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• Platform Builder: Disable the USB Driver Dialog

  - by Bruce Eitman

  For a long time, Windows CE developers and users have wanted to disable the USB Driver Dialog that is displayed when an unknown USB device is plugged into the host controller.   Of course the question is always why would you want to do such a thing? The simple answer is that there are USB devices that are needed, like printers, which expose multiple functions to the bus, like scanners and faxes, which no Windows CE driver exists to support.   So the printer quietly loads a driver, but then the other functions cause a dialog to be shown. One solution is to create a USB Class driver that loads by default if no other driver has been loaded. This driver just accepts anything that it sees and then does nothing with it. Starting with the Windows Embedded CE 6.0 R3 March QFE/update, the USB 2.0 driver has a registry value to disable the dialog: [HKEY_LOCAL_MACHINE\Drivers\USB\LoadClients]       "DoNotPromptUser"=dword:0   Setting the DoNotPromptUser value to 1 disables the dialog. The default value is zero, so the driver continues to behave in the same way it always did unless you change this registry value.     Copyright © 2010 – Bruce Eitman All Rights Reserved

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• Is it normal needing time to understand code i wrote recently

  - by user1478167

  By recently i mean some weeks ago. I am trying to continue a project i left 2 weeks ago and i need time to understand some functions i wrote(not copied from somewhere) and it takes me time. Normally i don't need to because my functions,methods etc are black boxes but when i need to change something it's really hard. Does this mean i write bad code? I am still in school and i am the only who writes/uses the code so i don't have feedback, but i am afraid that if it is difficult for me to understand it, it would be 10 times more difficult for someone else. What should i do? I write a lot of comments but most of the time are useless when reviewing. Do you have any suggestions?

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• Getting Started with TypeScript – Classes, Static Types and Interfaces

  - by dwahlin

  I had the opportunity to speak on different JavaScript topics at DevConnections in Las Vegas this fall and heard a lot of interesting comments about JavaScript as I talked with people. The most frequent comment I heard from people was, “I guess it’s time to start learning JavaScript”. Yep – if you don’t already know JavaScript then it’s time to learn it. As HTML5 becomes more and more popular the amount of JavaScript code written will definitely increase. After all, many of the HTML5 features available in browsers have little to do with “tags” and more to do with JavaScript (web workers, web sockets, canvas, local storage, etc.). As the amount of JavaScript code being used in applications increases, it’s more important than ever to structure the code in a way that’s maintainable and easy to debug. While JavaScript patterns can certainly be used (check out my previous posts on the subject or my course on Pluralsight.com), several alternatives have come onto the scene such as CoffeeScript, Dart and TypeScript. In this post I’ll describe some of the features TypeScript offers and the benefits that they can potentially offer enterprise-scale JavaScript applications. It’s important to note that while TypeScript has several great features, it’s definitely not for everyone or every project especially given how new it is. The goal of this post isn’t to convince you to use TypeScript instead of standard JavaScript….I’m a big fan of JavaScript. Instead, I’ll present several TypeScript features and let you make the decision as to whether TypeScript is a good fit for your applications. TypeScript Overview Here’s the official definition of TypeScript from the http://typescriptlang.org site: “TypeScript is a language for application-scale JavaScript development. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. Any browser. Any host. Any OS. Open Source.” TypeScript was created by Anders Hejlsberg (the creator of the C# language) and his team at Microsoft. To sum it up, TypeScript is a new language that can be compiled to JavaScript much like alternatives such as CoffeeScript or Dart. It isn’t a stand-alone language that’s completely separate from JavaScript’s roots though. It’s a superset of JavaScript which means that standard JavaScript code can be placed in a TypeScript file (a file with a .ts extension) and used directly. That’s a very important point/feature of the language since it means you can use existing code and frameworks with TypeScript without having to do major code conversions to make it all work. Once a TypeScript file is saved it can be compiled to JavaScript using TypeScript’s tsc.exe compiler tool or by using a variety of editors/tools. TypeScript offers several key features. First, it provides built-in type support meaning that you define variables and function parameters as being “string”, “number”, “bool”, and more to avoid incorrect types being assigned to variables or passed to functions. Second, TypeScript provides a way to write modular code by directly supporting class and module definitions and it even provides support for custom interfaces that can be used to drive consistency. Finally, TypeScript integrates with several different tools such as Visual Studio, Sublime Text, Emacs, and Vi to provide syntax highlighting, code help, build support, and more depending on the editor. Find out more about editor support at http://www.typescriptlang.org/#Download. TypeScript can also be used with existing JavaScript frameworks such as Node.js, jQuery, and others and even catch type issues and provide enhanced code help. Special “declaration” files that have a d.ts extension are available for Node.js, jQuery, and other libraries out-of-the-box. Visit http://typescript.codeplex.com/SourceControl/changeset/view/fe3bc0bfce1f#samples%2fjquery%2fjquery.d.ts for an example of a jQuery TypeScript declaration file that can be used with tools such as Visual Studio 2012 to provide additional code help and ensure that a string isn’t passed to a parameter that expects a number. Although declaration files certainly aren’t required, TypeScript’s support for declaration files makes it easier to catch issues upfront while working with existing libraries such as jQuery. In the future I expect TypeScript declaration files will be released for different HTML5 APIs such as canvas, local storage, and others as well as some of the more popular JavaScript libraries and frameworks. Getting Started with TypeScript To get started learning TypeScript visit the TypeScript Playground available at http://www.typescriptlang.org. Using the playground editor you can experiment with TypeScript code, get code help as you type, and see the JavaScript that TypeScript generates once it’s compiled. Here’s an example of the TypeScript playground in action:   One of the first things that may stand out to you about the code shown above is that classes can be defined in TypeScript. This makes it easy to group related variables and functions into a container which helps tremendously with re-use and maintainability especially in enterprise-scale JavaScript applications. While you can certainly simulate classes using JavaScript patterns (note that ECMAScript 6 will support classes directly), TypeScript makes it quite easy especially if you come from an object-oriented programming background. An example of the Greeter class shown in the TypeScript Playground is shown next: class Greeter { greeting: string; constructor (message: string) { this.greeting = message; } greet() { return "Hello, " + this.greeting; } } Looking through the code you’ll notice that static types can be defined on variables and parameters such as greeting: string, that constructors can be defined, and that functions can be defined such as greet(). The ability to define static types is a key feature of TypeScript (and where its name comes from) that can help identify bugs upfront before even running the code. Many types are supported including primitive types like string, number, bool, undefined, and null as well as object literals and more complex types such as HTMLInputElement (for an <input> tag). Custom types can be defined as well. The JavaScript output by compiling the TypeScript Greeter class (using an editor like Visual Studio, Sublime Text, or the tsc.exe compiler) is shown next: var Greeter = (function () { function Greeter(message) { this.greeting = message; } Greeter.prototype.greet = function () { return "Hello, " + this.greeting; }; return Greeter; })(); Notice that the code is using JavaScript prototyping and closures to simulate a Greeter class in JavaScript. The body of the code is wrapped with a self-invoking function to take the variables and functions out of the global JavaScript scope. This is important feature that helps avoid naming collisions between variables and functions. In cases where you’d like to wrap a class in a naming container (similar to a namespace in C# or a package in Java) you can use TypeScript’s module keyword. The following code shows an example of wrapping an AcmeCorp module around the Greeter class. In order to create a new instance of Greeter the module name must now be used. This can help avoid naming collisions that may occur with the Greeter class.   module AcmeCorp { export class Greeter { greeting: string; constructor (message: string) { this.greeting = message; } greet() { return "Hello, " + this.greeting; } } } var greeter = new AcmeCorp.Greeter("world"); In addition to being able to define custom classes and modules in TypeScript, you can also take advantage of inheritance by using TypeScript’s extends keyword. The following code shows an example of using inheritance to define two report objects:   class Report { name: string; constructor (name: string) { this.name = name; } print() { alert("Report: " + this.name); } } class FinanceReport extends Report { constructor (name: string) { super(name); } print() { alert("Finance Report: " + this.name); } getLineItems() { alert("5 line items"); } } var report = new FinanceReport("Month's Sales"); report.print(); report.getLineItems();   In this example a base Report class is defined that has a variable (name), a constructor that accepts a name parameter of type string, and a function named print(). The FinanceReport class inherits from Report by using TypeScript’s extends keyword. As a result, it automatically has access to the print() function in the base class. In this example the FinanceReport overrides the base class’s print() method and adds its own. The FinanceReport class also forwards the name value it receives in the constructor to the base class using the super() call. TypeScript also supports the creation of custom interfaces when you need to provide consistency across a set of objects. The following code shows an example of an interface named Thing (from the TypeScript samples) and a class named Plane that implements the interface to drive consistency across the app. Notice that the Plane class includes intersect and normal as a result of implementing the interface.   interface Thing { intersect: (ray: Ray) => Intersection; normal: (pos: Vector) => Vector; surface: Surface; } class Plane implements Thing { normal: (pos: Vector) =>Vector; intersect: (ray: Ray) =>Intersection; constructor (norm: Vector, offset: number, public surface: Surface) { this.normal = function (pos: Vector) { return norm; } this.intersect = function (ray: Ray): Intersection { var denom = Vector.dot(norm, ray.dir); if (denom > 0) { return null; } else { var dist = (Vector.dot(norm, ray.start) + offset) / (-denom); return { thing: this, ray: ray, dist: dist }; } } } }   At first glance it doesn’t appear that the surface member is implemented in Plane but it’s actually included automatically due to the public surface: Surface parameter in the constructor. Adding public varName: Type to a constructor automatically adds a typed variable into the class without having to explicitly write the code as with normal and intersect. TypeScript has additional language features but defining static types and creating classes, modules, and interfaces are some of the key features it offers. So is TypeScript right for you and your applications? That’s a not a question that I or anyone else can answer for you. You’ll need to give it a spin to see what you think. In future posts I’ll discuss additional details about TypeScript and how it can be used with enterprise-scale JavaScript applications. In the meantime, I’m in the process of working with John Papa on a new Typescript course for Pluralsight that we hope to have out in December of 2012.

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• Why do operating systems do low level stuff in C and C++? Why not just C++?

  - by Cole Johnson

  On the Wikipedia page for Windows, it states the Windows is written in Assembly for the bootloader and task switcher, and C and C++ for kernel routines. This confuses me because AFAIK, you can call C++ functions from an extern "C"'d block as C++ is just C with extra features (all of which can be rewritten in C if you wanted to AFAIK). I can get using C for the kernel functions so pure C apps can use them (like printf and such), but if they can just be wrapped in an extern "C " block, then why code in C? So my question is: Why would a kernel be written in both C and C++ instead of just C++

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• 1 Google Analytics account or top-level domain + profiles for sub-domains vs. 1 account for each sub-domain

  - by Eric Nguyen

  We have the following websites An online magazine Singapore edition - sg.abc.com The same online magazine Malaysia edition - my.abc.com Forums around the same subjects as the online magazine but functions independently - forums.abc.com Classifieds site rather also around the same subjects but functions independently - directory.abc.com Each of the above websites currently has its own Google Analytics account. abc.com has a separate Google Analytics account too. sg.abc.com has the most traffic and generates most revenues Are there any practical benefits of merging all the above sub-domains to be under abc.com? I can think of more reliable analytics and consistency for sure. Are there more? cross-sales?

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• IL and case-sensitivity

  - by Ali .NET

  Quoted from A Brief Introduction To IL code, CLR, CTS, CLS and JIT In .NET CLS stands for Common Language Specifications. It is a subset of CTS. CLS is a set of rules or guidelines which if followed ensures that code written in one .NET language can be used by another .NET language. For example one rule is that we cannot have member functions with same name with case difference only i.e we should not have add() and Add(). This may work in C# because it is case-sensitive but if try to use that C# code in VB.NET, it is not possible because VB.NET is not case-sensitive. Based on above text I want to confirm two points here: Does the case-sensitivity of IL is a condition for member functions only, and not for member properties? Is it true that C# wouldn't be inter-operable with VB.NET if it didn't take care of the case sensitivity?

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• Can the Clojure set and maps syntax be added to other Lisp dialects?

  - by Cedric Martin

  In addition to create list using parentheses, Clojure allows to create vectors using [ ], maps using { } and sets using #{ }. Lisp is always said to be a very extensible language in which you can easily create DSLs etc. But is Lisp so extensible that you can take any Lisp dialect and relatively easily add support for Clojure's vectors, maps and sets (which are all functions in Clojure)? I'm not necessarily asking about cons or similar actually working on these functions: what I'd like to know is if the other could be modified so that the source code would look like Clojure's source code (that is: using matching [ ], { } and #{ } in addition to ( )). Note that if it cannot be done this is not a criticism of Lisp: what I'd like to know is, technically, what should be done or what cannot be done if one were to add such a thing.

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• Using DLLEXPORT to export DLL function With Class to C#

  - by SICGames2013

  In my previous revision game engine I deported major functions for the game editor for C#. Now, I'm beginning to revise the game engine with a static library. There's a already dynamic library created in C++ to use DLLEXPORT for C#. Just now I want to test out the newer functions and created a DLL file from C++. Because the DLL contains classes I was wondering how would I be able to use DLL Export. Would I do this: [DLLEXPORT("GameEngine.dll", EntryPoint="SomeClass", Conventional=_stdcall)] static extern void functionFromClass(); I have a feeling it's probably DLLImport and not DLLExport. I was wondering how would I go about this? Another way I was thinking was because I already have the DLL in C++ prepared already to go the C# Class Library. I could just keep the new engine as a lib, and link the lib with the old DLL C++ file. Wouldn't the EntryPoint be able to point to the class the function is in?

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• Should programmers prefer making wide libraries or thin libraries?

  - by Telastyn

  For classes and functions, it is clear cut: each should do only one thing. For libraries though, this is less clear. If you have a library with collections, it might have multiple collections. It might have useful functions like sorting, which aren't strictly collection based but users would expect. Each of these results in a 'wider' library. On the other side is having a library for the specific collection type and/or with little built-in functionality. If you want a queue, it gives you a queue. If you want to sort that list, then the library lets you do that yourself. What is the best practice here (if any)? I can see arguments for each side.

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• Can a recursive function have iterations/loops?

  - by Omega

  I've been studying about recursive functions, and apparently, they're functions that call themselves, and don't use iterations/loops (otherwise it wouldn't be a recursive function). However, while surfing the web for examples (the 8-queens-recursive problem), I found this function: private boolean placeQueen(int rows, int queens, int n) { boolean result = false; if (row < n) { while ((queens[row] < n - 1) && !result) { queens[row]++; if (verify(row,queens,n)) { ok = placeQueen(row + 1,queens,n); } } if (!result) { queens[row] = -1; } }else{ result = true; } return result; } There is a while loop involved. ... so I'm a bit lost now. Can I use loops or not?

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• Windows and Online Banking, Like Oil and Water

  Windows may be safe enough for most functions, but it's not safe enough for the average user's online banking.

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• ODI 12c - Aggregating Data

  - by David Allan

  This posting will look at the aggregation component that was introduced in ODI 12c. For many ETL tool users this shouldn't be a big surprise, its a little different than ODI 11g but for good reason. You can use this component for composing data with relational like operations such as sum, average and so forth. Also, Oracle SQL supports special functions called Analytic SQL functions, you can use a specially configured aggregation component or the expression component for these now in ODI 12c. In database systems an aggregate transformation is a transformation where the values of multiple rows are grouped together as input on certain criteria to form a single value of more significant meaning - that's exactly the purpose of the aggregate component. In the image below you can see the aggregate component in action within a mapping, for how this and a few other examples are built look at the ODI 12c Aggregation Viewlet here - the viewlet illustrates a simple aggregation being built and then some Oracle analytic SQL such as AVG(EMP.SAL) OVER (PARTITION BY EMP.DEPTNO) built using both the aggregate component and the expression component. In 11g you used to just write the aggregate expression directly on the target, this made life easy for some cases, but it wan't a very obvious gesture plus had other drawbacks with ordering of transformations (agg before join/lookup. after set and so forth) and supporting analytic SQL for example - there are a lot of postings from creative folks working around this in 11g - anything from customizing KMs, to bypassing aggregation analysis in the ODI code generator. The aggregate component has a few interesting aspects. 1. Firstly and foremost it defines the attributes projected from it - ODI automatically will perform the grouping all you do is define the aggregation expressions for those columns aggregated. In 12c you can control this automatic grouping behavior so that you get the code you desire, so you can indicate that an attribute should not be included in the group by, that's what I did in the analytic SQL example using the aggregate component. 2. The component has a few other properties of interest; it has a HAVING clause and a manual group by clause. The HAVING clause includes a predicate used to filter rows resulting from the GROUP BY clause. Because it acts on the results of the GROUP BY clause, aggregation functions can be used in the HAVING clause predicate, in 11g the filter was overloaded and used for both having clause and filter clause, this is no longer the case. If a filter is after an aggregate, it is after the aggregate (not sometimes after, sometimes having).  3. The manual group by clause let's you use special database grouping grammar if you need to. For example Oracle has a wealth of highly specialized grouping capabilities for data warehousing such as the CUBE function. If you want to use specialized functions like that you can manually define the code here. The example below shows the use of a manual group from an example in the Oracle database data warehousing guide where the SUM aggregate function is used along with the CUBE function in the group by clause. The SQL I am trying to generate looks like the following from the data warehousing guide; SELECT channel_desc, calendar_month_desc, countries.country_iso_code,       TO_CHAR(SUM(amount_sold), '9,999,999,999') SALES$ FROM sales, customers, times, channels, countries WHERE sales.time_id=times.time_id AND sales.cust_id=customers.cust_id AND   sales.channel_id= channels.channel_id  AND customers.country_id = countries.country_id  AND channels.channel_desc IN   ('Direct Sales', 'Internet') AND times.calendar_month_desc IN   ('2000-09', '2000-10') AND countries.country_iso_code IN ('GB', 'US') GROUP BY CUBE(channel_desc, calendar_month_desc, countries.country_iso_code); I can capture the source datastores, the filters and joins using ODI's dataset (or as a traditional flow) which enables us to incrementally design the mapping and the aggregate component for the sum and group by as follows; In the above mapping you can see the joins and filters declared in ODI's dataset, allowing you to capture the relationships of the datastores required in an entity-relationship style just like ODI 11g. The mix of ODI's declarative design and the common flow design provides for a familiar design experience. The example below illustrates flow design (basic arbitrary ordering) - a table load where only the employees who have maximum commission are loaded into a target. The maximum commission is retrieved from the bonus datastore and there is a look using employees as the driving table and only those with maximum commission projected. Hopefully this has given you a taster for some of the new capabilities provided by the aggregate component in ODI 12c. In summary, the actions should be much more consistent in behavior and more easily discoverable for users, the use of the components in a flow graph also supports arbitrary designs and the tool (rather than the interface designer) takes care of the realization using ODI's knowledge modules. Interested to know if a deep dive into each component is interesting for folks. Any thoughts? 

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• Oracle Launches Telco-Oriented, Carrier-Grade Blade Server

  Upgrade to the Netra line of blade servers for telcos makes them more suitable for mission-critical functions.

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• How to join two collections with LINQ

  - by JustinGreenwood

  Here is a simple and complete example of how to perform joins on two collections with LINQ. I wrote it for a friend to show him, in one simple file, the power of LINQ queries and anonymous objects. In the file below, there are two simple data classes defined: Person and Item. In the beginning of the main method, two collections are created. Note that the Item's OwnerId field reference the PersonId of a Person object. The effect of the LINQ query below is equivalent to a SQL statement looking like this: select Person.PersonName as OwnerName, Item.ItemName as OwnedItem from Person inner join Item on Item.OwnerId = Person.PersonId order by Item.ItemName desc; using System; using System.Collections.Generic; using System.Linq; namespace LinqJoinAnonymousObjects { class Program { class Person { public int PersonId { get; set; } public string PersonName { get; set; } } class Item { public string ItemName { get; set; } public int OwnerId { get; set; } } static void Main(string[] args) { // Create two collections: one of people, and another with their possessions. var people = new List<Person> { new Person { PersonId=1, PersonName="Justin" }, new Person { PersonId=2, PersonName="Arthur" }, new Person { PersonId=3, PersonName="Bob" } }; var items = new List<Item> { new Item { OwnerId=1, ItemName="Armor" }, new Item { OwnerId=1, ItemName="Book" }, new Item { OwnerId=2, ItemName="Chain Mail" }, new Item { OwnerId=2, ItemName="Excalibur" }, new Item { OwnerId=3, ItemName="Bubbles" }, new Item { OwnerId=3, ItemName="Gold" } }; // Create a new, anonymous composite result for person id=2. var compositeResult = from p in people join i in items on p.PersonId equals i.OwnerId where p.PersonId == 2 orderby i.ItemName descending select new { OwnerName = p.PersonName, OwnedItem = i.ItemName }; // The query doesn't evaluate until you iterate through the query or convert it to a list Console.WriteLine("[" + compositeResult.GetType().Name + "]"); // Convert to a list and loop through it. var compositeList = compositeResult.ToList(); Console.WriteLine("[" + compositeList.GetType().Name + "]"); foreach (var o in compositeList) { Console.WriteLine("\t[" + o.GetType().Name + "] " + o.OwnerName + " - " + o.OwnedItem); } Console.ReadKey(); } } } The output of the program is below: [WhereSelectEnumerableIterator`2] [List`1] [<>f__AnonymousType1`2] Arthur - Excalibur [<>f__AnonymousType1`2] Arthur - Chain Mail

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• Why&rsquo;s Poignant Guide To Ruby

  - by Liam McLennan

  According to Wikipedia, “why the lucky stiff was the persona of an anonymous, but prolific writer, cartoonist, musician, artist, and computer programmer”. He looks a bit like Jack Black. His book, Why’s Poignant Guide to Ruby, is a classic, though it can be hard to find since Why disappeared. If you want to learn the Ruby programming language I highly recommend Why’s Poignant Guide to Ruby. I am including a link here so that others who search for it may find it more easily.

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• High Usage of RAM by wxPython's GUI and need some advice to reduce it

  - by user67024

  I've recently developed a GUI in wxPython for windows platform. It contains a five tabs, 4 of them are just richTextCtrl boxes and the other one has controls for uploading files, buttons, textctrls, a slider etc.. As I was new to GUI development in Python, I used wxFormBuilder to generate some of the code using a good amount of sizers. So, now the problem is that the GUI starts off with a initial memory of around 40MB which is too much for such a simple application (Or so I think) . Also, when the functions handling the functions use huge lists as the program is for debugging large data logs and identifying the problems in'em implying that I can't afford memory for GUI. So, how can I reduce that start working memory size? Is it a general issue in wxPython? And currently trying use profilers but not sure if it's going to help.

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• The perfect crossfade

  - by epologee

  I find it hard to describe this problem in words, which is why I made a video (45 seconds) to illustrate it. Here's a preview of the questions, please have a look at it on Vimeo: http://vimeo.com/epologee/perfect-crossfade The issue of creating a flawless crossfade or dissolve of two images or shapes has been recurring to me in a number of fields over the last decade. First in video editing, then in Flash animation and now in iOS programming. When you start googling it, there are many workarounds to be found, but I really want to solve this without a hack this time. The summary: What is the name of the technique or curve to apply in crossfading two semi-transparent, same-colored bitmaps, if you want the resulting transparency to match the original of either one? Is there a (mathematical) function to calculate the neccessary partial transparency/alpha values during the fade? Are there programming languages that have these functions as a preset, similar to the ease in, ease out or ease in out functions found in ActionScript or Cocoa?

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• How to have a maintainable and manageable Javascript code base

  - by dade

  I am starting a new job soon as a frontend developer. The App I would be working on is 100% Javascript on the client side. all the server returns is an index page that loads all the Javascript files needed by the app. Now here is the problem: The whole of the application is built around having functions wrapped to different namespaces. And from what I see, a simple function like rendering the HTML of a page can be accomplished by having a call to 2 or more functions across different namespace... My initial thought was "this does not feel like the perfect solution" and I can just envisage a lot of issues with maintaining the code and extending it down the line. Now I would soon start working on taking the project forward and would like to have suggestions on good case practices when it comes to writing and managing a relatively large amount of javascript code.

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• Basis of definitions

  - by Yttrill

  Let us suppose we have a set of functions which characterise something: in the OO world methods characterising a type. In mathematics these are propositions and we have two kinds: axioms and lemmas. Axioms are assumptions, lemmas are easily derived from them. In C++ axioms are pure virtual functions. Here's the problem: there's more than one way to axiomatise a system. Given a set of propositions or methods, a subset of the propositions which is necessary and sufficient to derive all the others is called a basis. So too, for methods or functions, we have a desired set which must be defined, and typically every one has one or more definitions in terms of the others, and we require the programmer to provide instance definitions which are sufficient to allow all the others to be defined, and, if there is an overspecification, then it is consistent. Let me give an example (in Felix, Haskell code would be similar): class Eq[t] { virtual fun ==(x:t,y:t):bool => eq(x,y); virtual fun eq(x:t, y:t)=> x == y; virtual fun != (x:t,y:t):bool => not (x == y); axiom reflex(x:t): x == x; axiom sym(x:t, y:t): (x == y) == (y == x); axiom trans(x:t, y:t, z:t): implies(x == y and y == z, x == z); } Here it is clear: the programmer must define either == or eq or both. If both are defined, the definitions must be equivalent. Failing to define one doesn't cause a compiler error, it causes an infinite loop at run time. Defining both inequivalently doesn't cause an error either, it is just inconsistent. Note the axioms specified constrain the semantics of any definition. Given a definition of == either directly or via a definition of eq, then != is defined automatically, although the programmer might replace the default with something more efficient, clearly such an overspecification has to be consistent. Please note, == could also be defined in terms of !=, but we didn't do that. A characterisation of a partial or total order is more complex. It is much more demanding since there is a combinatorial explosion of possible bases. There is an reason to desire overspecification: performance. There also another reason: choice and convenience. So here, there are several questions: one is how to check semantics are obeyed and I am not looking for an answer here (way too hard!). The other question is: How can we specify, and check, that an instance provides at least a basis? And a much harder question: how can we provide several default definitions which depend on the basis chosen?

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• Best open source ASP.NET MVC e-commerce projects

  - by Øyvind Knobloch-Bråthen

  I need to get a e-commerce site up and running, but I really don't want to program it from the bottom up if I don't need to. I want to program it using ASP.NET MVC. I'm looking for a good open source alternative (or one for purchase if it's modular enough) that I can use as a base and enhance with the needed functions? It has to have all "normal" e-commerce functions, and also the possibility to integrate with a credit card API of my choice. If anyone have any recommendations for me here, I would appreciate it :)

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• Error installing RVM

  - by Dbugger

  I am following this guide, but this is the output I receive. What am the problem? dbugger@mercury:~$ \curl -sSL https://get.rvm.io | bash -s stable --rails Downloading https://github.com/wayneeseguin/rvm/archive/stable.tar.gz Upgrading the RVM installation in /home/dbugger/.rvm/ RVM PATH line found in /home/dbugger/.profile /home/dbugger/.bashrc /home/dbugger/.zshrc. RVM sourcing line found in /home/dbugger/.bash_profile /home/dbugger/.zlogin. Upgrade of RVM in /home/dbugger/.rvm/ is complete. # Enrique, # # Thank you for using RVM! # We sincerely hope that RVM helps to make your life easier and more enjoyable!!! # # ~Wayne, Michal & team. In case of problems: http://rvm.io/help and https://twitter.com/rvm_io Upgrade Notes: * No new notes to display. rvm 1.25.27 (stable) by Wayne E. Seguin <[email protected]>, Michal Papis <[email protected]> [https://rvm.io/] Searching for binary rubies, this might take some time. No binary rubies available for: ubuntu/14.04/x86_64/ruby-2.1.2. Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies. Checking requirements for ubuntu. Installing requirements for ubuntu. Updating system.......... Installing required packages: gawk, libreadline6-dev, libssl-dev, libyaml-dev, libsqlite3-dev, sqlite3.... Error running 'requirements_debian_libs_install gawk libreadline6-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3', showing last 15 lines of /home/dbugger/.rvm/log/1401804140_ruby-2.1.2/package_install_gawk_libreadline6-dev_libssl-dev_libyaml-dev_libsqlite3-dev_sqlite3.log ++ /scripts/functions/utility : __rvm_try_sudo() 405 > sudo -p '%p password required for '\''apt-get --no-install-recommends --yes install gawk libreadline6-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3'\'': ' apt-get --no-install-recommends --yes install gawk libreadline6-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3 Reading package lists... Building dependency tree... Reading state information... Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: libssl-dev : Depends: libssl1.0.0 (= 1.0.1f-1ubuntu2) but 1.0.1f-1ubuntu2.1 is to be installed E: Unable to correct problems, you have held broken packages. ++ /scripts/functions/utility : __rvm_try_sudo() 405 > return 100 ++ /scripts/functions/requirements/ubuntu : requirements_debian_libs_install() 36 > return 100 Requirements installation failed with status: 100.

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• How to prevent forum spam [closed]

  - by whamsicore

  Possible Duplicate: Make your site anti-bot? I want to prevent spam from overrunning my website, but neither do I want to make the user type in captcha each time they make a post. Any suggestions? Context: My website allows anonymous users to make leave comments on the fly. Comments are randomly displayed, so the more spam = higher chance of it being shown. Need to prevent spam but don't want to have each comment require captcha input.

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• Testing Reference Data Mappings

  - by Michael Stephenson

  Background Mapping reference data is one of the common scenarios in BizTalk development and its usually a bit of a pain when you need to manage a lot of reference data whether it be through the BizTalk Cross Referencing features or some kind of custom solution. I have seen many cases where only a couple of the mapping conditions are ever tested. Approach As usual I like to see these things tested in isolation before you start using them in your BizTalk maps so you know your mapping functions are working as expected. This approach can be used for almost all of your reference data type mapping functions where you can take advantage of MSTests data driven tests to test lots of conditions without having to write millions of tests. Walk Through Rather than go into the details of this here, I'm going to call out to one of my colleagues who wrote a nice little walk through about using data driven tests a while back. Check out Callum's blog: http://callumhibbert.blogspot.com/2009/07/data-driven-tests-with-mstest.html

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• What is the politically correct way of refactoring other's code?

  - by dukeofgaming

  I'm currently working in a geographically distributed team in a big company. Everybody is just focused on today's tasks and getting things done, however this means sometimes things have to be done the quick way, and that causes problems... you know, same old, same old. I'm bumping into code with several smells such as: big functions pointless utility functions/methods (essentially just to save writing a word), overcomplicated algorithms, extremely big files that should be broken down into different files/classes (1,500+ lines), etc. What would be the best way of improving code without making other developers feel bad/wrong about any proposed improvements?

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• What are the basic skills a beginner JavaScript programmer should have?

  - by Sanford

  In NYC, we are working on creating a collaborative community programming environment and trying to segment out software engineers into differing buckets. At present, we are trying to define: Beginners Intermediates Advanced Experts (and/or Masters) Similar to an apprenticeship, you would need to demonstrate specific skills to achieve different levels. Right now, we have identified beginner programming skills as: Object - method, attributes, inheritance Variable - math, string, array, boolean - all are objects Basic arithmetic functions - precedence of functions String manipulation Looping - flow control Conditionals - boolean algebra This is a first attempt, and it is a challenge since we know the natural tension between programming and software engineering. How would you create such a skills-based ranking for JavaScript in this manner? For example, what would be the beginner JavaScript skills that you would need to have to advance to the intermediate training? And so on.

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