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• Database design and foreign keys: Where should they be added in related tables?

  - by Carvell Fenton

  I have a relatively simple subset of tables in my database for tracking something called sessions. These are academic sessions (think offerings of a particular program). The tables to represent a sessions information are: sessions session_terms session_subjects session_mark_item_info session_marks All of these tables have their own primary keys, and are like a tree, in that sessions have terms, terms have subjects, subjects have mark items, etc. So each on would have at least its "parent's" foreign key. My question is, design wise is it a good idea to include the sessions primary key in the other tables as a foreign key to easily select related session items, or is that too much redundency? If I include the session foreign key (or all parent foreign keys from tables up the heirarchy) in all the tables, I can easily select all the marks for a session. As an example, something like SELECT mark FROM session_marks WHERE sessionID=... If I don't, then I would have to combine selects with something like WHERE something IN (SELECT... Which approach is "more correct" or efficient? Thanks in advance!

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• How to design authentication in a thick client, to be fail safe?

  - by Jay

  Here's a use case: I have a desktop application (built using Eclipse RCP) which on start, pops open a dialog box with 'UserName' and 'Password' fields in it. Once the end user, inputs his UserName and Password, a server is contacted (a spring remote-servlet, with the client side being a spring httpclient: similar to the approaches here.), and authentication is performed on the server side. A few questions related to the above mentioned scenario: If said this authentication service were to go down, what would be the best way to handle further proceedings? Authentication is something that I cannot do away with. Would running the desktop client in a "limited" mode be a good idea? For instance, important features/menus/views will be disabled, rest of the application will be accessible? Should I have a back up authentication service running on a different machine, working as a backup? What are the general best-practices in this scenario? I remember reading about google gears and how it would let you edit and do stuff offline - should something like this be designed? Please let me know your design/architectural comments/suggestions. Appreciate your help.

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• How to amend return value design in OO manner?

  - by FrontierPsycho

  Hello. I am no newb on OO programming, but I am faced with a puzzling situation. I have been given a program to work on and extend, but the previous developers didn't seem that comfortable with OO, it seems they either had a C background or an unclear understanding of OO. Now, I don't suggest I am a better developer, I just think that I can spot some common OO errors. The difficult task is how to amend them. In my case, I see a lot of this: if (ret == 1) { out.print("yadda yadda"); } else if (ret == 2) { out.print("yadda yadda"); } else if (ret == 3) { out.print("yadda yadda"); } else if (ret == 0) { out.print("yadda yadda"); } else if (ret == 5) { out.print("yadda yadda"); } else if (ret == 6) { out.print("yadda yadda"); } else if (ret == 7) { out.print("yadda yadda"); } ret is a value returned by a function, in which all Exceptions are swallowed, and in the catch blocks, the above values are returned explicitly. Oftentimes, the Exceptions are simply swallowed, with empty catch blocks. It's obvious that swalllowing exceptions is wrong OO design. My question concerns the use of return values. I believe that too is wrong, however I think that using Exceptions for control flow is equally wrong, and I can't think of anything to replace the above in a correct, OO manner. Your input, please?

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• Scalability 101: How can I design a scalable web application using PHP?

  - by Legend

  I am building a web-application and have a couple of quick questions. From what I learnt, one should not worry about scalability when initially building the app and should only start worrying when the traffic increases. However, this being my first web-application, I am not quite sure if I should take an approach where I design things in an ad-hoc manner and later "fix" them. I have been reading stories about how people start off with an app that gets millions of users in a week or two. Not that I will face the same situation but I can't help but wonder, how do these people do it? Currently, I bought a shared hosting account on Lunarpages and that got me started in building and testing the application. However, I am interested in learning how to build the same application in a scalable-manner using the cloud, for instance, Amazon's EC2. From my understanding, I can see a couple of components: There is a load balancer that first receives requests and then decides where to route each request This request is then handled by a server replica that then processes the request and updates (if required) the database and sends back the response to the client If a similar request comes in, then a caching mechanism like memcached kicks into picture and returns objects from the cache A blackbox that handles database replication Specifically, I am trying to do the following: Setting up a load balancer (my homework revealed that HAProxy is one such load balancer) Setting up replication so that databases can be synchronized Using memcached Configuring Apache to work with multiple web servers Partitioning application to use Amazon EC2 and Amazon S3 (my application is something that will need great deal of storage) Finally, how can I avoid burning myself when using Amazon services? Because this is just a learning phase, I can probably do with 2-3 servers with a simple load balancer and replication but until I want to avoid paying loads of money accidentally. I am able to find resources on individual topics but am unable to find something that starts off from the big picture. Can someone please help me get started?

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• Is there a design pattern to cut down on code duplication when subclassing Activities in Android?

  - by Daniel Lew

  I've got a common task that I do with some Activities - downloading data then displaying it. I've got the downloading part down pat; it is, of course, a little tricky due to the possibility of the user changing the orientation or cancelling the Activity before the download is complete, but the code is there. There is enough code handling these cases such that I don't want to have to copy/paste it to each Activity I have, so I thought to create an abstract subclass Activity itself such that it handles a single background download which then launches a method which fills the page with data. This all works. The issue is that, due to single inheritance, I am forced to recreate the exact same class for any other type of Activity - for example, I use Activity, ListActivity and MapActivity. To use the same technique for all three requires three duplicate classes, except each extends a different Activity. Is there a design pattern that can cut down on the code duplication? As it stands, I have saved much duplication already, but it pains me to see the exact same code in three classes just so that they each subclass a different type of Activity.

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• Please guide this self-taught Web Developer.

  - by ChickenPuke

  One of the major regrets in life is that I didn't do something with my introversion. I didn't manage to get past the first year of college because of that. I have chosen the path where there are no video games and other time sinks, all I have is the internet to quench my thirst of learning the ins and outs of the field of Web Developing/Designing. Though currently, I'm taking a Web Design Associate course at one of the best Computer Arts and this is the last month of the class. Even though I'm still a sapling, I love this field so much. So basically, At school I'm learning web design while at home I'm teaching myself web-developing. First thing first, returning to college seems impossible at the moment because of some financial problems. I'm pretty comfortable with CSS and HTML and I'm into PHP/MySQL at the moment. Could you please provide me a web-development Curriculum to follow. And do I need to learn about the theories behind? And I think I'm still young(I'm 18 at the time of writing). Is it a good thing or bad thing for choosing this path? I'm glad with my decision but in all honesty, I'm worrying about my future and employment because I'm an undergrad, coming from a country where companies are degree b!tches, it saddens me so. Thank you. (My questions are the bold parts. )

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• Progressive Enhancement vs. Single Page Apps

  - by SeanPlusPlus

  I just got back from a conference in Boston called An Event Apart. A really popular theme amongst the speakers was the idea of progressive enhancement - a site's content should go in the HTML, and JavaScript should only be used to enhance behavior. The arguments that the speakers gave for progressive enhancement were very compelling. Not only is it a solid pattern for supporting older browsers, and devices on a network with low bandwidth, but HTML fails much more gracefully than JavaScript (i.e. markup that is not supported is just ignored, while if a browser throws an exception while executing your script - you are hosed). Jeremy Keith gave a particularly insightful talk about this. But what about single page web apps like Backbone and Angular? The whole design behind these frameworks seems to push the developer toward moving content out of the HTML, and into something like a JSON API. I can not seem to gel these two design patterns: progressive enhancement vs. single page web apps. Are there instances when one is better than the other? Or are they not even antagonistic technologies, and I am missing something here with my mental model?

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• Important Tips to make a user friendly Homepage

  - by Aditi

  We have done a lot of redesign work lately for many online businesses.. There are some basic things we want to stress into any web design which make it usable! Unfortunately most designers care about the graphic elements, clean code & navigation only. Most designers do not realize that a design they did could be a masterpiece to them but for a layman it could be tough to use. It is so very important to understand usability & call to action for any business and then implemented on their website Homepage. Showcase Offering The sole purpose of their websites needs to be mentioned on the homepage, what they are offering, why should one do business with them and why they are better than other competitors. Include a tag line under your logo that explicitly summarizes what the site or company does. Ease of Navigation Make it easier for your user to find what they are looking for, some archives, articles, services etc. A visible and easy to use Navigation allows just that. You may also want to feature some of the most visited content on the homepage itself. Search Form Let your users take advantage of a search form from your homepage, keep it visible enough so if they have trouble locating certain content using your navigation. The Search Bar will come handy in such situation. Especially if you have thousands and thousands of web pages. Liquid Layout There was a time when people used standard resolution, not any more. People have different screen sizes and most people now browse on handhelds. Try keeping liquid width so people can adjust as per their choice. First impression is last impression, leaving one through your perfect homepage can do wonders for your business.

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• What to think about when designing a simple GUI for a quiz game

  - by PeterK

  I am coming close to finish my first iPhone game ever, as a matter of fact also my first programming experience ever, which is a quiz game. I have all the functionality i want and is currently polishing it both from a code point of view as well as looking at the GUI. My initial idea was not to use any specific graphics but rather focus on the game experience and simplicity and by that only using background color, orange, and white text as well as buttons. The design is based on that all ages, from learning to read, should be able to host and play this game. However, as i am now getting close to the finish line i am starting to think what is needed from a GUI point of view. I would like to ask for some advice what to think about when designing a GUI. Is it considered OK without any 'fancy' graphics, what is the risk without it etc.? Also, what colors goes well together if i choose to use a simple GUI. I am thinking about color blindness etc. In other words how do i design a good and effective GUI for a simple game as mine? Thanks

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• Consistency of an object

  - by Stefano Borini

  I tend to keep my objects consistent during their lifetime. In some cases, setting up an object requires multiple calls to different routines. For example, a connection object may operate in this way: Connection c = new Connection(); c.setHost("http://whatever") c.setPort(8080) c.connect() please note this is just a stupid example to let you understand the point. In between calls to setHost and setPort the object is inconsistent, because the Port has not been specified yet, so this code would crash Connection c = new Connection(); c.setHost("http://whatever") c.connect() Meaning that it's a requisite for connect() to have previous calls to both setHost and setPort, otherwise it won't be able to operate as its state is inconsistent. You may fix the issue with a default value, but there may be cases where no sensible default may be devised. We assume in the later example that there's no default for the port, and therefore a call to c.connect() without first calling both setHost and setPort will be an inconsistent state of the object. This, to me, points at an incorrect interface design, but I may be wrong, so I want to hear your opinion. Do you organize your interface so that the object is always in a consistent (i.e. workable) state both before and after the call ? Edit: Please don't try to solve the problem I gave above. I know how to solve that. My question is much broader in sense. I am looking for a design principle, officially or informally stated, regarding consistency of object state between calls.

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• What are the boundaries between the responsibilities of a web designer and a web developer?

  - by Beofett

  I have been hired to do functional development for several web site redesigns. The company I work for has a relatively low technical level, and the previous development of the web sites were completed by a graphic designer who is self taught as far as web development is concerned. My responsibilities have extended beyond basic development, as I have been also tasked with creating the development environment, and migrating hosting from external CMS hosting to internal servers incorporating scripting languages (I opted for PHP/MySQL). I am working with the graphic designer, and he is responsible for the creative design of the web. We are running into a bit of friction over confusion between the boundaries of our respective tasks. For example, we had some differences of opinion on navigation. I was primarily concerned with ease-of-use (the majority of our userbase are not particularly web-savvy), as well as meeting W3 WAI standards (many of our users are older, and we have a higher than average proportion of users with visual impairment). His sole concern was what looked best for the website, and I felt that the direction he was pushing for caused some functional problems. I feel color choices, images, fonts, etc. are clearly his responsibility, and my expectation was that he would simply provide me with the CSS pages and style classes and IDs to use, but some elements of page layout also seem to fall more under the realm of "usability", which to me translates as near-synonymous with "functionality". I've been tasked with selecting the tools we'll use, which include frameworks, scripting languages, database design, and some open source applications (Moodle for example, and quite probably Drupal in the future). While these tools are quite customizable, working directly with some of the interfaces is beyond his familiarity with CSS, HTML, and PHP. This limits how much direct control he has over the appearance, which has lead to some discussion about the tool choices. Is there a generally accepted dividing line between the roles of a web designer and a web developer? Does his relatively inexperienced background in web technologies influence that dividing line?

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• Implementing MVC pattern in SWT application

  - by Pradeep Simha

  I am developing an SWT application (it's basically an Eclipse plugin, so I need to use SWT). Currently my design is as follows: Model: In model, I have POJOs which represents the actual fields in views. View: It is a dumb layer, it contains just UI and contains no logic (not even event handlers) Controller: It acts as a mediator b/w those two layers. Also it is responsible for creating view layer, handling events etc. Basically I have created all of the controls in view as a static like this public static Button btnLogin and in controller I have a code like this: public void createLoginView(Composite comp) { LoginFormView.createView(comp); //This createView method is in view layer ie LoginFormView LoginFormView.btnLogin.addSelectionListener(new SelectionListener() { //Code goes here }); } Similalrly I have done for other views and controls. So that in main class and other classes I am calling just createLoginView of controller. I am doing similar thing for other views. So my question, is what I am doing is correct? Is this design good? Or I should have followed any other approach. Since I am new to SWT and Eclipse plugin development (basically I am Java EE developer having 4+ years of exp). Any tips/pointers would be appreciated.

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• How to Be a Software Engineer?

  - by Mistrio

  My problem is kind of weird so please bear with me. I have been working in a start up concerned basically with mobile development since my graduation 2 years ago. I develop apps for iOS but it's not really relevant. The start up structure is simply founders developers, with no middle-tier technical supervision or project management whatsoever. A typical project cycle of ours is like this: meet with a client send very vague recruitment to an outsourced graphics designer dig in development right after we get the design, no questions asked then improvise improvise improvise! It's not that we are unaware that stuff like requirements analysis, UML, design patterns, source code control, testing, development methodologies... etc. exist, we just simply don't use them, and I mean like never. The result is usually a clunk of hardly-maintainable yet working code. Despite everything we are literally flourishing with many successful apps on all platforms and bigger clients each project. The thing is, we want the chaos and we're looking for advice. How would you fix our company technically? Given that you can't hire project managers or team leaders just because we are barely 5 developers, so it wouldn't be a justified cost for the founders, but one-time things like courses, books, private training... etc is an option. Lastly, if it's relevant, we are based in Egypt. Thank you a lot in advance.

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• Simple Multiplayer CCG System

  - by TobiHeidi

  I am working on a cross plattform Multiplayer CCG (web, android, ios). Here are my goals in design: I want to game to be easly accessible and understandable for non CCG players within the first minute of play. a single game should be played by 2 - 4 players a once, without problems if one players drops out during play. players should make their next turn simultaneous (without waiting for other to make their turns) My current approach: each Card has a point value for four Elements. In each Turn an Element is (randomly) selected and every Player chooses 1 card out of 3. The Player choosen the card with the highest value for that element wins the Round. After 10 Rounds the players a ranked by how many rounds they won. Why does this approach seems not optimal? It seems really to easy to determin the next best turn. Your own turn is to little affected by the play style of the others. I would love the have a system where some cards are better against other cards. A bit of rock paper scissors where you have to think about what next turn the other players will make or so. But really think freely. I would love to hear ideas may it be additions or new systems to make a CCG with roughly the stated design goals. Thanks

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• Should one always know what an API is doing just by looking at the code?

  - by markmnl

  Recently I have been developing my own API and with that invested interest in API design I have been keenly interested how I can improve my API design. One aspect that has come up a couple times is (not by users of my API but in my observing discussion about the topic): one should know just by looking at the code calling the API what it is doing. For example see this discussion on GitHub for the discourse repo, it goes something like: foo.update_pinned(true, true); Just by looking at the code (without knowing the parameter names, documentation etc.) one cannot guess what it is going to do - what does the 2nd argument mean? The suggested improvement is to have something like: foo.pin() foo.unpin() foo.pin_globally() And that clears things up (the 2nd arg was whether to pin foo globally, I am guessing), and I agree in this case the later would certainly be an improvement. However I believe there can be instances where methods to set different but logically related state would be better exposed as one method call rather than separate ones, even though you would not know what it is doing just by looking at the code. (So you would have to resort to looking at the parameter names and documentation to find out - which personally I would always do no matter what if I am unfamiliar with an API). For example I expose one method SetVisibility(bool, string, bool) on a FalconPeer and I acknowledge just looking at the line: falconPeer.SetVisibility(true, "aerw3", true); You would have no idea what it is doing. It is setting 3 different values that control the "visibility" of the falconPeer in the logical sense: accept join requests, only with password and reply to discovery requests. Splitting this out into 3 method calls could lead to a user of the API to set one aspect of "visibility" forgetting to set others that I force them to think about by only exposing the one method to set all aspects of "visibility". Furthermore when the user wants to change one aspect they almost always will want to change another aspect and can now do so in one call.

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• Implementing game rules in a tactical battle board game

  - by Setzer22

  I'm trying to create a game similar to what one would find in a typical D&D board game combat. For mor examples you could think of games like Advance Wars, Fire Emblem or Disgaea. I should say that I'm using design by component so far, but I can't find a nice way to fit components into the part I want to ask. I'm struggling right now with the "game rules" logic. That is, the code that displays the menu, allows the player to select units, and command them, then tells the unit game objects what to do given the player input. The best way I could thing of handling this was using a big state machine, so everything that could be done in a "turn" is handled by this state machine, and the update code of this state machine does different things depending on the state. This approach, though, leads to a large amount of code (anything not model-related) to go into a big class. Of course I can subdivide this big class into more classes, but it doesn't feel modular and upgradable enough. I'd like to know of better systems to handle this in order to be able to upgrade the game with new rules without having a monstruous if/else chain (or switch / case, for that matter). So, any ideas? I'd also like to ask that if you recommend me a specific design pattern to also provide some kind of example or further explanation and not stick to "Yeah you should use MVC and it'll work".

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• How to use the unit of work and repository patterns in a service oriented enviroment

  - by A. Karimi

  I've created an application framework using the unit of work and repository patterns for it's data layer. Data consumer layers such as presentation depend on the data layer design. For example a CRUD abstract form has a dependency to a repository (IRepository). This architecture works like a charm in client/server environments (Ex. a WPF application and a SQL Server). But I'm looking for a good pattern to change or reuse this architecture for a service oriented environment. Of course I have some ideas: Idea 1: The "Adapter" design pattern Keep the current architecture and create a new unit of work and repository implementation which can work with a service instead of the ORM. Data layer consumers are loosely coupled to the data layer so it's possible but the problem is about the unit of work; I have to create a context which tracks the objects state at the client side and sends the changes to the server side on calling the "Commit" (Something that I think the RIA has done for Silverlight). Here the diagram: ----------- CLIENT----------- | ------------------ SERVER ---------------------- [ UI ] -> [ UoW/Repository ] ---> [ Web Services ] -> [ UoW/Repository ] -> [DB] Idea 2: Add another layer Add another layer (let say "local services" or "data provider"), then put it between the data layer (unit of work and repository) and the data consumer layers (like UI). Then I have to rewrite the consumer classes (CRUD and other classes which are dependent to IRepository) to depend on another interface. And the diagram: ----------------- CLIENT ------------------ | ------------------- SERVER --------------------- [ UI ] -> [ Local Services/Data Provider ] ---> [ Web Services ] -> [ UoW/Repository ] -> [DB] Please note that I have the local services layer on the current architecture but it doesn't expose the data layer functionality. In another word the UI layer can communicate with both of the data and local services layers whereas the local services layer also uses the data layer. | | | | | | | | ---> | Local Services | ---> | | | UI | | | | Data | | | | | | | ----------------------------> | |

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• How common is prototyping as the first stage of development?

  - by EpsilonVector

  I've been taking some software design courses in the past few semesters, and while I see the benefit in a lot of the formalism, I feel like it doesn't tell me anything about the program itself: You can't tell how the program is going to operate from the Use Case spec, even though it discusses what the program can do. You can't tell anything about the user experience from the requirements document, even though it can include quality requirements. Sequence diagrams are a good description of how the software works as the call stack, but are very limited, and give a highly partial view of the overall system. Class diagrams are great for describing how the system is built, but are utterly useless in helping you figure out what the software needs to be. Where in all this formalism is the bottom line: how the program looks, operates, and what experience it gives? Doesn't it make more sense to design off of that? Isn't it better to figure out how the program should work via a prototype and strive to implement it for real? I know that I'm probably suffering from being taught engineering by theoreticians, but I need to ask, do they do this in the industry? How do people figure out what the program actually is, not what it should conform to? Do people prototype a lot, or do they mostly use the formal tools like UML and I just didn't get the hang of using them yet?

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• How common is prototyping as the first stage of development?

  - by EpsilonVector

  I've been taking some software design courses in the past few semesters, and while I see the benefit in a lot of the formalism, I still feel like it doesn't tell me anything about the program itself. You can't tell how the program is going to operate from the Use Case spec, even though it discusses what the program can do, and you can't tell anything about the user experience from the requirements document, even though it can include QA requirements. ...sequence diagrams are as good a description of how the software works as the call stack, in other words- very limited, highly partial view of the overall system, and a class diagram is great for describing how the system is built, but is utterly useless in helping you figure out what the software needs to be. Where in all this formalism is the bottom line- how the program looks, operates, and what experience it gives? Doesn't it make more sense to design off of that? Isn't it better to figure out how the program should work via a prototype and strive to implement it for real? I know that I'm probably suffering from being taught engineering by theoreticians, but I got to ask, do they do this in the industry? How do people figure out what the program actually is, not what it should conform to? Do people prototype a lot? ...or do they mostly use the formal tools like UML and I just didn't get the hang of using them yet?

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• How or why would this mechanic (not) work to bring game balance to a singleplayer RPG? [closed]

  - by 0xFFF1

  Mechanic details The player, the monsters, and the merchants act as three separate parties. The player needs to beat up monsters for exp points and resources to sell and to buy potions from merchants to continue to fight. The monsters need healing and reviving to survive (also bought from merchants) and the merchants need potion ingredients from the player and the monsters to make potions to sell. These potions are only able to be processed in such bulk by merchants thus their potions would be cheaper than making them yourself. Only the monsters can farm ingredients in bulk. Only the player is or has to be overly aggressive (in bulk). Monsters can farm and produce "Level up candies" that do the work of exp. they are eaten right away after they are made and are never stockpiled or held for fear of the player and merchants who want to sell to the player. The monsters will defend themselves. Reviving is very expensive. The merchants can be found either with a concerned expression or a grinning expression based on how much profit they are making compared to their morale standing. The economies of each monster town and merchant city are distinct but interconnected. Magic Swords are worth a lot. So what I need to know is what concerns would there be to design a game around this mechanic and/or design this mechanic around a developing game. which would fare better? Is game balance an issue here? (how strong the monsters get or how quickly they die off based on the player's input into the system), Or is game balance solely in the hands of the player? (he decides if he overkills monsters or get underleveled.) What do I need to think about to make sure it isn't too easy or too hard to swing the amount/strength of monsters compared to the player and the amount of profit the merchants get vs the player. Would indicating how out of whack things are getting in game help with this?

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• Be liberal in what you accept... or not?

  - by Matthieu M.

  [Disclaimer: this question is subjective, but I would prefer getting answers backed by facts and/or reflexions] I think everyone knows about the Robustness Principle, usually summed up by Postel's Law: Be conservative in what you send; be liberal in what you accept. I would agree that for the design of a widespread communication protocol this may make sense (with the goal of allowing easy extension), however I have always thought that its application to HTML / CSS was a total failure, each browser implementing its own silent tweak detection / behavior, making it near impossible to obtain a consistent rendering across multiple browsers. I do notice though that there the RFC of the TCP protocol deems "Silent Failure" acceptable unless otherwise specified... which is an interesting behavior, to say the least. There are other examples of the application of this principle throughout the software trade that regularly pop up because they have bitten developpers, from the top off my head: Javascript semi-colon insertion C (silent) builtin conversions (which would not be so bad if it did not truncated...) and there are tools to help implement "smart" behavior: name matching phonetic algorithms (Double Metaphone) string distances algorithms (Levenshtein distance) However I find that this approach, while it may be helpful when dealing with non-technical users or to help users in the process of error recovery, has some drawbacks when applied to the design of library/classes interface: it is somewhat subjective whether the algorithm guesses "right", and thus it may go against the Principle of Least Astonishment it makes the implementation more difficult, thus more chances to introduce bugs (violation of YAGNI ?) it makes the behavior more susceptible to change, as any modification of the "guess" routine may break old programs, nearly excluding refactoring possibilities... from the start! And this is what led me to the following question: When designing an interface (library, class, message), do you lean toward the robustness principle or not ? I myself tend to be quite strict, using extensive input validation on my interfaces, and I was wondering if I was perhaps too strict.

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• Capitalizing on JavaScript's prototypal inheritance

  - by keithjgrant

  JavaScript has a class-free object system in which objects inherit properties directly from other objects. This is really powerful, but it is unfamiliar to classically trained programmers. If you attempt to apply classical design patterns directly to JavaScript, you will be frustrated. But if you learn to work with JavaScript's prototypal nature, your efforts will be rewarded. ... It is Lisp in C's clothing. -Douglas Crockford What does this mean for a game developer working with canvas and HTML5? I've been looking over this question on useful design patterns in gaming, but prototypal inheritance is very different than classical inheritance, and there are surely differences in the best way to apply some of these common patterns. For example, classical inheritance allows us to create a moveableEntity class, and extend that with any classes that move in our game world (player, monster, bullet, etc.). Sure, you can strongarm JavaScript to work that way, but in doing so, you are kind of fighting against its nature. Is there a better approach to this sort of problem when we have prototypal inheritance at our fingertips?

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• Testcase runner for parametrized testcases

  - by Razer

  Let me explain my situation. I'm planning a kind of test case runner for doing testcases on external devices, which are microcontroller based. Lets consider the devices: Device 1 Device 2 There exist a lot of test cases which can be run with one of the devices above. For example: Testcase 1 Testcase 2 The main reason that all the testcases can be run with any device is, that the testcases validates some standard and this software should be extensible for future devices. The testcases itself must be runnable with changing parameters. For example Testcase 1 does some Timing Verification the testcase needs as input parameter the datarate: 4800, 9600, 19200. Now hoping you understand the situation, let me explain my design questions. For implementing the test cases I thought about an Attribute based approach, like nunit does it. The more complicated problem is, how to define the parametrized testcases? Like this: Device 1: Testcase 1: datarate: 4800, 9600, 19200 Testcase 2: supply: 1, 2, 3 Device 2: Testcase 1: datarate: 9600, 19200, 38400 Testcase 2: supply: 3, 4, 5 How would you design such a framework? I've done a similar desin in python where I had for every device a XML containing the testcase definitions like: <Testcase="Testcase 1" datarate=4800/> <Testcase="Testcase 1" datarate=9600/> <Testcase="Testcase 1" datarate=19200/>

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• Designing web-based plugin systems correctly so they don't waste as many resources?

  - by Xeoncross

  Many CMS systems which rely on third parties for much of their code often build "plugin" or "hooks" systems to make it easy for developers to modify the codebase's actions without editing the core files. This usually means an Observer or Event design pattern. However, when you look at systems like wordpress you see that on every page they load some kind of bootstrap file from each of the plugin's folders to see if that plugin will need to run that request. Its this poor design that causes systems like wordpress to spend many extra MB's of memory loading and parsing unneeded items each page. Are there alternative ways to do this? I'm looking for ideas in building my own. For example, Is there a way to load all this once and then cache the results so that your system knows how to lazy-load plugins? In other words, the system loads a configuration file that specifies all the events that plugin wishes to tie into and then saves it for future requests? If that also performs poorly, then perhaps there is a special file-structure that could be used to make educated guesses about when certain plugins are unneeded to fullfil the request. Any ideas? If anyone wants an example of the "plugin" concept you can find one here.

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• Designing a plug-in system

  - by madflame991

  I'm working on a Java project and I would like to add a plug-in system. More precisely, I would like to let the user design his own module, pack it into a jar, leave it in a "plugins/" subfolder of my application and be done with it. I've managed to get a child classloader to instantiate objects of classes located in external jars, but now I'm facing a design dilemma: Say Joe makes a plug-in and he packs it in joeplugin.jar. I would really like Joe to have a class named "instantiation.Factory" and I would also like everyone to have this class with this exact location and name. (This factory class obviously implements a interface that I provide and through it I get what I want from the plug-in.) If Joe wouldn't be restricted in this way I would have to look into his entire jar for some class that implements my factory interface and I don't want to imagine how complicated things get. So my question is: should I enforce a strict naming convention for this single class? I have no idea how plug-in systems work.

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