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• Invoke WCF rest service razor mvc 4

  - by Raj Esh

  I have been using jQuery to access my REST based wcf service which does not export the meta information. Using ajax, i could populate data into controls. I need guidance and directions as to how i can use these Rest service in my controller. I can't add Service reference to my MVC 4 project since my WCF rest does not to expose Metadata. Should i use UNITY? or any other DI frameworks?. Any sample would be of great help.

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• Is eval the defmacro of javascript?

  - by Florian Margaine

  In Common Lisp, defmacro basically allows us to build our own DSL. I read this page today and it explains something cleverly done: But I wasn't about to write out all these boring predicates myself, so I defined a function that, given a list of words, builds up the text for such a predicate automatically, and then evals it to produce a function. Which just looks like defmacro to me. Is eval the defmacro of javascript? Could it be used as such?

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• How should data be passed between client-side Javascript and C# code behind an ASP.NET app?

  - by ctck

  I'm looking for the most efficient / standard way of passing data between client-side Javascript code and C# code behind an ASP.NET application. I've been using the following methods to achieve this but they all feel a bit of a fudge. To pass data from Javascript to the C# code is by setting hidden ASP variables and triggering a postback: <asp:HiddenField ID="RandomList" runat="server" /> function SetDataField(data) { document.getElementById('<%=RandomList.ClientID%>').value = data; } Then in the C# code I collect the list: protected void GetData(object sender, EventArgs e) { var _list = RandomList.value; } Going back the other way I often use either ScriptManager to register a function and pass it data during Page_Load: ScriptManager.RegisterStartupScript(this.GetType(), "Set","get("Test();",true); or I add attributes to controls before a post back or during the initialization or pre-rendering stages: Btn.Attributes.Add("onclick", "DisplayMessage("Hello");"); These methods have served me well and do the job, but they just dont feel complete. Is there a more standard way of passing data between client side Javascript and C# backend code? Ive seen some posts like this one that describe HtmlElement class; is this something I should look into?

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• libssh2 and simultaneous connections

  - by Florian Margaine

  I'm writing a node.js C++ module using the C library libssh2. The module is supposed to be a bridge to connect to SSH over HTTPS. Right now, I'm still in the design/learning phase of v8 API and C++, and I have a design question: libssh2 is a C library, all its methods are global. From what I see in the examples, libssh2 can only handle one connection at a time. If I want to allow simultaneous connections to different SSH servers, do I have to fork a process to completely separate the libssh2 "instances", or is forking a thread enough? I don't know enough of the separation limit used there. Any idea on how to handle this is appreciated.

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• How much Ruby should I learn before moving to Rails?

  - by Kevin

  Just a quick question.. I can never get a definitive answer when googling this, either. Some people say you can learn Rails without knowing any Ruby, but at some point you'll run into a brick wall and wish you knew Ruby and will have to go back to learn it..and some say to learn the "basics" of Ruby before learning Rails and it will make your life that much easier.. My current knowledge is low. I'm not a beginner, but I'm not pro, either. I went through the Learn Python The Hard Way online book in about a month, but I stopped once I got to the OOP side of Python (I know booleans, elif/if/else/statements, for loops, while loops, functions) I agree with learning the "basics" of Ruby before learning Rails, but what exactly are the "basics" of Ruby? Would I need to learn the whole OOP side of Ruby before I went on to Rails? Or would I just need to learn the Ruby syntax up to where I learned Python (booleans, elif/if/else/statements, for loops, while loops, functions) before I went on to Rails? Thanks!

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• Writing a job requirement for a web application developer

  - by Raul Agrait

  I'm currently writing a job requirement for a software engineer position for my company, in which we are looking for a developer to work on client-side web application work. How should I title the job title / position? I don't necessarily want to call it a "Web Developer", for fear that it might attract more designer-y types. On the other hand, "Software Engineer" doesn't really give the indication that the work, while application based, will be web-based. Is "Web Application Software Engineer" a valid position title? Also, I'm somewhat torn on what the required skills set should be. I don't necessarily think that the ideal candidate should have x years of experience in say, JavaScript or ActionScript, but rather am just looking for someone who has experience in developing client-side applications, and is willing to learn and develop web applications. My current attempt at this, is that I have a section in which I state: Experience in the following frameworks and technologies are a plus, but not necessarily required for the position:

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• Task ownership with Wordpress - CSS - Designer or Developer?

  - by Syed Absar

  We have a dispute regarding who owns which tasks when it comes to the CSS on our live site. Our designer argues that he is not responsible to log-in to word press and modify the css or use ftp for any changes because that's not his job description while developer argues that since it is css, it belongs to designer and that he is to update the changes to the server and then compare and correct the output. I'd like experienced people working in professional development environment to put a light on this scenario. I'm not sure if this is the right place to ask this question, or is there a separate forum for business development or project management specific questions?

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• Don't Use Static? [closed]

  - by Joshiatto

  Possible Duplicate: Is static universally “evil” for unit testing and if so why does resharper recommend it? Heavy use of static methods in a Java EE web application? I submitted an application I wrote to some other architects for code review. One of them almost immediately wrote me back and said "Don't use "static". You can't write automated tests with static classes and methods. "Static" is to be avoided." I checked and fully 1/4 of my classes are marked "static". I use static when I am not going to create an instance of a class because the class is a single global class used throughout the code. He went on to mention something involving mocking, IOC/DI techniques that can't be used with static code. He says it is unfortunate when 3rd party libraries are static because of their un-testability. Is this other architect correct?

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• How is technical debt best measured? What metric(s) are most useful?

  - by throp

  If I wanted to help a customer understand the degree of technical debt in his application, what would be the best metric to use? I've stumbled across Erik Doernenburg's code toxicity, and also Sonar's technical debt plugin, but was wondering what others exist. Ideally, I'd like to say "system A has a score of 100 whereas system B has a score of 50, so system A will most likely be more difficult to maintain than system B". Obviously, I understand that boiling down a complex concepts like "technical debt" or "maintainability" into a single number might be misleading or inaccurate (in some cases), however I need a simple way to convey the to a customer (who is not hands-on in the code) roughly how much technical debt is built into their system (relative to other systems), for the goal of building a case for refactoring/unit tests/etc. Again, I'm looking for one single number/graph/visualization, and not a comprehensive list of violations (e.g. CheckStyle, PMD, etc.).

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• Is Python worth learning? Is it a useful tool?

  - by Kenneth

  I recently had a discussion with a professor of mine on the topic of web development. I had recently decided I would learn python to increase my arsenal of web tools which I mentioned to him at that time. He almost immediately asked why I would waste my time on that. I'm not certain but I think he recently started in on researching and studying web development so he could pick up the web development classes that haven't been taught for a while after the previous professor who taught those classes left. I've heard a lot about python and thought maybe he was mistaken about its usefulness. Is python a useful tool to have? What applications can it be used for? Is it better than other similar alternatives? Does it have useful applications outside of web development as well?

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• Project structure: where to put business logic

  - by Mister Smith

  First of all, I'm not asking where does business logic belong. This has been asked before and most answers I've read agree in that it belongs in the model: Where to put business logic in MVC design? How much business logic should be allowed to exist in the controller layer? How accurate is "Business logic should be in a service, not in a model"? Why put the business logic in the model? What happens when I have multiple types of storage? However people disagree in the way this logic should be distributed across classes. There seem to exist three major currents of thought: Fat model with business logic inside entity classes. Anemic model and business logic in "Service" classes. It depends. I find all of them problematic. The first option is what most Fowlerites stick to. The problem with a fat model is that sometimes a business logic funtion is not only related to a class, and instead uses a bunch of other classes. If, for example, we are developing a web store, there should be a function that calcs an order's total. We could think of putting this function inside the Order class, but what actually happens is that the logic needs to use different classes, not only data contained in the Order class, but also in the User class, the Session class, and maybe the Tax class, Country class, or Giftcard, Payment, etc. Some of these classes could be composed inside the Order class, but some others not. Sorry if the example is not very good, but I hope you understand what I mean. Putting such a function inside the Order class would break the single responsibility principle, adding unnecesary dependences. The business logic would be scattered across entity classes, making it hard to find. The second option is the one I usually follow, but after many projects I'm still in doubt about how to name the class or classes holding the business logic. In my company we usually develop apps with offline capabilities. The user is able to perform entire transactions offline, so all validation and business rules should be implemented in the client, and then there's usually a background thread that syncs with the server. So we usually have the following classes/packages in every project: Data model (DTOs) Data Access Layer (Persistence) Web Services layer (Usually one class per WS, and one method per WS method). Now for the business logic, what is the standard approach? A single class holding all the logic? Multiple classes? (if so, what criteria is used to distribute the logic across them?). And how should we name them? FooManager? FooService? (I know the last one is common, but in our case it is bad naming because the WS layer usually has classes named FooWebService). The third option is probably the right one, but it is also devoid of any useful info. To sum up: I don't like the first approach, but I accept that I might have been unable to fully understand the Zen of it. So if you advocate for fat models as the only and universal solution you are welcome to post links explaining how to do it the right way. I'd like to know what is the standard design and naming conventions for the second approach in OO languages. Class names and package structure, in particular. It would also be helpful too if you could include links to Open Source projects showing how it is done. Thanks in advance.

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• Explain Model View Controller

  - by Channel72

  My experience with developing dynamic websites is limited mostly to Java servlets. I've used Tomcat to develop various Java servlets, and I wouldn't hesitate to say that I'm reasonably proficient with this technology, as well as with client-side HTML/CSS/Javascript for the front-end. When I think "dynamic website", I think: user requests a URL with a query string, server receives the query, and then proceeds to output HTML dynamically in order to respond to the query. This often involves communication with a database in order to fetch requested data for display. This is basically the idea behind the doGet method of a Java HttpServlet. But these days, I'm hearing more and more about newer frameworks such as Django and Ruby on Rails, all of which take advantage of the "Model View Controller" architecture. I've read various articles which explain MVC, but I'm having trouble really understanding the benefits. I understand that the general idea is to separate business logic from UI logic, but I fail to see how this is anything really different from normal web programming. Web programming, by it's very nature, forces you to separate business logic (back-end server-side programming) from UI programming (client-side HTML or Javascript), because the two exist in entirely different spheres of programming. Question: What does MVC offer over something like a Java servlet, and more importantly, what exactly is MVC and how is it different from what you would normally do to develop a dynamic website using a more traditional approach such as a Java servlet (or even something older like CGI). If possible, when explaining MVC, please provide an example which illustrates how MVC is applied to the web development process, and how it is beneficial.

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• Is LISP still useful in, and which version is most used in todays world ?

  - by shan23

  I try to teach myself a new programming language in regular intervals of time. Recently, I've read how Lisp and its dialects are at the complete opposite end of the spectrum from languages like C/C++, which made me curious enough to know more about it. However, two things are unclear to me, and I'm looking for guidance on them : Is LISP still practiced/used in todays world, or is it a legacy language like FORTRAN/COBOL ? I mean, apart from maintaining existing code, is it used on new projects at all ? What is the most widely used dialect ? I came across Scheme and Common Lisp as the 2 most prevalent dialects, and wanted your opinion as to which is the most favored/useful one to learn - and would be immensely gratified if you can suggest any resources for a rank beginner to start from. While eager to learn a language which is fundamentally different from the procedural languages I'm used to, I don't want to invest undue effort in something if its totally obsolete - I'd still learn it if it was professionally "dead", but only with an academic perspective...

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• Where can I find video resources of people programming?

  - by Corey

  This might be a strange question. I'm looking for videos of people actively coding something while explaining it. However, I don't want is a beginner video that delves into what variables and objects are. Nick Gravelyn's tile engine tutorial is a great example of what I'm looking for. (He actually used to host the full, unbroken video files in his site's archive, but I guess he took them down...) I tend to learn best by "action" examples; it's difficult for me to learn by reading through documentation and text tutorials, but if I see somebody actively doing a task, I can immediately register it and apply it myself. I'm hard-of-hearing, so I would really prefer that if the video has a lot of talking, it have captioning or subtitling of some sort, or at the very least, a transcript. The tile engine videos did not have captions, but the code he was writing was very self-documenting, so I understood it for the most part. I've gone through most of the relevant GoogleDevelopers and GoogleTechTalks videos on Youtube, so those need not apply. Are there any resources out there, or even websites dedicated to this kind of thing?

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• Strategies for browser compatibility on web applications in a corporate environment

  - by TiagoBrenck

  With the new CSS 3 and HTML 5 technology, web applications have gained a lot of new tools for a better UI (user interface) interaction, beautiful templates and even responsive layout to fit into tablets and smartphones. Within a corporate environment, those new technologies are required so the company can "follow" the IT evolution and their concurrent, but they also want that those new web applications supports old browsers. How should I deal with this situation? By one side we are asked to follow the the evolution of technology, create responsive layouts and use a lot of cool jQuery plugins. On the other hand, we are asked to support old browsers that do not support those new responsive features, plugins or components. I would like advice and strategies on how to create "modern" web applications that are also supported on old browsers. How does your company deal with this situation? Is it possible to have the same web application run well and beautifully on old browsers, and be responsive and interactive on newer browsers?

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• How can I merge two SubVersion branches to one working copy without committing?

  - by Eric Belair

  My current SubVersion workflow is like so: The trunk is used to make small content changes and bug fixes to the main source code. Branches are used for adding/editing enhancements and projects. So, trunk changes are made, tested, committed and deployed pretty quickly. Whereas, enhancements and projects need additional user testing and approval. At time, I have two branches that need testing and approval at the same time. I don't want to merge to the trunk and commit until the changes are fully tested and approved. What I need to do is merge both branches to one working copy without any commits. I am using Tortoise SVN, and when I try to merge the second branch, I get an error message: Cannot merge into a working copy that has local modifications Is there a way that I can do this without committing either merge?

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• CPU Architecture and floating-point math

  - by Jo-Herman Haugholt

  I'm trying to wrap my head around some details about how floating point math is performed on the CPU, trying to better understand what data types to use etc. I think I have a fairly good understanding of how integer math is performed. If I've understood correctly, and disregarding SIMD, a 32-bit CPU will generally perform integer math at at least 32-bit precision etc. Is it correct that floating-point math is dependent on the presence of a FPU? And that the FPU on the x86 is 80-bit, so floating point math is performed at this precision unless using SIMD? What about ARM?

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• Is it wise to store a big lump of json on a database row

  - by Ieyasu Sawada

  I have this project which stores product details from amazon into the database. Just to give you an idea on how big it is: [{"title":"Genetic Engineering (Opposing Viewpoints)","short_title":"Genetic Engineering ...","brand":"","condition":"","sales_rank":"7171426","binding":"Book","item_detail_url":"http://localhost/wordpress/product/?asin=0737705124","node_list":"Books > Science & Math > Biological Sciences > Biotechnology","node_category":"Books","subcat":"","model_number":"","item_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=128","details_url":"http://localhost/wordpress/product/?asin=0737705124","large_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/large-notfound.png","medium_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/medium-notfound.png","small_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/small-notfound.png","thumbnail_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/thumbnail-notfound.png","tiny_img":"http://localhost/wordpress/wp-content/plugins/ecom/img/tiny-notfound.png","swatch_img":"http://localhost/wordpress/wp-content/plugins/ecom/img/swatch-notfound.png","total_images":"6","amount":"33.70","currency":"$","long_currency":"USD","price":"$33.70","price_type":"List Price","show_price_type":"0","stars_url":"","product_review":"","rating":"","yellow_star_class":"","white_star_class":"","rating_text":" of 5","reviews_url":"","review_label":"","reviews_label":"Read all ","review_count":"","create_review_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=132","create_review_label":"Write a review","buy_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=19186","add_to_cart_action":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/add_to_cart.php","asin":"0737705124","status":"Only 7 left in stock.","snippet_condition":"in_stock","status_class":"ninstck","customer_images":["http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/31FIM-YIUrL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg"],"disclaimer":"","item_attributes":[{"attr":"Author","value":"Greenhaven Press"},{"attr":"Binding","value":"Hardcover"},{"attr":"EAN","value":"9780737705126"},{"attr":"Edition","value":"1"},{"attr":"ISBN","value":"0737705124"},{"attr":"Label","value":"Greenhaven Press"},{"attr":"Manufacturer","value":"Greenhaven Press"},{"attr":"NumberOfItems","value":"1"},{"attr":"NumberOfPages","value":"224"},{"attr":"ProductGroup","value":"Book"},{"attr":"ProductTypeName","value":"ABIS_BOOK"},{"attr":"PublicationDate","value":"2000-06"},{"attr":"Publisher","value":"Greenhaven Press"},{"attr":"SKU","value":"G0737705124I2N00"},{"attr":"Studio","value":"Greenhaven Press"},{"attr":"Title","value":"Genetic Engineering (Opposing Viewpoints)"}],"customer_review_url":"http://localhost/wordpress/wp-content/ecom-customer-reviews/0737705124.html","flickr_results":["http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/5105560852_06c7d06f14_m.jpg"],"freebase_text":"No around the web data available yet","freebase_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/freebase-notfound.jpg","ebay_related_items":[{"title":"Genetic Engineering (Introducing Issues With Opposing Viewpoints), , Good Book","image":"http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/140.jpg","url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=12165","currency_id":"$","current_price":"26.2"},{"title":"Genetic Engineering Opposing Viewpoints by DAVID BENDER - 1964 Hardcover","image":"http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/140.jpg","url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=130","currency_id":"AUD","current_price":"11.99"}],"no_follow":"rel=\"nofollow\"","new_tab":"target=\"_blank\"","related_products":[],"super_saver_shipping":"","shipping_availability":"","total_offers":"7","added_to_cart":""}] So the structure for the table is: asin title details (the product details in json) Will the performance suffer if I have to store like 10,000 products? Is there any other way of doing this? I'm thinking of the following, but the current setup is really the most convenient one since I also have to use the data on the client side: store the product details in a file. So something like ASIN123.json store the product details in one big file. (I'm guessing it will be a drag to extract data from this file) store each of the fields in the details in its own table field Thanks in advance!

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• How do I classify using GLCM and SVM Classifier in Matlab?

  - by Gomathi

  I'm on a project of liver tumor segmentation and classification. I used Region Growing and FCM for liver and tumor segmentation respectively. Then, I used Gray Level Co-occurence matrix for texture feature extraction. I have to use Support Vector Machine for Classification. But I don't know how to normalize the feature vectors. Can anyone tell how to program it in Matlab? To the GLCM program, I gave the tumor segmented image as input. Was I correct? If so, I think, then, my output will also be correct. My glcm coding, as far as I have tried is, I = imread('fzliver3.jpg'); GLCM = graycomatrix(I,'Offset',[2 0;0 2]); stats = graycoprops(GLCM,'all') t1= struct2array(stats) I2 = imread('fzliver4.jpg'); GLCM2 = graycomatrix(I2,'Offset',[2 0;0 2]); stats2 = graycoprops(GLCM2,'all') t2= struct2array(stats2) I3 = imread('fzliver5.jpg'); GLCM3 = graycomatrix(I3,'Offset',[2 0;0 2]); stats3 = graycoprops(GLCM3,'all') t3= struct2array(stats3) t=[t1;t2;t3] xmin = min(t); xmax = max(t); scale = xmax-xmin; tf=(x-xmin)/scale Was this a correct implementation? Also, I get an error at the last line. My output is: stats = Contrast: [0.0510 0.0503] Correlation: [0.9513 0.9519] Energy: [0.8988 0.8988] Homogeneity: [0.9930 0.9935] t1 = Columns 1 through 6 0.0510 0.0503 0.9513 0.9519 0.8988 0.8988 Columns 7 through 8 0.9930 0.9935 stats2 = Contrast: [0.0345 0.0339] Correlation: [0.8223 0.8255] Energy: [0.9616 0.9617] Homogeneity: [0.9957 0.9957] t2 = Columns 1 through 6 0.0345 0.0339 0.8223 0.8255 0.9616 0.9617 Columns 7 through 8 0.9957 0.9957 stats3 = Contrast: [0.0230 0.0246] Correlation: [0.7450 0.7270] Energy: [0.9815 0.9813] Homogeneity: [0.9971 0.9970] t3 = Columns 1 through 6 0.0230 0.0246 0.7450 0.7270 0.9815 0.9813 Columns 7 through 8 0.9971 0.9970 t = Columns 1 through 6 0.0510 0.0503 0.9513 0.9519 0.8988 0.8988 0.0345 0.0339 0.8223 0.8255 0.9616 0.9617 0.0230 0.0246 0.7450 0.7270 0.9815 0.9813 Columns 7 through 8 0.9930 0.9935 0.9957 0.9957 0.9971 0.9970 ??? Error using ==> minus Matrix dimensions must agree. The images are:

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• Low latency technologies for c++, c# and java?

  - by James

  I've been reading job descriptions and many mention 'low latency'. However, I wondered if someone could clarify what type of technologies this would refer to? One of the adverts mentioned 'ACE' which I googled to find out was some CISCO telephony technology. If you were hiring someone for a low latency role, what would you use as a checklist for ensuring they knew about low latency programming? I'm using this to learn more about low latency programming myself.

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• Amazon SOA: database as a Service

  - by Martin Lee

  There is an interesting interview with Werner Vogels which is partly about how Amazon does Service Oriented Architecture: For us service orientation means encapsulating the data with the business logic that operates on the data, with the only access through a published service interface. No direct database access is allowed from outside the service, and there’s no data sharing among the services. I do not understand that. Why do they need to 'wrap' a database into some layer if it already can be consumed as a service by other service through database adaptors? Does Amazon do that just because they need to expose the database to third parties or because of anything else? Why "no direct database access is allowed"? What are the advantages of such an architectural decision?

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• How to name an subclass that add a minor, detailed thing?

  - by Louis Rhys

  What is the most concise (yet descriptive) way of naming a subclass that only add a specific minor thing to the parent? I encountered this case a lot in WPF, where sometime I have to add a small functionality to an out-of-the-box control for specific cases. Example: TreeView doesn't change the SelectedItem on right-click, but I have to make one that does in my application. Some possible names are TreeViewThatChangesSelectedItemOnRightClick (way too wordy and maybe difficult to read because there is so many words concantenated together) TreeView_SelectedItemChangesOnRightClick (slightly more readable, but still too wordy and the underscore also breaks the normal convention for class names) TreeViewThatChangesSIOnRC (non-obvious acronym), ExtendedTreeView (more concise, but doesn't describe what it is doing. Besides, I already found a class called this in the library, that I don't want to use/modify in my application). LouisTreeView, MyTreeView, etc. (doesn't describe what it is doing). It seems that I can't find a name which sounds right. What do you do in situation like this?

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• How do you keep code with continuations/callbacks readable?

  - by Heinzi

  Summary: Are there some well-established best-practice patterns that I can follow to keep my code readable in spite of using asynchronous code and callbacks? I'm using a JavaScript library that does a lot of stuff asynchronously and heavily relies on callbacks. It seems that writing a simple "load A, load B, ..." method becomes quite complicated and hard to follow using this pattern. Let me give a (contrived) example. Let's say I want to load a bunch of images (asynchronously) from a remote web server. In C#/async, I'd write something like this: disableStartButton(); foreach (myData in myRepository) { var result = await LoadImageAsync("http://my/server/GetImage?" + myData.Id); if (result.Success) { myData.Image = result.Data; } else { write("error loading Image " + myData.Id); return; } } write("success"); enableStartButton(); The code layout follows the "flow of events": First, the start button is disabled, then the images are loaded (await ensures that the UI stays responsive) and then the start button is enabled again. In JavaScript, using callbacks, I came up with this: disableStartButton(); var count = myRepository.length; function loadImage(i) { if (i >= count) { write("success"); enableStartButton(); return; } myData = myRepository[i]; LoadImageAsync("http://my/server/GetImage?" + myData.Id, function(success, data) { if (success) { myData.Image = data; } else { write("error loading image " + myData.Id); return; } loadImage(i+1); } ); } loadImage(0); I think the drawbacks are obvious: I had to rework the loop into a recursive call, the code that's supposed to be executed in the end is somewhere in the middle of the function, the code starting the download (loadImage(0)) is at the very bottom, and it's generally much harder to read and follow. It's ugly and I don't like it. I'm sure that I'm not the first one to encounter this problem, so my question is: Are there some well-established best-practice patterns that I can follow to keep my code readable in spite of using asynchronous code and callbacks?

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• How can Swift be so much faster than Objective-C?

  - by Yellow

  Apple launched its new programming language Swift today. In the presentation, they made some performance comparisons between Objective-C and Python. The following is a picture of one of their slides, of a comparison of those three languages performing some complex object sort: There was an even more incredible graph about a performance comparison working on some encryption algorithm. Obviously this is a marketing talk, and they didn't go into detail on how this was implemented in each. I leaves me wondering though: how can a new programming language be so much faster? In this example, surely you just have a bad Objective-C compiler or you're doing something in a less efficient way? How else would you explain a 40% performance increase? I understand that garbage collection/automated reference control might produce some additional overhead, but this much?

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• Compiler Dependencies [closed]

  - by asghar ashgari

  I'm a newbie researcher who's passion is programming languages (Web era). I'm wondering why all the Web frameworks and Web-based general purposes languages, have a huge number of dependencies when you want to install and then use (e.g., extend, alternate, etc.) their compilers. For example, Ruby on Rails or Scala. If I want to download their source code, and try to build it again, to me at least, feels like a can of worms. I have a MAC, so I need to install MACports, then update my XCode, then get the compiler source code that has bunch of other dependencies, then its hard to set things up; just to see the installed open-source compiler works fine.

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