. Others (the Python standard library comes to mind) favor usability even if it means treating the common case as "special" to make it easier. What is your opinion on how consistency and usability should be balanced?

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  • What is a 'good number' of exceptions to implement for my library?

    - by Fuzz
    I've always wondered how many different exception classes I should implement and throw for various pieces of my software. My particular development is usually C++/C#/Java related, but I believe this is a question for all languages. I want to understand what is a good number of different exceptions to throw, and what the developer community expect of a good library. The trade-offs I see include: More exception classes can allow very fine grain levels of error handling for API users (prone to user configuration or data errors, or files not being found) More exception classes allows error specific information to be embedded in the exception, rather than just a string message or error code More exception classes can mean more code maintenance More exception classes can mean the API is less approachable to users The scenarios I wish to understand exception usage in include: During 'configuration' stage, which might include loading files or setting parameters During an 'operation' type phase where the library might be running tasks and doing some work, perhaps in another thread Other patterns of error reporting without using exceptions, or less exceptions (as a comparison) might include: Less exceptions, but embedding an error code that can be used as a lookup Returning error codes and flags directly from functions (sometimes not possible from threads) Implemented an event or callback system upon error (avoids stack unwinding) As developers, what do you prefer to see? If there are MANY exceptions, do you bother error handling them separately anyway? Do you have a preference for error handling types depending on the stage of operation?

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  • overriding implemented base class methods

    - by user793468
    I read somewhere that the chain of inheritance breaks when you alter a behavior from derived class. What does "altering a behavior" mean here? Is overriding an already implemented method in base class considered as "altering behavior"? Or, does the author mean altering method signatures and the output? Also, I ready Duplicating code is not a good practice, and its a maintenance nightmare. Again, does overriding an already implemented method in base class considered "Duplicating code"? If not, what would be considered as "Duplicating code"? I

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  • How should compound words be handled when coding? Is there a definitive list of compound words? [closed]

    - by Ray
    QUESTION: How should you handle compound words when programming? Are there any good lists available online for developers of generally accepted technology-related compound words? I can see how this is highly ambiguous, so should I just use common-sense? EXAMPLE: I would be inclined to do this: filename NOT FileName or login NOT LogIn However, the microsoft documentation indicates that filename is not compound. So I wonder, is there a more definitive source? See also, this english.stackexchange discussion on filename. Under the section "Capitalization Rules for Compound Words and Common Terms" located here: Microsoft .NET Capitalization Conventions only offers a limited introduction into the topic, and leaves it up to the developer to use their intuition with the rest.

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  • Creating new games on Android and/or iPhone

    - by James Clifton
    I have a succesfull facebook poker game that is running very nicely, now some people have asked if I can port this to other platforms - mainly mobile devices (and I have been asked to make a tablet version, do I really need a seperate version?) I am currently a PHP programmer (and game designer) and I simply dont' have the time to learn Android and other languages - so I have decided to pay third parties to program them (if viable). The information I need to know is what programming language is needed for the following four devices - Android mobile phone, iPhone, iPad and tablets? Can they all run off a central sql database? If they can't then i'm not interested :( Do any of these run FLASH? Have I covered all my main bases here? For example if a person programs for a ANDROID mobile phone is that to much differant to an ANDROID tablet? They will have slightly differant graphics (because the tablet has a greater screen area might as well use it) but do they need to be started from scratch? Same goes for iPhone/iPad, do they really need to be programmed differantly if the only differance is the graphics?

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  • Self-Executing Anonymous Function vs Prototype

    - by Robotsushi
    In Javascript there are a few clearly prominent techniques for create and manage classes/namespaces in javascript. I am curious what situations warrant using one technique vs. the other. I want to pick one and stick with it moving forward. I write enterprise code that is maintained and shared across multiple teams, and I want to know what is the best practice when writing maintainable javascript ? I tend to prefer Self-Executing Anonymous Functions however I am curious what the community vote is on these techniques. Prototype : function obj() { } obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test(); Self-Closing Anonymous Function : //Self-Executing Anonymous Function (function( skillet, $, undefined ) { //Private Property var isHot = true; //Public Property skillet.ingredient = "Bacon Strips"; //Public Method skillet.fry = function() { var oliveOil; addItem( "\t\n Butter \n\t" ); addItem( oliveOil ); console.log( "Frying " + skillet.ingredient ); }; //Private Method function addItem( item ) { if ( item !== undefined ) { console.log( "Adding " + $.trim(item) ); } } }( window.skillet = window.skillet || {}, jQuery )); //Public Properties console.log( skillet.ingredient ); //Bacon Strips //Public Methods skillet.fry(); //Adding Butter & Fraying Bacon Strips //Adding a Public Property skillet.quantity = "12"; console.log( skillet.quantity ); //12 //Adding New Functionality to the Skillet (function( skillet, $, undefined ) { //Private Property var amountOfGrease = "1 Cup"; //Public Method skillet.toString = function() { console.log( skillet.quantity + " " + skillet.ingredient + " & " + amountOfGrease + " of Grease" ); console.log( isHot ? "Hot" : "Cold" ); }; }( window.skillet = window.skillet || {}, jQuery )); //end of skillet definition try { //12 Bacon Strips & 1 Cup of Grease skillet.toString(); //Throws Exception } catch( e ) { console.log( e.message ); //isHot is not defined } I feel that I should mention that the Self-Executing Anonymous Function is the pattern used by the jQuery team. Update When I asked this question I didn't truly see the importance of what I was trying to understand. The real issue at hand is whether or not to use new to create instances of your objects or to use patterns which do not require constructors of the use of the new keyword. I added my own answer, because in my opinion we should make use of patterns which don't use the new keyword. For more information please see my answer.

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  • How to determine if class meets single responsibility principle ?

    - by user1483278
    Single Responsibility Principle is based on high cohesion principle. The difference between the two is that highly cohesive classes feature a set of responsibilities that are strongly related, while classes adhering to SRP have just one responsibility. But how do we determine whether particular class features a set of responsibilities and is thus just highly cohesive, or whether it has only one responsibility and is thus adhering to SRP? Namely, isn't it more or less subjective, since some may find class very granular ( and as such will consider a class as adhering to SRP ), while others may find it not granular enough?

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  • How do I deal with the problems of a fast side-scroller?

    - by Ska
    I'm making a side scrolling airplane game and when I begin going very fast I begin to experience some problems as a player: Elements are not distinguishable, like power-ups from bullets, etc I start to feel dizzy and uncomfortable There isn't enough time to see what's coming How can I sort this out? Do I use less details in all the grahpics? Tiny Wings has the same horizontal movement speed as in my game but it doesn't suffer from these problems. Are there any other really fast side-scrollers I could take as a reference?

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  • Why do old programming languages continue to be revised?

    - by SunAvatar
    This question is not, "Why do people still use old programming languages?" I understand that quite well. In fact the two programming languages I know best are C and Scheme, both of which date back to the 70s. Recently I was reading about the changes in C99 and C11 versus C89 (which seems to still be the most-used version of C in practice and the version I learned from K&R). Looking around, it seems like every programming language in heavy use gets a new specification at least once per decade or so. Even Fortran is still getting new revisions, despite the fact that most people using it are still using FORTRAN 77. Contrast this with the approach of, say, the typesetting system TeX. In 1989, with the release of TeX 3.0, Donald Knuth declared that TeX was feature-complete and future releases would contain only bug fixes. Even beyond this, he has stated that upon his death, "all remaining bugs will become features" and absolutely no further updates will be made. Others are free to fork TeX and have done so, but the resulting systems are renamed to indicate that they are different from the official TeX. This is not because Knuth thinks TeX is perfect, but because he understands the value of a stable, predictable system that will do the same thing in fifty years that it does now. Why do most programming language designers not follow the same principle? Of course, when a language is relatively new, it makes sense that it will go through a period of rapid change before settling down. And no one can really object to minor changes that don't do much more than codify existing pseudo-standards or correct unintended readings. But when a language still seems to need improvement after ten or twenty years, why not just fork it or start over, rather than try to change what is already in use? If some people really want to do object-oriented programming in Fortran, why not create "Objective Fortran" for that purpose, and leave Fortran itself alone? I suppose one could say that, regardless of future revisions, C89 is already a standard and nothing stops people from continuing to use it. This is sort of true, but connotations do have consequences. GCC will, in pedantic mode, warn about syntax that is either deprecated or has a subtly different meaning in C99, which means C89 programmers can't just totally ignore the new standard. So there must be some benefit in C99 that is sufficient to impose this overhead on everyone who uses the language. This is a real question, not an invitation to argue. Obviously I do have an opinion on this, but at the moment I'm just trying to understand why this isn't just how things are done already. I suppose the question is: What are the (real or perceived) advantages of updating a language standard, as opposed to creating a new language based on the old?

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  • Triggering Data Changes in N-Tier

    - by Ryan Kinal
    I've been studying n-tier architectures as of late, particularly in VB.NET with Entity Framework and/or LINQ to SQL. I understand the basic concepts, but have been wondering about best practices in regard to triggering CRUD-type operations from user input/action. So, the arcitecture looks something like the following: [presentation layer] - [business layer] - [data layer] - (database) Getting information from the database into the presentation layer is simple and abstracted. It's just a matter of instantiating a new object from the business layer, which in turn uses the data layer to get at the correct information. However, saving (updating and inserting), and deleting seem to require particular APIs on the relevant business objects. I have to assume this is standard practice, unless a business object will save itself on various operations (which seems inefficient), or on disposal (which seems like it just wouldn't work, or may be unwieldy and unreliable). Should my "savable" business objects all implement a particular "ISavable" or "IDatabaseObject" interface? Is this a recognized (anti-)pattern? Are there other, better patterns I should be using that I'm just unaware of? The TLDR question, I suppose, is How does the presentation layer trigger database changes?

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  • Should developers make their games easier with new versions?

    - by Gil Kalai
    It seems that the game Angry Birds is becoming gradually easier with new versions. Maybe so people get the illusion of progress and satisfaction of breaking new records? I would like to know if gradual small modifications of games to enhance the sense of improvement and learning by users is known/common/standard practice in game developing. (I don't mean to say that there is anything wrong with such a practice.)

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  • Java word scramble game [closed]

    - by Dan
    I'm working on code for a word scramble game in Java. I know the code itself is full of bugs right now, but my main focus is getting a vector of strings broken into two separate vectors containing hints and words. The text file that the strings are taken from has a colon separating them. So here is what I have so far. public WordApp() { inputRow = new TextInputBox(); inputRow.setLocation(200,100); phrases = new Vector <String>(FileUtilities.getStrings()); v_hints = new Vector<String>(); v_words = new Vector<String>(); textBox = new TextBox(200,100); textBox.setLocation(200,200); textBox.setText(scrambled + "\n\n Time Left: \t" + seconds/10 + "\n Score: \t" + score); hintBox = new TextBox(200,200); hintBox.setLocation(300,400); hintBox.hide(); Iterator <String> categorize = phrases.iterator(); while(categorize.hasNext()) { int index = phrases.indexOf(":"); String element = categorize.next(); v_words.add(element.substring(0,index)); v_hints.add(element.substring(index +1)); phrases.remove(index); System.out.print(index); } The FileUtilities file was given to us by the pofessor, here it is. import java.util.*; import java.io.*; public class FileUtilities { private static final String FILE_NAME = "javawords.txt"; //------------------ getStrings ------------------------- // // returns a Vector of Strings // Each string is of the form: word:hint // where word contains no spaces. // The words and hints are read from FILE_NAME // // public static Vector<String> getStrings ( ) { Vector<String> words = new Vector<String>(); File file = new File( FILE_NAME ); Scanner scanFile; try { scanFile = new Scanner( file); } catch ( IOException e) { System.err.println( "LineInput Error: " + e.getMessage() ); return null; } while ( scanFile.hasNextLine() ) { // read the word and follow it by a colon String s = scanFile.nextLine().trim().toUpperCase() + ":"; if( s.length()>1 && scanFile.hasNextLine() ) { // append the hint and add to collection s+= scanFile.nextLine().trim(); words.add(s); } } // shuffle Collections.shuffle(words); return words; } }

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  • Traverse tree with results. Maybe type in Java?

    - by Angelo.Hannes
    I need to check a tree's node state. It can either be OK or NOT_OK. But that state is dependent on its children. So for a node to be OK, every of its children needs to be OK. If one or more of its children is NOT_OK the whole node is NOT_OK. To determine the state of a node I need to aggregate some properties of the node. So I thought of two possible implementations. And they are more or less covered in this question: Why is Option/Maybe considered a good idea and checked exceptions are not? Exception I could pass the properties up the recursion path, and throw an exception if something went wrong. Maybe I implement an Maybe type and let it either hold an error or the aggregated properties. Maybe it is more an Either. I tend towards the last option. And I'm thinking of an enum with two objects. Where I can additionally set those aggregated properties. Am I on the right track? I'm not familiar with the new JDK8 functional stuff. But I'm stuck on JDK7 anyway, so please focus on JDK7.

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  • Implementing new required feature after software release

    - by TiagoBrenck
    Fake Scenario There is a software that was released 1 year ago. The software is to map and register all kind of animals on our planet. When the software was released, the client only needed to know the scientific name of the animal, a flag if it is in risk of extinction and a scale of dangerous(that is a fake software and specification, I don't want to discuss this here). There are already 100.000 animals records saved on DB. New Feature One year later, the client wants a new feature. It is really important to him to know the animals classes, and this is a required field. So he asks me to put a field to input the animal class, and this field is required. Or maybe where this animal was discovered. Problem I have already 100.000 recorded animals without a class or where it was discovered, but I need to insert a new column to storage this information and this column can't be null. I don't have a default value for this situation (there isn't a default animal class or where it was discovered). I don't want to keep the requirement rule only on my software, my DB must have this requirement too(I like to keep business rules on DB too). What are the alternatives to solve this situation? I am on a situation that this new feature cannot be previewed or reviewed for the existing records. The time already passed and I can't go back on time to get it

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  • Preferred lambda syntax?

    - by Roger Alsing
    I'm playing around a bit with my own C like DSL grammar and would like some oppinions. I've reserved the use of "(...)" for invocations. eg: foo(1,2); My grammar supports "trailing closures" , pretty much like Ruby's blocks that can be passed as the last argument of an invocation. Currently my grammar support trailing closures like this: foo(1,2) { //parameterless closure passed as the last argument to foo } or foo(1,2) [x] { //closure with one argument (x) passed as the last argument to foo print (x); } The reason why I use [args] instead of (args) is that (args) is ambigious: foo(1,2) (x) { } There is no way in this case to tell if foo expects 3 arguments (int,int,closure(x)) or if foo expects 2 arguments and returns a closure with one argument(int,int) - closure(x) So thats pretty much the reason why I use [] as for now. I could change this to something like: foo(1,2) : (x) { } or foo(1,2) (x) -> { } So the actual question is, what do you think looks best? [...] is somewhat wrist unfriendly. let x = [a,b] { } Ideas?

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  • Is it okay to showcase templates/layouts recreated in different codes in a portfolio?

    - by Souta
    I have several different templates/layouts, both simple and complex. I recreated these templates multiple times, just using different codes. (Say, a complex one was originally made in only HTML and CSS, I recreated it using HTML, Javascript, CSS, then again with a HTML and PHP concoction, and etc.) I wanted to showcase my work and skills by doing this, but I don't know if it would be okay for that all to go into a resumé/portfolio. This is why: Freelancing Does potential business really care about how their site is made, as long as it looks and functions to their liking? (As in, should I just only show the one example of each template/layout and not the multiple recreations?) Potential Hire However, if a potential employer were to stumble across my resumé/portfolio, would having the multiple recreations do any good for a career outlook? (As in, this potential employer is a company where I could be working on a team to create/develop sites and not be freelancing; would a lack of skill-shining turn this employer away because I didn't set myself apart and show that I'm not just like every other budding web designer?) Those two issues have me wondering if it is okay to have a resumé/portfolio combined for this specific reason. Or does something like this not matter to potential business (as a freelancer) because they wouldn't care either way as long as it looks and functions to their liking and therefore it is okay to showcase the recreations with the originals?

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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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  • Master Data Management

    - by Logicalj
    I am looking for a very flexible, easy to integrate and dynamic application with as many features as possible for Master Data Management. As Master Data Management is used to Manage Operational Data, Analytical Data and Master Data so, I want guidance about "What is exactly expected from Master Data Management and What are the Basic and Challenging Scenarios to be covered or resolved in Master Data Management". Please guide me with all the possible aspects of Master Data Management like Data Cleansing, Data Management and Start Data Analyzing, etc.

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  • Cliché monsters to populate a steampunk fantasy setting dwarven dungeon?

    - by Alexander Gladysh
    I'm looking for a list of cliché monsters for a steampunk computer game (assume one kind or another of casual rogue-like RPG), to populate lower levels of ancient dwarven-built dungeons. Dwarves are a technology/science race in the setting I am aiming for. The world is a low-magic one. I'm stuck after listing various mechanical golems, gigantic spiders (every dungeon must have some of them!), and maybe a mechanical barlog as a megaboss. What would player expect? What are the key cultural references for such setting? I know a couple of games with suitable steampunk dwarves, but none are detailed enough in the underworld monsters area. Please point me in the right direction. (If you have a single funny monster suggestion, please mention it in comments, not in answer. ;-) )

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  • does class reference itself static anti pattern in prism

    - by Michael Riva
    I have an application and my desing approach look like this: class Manager { public int State; static Manager _instance = null; public static Manager Instance { get { return _instance; } set { if (_instance == value) return; _instance = value; } } public Manager() { State = 0; Instance=this; } } class Module1 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } class Module2 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } class Module3 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } Manager class already registered in Bootstrapper like : protected override void ConfigureContainer() { base.ConfigureContainer(); Container.RegisterType<Manager>(new ContainerControlledLifetimeManager()); } protected override void InitializeModules() { Manager man= Container.Resolve<Manager>(); } Question is do I need to define my manager object as static in its field to be able to reach its state? Or this is anti pattern or bad for performance?

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  • Player & Level class structure in 2D python console game?

    - by Markus Meskanen
    I'm trying to create a 2D console game, where I have a player who can freely move around in a level (~map, but map is a reserved keyword) and interfere with other objects. Levels construct out of multiple Blocks, such as player(s), rocks, etc. Here's the Block class: class Block(object): def __init__(self, x=0, y=0, char=' ', solid=False): self.x = x self.y = y self.char = char self.solid = solid As you see, each block has a position (x, y) and a character to represent the block when it's printed. Each block also has a solid attribute, defining whether it can overlap with other solids or not. (Two solid blocks cannot overlap) I've now created few subclasses from Block (Rock might be useless for now) class Rock(Block): def __init__(self, x=0, y=0): super(Rock, self).__init__(x, y, 'x', True) class Player(Block): def __init__(self, x=0, y=0): super(Player, self).__init__(x, y, 'i', True) def move_left(self, x=1): ... # How do I make sure Player wont overlap with rocks? self.x -= x And here's the Level class: class Level(object): def __init__(self, name='', blocks=None): self.name = name self.blocks = blocks or [] Only way I can think of is to store a Player instance into Level's attributes (self.player=Player(), or so) and then give Level a method: def player_move_left(self): for block in self.blocks: if block.x == self.player.x - 1 and block.solid: return False But this doesn't really make any sense, why have a Player class if it can't even be moved without Level? Imo. player should be moved by a method inside Player. Am I wrong at something here, if not, how could I implement such behavior?

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  • How to handle sorting of complex objects?

    - by AedonEtLIRA
    How would one sort a list of objects that have more than one sortable element? Suppose you have a simple object Car and car is a defined as such: class Car { public String make; public String model; public int year; public String color; // ... No methods, just a structure / container } I designed a simple framework that would allow for multiple SortOptions to be provided to a Sorter that would then sort the list. interface ISorter<T> { List<T> sort(List<T> items); void addSortOption(ISortOption<T> option); ISortOption<T>[] getSortOptions(); void setSortOption(ISortOption<T> option); } interface ISortOption<T> { String getLabel(); int compare(T t1, T t2); } Example use class SimpleStringSorter extends MergeSorter<String> { { addSorter(new AlphaSorter()); } private static final class AlphaSorter implements ISortOption<String> { // ... implementation of alpha compare and get label } } The issue with this solution is that it is not easily expandable. If car was to ever receive a new field, say, currentOwner. I would need to add the field, then track down the sorter class file, implement a new sort option class then recompile the application for redistribution. Is there an easier more expandable/practical way to sort data like this?

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  • Is programming in layers real?

    - by Aura
    I am fairly new in product development and I am trying to work over a product. The problem that I have realized is that people draw diagrams and charts showing different modules and layers. But as I am working alone (I am my own team) I got a bit confused about the interaction I am facing in the development within the programs and I am wondering whether developing a product in modules is real or not? Maybe I am not a great programmer, but I see no boundaries when data start to travel from frontend to backend.

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