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  • How to structure my GUI agnostic project?

    - by Nezreli
    I have a project which loads from database a XML file which defines a form for some user. XML is transformed into a collection of objects whose classes derive from single parent. Something like Control - EditControl - TextBox Control - ContainterControl - Panel Those classes are responsible for creation of GUI controls for three different enviroments: WinForms, DevExpress XtraReports and WebForms. All three frameworks share mostly the same control tree and have a common single parent (Windows.Forms.Control, XrControl and WebControl). So, how to do it? Solution a) Control class has abstract methods Control CreateWinControl(); XrControl CreateXtraControl(); WebControl CreateWebControl(); This could work but the project has to reference all three frameworks and the classes are going to be fat with methods which would support all three implementations. Solution b) Each framework implementation is done in separate projects and have the exact class tree like the Core project. All three implementations are connected using a interface to the Core class. This seems clean but I'm having a hard time wrapping my head around it. Does anyone have a simpler solution or a suggestion how should I approach this task?

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  • C++ and system exceptions

    - by Abyx
    Why standard C++ doesn't respect system (foreign or hardware) exceptions? E.g. when null pointer dereference occurs, stack isn't unwound, destructors aren't called, and RAII doesn't work. The common advice is "to use system API". But on certain systems, specifically Win32, this doesn't work. To enable stack unwinding for this C++ code // class Foo; // void bar(const Foo&); bar(Foo(1, 2)); one should generate something like this C code Foo tempFoo; Foo_ctor(&tempFoo); __try { bar(&tempFoo); } __finally { Foo_dtor(&tempFoo); } Foo_dtor(&tempFoo); and it's impossible to implement this as C++ library. Upd: Standard doesn't forbid handling system exceptions. But it seems that popular compilers like g++ doesn't respect system exceptions on any platforms just because standard doesn't require this. The only thing that I want - is to use RAII to make code readable and program reliable. I don't want to put hand-crafted try\finally around every call to unknown code. For example in this reusable code, AbstractA::foo is such unknown code: void func(AbstractA* a, AbstractB* b) { TempFile file; a->foo(b, file); } Maybe one will pass to func such implementation of AbstractA, which every Friday will not check if b is NULL, so access violation will happen, application will terminate and temporary file will not be deleted. How many months uses will suffer because of this issue, until either author of func or author of AbstractA will do something with it? Related: Is `catch(...) { throw; }` a bad practice?

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  • Book Review: Professional ASP.Net MVC4

    - by Sam Abraham
    The past few weeks have been particularly busy as I continue to dedicate a bigger portion of my free time to refreshing my memory and enhancing my knowledge of best practices pertaining to technologies we plan on using for a major upcoming project. In this blog post, I will be providing a brief overview of my latest reading “Professional ASP.Net MVC4” by Jon Galloway, Phil Haack, Brad Wilson and K. Scott Allen. This book is a must read for web developers looking to enhance their MVC expertise with best practices and tips shared from recognized industry experts. This book takes the reader on a 16-chapter long journey towards being a better ASP.NET MVC developer with chapter 16 putting all information covered in practical context by dissecting the implementation of Nuget.org, a real-life open-source, ASP.NET MVC project.  All code samples referenced in this book are conveniently accessible via NuGet, a free, open-source Library package manager that installs as a Visual Studio Extension. Chapters 2, 3 and 4 thoroughly cover MVC’s various components: Controllers “C”, Views “V” and Models “M” respectively. Chapter 5 covers additional extension methods (Helpers) provided to speed and ease the use of common HTML elements such as forms, textboxes, grids, to name a few… Chapter 6 tackles built-in validation while providing examples and use cases on implementing custom validation that plugs into the MVC framework. Chapters 7 thru 13 discusses the latest on Membership, Ajax, Routing, NuGet and the ASP.Net Web API. Chapters 12 (Dependency Injection) and 13 (Unit Testing) demonstrate a big competitive advantage of MVC with its ease of test-ability and plug-ability. Chapters 14 and 15 targets the advanced developer showcasing how to extend MVC to customize and replace every piece in the framework.In conclusion, I strongly recommend Professional ASP.NET MVC 4 as an excellent read for both developers already using MVC as well as those getting started with the framework.   Many thanks to the Wiley/Wrox User Group Program for their support of our West Palm Beach Developers’ Group.  You can access my reviews of books I recently read: Professional ASP.NET Design Patterns Professional WCF 4.0 Inside Windows Communication Foundation Inside Microsoft SQL Server 2008 series

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  • Linking Libraries in iOS?

    - by Bob Dole
    This is probably a totally noob question but I have missing links in my mind when thinking about linking libraries in iOS. I usually just add a new library that's been cross compiled and set the build and linker paths without really know what I'm doing. I'm hoping someone can help me fill in some gaps. Let's take the OpenCV library for instance. I have this totally working btw because of a really well written tutorial( http://niw.at/articles/2009/03/14/using-opencv-on-iphone/en ), but I'm just wanting to know what is exactly going on. What I'm thinking is happening is that when I build OpenCV for iOS is that your creating object code that gets placed in the .a files. This object code is just the implementation files( .m ) compiled. One reason you would want to do this is to make it hard to see the source code and so that you don't have to compile that source code every time. The .h files won't be put in the library ( .a ). You include the .h in your source files and these header files communicate with the object code library ( .a ) in some way. You also have to include the header files for your library in the Build Path and the Library itself in the Linker Path. So, is the way I view linking libraries correct? If , not can someone correct me on this ?

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  • Oracle Database 12c Technical Trainin

    - by mseika
    Audience Database Administrators, Solutions Architects, System Engineers, Technical Consultants, Implementation and support personnel, Technical Analysts, and Developers. What We Are Announcing During his opening keynote at Oracle OpenWorld 2012, Larry Ellison previewed Oracle Database 12c - the latest generation of the database market leader and Oracle flagship product. Oracle Database 12c introduces many groundbreaking features making it the database foundation of choice for the cloud. Many years of development effort have been focused on introducing innumerable new technological innovations centered on the cloud computing platform. This training session will focus on the specific needs of our Oracle partner community and developers, and provide insight into the many features and capabilities your customers will be looking to leverage in their own environments. Topics includes: Consolidation and Cloud Strategies Deep dive into the key Database 12c Options Migrating to Oracle Database 12c Webcast Details Speaker: Sean Stacey, Director of Platform Technology Solutions.Please note that you will need to join both the Audio and Web Conferences to attend. Please plan on joining 10 minutes before the scheduled time. Region: Date & Time Audio Conference Web Conference Calendar NAS, LAD, EMEA July 28am PT (US) Duration: 1 hour US/Canada: (866) 900-7470Click for local numberIf your country is not listed, dial +1 (706) 634-7953. Local charges may applyCONFERENCE ID: 98498078 Click here to joinPassword: Oracle123 Add this session to your calendar If you have any questions, please contact: Yvonne OungSenior Manager, Channel [email protected]

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  • How to decide on a price for the project as a freelancer

    - by Shekhar_Pro
    I have seen similar question on this SE site but none comes close to a sure shot answer and many are rather subjective. So i am taking a website as an example to be more objective for you to decide its development price i should quote for the complete work.I would like to have specific figures. In past I have developed many projects for my classmates (Computer science and few .net) when i was in college and there i just arbitrarily quoted the price i will take depending on my mood and customer's ability to pay.. usually ranging from Rs.500 (about $10 USD) to Rs. 1500 (about $30 USD). I have also developed few websites but that was open-source and free. But this time impressed by my work i have got a client that wants to get a website developed similar to this: [ http://www.jeetle.in/ ]. So taking this website as an example tell me how much should i charge for complete work from designing to payment gateway implementation (Excluding the charge the payment gateway provider will take). Few information you might like to consider. I am the only developer on this project if that makes any difference. And i would be using ASP.Net and MSSQL Express for server side processing and jQuery on client. Time period for development offered is about 4 to 6 Weeks. Its like i know my work but not how much I'm worth

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  • Empty interface to combine multiple interfaces

    - by user1109519
    Suppose you have two interfaces: interface Readable { public void read(); } interface Writable { public void write(); } In some cases the implementing objects can only support one of these but in a lot of cases the implementations will support both interfaces. The people who use the interfaces will have to do something like: // can't write to it without explicit casting Readable myObject = new MyObject(); // can't read from it without explicit casting Writable myObject = new MyObject(); // tight coupling to actual implementation MyObject myObject = new MyObject(); None of these options is terribly convenient, even more so when considering that you want this as a method parameter. One solution would be to declare a wrapping interface: interface TheWholeShabam extends Readable, Writable {} But this has one specific problem: all implementations that support both Readable and Writable have to implement TheWholeShabam if they want to be compatible with people using the interface. Even though it offers nothing apart from the guaranteed presence of both interfaces. Is there a clean solution to this problem or should I go for the wrapper interface? UPDATE It is in fact often necessary to have an object that is both readable and writable so simply seperating the concerns in the arguments is not always a clean solution. UPDATE2 (extracted as answer so it's easier to comment on) UPDATE3 Please beware that the primary usecase for this is not streams (although they too must be supported). Streams make a very specific distinction between input and output and there is a clear separation of responsibilities. Rather, think of something like a bytebuffer where you need one object you can write to and read from, one object that has a very specific state attached to it. These objects exist because they are very useful for some things like asynchronous I/O, encodings,...

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  • Which Graphics/Geometry abstraction to choose?

    - by Robz
    I've been thinking about the design for a browser app on the HTML5 canvas that simulates a 2D robot zooming around, sensing the world around it. I decided to do this from scratch just for fun. I need shapes, like polygons, circles, and lines in order to model the robot and the world it lives in. These shapes need to be drawn with different appearance attributes, like border/fill style/width/color. I also need to have geometry functions to detect intersections and containment for the robot's sensors and so that the robot doesn't go inside stuff. One idea for functions is to have two totally separate libraries, one to implement graphics (like drawShape(context, shape)) and one for geometry operations (like shapeIntersectsShape(shape1, shape2)). Or, in a more object-oriented approach, the shape objects themselves could implement methods to do their own graphics (shape.draw(context)) and geometry operations (shape1.intersects(shape2)). Then there is the data itself: whether the data to draw a shape and the data to do geometric operations on that shape should be encapsulated within the same object, or be separate structures (where one would contain the other, or both be contained inside another structure). How do existing applications that do graphics/geometry stuff deal with this? Is there one model that is best, or is each good for certain applications? Should the fact that I'm using Javascript instead of a more classical language change how I approach the design?

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  • Developing wheel reinventing tendencies into a skill as opposed to reluctantly learning wheel-finding skills? [duplicate]

    - by Korey Hinton
    This question already has an answer here: Is reinventing the wheel really all that bad? 20 answers I am more of a high-level wheel reinventor. I definitely prefer to make use of existing API features built into a language and popular third-party frameworks that I know can solve the problem, however when I have a particular problem that I feel capable of solving within a reasonable time I am very reluctant to find someone else's solution. Here are a few reasons why I reinvent: It takes time to learn a new API API restrictions might exist that I don't know about Avoiding re-work of unfamiliar code I am conflicted between doing what I know and shifting to a new technique I don't feel comfortable with. On one hand I feel like following my instincts and getting really good at solving problems, especially ones that I would never challenge myself with if all I did was try to find answers. And on the other hand I feel like I might be missing out on important skills like saving time by finding the right framework and expanding my knowledge by learning how to use a new framework. I guess my question comes down to this: My current attitude is to stick to the built-in API and APIs I know well* and to not spend my time searching github for a solution to a problem I know I can solve myself within a reasonable amount of time. Is that a reasonable balance for a successful programmer? *Obviously I will still look around for new frameworks that save time and solve/simplify difficult problems.

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  • Everything has an Interface [closed]

    - by Shane
    Possible Duplicate: Do I need to use an interface when only one class will ever implement it? I am taking over a project where every single real class is implementing an Interface. The vast majority of these interfaces are implemented by a single class that share a similar name and the exact same methods (ex: MyCar and MyCarImpl). Almost no 2 classes in the project implement more than the interface that shares its name. I know the general recommendation is to code to an interface rather than an implementation, but isn't this taking it a bit too far? The system might be more flexible in that it is easier to add a new class that behaves very much like an existing class. However, it is significantly harder to parse through the code and method changes now require 2 edits instead of 1. Personally, I normally only create interfaces when there is a need for multiple classes to have the same behavior. I subscribe to YAGNI, so I don't create something unless I see a real need for it. Am I doing it all wrong or is this project going way overboard?

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  • How do client-server cooperation based games like Diablo 3 work?

    - by edgar
    Diablo 3 cooperates with Blizzard servers even during single player games. In fact, Blizzard has had problems with the games "melting their servers." I would like to ask: How do the client and the server communicate? What details does the client leave to the server, and vice versa? What details are redundant - both the client and the server know - and how often do they disagree? The previous paragraph contains the important questions, but I have a few more that I must explain my motivation towards. I am interested in the programming of botting. Ethical botting - I don't plan on actually abusing the automation to run 24/7. I just find it to be a great programming challenge to glean information from a game, and then make decisions from that information. I am stuck in the starting gate. The unofficial questions from this post would be: How can I make a bot (language, tools, libraries)? Can I get information through the communication between client and server, rather than the brute force pixel detection easily used in more static games? There probably is a trust issue, and to that all I can say is that I promise not to abuse the answers. But please feel free to answer any of the questions you feel comfortable with. Thank you!

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  • Configuring Team Foundation Server Basic on Home Server.

    - by Enrique Lima
    For the installation I selected only the Team Foundation Server role. Then, I opened the Team Foundation Server Administration Console (which I think is a great addition and improvement over the way TFS was configured in the past) to proceed with the configuration of the pieces. Once I selected the Configure Installed Features, the Configuration Center opened up. Now, the choices … In my implementation here I just want to take advantage of Source Control primarily.  I want to be able to store my code and projects.  So, Basic it is! So, the Basic Configuration Wizard opens up.  Now the options to configure are very limited, but we have to provide details for the SQL Server Instance. And now, to select Install SQL Server express.  If you want to take advantage of another system in your environment to host your database, well you could Use an existing SQL Server Instance. Once it has the details it needs, you get a Summary view to confirm your choices. Once, you click next or verify, it runs readiness checks on your system to make sure the installation will have a successful pass.  And we love GREEN! Now, since got the green flag, our next stop is to let the wizard do its magic, click on Configure.  And once again, we love GREEN! We click Next, and … We like a big Green Success sign … We close the Configuration Center … First results … Web Access …  Nothing to show … but we are there! And all this running from a Microsoft Home Server installation.

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  • Designing business objects, and gui actions

    - by fozz
    Developing a product ordering system using Java SE 6. The previous implementations used combo boxes, text fields, and check boxes. Preforming validation on action events from the GUI. The validation includes limiting existing combo boxes items, or even availability. The issue in the old system was that the action was received and all rules were applied to the entire business object. This resulted in a huge event change as options were changed multiple times. To be honest I have no idea how an infinite loop wasn't produced. Through the next iteration I stepped in and attempted to limit the chaos by controlling the order in which the selections could be made. Making configuration of BO's a top down approach. I implemented custom box models, action events, beans/binding, and an MVC pattern. However I still am unable to fully isolate action even chains. I'm thinking that I've approached the whole concept backwards in an attempt to stay closest to what was already in place. So the question becomes what do I design instead? I'm currently considering an implementation of Interfaces, Beans, Property Change Listeners to manage the back and forth. Other thoughts were validation exceptions, dynamic proxies.... I'm sure there are a ton of different ways. To say that one way is right is crazy, and I'm sure it will take a blending of multiple patterns. My knowledge of swing/awt validation is limited, previously I did backend logic only. Other considerations are were some sort of binding(jgoodies or otherwise) to directly bind GUI state to BO's.

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  • An ideal way to decode JSON documents in C?

    - by AzizAG
    Assuming I have an API to consume that uses JSON as a data transmission method, what is an ideal way to decode the JSON returned by each API resource? For example, in Java I'd create a class for each API resource then initiate an object of that class and consume data from it. for example: class UserJson extends JsonParser { public function UserJson(String document) { /*Initial document parsing goes here...*/ } //A bunch of getter methods . . . . } The probably do something like this: UserJson userJson = new UserJson(jsonString);//Initial parsing goes in the constructor String username = userJson.getName();//Parse JSON name property then return it as a String. Or when using a programming language with associative arrays(i.e., hash table) the decoding process doesn't require creating a class: (PHP) $userJson = json_decode($jsonString);//Decode JSON as key=>value $username = $userJson['name']; But, when I'm programming in procedural programming languages (C), I can't go with either method, since C is neither OOP nor supports associative arrays(by default, at least). What is the "correct" method of parsing pre-defined JSON strings(i.e., JSON documents specified by the API provider via examples or documentation)? The method I'm currently using is creating a file for each API resource to parse, the problem with this method is that it's basically a lousy version of the OOP method, as it looks exactly like the OOP method but doesn't provide any OOP benefits(e.g., can't pass an object of the parser, etc.). I've been thinking about encapsulating each API resource parser file in a publicly accessed structure(pointing all functions/publicly usable variables to the structure) then accessing the parser file code from within the structure(parser.parse(), parser.getName(), etc.). As this way looks a bit better than the my current method, it still just a rip off the OOP way, isn't it? Any suggestions for methods to parse JSON documents on procedural programming lanauges? Any comments on the methods I'm currently using(either 3 of them)?

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  • EMEA OTN Virtual Technology Summit - Hands-On Learning

    - by Thanos Terentes Printzios
    The Oracle Technology Network (OTN) is excited to invite you to our first Virtual Technology Summit. EMEA – Thursday July 10th / 9am to 1pm BST / 10am – 2pm CET / 12pm to 4pm MSK / GST - Register Now Learn first hand from Oracle ACEs, Java Champions, and Oracle product experts, as they share their insight and expertise on using Oracle technologies to meet today’s IT challenges. This interactive, online event offers four technical tracks, each with a unique focus on specific tools, technologies, and tips in these focus areas. Java – Big Trends and Technologies – Java lets you mine Big Data, build robust apps with HTML5, JavaScript and Java EE, and expand into the Internet of Things. Experts will present and you’ll be able to chat with them live online. Don’t miss out on this great opportunity to learn from some of the best minds in the Java community. Systems – OS Tips and Tricks for Sysadmins – Learn first hand how to configure Oracle Linux to run Oracle Database 11g and 12c, how to use the latest networking capabilities in Oracle Solaris 11, and how to troubleshoot networking problems in Unix and Linux systems. Database – Mastering Oracle Database Management & Development Techniques – Experts will present advanced features and management methods that will help you master your Oracle Database capabilities and drive greater performance, agility and manageability of your IT implementation. This track will build upon your skills with data management, migration, and performance. Middleware – The Architecture of Analytics: Big Time Big Data and Business Intelligence – This track will present a solution architect’s perspective on how business intelligence products in Oracle’s Fusion Middleware family and beyond fit into an effective big data architecture, and present insight and expertise from Oracle ACEs specializing in business Intelligence to help you meet your big data business intelligence challenges. This same content is being offered at 3 different dates listed below, at times convenient for all regions Americas - Wednesday July 9th EMEA – Thursday July 10th APAC English - July 16th 9am to 1pm PST12pm to 4pm  EST1 to 5 pm BRTRegister 9am to 1pm BST10am – 2pm CET12pm to 4pm MSK / GSTRegister IST – 10:00amSG – 12:30pmAEST – 2:30pmRegister The full event agenda is available at https://wikis.oracle.com/display/OTNVirtualTechSummit/Home

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  • Field symbol and Data reference in SAP-ABAP

    - by PDP-21
    If we compare field symbol and data refernece with that of the pointer in C i concluded that :- In C language, Say we declare a variable "var" type "Integer" with default value "5". The variable "var" will be stored some where in the memory and say the memory address which holds this variable is "1000". Now we define a pointer "ptr" and this pointer is assigned to our variable. So, "&ptr" will be "1000" and " *ptr " will be 5. Lets comapre the above situation in SAP ABAP. Here we declare a Field symbol "FS" and assign that to the variable "var". Now my question is what "FS" holds ? I have searched this rigorously in the internet but found out many ABAP consultants have the opinion that FS holds the address of the variable i.e. 1000. But that is wrong. While debugging i found out that fs holds only 5. So fs (in ABAP) is equivalent to *ptr (in C). Please correct me if my understanding is wrong. Now lets declare a data reference "dref" and another filed symbol "fsym" and after creating the data reference we assign the same to field symbol . Now we can do operations on this field symbol. So the difference between data refernec and field symbol is :- in case of field symbol first we will declare a variable and assign it to a field symbol. in case of data reference first we craete a data reference and then assign that to field symbol. Then what is the use of data reference? The same functionality we can achive through field symbol also.

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  • Partner Training for Oracle Business Intelligence Applications 4-Day Bootcamp

    - by Mike.Hallett(at)Oracle-BI&EPM
    Partners 4-Day training from 15th - 18th October 2012, at Oracle Reading (UK) The Oracle Business Intelligence Applications provide pre-built Operational BI solutions for eBusiness Suite, Peoplesoft, Siebel, JDE and SAP; offering out-of-the-box integration. This FREE for Partners 4-Day training will provide attendees with an in-depth working understanding of the architecture, the technical and the functional content of the Oracle Business Intelligence Applications, whilst also providing an understanding of their installation, configuration and extension. The course will cover the following topics: Overview of Oracle Business Intelligence Applications Oracle BI Applications Fundamentals and Features Configuring BI Applications for Oracle E-Business Suite Understanding BI Applications Architecture Fundamentals of BI Applications Security   REGISTER HERE NOW    (acceptance is subject to availability and your place will be confirmed within two weeks: for help see the Partner Registration Guide) Location: Bray Room, at Oracle Corporation UK Ltd Oracle Parkway Thames Valley Park Reading, Berkshire RG6 1RA 15th - 18th October 2012, 4-Days :  9:30 am – 5:00 pm BST Audience The seminar is aimed at BI Consultants and Implementation Consultants within Oracle's Gold and Platinum Partners. Good understanding of basic data warehousing concepts Hands on experience in Oracle Business Intelligence Enterprise Edition Hands on experience in Informatica Some understanding of  Oracle BI Applications is required (See Sales & Technical Tutorials for OBI, BI-Apps and Hyperion EPM)  Good understanding of any of the following Oracle EBS modules: General Ledger, Accounts Receivables, Accounts Payables Please note that attendees are required to bring a laptop: 4GB RAM Windows 64 bits 80GB free space in Hard drive or External Device CPU Core 2 Duo or Higher Windows 7, Windows XP, Windows 2003 NOT ALLOWED with Windows Vista An Administrator User For more information please contact [email protected].

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  • Making Modular, Reusable and Loosely Coupled MVC Components

    - by Dusan
    I am building MVC3 application and need some general guidelines on how to manage complex client side interaction between my components. Here is my definition of one component in general way: Component which has it's own controller, model and view. All of the component's logic is placed inside these three parts and component is sort of "standalone", it contains it's own form, data needed for interaction, updates itself with Ajax and so on. Beside this internal logic and behavior of the component, it needs to be able to "Talk" to the outside world. By this I mean it should provide data and events (sort of) so when this component gets embedded in pages can notify other components which then can update based on the current state and data. I have an idea to use client ViewModel (in java-script) which would hookup all relevant components on page and control interaction between them. This would make components reusable, modular - independent of the context in which they are used. How would you do this, I am a bit stuck as I do not know if this is a good approach and there is a technical possibility to achieve this using java-script/jquery. The confusing part is about update via Ajax, how to ensure that component is properly linked to ViewModel when component is Ajax updated (or even worse removed or dynamically added). Also, how should this ViewModel be constructed and which technicalities to use here and in components to work as synergy??? On the web, I have found the various examples of the similar approach, but they are oversimplified (even for dummies) or over specific and do not provide valuable resource or general solution for this kind of implementation. If you have some serious examples it would be, also, very helpful. Note: My aim is to make interactions between many components on the same page simpler and more robust and elegant.

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  • Composing programs from small simple pieces: OOP vs Functional Programming

    - by Jay Godse
    I started programming when imperative programming languages such as C were virtually the only game in town for paid gigs. I'm not a computer scientist by training so I was only exposed to Assembler and Pascal in school, and not Lisp or Prolog. Over the 1990s, Object-Oriented Programming (OOP) became more popular because one of the marketing memes for OOP was that complex programs could be composed of loosely coupled but well-defined, well-tested, cohesive, and reusable classes and objects. And in many cases that is quite true. Once I learned object-oriented programming my C programs became better because I structured them more like classes and objects. In the last few years (2008-2014) I have programmed in Ruby, an OOP language. However, Ruby has many functional programming (FP) features such as lambdas and procs, which enable a different style of programming using recursion, currying, lazy evaluation and the like. (Through ignorance I am at a loss to explain why these techniques are so great). Very recently, I have written code to use methods from the Ruby Enumerable library, such as map(), reduce(), and select(). Apparently this is a functional style of programming. I have found that using these methods significantly reduce code volume, and make my code easier to debug. Upon reading more about FP, one of the marketing claims made by advocates is that FP enables developers to compose programs out of small well-defined, well-tested, and reusable functions, which leads to less buggy code, and low code volume. QUESTIONS: Is the composition of complex program by using FP techniques contradictory to or complementary to composition of a complex program by using OOP techniques? In which situations is OOP more effective, and when is FP more effective? Is it possible to use both techniques in the same complex program? Do the techniques overlap or contradict each other?

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  • Interview Questions in OOP

    - by Fero
    Hi all, I faced the below interview questions in OOP under PHP language. Kindly clear my clarifications regarding this. I am very confused. As i am a beginner to OOP i got too confused. Could anyone clarify these things clearly? Difference between Abstract class and interface. Interviewer : Let us consider abstract class contains three abstract methods such as a,b,c and interface contains three methods a,b,c. In this case these do the same functionality. Then why are going for abstract and why are we going for interface. Me : ? static keyword. Interviewer: We call static method without creating object by using scope resolution operator in PHP. As well as we can able to call concrete methods also. Then what is need of static keyword there? Me : .... final keyword. Interviewer: Give me any scenario of using final keyword. Me : For db connection related method Interviewer: Other than that? Me: ... Constructor. Interviewer: What is the use of constructor? Me : There is no need for object to access this. It will call automatically when the class calls. Interviewer: Other than that? Me : .... Thanks in advance...

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  • How can I improve my isometric tile-picking algorithm?

    - by Cypher
    I've spent the last few days researching isometric tile-picking algorithms (converting screen-coordinates to tile-coordinates), and have obviously found a lot of the math beyond my grasp. I have come fairly close and what I have is workable, but I would like to improve on this algorithm as it's a little off and seems to pick down and to the right of the mouse pointer. I've uploaded a video to help visualize the current implementation: http://youtu.be/EqwWcq1zuaM My isometric rendering algorithm is based on what is found at this stackoverflow question's answer, with the exception that my x and y axis' are inverted (x increased down-right, while y increased up-right). Here is where I am converting from screen to tiles: // these next few lines convert the mouse pointer position from screen // coordinates to tile-grid coordinates. cameraOffset captures the current // mouse location and takes into consideration the camera's position on screen. System.Drawing.Point cameraOffset = new System.Drawing.Point( 0, 0 ); cameraOffset.X = mouseLocation.X + (int)camera.Left; cameraOffset.Y = ( mouseLocation.Y + (int)camera.Top ); // the camera-aware mouse coordinates are then further converted in an attempt // to select only the "tile" portion of the grid tiles, instead of the entire // rectangle. this algorithm gets close, but could use improvement. mouseTileLocation.X = ( cameraOffset.X + 2 * cameraOffset.Y ) / Global.TileWidth; mouseTileLocation.Y = -( ( 2 * cameraOffset.Y - cameraOffset.X ) / Global.TileWidth ); Things to make note of: mouseLocation is a System.Drawing.Point that represents the screen coordinates of the mouse pointer. cameraOffset is the screen position of the mouse pointer that includes the position of the game camera. mouseTileLocation is a System.Drawing.Point that is supposed to represent the tile coordinates of the mouse pointer. If you check out the above link to youtube, you'll notice that the picking algorithm is off a bit. How can I improve on this?

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  • Is an event loop just a for/while loop with optimized polling?

    - by Alan
    I'm trying to understand what an event loop is. Often the explanation is that in the event loop, you do something until you're notified that an event occurred. You than handle the event and continue doing what you did before. To map the above definition with an example. I have a server which 'listens' in a event loop, and when a socket connection is detected, the data from it gets read and displayed, after which the server goes to the listening it did before. However, this event happening and us getting notified 'just like that' are to much for me to handle. You can say: "It's not 'just like that' you have to register an event listener". But what's an event listener but a function which for some reason isn't returning. Is it in it's own loop, waiting to be notified when an event happens? Should the event listener also register an event listener? Where does it end? Events are a nice abstraction to work with, however just an abstraction. I believe that in the end, polling is unavoidable. Perhaps we are not doing it in our code, but the lower levels (the programming language implementation or the OS) are doing it for us. It basically comes down to the following pseudo code which is running somewhere low enough so it doesn't result in busy waiting: while(True): do stuff check if event has happened (poll) do other stuff This is my understanding of the whole idea, and i would like to hear if this is correct. I am open in accepting that the whole idea is fundamentally wrong, in which case I would like the correct explanation. Best regards

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  • XPath & XML EDI B2B

    - by PearlFactory
    GoodToGo :) Best XML Editor is Altova XMLSpy 2011 http://www.torrenthound.com/hash/bfdbf55baa4ca6f8e93464c9a42cbd66450bb950/torrent-info/Altova-XMLSpy-Enterprise-Edition-SP1-2011-v13-0-1-0-h33t-com-Full For whatever reason Piratebay has trojans and other nasties..Search in torrent.eu for Altova XMLSpy Enterprise Edition SP1 2011 v13.0.1.0 Also if you like the product purchase it in a Commercial Enviroment Any well structured/complex XML can be parsed @ the speed of light using XPATH querys and not the C# objects XPathNodeIterator and others etc ....Never do loops  or Genirics or whatever highlevel language technology. Use the power of XPATH i.e Will use a Simple (Do while) as an example. We could have many different techs all achieveing the same result Instead of   xmlNI2 = xmlNav.Select("/p:BookShop")         if (xmlNI2.Count != 0)            {                                 while ((xmlNI2.MoveNext()))              string aNode =xmlNI2.SelectSingleNode('Book', nsmgr); if (aNode =="The Book I am after")       Console.WriteLine("Found My Book);   This lengthy cumbersome task can be achieved with a simple XPATH query Console.WriteLine((xmlNavg.SelectSingleNode("/p:BookShop/Book[.='The Book I am aFter ']", nsmgr)).Value.ToString()); Use the power of the parser and eliminate the middleman C#/MSIL/JIT etc etc Get Started Fast and use the parser as Outlined 1) Open XML and goto Grid Mode 2) Select XPATH tab on the bottom viewer/window as shown  From here you get intellisense and can quickly learn how to navigate/find the data using XPATH A key component to Navigation with XPATH is to use the "../ " command . This basically says from where I am now go up 1 level . With Xpath all commands are cumalative. i.e you can search for a book title @ the 2nd level of the XML and from there traverse 15 layers to paragraphs or words on a page with expression validation occuring throughout this process etc  (So in essence you may have arrived @ a node within the XML and have met 15 conditions along the way ) Given 1-2 days with XmlSpy and XPATH you unlock a technology that is super fast and simple to use. XML is a core component to what lays under the hood of so many techs. So it is no wonder that you want to be able to goto  the atomic level to achieve the result you want Justin P.S For a long time I saw XML as slow and a bit boring but now converted

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  • Does unit testing lead to premature generalization (specifically in the context of C++)?

    - by Martin
    Preliminary notes I'll not go into the distinction of the different kinds of test there are, there are already a few questions on these sites regarding that. I'll take what's there and that says: unit testing in the sense of "testing the smallest isolatable unit of an application" from which this question actually derives The isolation problem What is the smallest isolatable unit of a program. Well, as I see it, it (highly?) depends on what language you are coding in. Micheal Feathers talks about the concept of a seam: [WEwLC, p31] A seam is a place where you can alter behavior in your program without editing in that place. And without going into the details, I understand a seam -- in the context of unit testing -- to be a place in a program where your "test" can interface with your "unit". Examples Unit test -- especially in C++ -- require from the code under test to add more seams that would be strictly called for for a given problem. Example: Adding a virtual interface where non-virtual implementation would have been sufficient Splitting -- generalizing(?) -- a (smallish) class further "just" to facilitate adding a test. Splitting a single-executable project into seemingly "independent" libs, "just" to facilitate compiling them independently for the tests. The question I'll try a few versions that hopefully ask about the same point: Is the way that Unit Tests require one to structure an application's code "only" beneficial for the unit tests or is it actually beneficial to the applications structure. Is the generalization code need to exhibit to be unit-testable useful for anything but the unit tests? Does adding unit tests force one to generalize unnecessarily? Is the shape unit tests force on code "always" also a good shape for the code in general as seen from the problem domain? I remember a rule of thumb that said don't generalize until you need to / until there's a second place that uses the code. With Unit Tests, there's always a second place that uses the code -- namely the unit test. So is this reason enough to generalize?

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  • How to document requirements for an API systematically?

    - by Heinrich
    I am currently working on a project, where I have to analyze the requirements of two given IT systems, that use cloud computing, for a Cloud API. In other words, I have to analyze what requirements these systems have for a Cloud API, such that they would be able to switch it, while being able to accomplish their current goals. Let me give you an example for some informal requirements of Project A: When starting virtual machines in the cloud through the API, it must be possible to specify the memory size, CPU type, operating system and a SSH key for the root user. It must be possible to monitor the inbound and outbound network traffic per hour per virtual machine. The API must support the assignment of public IPs to a virtual machine and the retrieval of the public IPs. ... In a later stage of the project I will analyze some Cloud Computing standards that standardize cloud APIs to find out where possible shortcomings in the current standards are. A finding could and will probably be, that a certain standard does not support monitoring resource usage and thus is not currently usable. I am currently trying to find a way to systematically write down and classify my requirements. I feel that the way I currently have them written down (like the three points above) is too informal. I have read in a couple of requirements enineering and software architecture books, but they all focus too much on details and implementation. I do really only care about the functionalities provided through the API/interface and I don't think UML diagrams etc. are the right choice for me. I think currently the requirements that I collected can be described as user stories, but is that already enough for a sophisticated requirements analysis? Probably I should go "one level deeper" ... Any advice/learning resources for me?

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