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• Writing C# Code Using SOLID Principles

  - by bipinjoshi

  Most of the modern programming languages including C# support objected oriented programming. Features such as encapsulation, inheritance, overloading and polymorphism are code level features. Using these features is just one part of the story. Equally important is to apply some object oriented design principles while writing your C# code. SOLID principles is a set of five such principles--namely Single Responsibility Principle, Open/Closed Principle, Liskov Substitution Principle, Interface Segregation Principle and Dependency Inversion Principle. Applying these time proven principles make your code structured, neat and easy to maintain. This article discusses SOLID principles and also illustrates how they can be applied to your C# code.http://www.binaryintellect.net/articles/7f857089-68f5-4d76-a3b7-57b898b6f4a8.aspx 

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• JavaScript Class Patterns

  - by Liam McLennan

  To write object-oriented programs we need objects, and likely lots of them. JavaScript makes it easy to create objects: var liam = { name: "Liam", age: Number.MAX_VALUE }; But JavaScript does not provide an easy way to create similar objects. Most object-oriented languages include the idea of a class, which is a template for creating objects of the same type. From one class many similar objects can be instantiated. Many patterns have been proposed to address the absence of a class concept in JavaScript. This post will compare and contrast the most significant of them. Simple Constructor Functions Classes may be missing but JavaScript does support special constructor functions. By prefixing a call to a constructor function with the ‘new’ keyword we can tell the JavaScript runtime that we want the function to behave like a constructor and instantiate a new object containing the members defined by that function. Within a constructor function the ‘this’ keyword references the new object being created -  so a basic constructor function might be: function Person(name, age) { this.name = name; this.age = age; this.toString = function() { return this.name + " is " + age + " years old."; }; } var john = new Person("John Galt", 50); console.log(john.toString()); Note that by convention the name of a constructor function is always written in Pascal Case (the first letter of each word is capital). This is to distinguish between constructor functions and other functions. It is important that constructor functions be called with the ‘new’ keyword and that not constructor functions are not. There are two problems with the pattern constructor function pattern shown above: It makes inheritance difficult The toString() function is redefined for each new object created by the Person constructor. This is sub-optimal because the function should be shared between all of the instances of the Person type. Constructor Functions with a Prototype JavaScript functions have a special property called prototype. When an object is created by calling a JavaScript constructor all of the properties of the constructor’s prototype become available to the new object. In this way many Person objects can be created that can access the same prototype. An improved version of the above example can be written: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); In this version a single instance of the toString() function will now be shared between all Person objects. Private Members The short version is: there aren’t any. If a variable is defined, with the var keyword, within the constructor function then its scope is that function. Other functions defined within the constructor function will be able to access the private variable, but anything defined outside the constructor (such as functions on the prototype property) won’t have access to the private variable. Any variables defined on the constructor are automatically public. Some people solve this problem by prefixing properties with an underscore and then not calling those properties by convention. function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { _getName: function() { return this.name; }, toString: function() { return this._getName() + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); Note that the _getName() function is only private by convention – it is in fact a public function. Functional Object Construction Because of the weirdness involved in using constructor functions some JavaScript developers prefer to eschew them completely. They theorize that it is better to work with JavaScript’s functional nature than to try and force it to behave like a traditional class-oriented language. When using the functional approach objects are created by returning them from a factory function. An excellent side effect of this pattern is that variables defined with the factory function are accessible to the new object (due to closure) but are inaccessible from anywhere else. The Person example implemented using the functional object construction pattern is: var personFactory = function(name, age) { var privateVar = 7; return { toString: function() { return name + " is " + age * privateVar / privateVar + " years old."; } }; }; var john2 = personFactory("John Lennon", 40); console.log(john2.toString()); Note that the ‘new’ keyword is not used for this pattern, and that the toString() function has access to the name, age and privateVar variables because of closure. This pattern can be extended to provide inheritance and, unlike the constructor function pattern, it supports private variables. However, when working with JavaScript code bases you will find that the constructor function is more common – probably because it is a better approximation of mainstream class oriented languages like C# and Java. Inheritance Both of the above patterns can support inheritance but for now, favour composition over inheritance. Summary When JavaScript code exceeds simple browser automation object orientation can provide a powerful paradigm for controlling complexity. Both of the patterns presented in this article work – the choice is a matter of style. Only one question still remains; who is John Galt?

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• JavaScript Class Patterns

  - by Liam McLennan

  To write object-oriented programs we need objects, and likely lots of them. JavaScript makes it easy to create objects: var liam = { name: "Liam", age: Number.MAX_VALUE }; But JavaScript does not provide an easy way to create similar objects. Most object-oriented languages include the idea of a class, which is a template for creating objects of the same type. From one class many similar objects can be instantiated. Many patterns have been proposed to address the absence of a class concept in JavaScript. This post will compare and contrast the most significant of them. Simple Constructor Functions Classes may be missing but JavaScript does support special constructor functions. By prefixing a call to a constructor function with the ‘new’ keyword we can tell the JavaScript runtime that we want the function to behave like a constructor and instantiate a new object containing the members defined by that function. Within a constructor function the ‘this’ keyword references the new object being created -  so a basic constructor function might be: function Person(name, age) { this.name = name; this.age = age; this.toString = function() { return this.name + " is " + age + " years old."; }; } var john = new Person("John Galt", 50); console.log(john.toString()); Note that by convention the name of a constructor function is always written in Pascal Case (the first letter of each word is capital). This is to distinguish between constructor functions and other functions. It is important that constructor functions be called with the ‘new’ keyword and that not constructor functions are not. There are two problems with the pattern constructor function pattern shown above: It makes inheritance difficult The toString() function is redefined for each new object created by the Person constructor. This is sub-optimal because the function should be shared between all of the instances of the Person type. Constructor Functions with a Prototype JavaScript functions have a special property called prototype. When an object is created by calling a JavaScript constructor all of the properties of the constructor’s prototype become available to the new object. In this way many Person objects can be created that can access the same prototype. An improved version of the above example can be written: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); In this version a single instance of the toString() function will now be shared between all Person objects. Private Members The short version is: there aren’t any. If a variable is defined, with the var keyword, within the constructor function then its scope is that function. Other functions defined within the constructor function will be able to access the private variable, but anything defined outside the constructor (such as functions on the prototype property) won’t have access to the private variable. Any variables defined on the constructor are automatically public. Some people solve this problem by prefixing properties with an underscore and then not calling those properties by convention. function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { _getName: function() { return this.name; }, toString: function() { return this._getName() + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); Note that the _getName() function is only private by convention – it is in fact a public function. Functional Object Construction Because of the weirdness involved in using constructor functions some JavaScript developers prefer to eschew them completely. They theorize that it is better to work with JavaScript’s functional nature than to try and force it to behave like a traditional class-oriented language. When using the functional approach objects are created by returning them from a factory function. An excellent side effect of this pattern is that variables defined with the factory function are accessible to the new object (due to closure) but are inaccessible from anywhere else. The Person example implemented using the functional object construction pattern is: var john = new Person("John Galt", 50); console.log(john.toString()); var personFactory = function(name, age) { var privateVar = 7; return { toString: function() { return name + " is " + age * privateVar / privateVar + " years old."; } }; }; var john2 = personFactory("John Lennon", 40); console.log(john2.toString()); Note that the ‘new’ keyword is not used for this pattern, and that the toString() function has access to the name, age and privateVar variables because of closure. This pattern can be extended to provide inheritance and, unlike the constructor function pattern, it supports private variables. However, when working with JavaScript code bases you will find that the constructor function is more common – probably because it is a better approximation of mainstream class oriented languages like C# and Java. Inheritance Both of the above patterns can support inheritance but for now, favour composition over inheritance. Summary When JavaScript code exceeds simple browser automation object orientation can provide a powerful paradigm for controlling complexity. Both of the patterns presented in this article work – the choice is a matter of style. Only one question still remains; who is John Galt?

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• What do the 4 keyboard input method systems in 10.04 mean?

  - by Android Eve

  I am trying to install another language support (in addition to the default US). Checking that language checkbox in "Install / Remove Languages..." wasn't too difficult. :) But now I want to add keyboard support, too, for that language. Again, I am prompted with a nice listbox with the following 4 options: none ibus lo-gtk th-gtk But I have no idea what these mean. I googled "ubuntu 10.04 keyboard input method system none ibus lo-gtk th-gtk" but all I could find was descriptions of problems, not an actual definition. Could you please point me to a webpage where I can learn about the meanings of these 4 different methods and +'s and -'s of each?

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• O&rsquo;Reilly Deals to 9/June/2014 05:00 PT&ndash;50% off E-Books on Regular Expressions

  - by TATWORTH

  Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2014/06/06/orsquoreilly-deals-to-9june2014-0500-ptndash50-off-e-books-on-regular.aspxUntil 9/June/2014 05:00 PT, O’Reilly are offering 50% off E-Books on Regular Expressions at http://shop.oreilly.com/category/deals/regular-expressions-owo.do?code=DEAL&imm_mid=0bd938&cmp=em-prog-books-videos-lp-dod_regex. “Regular expressions—powerful tools for manipulating text and data—are now standard features in most languages and tools. Yet despite their widespread availability and unparalleled power, regular expressions are frequently underused. With ebooks and videos from shop.oreilly.com, learn tips for matching, extracting, and transforming text and data. Today only, save 50% and discover the epic functionality of Reg Ex.”

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• Change the Default Font Size in Word

  - by Matthew Guay

  Are you frustrated by always having to change the font size before you create a document it Word?  Here’s how you can end that frustration and set your favorite default font size for once and for all! Microsoft changed the default font font to 11 point Calibri in Word 2007 after years of 12 point Times New Roman being the default.  Although it can be easily overlooked, there are ways in Word to change the default settings to anything you want.  Whether you want to change your default to 12 point Calibri or to 48 point Comic Sans…here’s how to change your default font settings in Word 2007 and 2010. Changing Default Fonts in Word To change the default font settings, click the small box with an arrow in the right left corner of the Font section of the Home tab in the Ribbon.   In the Font dialog box, choose the default font settings you want.  Notice in the Font box it says “+Body”; this means that the font will be chosen by the document style you choose, and you are only selecting the default font style and size.  So, if your style uses Calibri, then your font will be Calibri at the size and style you chose.  If you’d prefer to choose a specific font to be the default, just select one from the drop-down box and this selection will override the font selection in your document style. Here we left all the default settings, except we selected 12 point font in the Latin text box (this is your standard body text; users of Asian languages such as Chinese may see a box for Asian languages).  When you’ve made your selections, click the “Set as Default” button in the bottom left corner of the dialog. You will be asked to confirm that you want these settings to be made default.  In Word 2010, you will be given the option to set these settings for this document only or for all documents.  Click the bullet beside “All documents based on the Normal.dotm template?”, and then click Ok. In Word 2007, simply click Ok to save these settings as default. Now, whenever you open Word or create a new document, your default font settings should be set exactly to what you want.  And simply repeat these steps to change your default font settings again if you want. Editing your default template file Another way to change your default font settings is to edit your Normal.dotm file.  This file is what Word uses to create new documents; it basically copies the formatting in this document each time you make a new document. To edit your Normal.dotm file, enter the following in the address bar in Explorer or in the Run prompt: %appdata%\Microsoft\Templates This will open your Office Templates folder.  Right-click on the Normal.dotm file, and click Open to edit it.  Note: Do not double-click on the file, as this will only create a new document based on Normal.dotm and any edits you make will not be saved in this file.   Now, change any font settings as you normally would.  Remember: anything you change or enter in this document will appear in any new document you create using Word. If you want to revert to your default settings, simply delete your Normal.dotm file.  Word will recreate it with the standard default settings the next time you open Word. Please Note: Changing your default font size will not change the font size in existing documents, so these will still show the settings you used when these documents were created.  Also, some addins can affect your Normal.dotm template.  If Word does not seem to remember your font settings, try disabling Word addins to see if this helps. Conclusion Sometimes it’s the small things that can be the most frustrating.  Getting your default font settings the way you want is a great way to take away a frustration and make you more productive. And here’s a quick question: Do you prefer the new default 11 point Calibri, or do you prefer 12 point Times New Roman or some other combination?  Sound off in the comments, and let the world know your favorite font settings. Similar Articles Productive Geek Tips Change the Default Font in Excel 2007Add Emphasis to Paragraphs with Drop Caps in Word 2007Keep Websites From Using Tiny Fonts in SafariMake Word 2007 Always Save in Word 2003 FormatStupid Geek Tricks: Enable More Fonts for the Windows Command Prompt TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Spyware Blaster v4.3 Yes, it’s Patch Tuesday Generate Stunning Tag Clouds With Tagxedo Install, Remove and HIDE Fonts in Windows 7 Need Help with Your Home Network? Awesome Lyrics Finder for Winamp & Windows Media Player

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• Are VB.NET to C# converters actually compilers?

  - by Rowan Freeman

  Whenever I see programs or scripts that convert between high-level programming languages they are always labelled as converters. "VB.NET to C# converter" on Google results in expected, useful hits. However "VB.NET to C# compiler" on Google results in things like comparisons between the C# and VB.NET compilers and other hits that are not quite what you'd be looking for. Webopedia defines Compiler as A program that translates source code into object code Eric Lipper in an answer to: "How do I create my own programming language and a compiler for it" suggests: One of the best ways to get started writing a compiler is by writing a high-level-language-to-high-level-language compiler. Is a converter really just a compiler? What separates the two?

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• F# for the C# Programmer

  - by mbcrump

  Are you a C# Programmer and can’t make it past a day without seeing or hearing someone mention F#?  Today, I’m going to walk you through your first F# application and give you a brief introduction to the language. Sit back this will only take about 20 minutes. Introduction Microsoft's F# programming language is a functional language for the .NET framework that was originally developed at Microsoft Research Cambridge by Don Syme. In October 2007, the senior vice president of the developer division at Microsoft announced that F# was being officially productized to become a fully supported .NET language and professional developers were hired to create a team of around ten people to build the product version. In September 2008, Microsoft released the first Community Technology Preview (CTP), an official beta release, of the F# distribution . In December 2008, Microsoft announced that the success of this CTP had encouraged them to escalate F# and it is now will now be shipped as one of the core languages in Visual Studio 2010 , alongside C++, C# 4.0 and VB. The F# programming language incorporates many state-of-the-art features from programming language research and ossifies them in an industrial strength implementation that promises to revolutionize interactive, parallel and concurrent programming. Advantages of F# F# is the world's first language to combine all of the following features: Type inference: types are inferred by the compiler and generic definitions are created automatically. Algebraic data types: a succinct way to represent trees. Pattern matching: a comprehensible and efficient way to dissect data structures. Active patterns: pattern matching over foreign data structures. Interactive sessions: as easy to use as Python and Mathematica. High performance JIT compilation to native code: as fast as C#. Rich data structures: lists and arrays built into the language with syntactic support. Functional programming: first-class functions and tail calls. Expressive static type system: finds bugs during compilation and provides machine-verified documentation. Sequence expressions: interrogate huge data sets efficiently. Asynchronous workflows: syntactic support for monadic style concurrent programming with cancellations. Industrial-strength IDE support: multithreaded debugging, and graphical throwback of inferred types and documentation. Commerce friendly design and a viable commercial market. Lets try a short program in C# then F# to understand the differences. Using C#: Create a variable and output the value to the console window: Sample Program. using System;   namespace ConsoleApplication9 {     class Program     {         static void Main(string[] args)         {             var a = 2;             Console.WriteLine(a);             Console.ReadLine();         }     } } A breeze right? 14 Lines of code. We could have condensed it a bit by removing the “using” statment and tossing the namespace. But this is the typical C# program. Using F#: Create a variable and output the value to the console window: To start, open Visual Studio 2010 or Visual Studio 2008. Note: If using VS2008, then please download the SDK first before getting started. If you are using VS2010 then you are already setup and ready to go. So, click File-> New Project –> Other Languages –> Visual F# –> Windows –> F# Application. You will get the screen below. Go ahead and enter a name and click OK. Now, you will notice that the Solution Explorer contains the following: Double click the Program.fs and enter the following information. Hit F5 and it should run successfully. Sample Program. open System let a = 2        Console.WriteLine a As Shown below: Hmm, what? F# did the same thing in 3 lines of code. Show me the interactive evaluation that I keep hearing about. The F# development environment for Visual Studio 2010 provides two different modes of execution for F# code: Batch compilation to a .NET executable or DLL. (This was accomplished above). Interactive evaluation. (Demo is below) The interactive session provides a > prompt, requires a double semicolon ;; identifier at the end of a code snippet to force evaluation, and returns the names (if any) and types of resulting definitions and values. To access the F# prompt, in VS2010 Goto View –> Other Window then F# Interactive. Once you have the interactive window type in the following expression: 2+3;; as shown in the screenshot below: I hope this guide helps you get started with the language, please check out the following books for further information. F# Books for further reading   Foundations of F# Author: Robert Pickering An introduction to functional programming with F#. Including many samples, this book walks through the features of the F# language and libraries, and covers many of the .NET Framework features which can be leveraged with F#.       Functional Programming for the Real World: With Examples in F# and C# Authors: Tomas Petricek and Jon Skeet An introduction to functional programming for existing C# developers written by Tomas Petricek and Jon Skeet. This book explains the core principles using both C# and F#, shows how to use functional ideas when designing .NET applications and presents practical examples such as design of domain specific language, development of multi-core applications and programming of reactive applications.

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• Maps for Business: Generating Valid Signatures

  Maps for Business: Generating Valid Signatures This video shows developers how to generate signed requests to Google Maps for Business Web Services such as the Geocoding API. It also points Maps for Business developers to pertinent documentation like developers.google.com and shows an example of the Maps for Business Welcome Letter. To get a response from the Maps for Business API Web Services, developers need to know: how to find their Maps For Business client ID; how to include that client ID in requests; how to retrieve their Maps for Business digital signing key from the Maps for Business welcome materials; and how to use the key to generate a signature. The video will walk developers through the signature generation steps using Python, and provides pointers to examples in other languages. From: GoogleDevelopers Views: 7 0 ratings Time: 10:42 More in Science & Technology

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• Computer Science or Computer Engineering for Data Science and Machine Learning

  - by ATMathew

  I'm a 25 year old data consultant who is considering returning to school to get a second bachelors degree in computer science or engineering. My interest is data science and machine learning. I use programming as a means to an end, and use languages like Python, R, C, Java, and Hadoop to find meaning in large data sets. Would a computer science or computer engineering degree be better for this? I realize that a statistics degree may be even more beneficial, but I'll be at a school which dosn't have a stats department or a computational math department.

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• Starting a career with broad experience or specific experience

  - by TMP

  I am a senior in college going for a CS degree. I have an internship that works with a variety of languages and gives me a pretty good amount of responsibility. The only problem is that it is the only job experience I've had. My question is whether or not it might be a good idea to work another internship, keep the same internship, or in addition to the previous options, to get a masters degree so that i can extend my education and time to gather the usually necessary 2-3 years of industry experience. Obviously there's no outright correct way, but i just want to know if it is more accepted to get experience with different companies or to stick with one to show commitment.

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• Best way to throw exception and avoid code duplication

  - by JF Dion

  I am currently writing code and want to make sure all the params that get passed to a function/method are valid. Since I am writing in PHP I don't have access to all the facilities of other languages like C, C++ or Java to check for parameters values and types public function inscriptionExists($sectionId, $userId) // PHP vs. public boolean inscriptionExists(int sectionId, int userId) // Java So I have to rely on exceptions if I want to make sure that my params are both integers. Since I have a lot of places where I need to check for param validity, what would be the best way to create a validation/exception machine and avoid code duplication? I was thinking on a static factory (since I don't want to pass it to all of my classes) with a signature like: public static function factory ($value, $valueType, $exceptionType = 'InvalidArgumentException'); Which would then call the right sub process to validate based on the type. Am I on the right way, or am I going completely off the road and overthinking my problem?

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• India's Largest Polyglot Conference and Workshops for IT Software Professionals - Great Indian Devel

  Great Indian Developer Summit is the gold standard for India's software developer ecosystem for gaining exposure to and evaluating new projects, tools, services, platforms, languages, software and standards. Packed with premium knowledge, action plans and advise from been-there-done-it veterans, creators, and visionaries, the 2010 edition of Great Indian Developer Summit features focused sessions, case studies, workshops and power panels that will transform you into a force to reckon with. Featuring...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• End user query syntax?

  - by weberc2

  I'm making a command line tool that allows end users to query a statically-schemed database; however, I want users to be able to specify boolean matchers in their query (effectively things like "get rows where (field1=abcd && field2=efgh) || field3=1234"). I did Googling a solution, but I couldn't find anything suitable for end users--still, this seems like it would be a very common problem so I suspect there is a standard solution. So: What (if any) standard query "languages" are there that might be appropriate for end users? What (if any) de facto standards are there (for example, Unix tools that solve similar problems). Failing the previous two options, can you suggest a syntax that would be simple, concise, and easy to validate?

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• How do I do TDD on embedded devices?

  - by Darth

  I'm not new to programming and I've even worked with some low level C and ASM on AVR, but I really can't get my head around a larger-scale embedded C project. Being degenerated by the Ruby's philosophy of TDD/BDD, I'm unable to understand how people write and test code like this. I'm not saying it's a bad code, I just don't understand how this can work. I wanted to get more into some low level programming, but I really have no idea how to approach this, since it looks like a completely different mindset that I'm used to. I don't have trouble understanding pointer arithmetics, or how allocating memory works, but when I see how complex C/C++ code looks compared to Ruby, it just seems impossibly hard. Since I already ordered myself an Arduino board, I'd love to get more into some low level C and really understand how to do things properly, but it seems like none of the rules of high level languages apply. Is it even possible to do TDD on embedded devices or when developing drivers or things like custom bootloader, etc.?

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• how to get all programming skills. guys help me to become a good programmer [closed]

  - by Dhananjay

  okay guys i dropped out and now self teaching myself programming.i want to be a good programmer.i downloaded c++ primer plus by stephen prata .i thought its a good book but here many peoples are saying that its not a good book.so please suggest me from where i should start.which books i should read..i know little programming just basic not much.but i want to be expert so please suggest books and also tell that in which pattern i should study as i m free 24 hours.should i only study c++ untill i finsh it or side by side other languages too?from which book did u learned it? give some advises/tips. i want to make my own apps and i want to learn web development also.. thank you ?

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• Towards an F# .NET Reflector add-in

  - by CliveT

  When I had the opportunity to spent some time during Red Gate's recent "down tools" week on a project of my choice, the obvious project was an F# add-in for Reflector . To be honest, this was a bit of a misnomer as the amount of time in the designated week for coding was really less than three days, so it was always unlikely that very much progress would be made in such a small amount of time (and that certainly proved to be the case), but I did learn some things from the experiment. Like lots of problems, one useful technique is to take examples, get them to work, and then generalise to get something that works across the board. Unfortunately, I didn't have enough time to do the last stage. The obvious first step is to take a few function definitions, starting with the obvious hello world, moving on to a non-recursive function and finishing with the ubiquitous recursive Fibonacci function. let rec printMessage message  =     printfn  message let foo x  =    (x + 1) let rec fib x  =     if (x >= 2) then (fib (x - 1) + fib (x - 2)) else 1 The major problem in decompiling these simple functions is that Reflector has an in-memory object model that is designed to support object-oriented languages. In particular it has a return statement that allows function bodies to finish early. I used some of the in-built functionality to take the IL and produce an in-memory object model for the language, but then needed to write a transformer to push the return statements to the top of the tree to make it easy to render the code into a functional language. This tree transform works in some scenarios, but not in others where we simply regenerate code that looks more like CPS style. The next thing to get working was library level bindings of values where these values are calculated at runtime. let x = [1 ; 2 ; 3 ; 4] let y = List.map  (fun x -> foo x) x The way that this is translated into a set of classes for the underlying platform means that the code needs to follow references around, from the property exposing the calculated value to the class in which the code for generating the value is embedded. One of the strongest selling points of functional languages is the algebraic datatypes, which allow definitions via standard mathematical-style inductive definitions across the union cases. type Foo =     | Something of int     | Nothing type 'a Foo2 =     | Something2 of 'a     | Nothing2 Such a definition is compiled into a number of classes for the cases of the union, which all inherit from a class representing the type itself. It wasn't too hard to get such a de-compilation happening in the cases I tried. What did I learn from this? Firstly, that there are various bits of functionality inside Reflector that it would be useful for us to allow add-in writers to access. In particular, there are various implementations of the Visitor pattern which implement algorithms such as calculating the number of references for particular variables, and which perform various substitutions which could be more generally useful to add-in writers. I hope to do something about this at some point in the future. Secondly, when you transform a functional language into something that runs on top of an object-based platform, you lose some fidelity in the representation. The F# compiler leaves attributes in place so that tools can tell which classes represent classes from the source program and which are there for purposes of the implementation, allowing the decompiler to regenerate these constructs again. However, decompilation technology is a long way from being able to take unannotated IL and transform it into a program in a different language. For a simple function definition, like Fibonacci, I could write a simple static function and have it come out in F# as the same function, but it would be practically impossible to take a mass of class definitions and have a decompiler translate it automatically into an F# algebraic data type. What have we got out of this? Some data on the feasibility of implementing an F# decompiler inside Reflector, though it's hard at the moment to say how long this would take to do. The work we did is included the 6.5 EAP for Reflector that you can get from the EAP forum. All things considered though, it was a useful way to gain more familiarity with the process of writing an add-in and understand difficulties other add-in authors might experience. If you'd like to check out a video of Down Tools Week, click here.

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• Linux multiplayer server, need some help.

  - by Viktor

  I need to write a server for a game, which is closer to action type game, so needs fast communication. There must be only one server, I'll just split the world in zones, but this is not the question. Client will be written in java using jMonkeyEngine. In my opinion I should write the server in java. I don't want to implement any low level features such as communication, reliable udp, etc. Can you suggest any java libraries that already implement this? Or maybe there is more suitable languages to implement this project (must run on linux)?

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• How can I get Japanese, Chinese and Korean input to work properly on Skype, aMsn and other softwares

  - by Camilo García

  I have installed the packages for Japanese (Anthy),and those for Chinese and Korean input. They work perfectly on most of the software that come with Ubuntu, such as the LibreOffice suite and the browsers, however, I cannot input any of these three languages on Skype, aMsn or almost any software I have downloaded/installed myself. For example I have installed a Japanese-English dictionary called Tagaini Jisho, and I CANNOT input Japanese on it! I love Ubuntu, except the issues I have been experincing when I want to use these language tools. Can anybody please help me about this issue. Thank you in advance. Best regards

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• Getting to grips with the stack in nasm

  - by MarkPearl

  Today I spent a good part of my day getting to grips with the stack and nasm. After looking at my notes on nasm I think this is one area for the course I am doing they could focus more on… So here are some snippets I have put together that have helped me understand a little bit about the stack… Simplest example of the stack You will probably see examples like the following in circulation… these demonstrate the simplest use of the stack… org 0x100 bits 16 jmp main main: push 42h push 43h push 44h mov ah,2h ;set to display characters pop dx    ;get the first value int 21h   ;and display it pop dx    ;get 2nd value int 21h   ;and display it pop dx    ;get 3rd value int 21h   ;and display it int 20h The output from above code would be… DCB Decoupling code using “call” and “ret” This is great, but it oversimplifies what I want to use the stack for… I do not know if this goes against the grain of assembly programmers or not, but I want to write loosely coupled assembly code – and I want to use the stack as a mechanism for passing values into my decoupled code. In nasm we have the call and return instructions, which provides a mechanism for decoupling code, for example the following could be done… org 0x100 bits 16 jmp main ;---------------------------------------- displayChar: mov ah,2h mov dx,41h int 21h ret ;---------------------------------------- main: call displayChar int 20h   This would output the following to the console A So, it would seem that call and ret allow us to jump to segments of our code and then return back to the calling position – a form of segmenting the code into what we would called in higher order languages “functions” or “methods”. The only issue is, in higher order languages there is a way to pass parameters into the functions and return results. Because of the primitive nature of the call and ret instructions, this does not seem to be obvious. We could of course use the registers to pass values into the subroutine and set values coming out, but the problem with this is we… Have a limited number of registers Are threading our code with tight coupling (it would be hard to migrate methods outside of their intended use in a particular program to another one) With that in mind, I turn to the stack to provide a loosely coupled way of calling subroutines… First attempt with the Stack Initially I thought this would be simple… we could use code that looks as follows to achieve what I want… org 0x100 bits 16 jmp main ;---------------------------------------- displayChar: mov ah,2h pop dx int 21h ret ;---------------------------------------- main: push 41h call displayChar int 20h   However running this application does not give the desired result, I want an ‘A’ to be returned, and I am getting something totally different (you will to). Reading up on the call and ret instructions a discovery is made… they are pushing and popping things onto and off the stack as well… When the call instruction is executed, the current value of IP (the address of the instruction to follow) is pushed onto the stack, when ret is called, the last value on the stack is popped off into the IP register. In effect what the above code is doing is as follows with the stack… push 41h push current value of ip pop current value of ip to dx pop 41h to ip This is not what I want, I need to access the 41h that I pushed onto the stack, but the call value (which is necessary) is putting something in my way. So, what to do? Remember we have other registers we can use as well as a thing called indirect addressing… So, after some reading around, I came up with the following approach using indirect addressing… org 0x100 bits 16 jmp main ;---------------------------------------- displayChar: mov bp,sp mov ah,2h mov dx,[bp+2] int 21h ret ;---------------------------------------- main: push 41h call displayChar int 20h In essence, what I have done here is used a trick with the stack pointer… it goes as follows… Push 41 onto the stack Make the call to the function, which will push the IP register onto the stack and then jump to the displayChar label Move the value in the stack point to the bp register (sp currently points at IP register) Move the at the location of bp minus 2 bytes to dx (this is now the value 41h) display it, execute the ret instruction, which pops the ip value off the stack and goes back to the calling point This approach is still very raw, some further reading around shows that I should be pushing the value of bp onto the stack before replacing it with sp, but it is the starting thread to getting loosely coupled subroutines. Let’s see if you get what the following output would be? org 0x100 bits 16 jmp main ;---------------------------------------- displayChar: mov bp,sp mov ah,2h mov dx,[bp+4] int 21h mov dx,[bp+2] int 21h ret ;---------------------------------------- main: push 41h push 42h call displayChar int 20h The output is… AB Where to from here? If by any luck some assembly programmer comes along and see this code and notices that I have made some fundamental flaw in my logic… I would like to know, so please leave a comment… appreciate any feedback!

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• Visual Studio 2010 tip: Cut empty lines

  - by koevoeter

  How many times you wanted to move 2 lines by cut and pasting them, but the line you cut last is actually a blank line and your actual code is removed from the clipboard? Visual Studio 2010 has an option that keeps cutting blank lines from overwriting the clipboard. Go and uncheck this one: Tools » Options » Text Editor » All Languages » General » Apply Cut or Copy commands to blank lines when there is no selection Extra (related) tip The (free) Visual Studio 2010 extension Visual Studio 2010 Pro Power Tools contains (apart from a bunch of other handy features) the commands Edit.MoveLineUp and Edit.MoveLineDown to do whatever they say they do and maps them automatically to keyboard shortcuts Alt+Up & Alt+Down. Resharper (not-free) has similar commands for moving lines, by default mapped to Ctrl+Alt+Shift+Up/Down.

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• What can Go chan do that a list cannot?

  - by alpav

  I want to know in which situation Go chan makes code much simpler than using list or queue or array that is usually available in all languages. As it was stated by Rob Pike in one of his speeches about Go lexer, Go channels help to organize data flow between structures that are not homomorphic. I am interested in a simple Go code sample with chan that becomes MUCH more complicated in another language (for example C#) where chan is not available. I am not interested in samples that use chan just to increase performance by avoiding waiting of data between generating list and consuming the list (which can be solved by chunking) or as a way to organize thread safe queue or thread-safe communication (which can be easily solved by locking primitives). I am interested in a sample that makes code simpler structurally disregarding size of data. If such sample does not exist then sample where size of data matters. I guess desired sample would contain bi-directional communication between generator and consumer. Also if someone could add tag [channel] to the list of available tags, that would be great.

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• I don't really understand "Backend/Serverside" when it comes to web-development?

  - by Mercfh

  In the Web development world, what exactly do backend/server-side programmers do? I guess I don't really understand the whole concept. I've done the HTML/CSS layouts and website design and a little bit of SQL with PHP (still enhancing my skills, it's more of a side project for me). I've also done a small amount of JavaScript/JQuery. But I don't understand the "backend" work, such as the scripting languages (Rails/Python/etc) and such. What exactly do you "do" with them? Are there any books on the subject? I'm not even sure what it means. Is it kinda like what Web Application Frameworks do? Or not so much?

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• Boston: Free Java Developer Event March 3rd!

  - by Jacob Lehrbaum

  Attention Boston area developers!  Oracle has been running a series of free one-day Java Developer events in the US, Europe, and Asia since last November, and on March 3rd, this highly popular series is coming to the Westin Copley Place in Boston.  The Java Developer Day will include four tracks of sessions and hands-on-labs designed for developers interested in Server, Desktop, Embedded, and core Java SE platform topics.  Technologies covered include Java EE, Java ME and Java SE (including the JDK).  From the event page: Come to this free event if you are interested in:Evaluating the Java platformUsing other languages on the JVMBuilding server side JavaConstructing Rich Web or Desktop ApplicationsUnderstanding the JVM and its built in diagnosticsMaking Smart Devices even smarterCheck out the event page to read more and/or register.  The event is free, but space is limited so register today!

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• Understanding The Very Nature Of Linux - Becoming Core Programmer

  - by MrWho

  Well, I want to know how I should exactly start and get into the right path to become a core programmer and also get decent understanding of Linux infrastructure and fundamentals. I know my question may seem general or something but that's not because of my inability to ask a question.I'm just confused, I've programmed in a few languages and have got my hand dirty to code so I'm aware of the big picture of what the programmers actually do.Now, I want to get deeper and start my studies in a different level than I used to learn before, I want to become advanced core programmer and learn where it really start from.I'd like to know the bit by bit of what the today's operating systems like linux have been built on. I DO really need good references, books would be preferred for learning the fundamentals.If someone tell me the general path of what I'm supposed to do, it would be really appreciated.

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