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• What could be the best way to generalize data from Facebook and Twitter?

  - by Sjaak van der Heide

  I am not sure if this is the best subsite to ask this question, but I'm pretty sure it doesn't fit on the normal or facebook SO page... I've been asked to make a general API for connecting to several Social Media platforms (at the moment Facebook and Twitter). I have already realised both of them seperately. Meaning I retrieve the data I need from both Facebook and Twitter and hold the data in it's own dataclass. In my case a list of FacebookTimelineItems and a list of TwitterTimelineItems. now the hard part is taking the parts that are used in both (username, id, message and such) and make 1 general class that is eventually passed on to who/whatever sent the call to my API. these are two pics of the data classes I have: http://imageshack.us/photo/my-images/703/facebookdata.png/ http://imageshack.us/photo/my-images/204/twitterdata.png/ probably not 100% correct but it gives an idea what it looks like. Now I've been having several idea about how to go about and generalize the two, which is harder then I thought at first. Create an interface (TimelineItem) and let the other classes extend that one. this way I'll always be sure I have a class that contains at least the basic info I need. downside is that deserializing the JSON seems to be a nightmare. Use the two dataclasses I have and combine them into a new class afterwards, then pass that one back to whoever requested it. This would probably work but I get the idea it's not the best way to tackle this problem, and is pretty dodgy IF I get it working. Or, in case of the other two being nearly impossible. Keep the two seperated in the front end, and go sit in the corner crying because I've just figured out you can't lump together facebook and twitter... Note: I don't have to make the front end part (view), I just make sure the Model is nicely filled with data :) I hope I placed this in the right section, if I didn't I apologise and would like to know where I should go with my question. Thanks in advance for any replied/ideas/opinions on this.

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• Interesting Topics in Comp. Sci. for New Students?

  - by SoulBeaver

  I hope this is the right forum to ask this question. Last friday I was in a discussion with my professors about the students' lack of motivation and interest in the field of Computer Science. All of the students are enrolled, but through questionnaires and other questions that my professor posed it was revealed that over 90% of all enrolled students are just in it for the reward of getting a job sometime in the future (since it's a growing field with high job potential) I asked my professor for the permission to take over the first couple of lectures and try and motivate, interest and inspire students for the field of Computer Science and programming in particular (this is the Intro to Programming course). This request was granted and I now have a week to come up with a lecture topic for my professor's five groups. My main goal isn't to teach, I just want to get students to be as interested in the field as I am. I want to show them what's possible, what awesome magical things have been done in the field, the future we are heading towards using programming and Comp. Sci. Therefore, I would like to pose this question: I have a few topics, materials and sample projects that I would like to talk about: -- Grace Hopper (It is my hope to interest the female programmers in the class. There are never more than two or three per group and they, more than males, are prone to jumping ship and abandoning Comp. Sci.) -- The Singularity Institute -- Alan Turing -- Robotics -- Programming not as a chore or a must, but the idea that we are, at our core, the nexus to which anything anybody does in the digital world is connected to. We are the problem solvers; we assemble all the parts together and we are the ones that, essentially, make the vision a reality. -- Give them an idea for a programming project which, through the help of the professor, could be significant to every student (I want students to not only feel interested in the topic, but they should feel important, that what they do here makes a difference) Do you have interesting topics worthy of discussion, something I can tell the students which they can get interested about? How would you approach the lecture? If you had 90 minutes worth of time to try and get students interested in the project, what would you do?

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• What shall I include in a 10 week web technologies course?

  - by Iain

  In September I will be teaching a university module on web technologies. This session will be available to 1st year (freshman) students who don't necessarily have any programming knowledge or know how the web works. In the 2nd semester I will be teaching Flash, which is my specialism, so I know exactly what I am going to teach, but in the 1st semester I will be teaching them web standards technologies - HTML, CSS, JS, jQuery, PHP and MySQL. Where I need advice is how to proportion the emphasis for each part, and which parts of each technology to cover. Another real issue I'm struggling with is how much of the bad old ways should I teach them? Do they need to know about bold as well as strong, etc. UPDATE: based, on your feedback I will only be teaching the latest version of everything - CSS3, HTML5 etc. I'm not sure exactly how long the semester will be but I'm guessing about 10-12 weeks. Each session is a 2 hour lab. Obviously there's only so much I can cover in that time and it will be up to the students to go a research this stuff properly on W3 schools etc. My ideas so far were: Lesson 0 - Course intro and overview of the current tech landscape. What is out there, what will we be learning, what won't we. What is a web server, URL etc. Looking at different example websites and discussing how they work. Lesson 1 - HTML basics (head, body, title, img, table, a, lists, h1, strong etc) Lesson 2 - CSS for styling and layout - fonts, webfonts, float etc Lesson 3 - Intro to programming JS (variables, loops, conditionals, functions) Lesson 4 - more JS programming fundamentals, DOM manipulation Lesson 5 - jQuery - making things fly about and look cool Lesson 6 - XML and Ajax Lesson 7 - PHP basics - syntax, server-side principles Lesson 8 - PHP and MySQL - forms, logins, saving user info Lesson 9 - don't know Lesson 10 - don't know Please let me know if you think this is the right order, what have I missed, how to use any spare sessions etc. Thanks :) UPDATE BASED ON RESPONSES: Thanks for all your responses - some great stuff. To be absolutely clear, this is not a computer science course, it is a practical module on a creative technology course. The emphasis definitely has to be on making cool things work rather than understanding how the backbone of the internet works. That can come later, if the students are interested. At the end of the module I would like the students to be able to produce a web page or pages that does something cool, using some or all of the technologies I cover. Many of these topics are of course far beyond the scope of a 2 hour session, however I do not have the option of reducing the syllabus, I will just have to explain what the technology does and encourage the student to research it in their own time.

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• Caching items in Orchard

  - by Bertrand Le Roy

  Orchard has its own caching API that while built on top of ASP.NET's caching feature adds a couple of interesting twists. In addition to its usual work, the Orchard cache API must transparently separate the cache entries by tenant but beyond that, it does offer a more modern API. Here's for example how I'm using the API in the new version of my Favicon module: _cacheManager.Get( "Vandelay.Favicon.Url", ctx => { ctx.Monitor(_signals.When("Vandelay.Favicon.Changed")); var faviconSettings = ...; return faviconSettings.FaviconUrl; }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } There is no need for any code to test for the existence of the cache entry or to later fill that entry. Seriously, how many times have you written code like this: var faviconUrl = (string)cache["Vandelay.Favicon.Url"]; if (faviconUrl == null) { faviconUrl = ...; cache.Add("Vandelay.Favicon.Url", faviconUrl, ...); } Orchard's cache API takes that control flow and internalizes it into the API so that you never have to write it again. Notice how even casting the object from the cache is no longer necessary as the type can be inferred from the return type of the Lambda. The Lambda itself is of course only hit when the cache entry is not found. In addition to fetching the object we're looking for, it also sets up the dependencies to monitor. You can monitor anything that implements IVolatileToken. Here, we are monitoring a specific signal ("Vandelay.Favicon.Changed") that can be triggered by other parts of the application like so: _signals.Trigger("Vandelay.Favicon.Changed"); In other words, you don't explicitly expire the cache entry. Instead, something happens that triggers the expiration. Other implementations of IVolatileToken include absolute expiration or monitoring of the files under a virtual path, but you can also come up with your own.

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• Travelling at Magenic

  - by Chris G. Williams

  I occasionally get asked if we travel "a lot" at Magenic. Sometimes the question comes from job candidates. Other times it's clients, recruiters or friends. To give a simple yes or no answer would be a disservice to the person asking the question. So here is my standard answer:It depends.(That was the short version.  Here's the long version...)We do have some guys that are more "national" in focus, and they can travel a fair amount. They also receive a little extra in compensation for doing so. It's a balancing act, and not necessarily a one-size-fits-all situation. Not everyone is well suited to constant travel. Some folks enjoy it and some folks hate it.With our local guys, our general policy is to TRY and keep them close to home whenever possible, but sometimes the needs of the client will dictate otherwise. (As Spock would say... the needs of the many outweigh the needs of the few, or the one.)In most cases though, we really do try to avoid sending our guys on extended travel gigs (i.e. every week for 6 months) when a simple kickoff trip and occasional visit will do. This depends on the nature of the gig, of course. Some types of work lend themselves to this model better than others. Additionally, this can and does vary by office. If one office is having trouble staffing a gig (not enough available bodies) and another office has a few too many folks on the bench, well... you can connect the dots. But again, we try to keep that to a minimum.Lastly, we all have our own thresholds for what we consider "a lot" of travel. There are two parts to this threshold:Half of it is whatever you're accustomed to already. The other half is being honest with yourself about how much you [like/hate] dealing with airports, car rentals, taxis, hotels, disruptions to your workout schedule, time away from friends/family, etc.Knowing a bit about yourself will definitely help you decide how much travel is too much for you.

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• Modelling highly specific business requirements

  - by AndyBursh

  How can one go about modelling highly specific business requirements, which have no precedent in the system? Take for example the following requirement: When a purchase order contains N lines, is over X value in total and is being recorded against project Y, an email needs to be sent to persons A and B with the details This requirement supplements other requirements surrounding purchase orders, but comes in at a much later date in response to some ongoing problem elsewhere in the business. Persons A and B are not part of any role or group in the system, and don't hold any specific responsibility; they are simply the two people the business has appointed to receive these emails in this very specific case. Projects are also data driven, so project Y has no special properties to distinguish it from any other project. The only way to identify it is to compare its identifier to a magic number. How can one go about modelling this kind of case without introducing too much additional complexity? That I can think of right now, there are a couple of options. Perform the checks and actions inline with the existing code. Here we find the correct spot in the code, check the conditions in the requirement and send the emails to hardcoded addresses. Of course this is fraught with issues. At the very least it stops working if one of these people leaves or changes their email address. At worst you have to ensure that any tests and test data are aware that additional actions are taken for a specific set of criteria. Introduce some form of events system. Here we introduce an eventing system, so that we might react to some event, and fulfil the requirement outside of the usual path of execution. This sounds like a cleaner solution than option 1, but the work involved is ultimately probably slightly overkill for this one small requirement. That said, having it in place does allow the system to handle these kinds of specific requirements consistently and easily in the future. Are there any other (good/better) ways of handling highly specific requirements? I mean other than telling the other parts of the business no!

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• C Minishell Command Expansion Printing Gibberish

  - by Optimus_Pwn

  I'm writing a unix minishell in C, and am at the point where I'm adding command expansion. What I mean by this is that I can nest commands in other commands, for example: $> echo hello $(echo world! ... $(echo and stuff)) hello world! ... and stuff I think I have it working mostly, however it isn't marking the end of the expanded string correctly, for example if I do: $> echo a $(echo b $(echo c)) a b c $> echo d $(echo e) d e c See it prints the c, even though I didn't ask it to. Here is my code: msh.c - http://pastebin.com/sd6DZYwB expand.c - http://pastebin.com/uLqvFGPw I have a more code, but there's a lot of it, and these are the parts that I'm having trouble with at the moment. I'll try to tell you the basic way I'm doing this. Main is in msh.c, here it gets a line of input from either the commandline or a shellfile, and then calls processline (char *line, int outFD, int waitFlag), where line is the line we just got, outFD is the file descriptor of the output file, and waitFlag tells us whether or not we should wait if we fork. When we call this from main we do it like this: processline (buffer, 1, 1); In processline, we allocate a new line: char expanded_line[EXPANDEDLEN]; We then call expand, in expand.c: expand(line, expanded_line, EXPANDEDLEN); In expand, we copy the characters literally from line to expanded_line until we find a $(, which then calls: static int expCmdOutput(char *orig, char *new, int *oldl_ind, int *newl_ind) orig is line, and new is expanded line. oldl_ind and newl_ind are the current positions in the line and expanded line, respectively. Then we pipe, and recursively call processline, passing it the nested command(for example, if we had "echo a $(echo b)", we would pass processline "echo b"). This is where I get confused, each time expand is called, is it allocating a new chunk of memory EXPANDEDLEN long? If so, this is bad because I'll run out of stack room really quickly(in the case of a hugely nested commandline input). In expand I insert a null character at the end of the expanded string, so why is it printing past it? If you guys need any more code, or explanations, just ask. Secondly, I put the code in pastebin because there's a ton of it, and in my experience people don't like it when I fill up several pages with code. Thanks.

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• Handling bugs, quirks, or annoyances in vendor-supplied headers

  - by supercat

  If the header file supplied by a vendor of something with whom one's code must interact is deficient in some way, in what cases is it better to: Work around the header's deficiencies in the main code Copy the header file to the local project and fix it Fix the header file in the spot where it's stored as a vendor-supplied tool Fix the header file in the central spot, but also make a local copy and try to always have the two match Do something else As an example, the header file supplied by ST Micro for the STM320LF series contains the lines: typedef struct { __IO uint32_t MODER; __IO uint16_t OTYPER; uint16_t RESERVED0; .... __IO uint16_t BSRRL; /* BSRR register is split to 2 * 16-bit fields BSRRL */ __IO uint16_t BSRRH; /* BSRR register is split to 2 * 16-bit fields BSRRH */ .... } GPIO_TypeDef; In the hardware, and in the hardware documentation, BSRR is described as a single 32-bit register. About 98% of the time one wants to write to BSRR, one will only be interested in writing the upper half or the lower half; it is thus convenient to be able to use BSSRH and BSSRL as a means of writing half the register. On the other hand, there are occasions when it is necessary that the entire 32-bit register be written as a single atomic operation. The "optimal" way to write it (setting aside white-spacing issues) would be: typedef struct { __IO uint32_t MODER; __IO uint16_t OTYPER; uint16_t RESERVED0; .... union // Allow BSRR access as 32-bit register or two 16-bit registers { __IO uint32_t BSRR; // 32-bit BSSR register as a whole struct { __IO uint16_t BSRRL, BSRRH; };// Two 16-bit parts }; .... } GPIO_TypeDef; If the struct were defined that way, code could use BSRR when necessary to write all 32 bits, or BSRRH/BSRRL when writing 16 bits. Given that the header isn't that way, would better practice be to use the header as-is, but apply an icky typecast in the main code writing what would be idiomatically written as thePort->BSRR = 0x12345678; as *((uint32_t)&(thePort->BSSRH)) = 0x12345678;, or would be be better to use a patched header file? If the latter, where should the patched file me stored and how should it be managed?

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• RTS Game Style Application [closed]

  - by Daniel Wynand van Wyk

  My question may seem somewhat odd, but I hope that my specifications will clarify EXACTLY what it is that I am after. I need some help choosing the right tooling for a particular endeavour. My background is in desktop application development and large back-end systems. I have worked primarily on the Microsoft stack using C# and the .Net framework. My goal is to develop a 2D, RTS style, interactive office simulation. The simulation will model various office spaces, office equipment, employees and their interactions with one another. The idea is to abstract the concept of an office completely. Under the hood the application will do many things that are nothing like a game. This includes P2P networking, VPN tunnelling, streaming video, instant messaging, document collaboration, remote screen sharing, file-sharing, virus scanning, VOIP, document scanning, faxing, emailing, distributed computing, content management and much more! A somewhat similar thing has been attempted by IBM, where they created a virtual office in second life. If their attempt was a game, the game-play would be notably horrible, to say the least! The users/players will drive and control my application through the various objects modelled in the simulation. A single application capable of performing all of these various tasks would be a nightmare to navigate for even the most expert user. Using the concept of a game, I can easily separate functionality by assigning them to objects that relate 1-1 with their real world counter-parts. This can greatly simplify computing for novice users, with many added benefits in terms of visibility, transparency of process and centralized configuration. My hope is to make complex computing tasks accessible to all kinds of users and to greatly reduce the cognitive load associated with using the many different utilities and applications inside office settings. The complexity is therefore limited to the complexity of the space in which you find yourself. I want the application to target as many platforms as possible and run on computers that have no accelerated graphics capabilities. The simulation won't contain any of the fancy eye-candy you find in modern games, to the contrary, my "game" will purposefully be clean and simple. The closest thing I could imagine would be an old game like "Theme Hospital" or the first instalment of "The Sims". All the content will be pre-created and not user-generated like Second Life. New functionality will be added via a plugin system. Given my background and nature of my "game", I would like to spend most of my time writing code that does not have to do with the simulated office, as the "game" is really just a glorified application menu. I have done much reading about existing engines, frameworks and tools. I need the help of an experienced game developer who has tried and tested various products over the years who can guide me in the right direction given my very particular needs. I would appreciate any help I can get!

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• How is fundamental mathematics efficiently evaluated by programming languages?

  - by Korvin Szanto

  As I get more and more involved with the theory behind programming, I find myself fascinated and dumbfounded by seemingly simple things.. I realize that my understanding of the majority of fundamental processes is justified through circular logic Q: How does this work? A: Because it does! I hate this realization! I love knowledge, and on top of that I love learning, which leads me to my question (albeit it's a broad one). Question: How are fundamental mathematical operators assessed with programming languages? How have current methods been improved? Example var = 5 * 5; My interpretation: $num1 = 5; $num2 = 5; $num3 = 0; while ($num2 > 0) { $num3 = $num3 + $num1; $num2 = $num2 - 1; } echo $num3; This seems to be highly inefficient. With Higher factors, this method is very slow while the standard built in method is instantanious. How would you simulate multiplication without iterating addition? var = 5 / 5; How is this even done? I can't think of a way to literally split it 5 into 5 equal parts. var = 5 ^ 5; Iterations of iterations of addition? My interpretation: $base = 5; $mod = 5; $num1 = $base; while ($mod > 1) { $num2 = 5; $num3 = 0; while ($num2 > 0) { $num3 = $num3 + $num1; $num2 = $num2 - 1; } $num1 = $num3; $mod -=1; } echo $num3; Again, this is EXTREMELY inefficient, yet I can't think of another way to do this. This same question extends to all mathematical related functions that are handled automagically.

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• Access Control Service v2: Registering Web Identities in your Applications [code]

  - by Your DisplayName here!

  You can download the full solution here. The relevant parts in the sample are: Configuration I use the standard WIF configuration with passive redirect. This kicks automatically in, whenever authorization fails in the application (e.g. when the user tries to get to an area the requires authentication or needs registration). Checking and transforming incoming claims In the claims authentication manager we have to deal with two situations. Users that are authenticated but not registered, and registered (and authenticated) users. Registered users will have claims that come from the application domain, the claims of unregistered users come directly from ACS and get passed through. In both case a claim for the unique user identifier will be generated. The high level logic is as follows: public override IClaimsPrincipal Authenticate( string resourceName, IClaimsPrincipal incomingPrincipal) {     // do nothing if anonymous request     if (!incomingPrincipal.Identity.IsAuthenticated)     {         return base.Authenticate(resourceName, incomingPrincipal);     } string uniqueId = GetUniqueId(incomingPrincipal);     // check if user is registered     RegisterModel data;     if (Repository.TryGetRegisteredUser(uniqueId, out data))     {         return CreateRegisteredUserPrincipal(uniqueId, data);     }     // authenticated by ACS, but not registered     // create unique id claim     incomingPrincipal.Identities[0].Claims.Add( new Claim(Constants.ClaimTypes.Id, uniqueId));     return incomingPrincipal; } User Registration The registration page is handled by a controller with the [Authorize] attribute. That means you need to authenticate before you can register (crazy eh? ;). The controller then fetches some claims from the identity provider (if available) to pre-fill form fields. After successful registration, the user is stored in the local data store and a new session token gets issued. This effectively replaces the ACS claims with application defined claims without requiring the user to re-signin. Authorization All pages that should be only reachable by registered users check for a special application defined claim that only registered users have. You can nicely wrap that in a custom attribute in MVC: [RegisteredUsersOnly] public ActionResult Registered() {     return View(); } HTH

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• LINQ to Twitter v2.1.09 Released

  - by Joe Mayo

  Originally posted on: http://geekswithblogs.net/WinAZ/archive/2013/10/15/linq-to-twitter-v2.1.09-released.aspxToday, I released LINQ to Twitter v2.1.09. Here are important new changes. Bug Fixes This is primarily a bug fix release. Most notably, there were authentication problems in WinRT apps. This is now fixed. New Features One new feature is the addition of ApplicationOnlyAuthentication for WinRT. It is fully async.  Here’s how it works: var auth = new WinRtApplicationOnlyAuthorizer { Credentials = new InMemoryCredentials { ConsumerKey = "", ConsumerSecret = "" } }; if (auth == null || !auth.IsAuthorized) { await auth.AuthorizeAsync(); } var twitterCtx = new TwitterContext(auth); (from search in twitterCtx.Search where search.Type == SearchType.Search && search.Query == SearchTextBox.Text select search) .MaterializedAsyncCallback( async response => await Dispatcher.RunAsync( CoreDispatcherPriority.Normal, async () => { Search searchResponse = response.State.Single(); string message = string.Format( "Search returned {0} statuses", searchResponse.Statuses.Count); await new MessageDialog(message, "Search Complete").ShowAsync(); })); It’s called the WinRtApplicationOnlyAuthorizer. You only need two tokens, ConsumerKey and ConsumerSecret, which come from your Twitter API application settings page. Note: You need a Twitter Application, which you can create at https://dev.twitter.com/. The MaterializedAsyncCallback materializes your query and handles the response. I put everything together in a lambda for demonstration purposes, but you can always replace the callback with a handler of type Action<TwitterAsyncResponse<IEnumerable<T>>>, where T is Search for this example. On the Horizon The next version of LINQ to Twitter is in development. I discussed it at LINQ to Twitter Async. This isn’t complete, but you can download the source code at the LINQ to Twitter site on CodePlex. I’ve competed all the spikes for what I thought would be the hard parts and now have prototypes of queries and commands working. This would be a good time to provide feedback if there are features in the current version that you think could be improved. The current driving forces for the next version will be async and PCL.   @JoeMayo

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• Are closures with side-effects considered "functional style"?

  - by Giorgio

  Many modern programming languages support some concept of closure, i.e. of a piece of code (a block or a function) that Can be treated as a value, and therefore stored in a variable, passed around to different parts of the code, be defined in one part of a program and invoked in a totally different part of the same program. Can capture variables from the context in which it is defined, and access them when it is later invoked (possibly in a totally different context). Here is an example of a closure written in Scala: def filterList(xs: List[Int], lowerBound: Int): List[Int] = xs.filter(x => x >= lowerBound) The function literal x => x >= lowerBound contains the free variable lowerBound, which is closed (bound) by the argument of the function filterList that has the same name. The closure is passed to the library method filter, which can invoke it repeatedly as a normal function. I have been reading a lot of questions and answers on this site and, as far as I understand, the term closure is often automatically associated with functional programming and functional programming style. The definition of function programming on wikipedia reads: In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. and further on [...] in functional code, the output value of a function depends only on the arguments that are input to the function [...]. Eliminating side effects can make it much easier to understand and predict the behavior of a program, which is one of the key motivations for the development of functional programming. On the other hand, many closure constructs provided by programming languages allow a closure to capture non-local variables and change them when the closure is invoked, thus producing a side effect on the environment in which they were defined. In this case, closures implement the first idea of functional programming (functions are first-class entities that can be moved around like other values) but neglect the second idea (avoiding side-effects). Is this use of closures with side effects considered functional style or are closures considered a more general construct that can be used both for a functional and a non-functional programming style? Is there any literature on this topic? IMPORTANT NOTE I am not questioning the usefulness of side-effects or of having closures with side effects. Also, I am not interested in a discussion about the advantages / disadvantages of closures with or without side effects. I am only interested to know if using such closures is still considered functional style by the proponent of functional programming or if, on the contrary, their use is discouraged when using a functional style.

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• Rending 2D Tile World (With Player In The Middle)

  - by Mick

  What I have at the moment is a series of data structures I'm using, and I would like to render the world onto the screen (just the visible parts). I've actually already done this several times (lots of rewrites), but it's a bit buggy (rounding seems to make the screen jump ever so slightly every x tiles the player walks past). Basically I've been confusing myself heavily on what I feel should be a pretty simple problem... so here I am asking for some help! OK! So I have a 50x50 array holding the tiles of the world. I have the player position as 2 floats, x ([0, 49]) and y ([0, 49]) in that array. I have the application size exactly in pixels (x and y). I have an arbitrary TILE_SIZE static int (based on screen pixels). What I think is heavily confusing me is using a 2d orthogonal projection in opengl which maps (0,0) to the top left of the screen and (SCREEN_SIZE_X, SCREEN_SIZE_Y) to the bottom right of the screen. gl.glMatrixMode(GL.GL_PROJECTION); gl.glLoadIdentity(); glu.gluOrtho2D(0, getActualWidth(), getActualHeight(), 0); gl.glMatrixMode(GL.GL_MODELVIEW); gl.glLoadIdentity(); The map tiles are set so that the (0,0) in the array is the bottom left. And the player has to be in the middle on the screen (SCREEN_SIZE_X/2, SCREEN_SIZE_Y/2). What I've been doing so far is trying to render 1-2 tiles more all around what would be displayed on the screen so that I don't have to worry about figuring out rendering half a tile from the top left, depending where the player is. It seems like such an easy problem but after spending about 40+hours on it rewriting it many times I think I'm at a point where I just can't think clearly anymore... Any help would be appreciated. It would be great if someone can provide some very basic pseudo code on keeping the player in the middle when your projection is mapped to screen coordinates and only rendering basically the tiles that you would be any be see. Thanks!

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• What does path finding in internet routing do and how is it different from A*?

  - by alan2here

  Note: If you don't understand this question then feel free to ask clarification in the comments instead of voting down, it might be that this question needs some more work at the moment. I've been directed here from the Stack Excange chat room Root Access because my question didn't fit on Super User. In many aspects path finding algorithms like A star are very similar to internet routing. For example: A node in an A* path finding system can search for a path though edges between other nodes. A router that's part of the internet can search for a route though cables between other routers. In the case of A*, open and closed lists are kept by the system as a whole, sepratly from any individual node as well as each node being able to temporarily store a state involving several numbers. Routers on the internet seem to have remarkable properties, as I understand it: They are very performant. New nodes can be added at any time that use a free address from a finite (not tree like) address space. It's real routing, like A*, there's never any doubling back for example. Similar IP addresses don't have to be geographically nearby. The network reacts quickly to changes to the networks shape, for example if a line is down. Routers share information and it takes time for new IP's to be registered everywhere, but presumably every router doesn't have to store a list of all the addresses each of it's directions leads most directly to. I'm looking for a basic, general, high level description of the algorithms workings from the point of view of an individual router. Does anyone have one? I presume public internet routers don't use A* as the overheads would be to large, and scale to poorly. I also presume there is a single method worldwide because it seems as if must involve a lot of transferring data to update and communicate a reasonable amount of state between neighboring routers. For example, perhaps the amount of data that needs to be stored in each router scales logarithmically with the number of routers that exist worldwide, the detail and reliability of the routing is reduced over increasing distances, there is increasing backtracking involved in parts of the network that are less geographically uniform or maybe each router really does perform an A* style search, temporarily maintaining open and closed lists when a packet arrives.

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• Are these non-standard applications of rendering practical in games?

  - by maul

  I've recently got into 3D and I came up with a few different "tricky" rendering techniques. Unfortunately I don't have the time to work on this myself, but I'd like to know if these are known methods and if they can be used in practice. Hybrid rendering Now I know that ray-tracing is still not fast enough for real-time rendering, at least on home computers. I also know that hybrid rendering (a combination of rasterization and ray-tracing) is a well known theory. However I had the following idea: one could separate a scene into "important" and "not important" objects. First you render the "not important" objects using traditional rasterization. In this pass you also render the "important" objects using a special shader that simply marks these parts on the image using a special color, or some stencil/depth buffer trickery. Then in the second pass you read back the results of the first pass and start ray tracing, but only from the pixels that were marked by the "important" object's shader. This would allow you to only ray-trace exactly what you need to. Could this be fast enough for real-time effects? Rendered physics I'm specifically talking about bullet physics - intersection of a very small object (point/bullet) that travels across a straight line with other, relatively slow-moving, fairly constant objects. More specifically: hit detection. My idea is that you could render the scene from the point of view of the gun (or the bullet). Every object in the scene would draw a different color. You only need to render a 1x1 pixel window - the center of the screen (again, from the gun's point of view). Then you simply check that central pixel and the color tells you what you hit. This is pixel-perfect hit detection based on the graphical representation of objects, which is not common in games. Afaik traditional OpenGL "picking" is a similar method. This could be extended in a few ways: For larger (non-bullet) objects you render a larger portion of the screen. If you put a special-colored plane in the middle of the scene (exactly where the bullet will be after the current frame) you get a method that works as the traditional slow-moving iterative physics test as well. You could simulate objects that the bullet can pass through (with decreased velocity) using alpha blending or some similar trick. So are these techniques in use anywhere, and/or are they practical at all?

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• Code testing practice

  - by Robin Castlin

  So now I have come to the conclusion like many others that having some way of constantly testing your code is good practice since it enables fewer people to be involved (colleges and customers alike) by simply knowing what's wrong before someone else finds out the hard way. I've heard and read some about Unit Testing and understand what it's supposed to do and all. The there are so many different types of bugs. It can be everything from web browser not being able not being able to send correct values, javascript failing, a global function messing up a piece of code somewhere to a change that looked good when testing it out but fails in some special case which was hard to anticipate. My simply finding these errors I learn to rarely repeat them again, but there seems to always be new bugs to be found and learnt from. I would guess maybe the best practice would be to run every page and it's functions a couple of times, witness the result and repeat this in Firefox, Chrome and Internet Explorer (and all smartphones apparently) to make sure it works as intended. However this would take quite some time to do consider I don't work with patches/versions and do little fixes here and there a couple of times per week. What I prefer would be some kind of page I can just load that tests as much things as possible to make sure the site works as intended. Basicly just run a lot of cURL's with POST-values and see if I get expected result. But how would I preferably not increase the IDs of every mysql rows if I delete these testing rows? It feels silly to be on ID 1000 with maybe 50 rows in total. If I could build a new project from scratch I would probably implement some kind of smooth way to return a "TRUE" on testing instead of the actual page. But this solution would for the moment being have to be passed on existing projects. My question What would you recommend to be the best way to test my site to make sure that existing functions does their job upon editing the code? Should I consider to implement a lot of edits first, then test manually the entire code to make sure it still works? Is there any nice way of testing codes without "hurting" the ID columns? Extra thoughs Would it be a good idea to associate all of my files to the different parts of my site which they affect? For instance if I edit home.php I will through documentation test if my homepage's start works as intended since it's the only part of my site it should affect.

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• Developing a Support Plan for Cloud Applications

  - by BuckWoody

  Last week I blogged about developing a High-Availability plan. The specifics of a given plan aren't as simple as "Step 1, then Step 2" because in a hybrid environment (which most of us have) the situation changes the requirements. There are those that look for simple "template" solutions, but unless you settle on a single vendor and a single way of doing things, that's not really viable. The same holds true for support. As I've mentioned before, I'm not fond of the term "cloud", and would rather use the tem "Distributed Computing". That being said, more people understand the former, so I'll just use that for now. What I mean by Distributed Computing is leveraging another system or setup to perform all or some of a computing function. If this definition holds true, then you're essentially creating a partnership with a vendor to run some of your IT - whether that be IaaS, PaaS or SaaS, or more often, a mix. In your on-premises systems, you're the first and sometimes only line of support. That changes when you bring in a Cloud vendor. For Windows Azure, we have plans for support that you can pay for if you like. http://www.windowsazure.com/en-us/support/plans/ You're not off the hook entirely, however. You still need to create a plan to support your users in their applications, especially for the parts you control. The last thing they want to hear is "That's vendor X's problem - you'll have to call them." I find that this is often the last thing the architects think about in a solution. It's fine to put off the support question prior to deployment, but I would hold off on calling it "production" until you have that plan in place. There are lots of examples, like this one: http://www.va-interactive.com/inbusiness/editorial/sales/ibt/customer.html some of which are technology-specific. Once again, this is an "it depends" kind of approach. While it would be nice if there was just something in a box we could buy, it just doesn't work that way in a hybrid system. You have to know your options and apply them appropriately.

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• Developing a Support Plan for Cloud Applications

  - by BuckWoody

  Last week I blogged about developing a High-Availability plan. The specifics of a given plan aren't as simple as "Step 1, then Step 2" because in a hybrid environment (which most of us have) the situation changes the requirements. There are those that look for simple "template" solutions, but unless you settle on a single vendor and a single way of doing things, that's not really viable. The same holds true for support. As I've mentioned before, I'm not fond of the term "cloud", and would rather use the tem "Distributed Computing". That being said, more people understand the former, so I'll just use that for now. What I mean by Distributed Computing is leveraging another system or setup to perform all or some of a computing function. If this definition holds true, then you're essentially creating a partnership with a vendor to run some of your IT - whether that be IaaS, PaaS or SaaS, or more often, a mix. In your on-premises systems, you're the first and sometimes only line of support. That changes when you bring in a Cloud vendor. For Windows Azure, we have plans for support that you can pay for if you like. http://www.windowsazure.com/en-us/support/plans/ You're not off the hook entirely, however. You still need to create a plan to support your users in their applications, especially for the parts you control. The last thing they want to hear is "That's vendor X's problem - you'll have to call them." I find that this is often the last thing the architects think about in a solution. It's fine to put off the support question prior to deployment, but I would hold off on calling it "production" until you have that plan in place. There are lots of examples, like this one: http://www.va-interactive.com/inbusiness/editorial/sales/ibt/customer.html some of which are technology-specific. Once again, this is an "it depends" kind of approach. While it would be nice if there was just something in a box we could buy, it just doesn't work that way in a hybrid system. You have to know your options and apply them appropriately.

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• Strategy for avoiding duplicate object ids for data shared across devices using iCloud

  - by rmaddy

  I have a data intensive iOS app that is not using CoreData nor does it support iCloud synching (yet). All of my objects are created with unique keys. I use a simple long long initialized with the current time. Then as I need a new key I increment the value by 1. This has all worked well for a few years with the app running isolated on a single device. Now I want to add support for automatic data sync across devices using iCloud. As my app is written, there is the possibility that two objects created on two different devices could end up with the same key. I need to avoid this possibility. I'm looking for ideas for solving this issue. I have a few requirements that the solution must meet: 1) The key needs to remain a single integral data type. Converting all existing keys to a compound key or to a string or other type would affect the entire code base and likely result in more bugs than it's worth. 2) The solution can't depend on an Internet connection. A user must be able to run the app and add data even with no Internet connection. The data should still resolve properly later when the data syncs through iCloud once a connection is available. I'll accept one exception to this rule. If no other option is available, I may be open to requiring an Internet connection the first time the app's data is initialized. One idea I have been toying around with in my head is logically splitting the integer key into two parts. The high 4 or 5 bits could be used as some sort of device id while the rest represents the actual key. The fuzzy part is figuring out how to come up with non-conflicting device ids that fit in a few bits. This should be viable since I don't need to deal will millions of devices. I just need to deal with the few devices that would be shared by a given iCloud account. I'm open to suggestions. Thanks.

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• AS3 - At exactly 23 empty alpha channels, images below stop drawing

  - by user46851

  I noticed, while trying to draw large numbers of circles, that occasionally, there would be some kind of visual bug where some circles wouldn't draw properly. Well, I narrowed it down, and have noticed that if there is 23 or more objects with 00 for an alpha value on the same spot, then the objects below don't draw. It appears to be on a pixel-by-pixel basis, since parts of the image still draw. Originally, this problem was noticed with a class that inherited Sprite. It was confirmed to also be a problem with Sprites, and now Bitmaps, too. If anyone can find a lower-level class than Bitmap which doesn't have this problem, please speak up so we can try to find the origin of the problem. I prepared a small test class that demonstrates what I mean. You can change the integer value at line 20 in order to see the three tests I came up with to clearly show the problem. Is there any kind of workaround, or is this just a limit that I have to work with? Has anyone experienced this before? Is it possible I'm doing something wrong, despite the bare-bones implementation? package { import flash.display.Sprite; import flash.events.Event; import flash.display.Bitmap; import flash.display.BitmapData; public class Main extends Sprite { public function Main():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); // entry point Test(3); } private function Test(testInt:int):void { if(testInt==1){ addChild(new Bitmap(new BitmapData(200, 200, true, 0xFFFF0000))); for (var i:int = 0; i < 22; i++) { addChild(new Bitmap(new BitmapData(100, 100, true, 0x00000000))); } } if(testInt==2){ addChild(new Bitmap(new BitmapData(200, 200, true, 0xFFFF0000))); for (var j:int = 0; j < 23; j++) { addChild(new Bitmap(new BitmapData(100, 100, true, 0x00000000))); } } if(testInt==3){ addChild(new Bitmap(new BitmapData(200, 200, true, 0xFFFF0000))); for (var k:int = 0; k < 22; k++) { addChild(new Bitmap(new BitmapData(100, 100, true, 0x00000000))); } var M:Bitmap = new Bitmap(new BitmapData(100, 100, true, 0x00000000)); M.x += 50; M.y += 50; addChild(M); } } } }

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• How to implement a multi-part snake with smooth movement? [closed]

  - by Jamie

  Sorry that i couldnt answer on my previous post but it got closed. I couldnt answer because i had to prepair for my finals. As there were problems with understanding of what im trying to achieve, im going to describe a little bit more in depth. Im creating a game in which you steer a snake. I assume everybody knows how that works. But in my case the snake isnt just propagating in an array element by element. Imagine a 2Dgrid on which the snake moves. Its 10x10 tiles. Lets say one tile is 4x4 meters. The snakes head spawns in the middle of the (3,2) tile (beginning with (0,0)), so its position is (4*3+2,4*2+2)(the 2's are so that the snake is in the middle of the 4x4 tile). And heres where the fun begins. when the snake moves, it doesnt jump to next tile. Instead it moves a fraction of the way there. So lets say the snake is heading to tile (4,2). After it moved once, its position is (4*3+2+0.1,4*2+2), where 0.1 is the fraction of the way it moved. This is done to achieve smooth movement. So now im adding the rest of the body. The rest is supposed to move along the exact same path as the head did. I implemented it so that each part of the body has its own position and direction. Then i apply this algorithm: 1.Move each part in its direction. 2.If a part is in the middle of the tile(which implies all of them are), change each parts direction to the direction of the part proceeding it. As i said before i could make this work, but i cant stop thinking that im overlooking a much easier and cleaner solution. So this is my question. Is there any easier/better/faster way to do this?

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• Cloud Computing Business Benefits

  - by workflowman

  If you have been living under a rock for the past year, you wouldn't have heard about cloud computing. Cloud computing is a loose term that describes anything that is hosted in data centers and accessed via the internet. It is normally associated with developers who draw clouds in diagrams indicating where services or how systems communicate with each other. Cloud computing also incorporates such well-known trends as Web 2.0 and Software as a Service (SaaS) and more recently Infrastructure as a Service (IaaS) and Platform as a Service (PaaS). Its aim is to change the way we compute, moving from traditional desktop and on-premises servers to services and resources that are hosted in the cloud.  Benefits of Cloud Computing  There are clearly benefits in building applications using cloud computing, some of which are listed here:  Zero up- front investment:  Delivering a large-scale system costs a fortune in both time and money. Often IT departments are split into hardware/network and software services. The hardware team provisions servers and so forth under the requirements of the software team. Often the hardware team has a different budget that requires approval. Although hardware and software management are two separate disciplines, sometimes what happens is developers are given the task to estimate CPU cycles, disk space, and so forth, which ends up in underutilized servers.  Usage-based costing:  You pay for what you use, no more, no less, because you never actually own the server. This is similar to car leasing, where in the long run you get a new car every three years and maintenance is never a worry.  Potential for shrinking the processing time:  If processes are split over multiple machines, parallel processing is performed, which decreases processing time.  More office space:  Walk into most offices, and guaranteed you will find a medium- sized room dedicated to servers.  Efficient resource utilization:  The resource utilization is handed by a centralized cloud administrator who is in charge of deciding exactly the right amount of resources for a system. This takes the task away from local administrators, who have to regularly monitor these servers.  Just-in-time infrastructure:  If your system is a success and needs to scale to meet demand, this can cause further time delays or a slow- performing service. Cloud computing solves this because you can add more resources at any time.  Lower environmental impact:  If servers are centralized, potentially an environment initiative is more likely to succeed. As an example, if servers are placed in sunny or windy parts of the world, then why not use these resources to power those servers?  Lower costs:  Unfortunately, this is one point that administrators will not like. If you have people administrating your e-mail server and network along with support staff doing other cloud-based tasks, this workforce can be reduced. This saves costs, though it also reduces jobs.

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• "Whole-team" C++ features?

  - by Blaisorblade

  In C++, features like exceptions impact your whole program: you can either disable them in your whole program, or you need to deal with them throughout your code. As a famous article on C++ Report puts it: Counter-intuitively, the hard part of coding exceptions is not the explicit throws and catches. The really hard part of using exceptions is to write all the intervening code in such a way that an arbitrary exception can propagate from its throw site to its handler, arriving safely and without damaging other parts of the program along the way. Since even new throws exceptions, every function needs to provide basic exception safety — unless it only calls functions which guarantee throwing no exception — unless you disable exceptions altogether in your whole project. Hence, exceptions are a "whole-program" or "whole-team" feature, since they must be understood by everybody in a team using them. But not all C++ features are like that, as far as I know. A possible example is that if I don't get templates but I do not use them, I will still be able to write correct C++ — or will I not?. I can even call sort on an array of integers and enjoy its amazing speed advantage wrt. C's qsort (because no function pointer is called), without risking bugs — or not? It seems templates are not "whole-team". Are there other C++ features which impact code not directly using them, and are hence "whole-team"? I am especially interested in features not present in C. Update: I'm especially looking for features where there's no language-enforced sign you need to be aware of them. The first answer I got mentioned const-correctness, which is also whole-team, hence everybody needs to learn about it; however, AFAICS it will impact you only if you call a function which is marked const, and the compiler will prevent you from calling it on non-const objects, so you get something to google for. With exceptions, you don't even get that; moreover, they're always used as soon as you use new, hence exceptions are more "insidious". Since I can't phrase this as objectively, though, I will appreciate any whole-team feature. Appendix: Why this question is objective (if you wonder) C++ is a complex language, so many projects or coding guides try to select "simple" C++ features, and many people try to include or exclude some ones according to mostly subjective criteria. Questions about that get rightfully closed regularly here on SO. Above, instead, I defined (as precisely as possible) what a "whole-team" language feature is, provide an example (exceptions), together with extensive supporting evidence in the literature about C++, and ask for whole-team features in C++ beyond exceptions. Whether you should use "whole-team" features, or whether that's a relevant concept, might be subjective — but that only means the importance of this question is subjective, like always.

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• [AJAX Numeric Updown Control] Microsoft JScript runtime error: The number of fractional digits is out of range

  - by Jenson

  If you have using Ajax control toolkits a lot (which I will skip the parts on where to download and how to configure it in Visual Studio 2010), you might have encountered some bugs or limitations of the controls, or rather, some weird behaviours. I would call them weird behaviours though. Recently, I've been working on a Ajax numeric updown control, which i remember clearly it was working fine without problems. In fact, I use 2 numeric updown control this time. So I went on to configure it to be as simple as possible and I will just use the default up and down buttons provided by it (so that I won't need to design my own). I have two textbox controls to display the value controlled by the updown control. One for month, and another for year. <asp:TextBox ID="txtMonth" runat="server" CssClass="txtNumeric" ReadOnly="True" Width="150px" /> <asp:TextBox ID="txtYear" runat="server" CssClass="txtNumeric" ReadOnly="True" Width="150px" /> So I will now drop 1 numeric updown control for each of the textboxes. <asp:NumericUpDownExtender ID="txtMonth_NumericUpDownExtender"     runat="server" TargetControlID="txtMonth" Maximum="12" Minimum="1" Width="152"> </asp:NumericUpDownExtender>                          <asp:NumericUpDownExtender ID="txtYear_NumericUpDownExtender"     runat="server" TargetControlID="txtYear" Width="152"> </asp:NumericUpDownExtender>                                                  You noticed that I configure the Maximum and Minimum value for the first numericupdown control, but I never did the same for the second one (for txtYear). That's because it won't work, well, at least for me. So I remove the Minimum="2000" and Maximum="2099" from there. Then I would configure the initial value to the the current year, and let the year to flow up and down freely. If you want, you want write the codes to restrict it. Here are the codes I used on PageLoad:     Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load         If Not Page.IsPostBack Then             If Trim(txtMonth.Text) = "" Then                 Me.txtMonth.Text = System.DateTime.Today.Month             End If             If Trim(txtYear.Text) = "" Then                 Me.txtYear.Text = System.DateTime.Today.Year             End If         End If     End Sub   Enjoy!

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