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  • URL Routing in ASP.NET 4.0

    In the .NET Framework 3.5 SP1, Microsoft introduced ASP.NET Routing, which decouples the URL of a resource from the physical file on the web server. With ASP.NET Routing you, the developer, define routing rules map route patterns to a class that generates the content. For example, you might indicate that the URL Categories/CategoryName maps to a class that takes the CategoryName and generates HTML that lists that category's products in a grid. With such a mapping, users could view products for the Beverages category by visiting www.yoursite.com/Categories/Beverages. In .NET 3.5 SP1, ASP.NET Routing was primarily designed for ASP.NET MVC applications, although as discussed in Using ASP.NET Routing Without ASP.NET MVC it is possible to implement ASP.NET Routing in a Web Forms application, as well. However, implementing ASP.NET Routing in a Web Forms application involves a bit of seemingly excessive legwork. In a Web Forms scenario we typically want to map a routing pattern to an actual ASP.NET page. To do so we need to create a route handler class that is invoked when the routing URL is requested and, in a sense, dispatches the request to the appropriate ASP.NET page. For instance, to map a route to a physical file, such as mapping Categories/CategoryName to ShowProductsByCategory.aspx - requires three steps: (1) Define the mapping in Global.asax, which maps a route pattern to a route handler class; (2) Create the route handler class, which is responsible for parsing the URL, storing any route parameters into some location that is accessible to the target page (such as HttpContext.Items), and returning an instance of the target page or HTTP Handler that handles the requested route; and (3) writing code in the target page to grab the route parameters and use them in rendering its content. Given how much effort it took to just read the preceding sentence (let alone write it) you can imagine that implementing ASP.NET Routing in a Web Forms application is not necessarily the most straightforward task. The good news is that ASP.NET 4.0 has greatly simplified ASP.NET Routing for Web Form applications by adding a number of classes and helper methods that can be used to encapsulate the aforementioned complexity. With ASP.NET 4.0 it's easier to define the routing rules and there's no need to create a custom route handling class. This article details these enhancements. Read on to learn more! Read More >

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  • What's brewing in the world of Java? (Dec 22nd 2010)

    - by Jacob Lehrbaum
    The nights are getting darker, the email traffic seems to be getting lighter and the holiday season feels like its right around the corner - but the world of Java is still as active as ever and shows no signs of taking a break!  Let's take a look at everything that has been brewing over the past couple of weeks:Product Updates and ResourcesJCP Approves JSRs for Java SE 7, Java SE 8, Project Coin and Lambda (read more)Java SE Update 23 Released, delivers improved performance and enhanced support for right-left languages. (read more or download)New Tutorial: JDK 7 Support in NetBeans IDE 7.0Java EE 6 and Glassfish 3.0 have celebrated their respective one year anniversaries!  (read more) So naturally, it's time to start talking about Java EE 7 (read more)WebcastsOn Demand: Developing Rich Clients for the Enterprise with the JavaFX Composer, Part 1Coming soon: Smarter Devices with Oracle's Embedded Java SolutionsPodcastsJava Spotlight Podcast Episode 7: Interview with Adam Messinger, Vice President of Java Development on Java One Brazil, Java SE Development, OpenJDK, JavaFX 2.0 and more!  The NetBeans team released Episode 53 of the NetBeans Podcast series on December 3rd marking the first episode in nearly 12 months.  Sign of things to come?Community and EventsJavaOne was held for the first time in Brazil this year, and by all accounts it was a great success!  Read more about this exciting first in the following posts from Tori Wieldt (JavaOne Latin America Underway) and Janice Heiss (JavaOne in Brazil)JavaOne was also held in Bejing for the first time last week and was also a huge success. Will try to include coverage of this event in the near futureArticles and InterviewsAn update on JavaServer Faces with Oracle's Ed Burns (read more)Interview with Java Champion Matjaz B. Juric on Cloud Computing, SOA, and Java EE 6 (read more)The 2010 JavaOne Java EE 6 Panel: Where We Are and Where We're Going (read more)Oracle MagazineThe latest issue of Oracle Magazine is up and in what will hopefully be a sign of the future, it includes a number of columns and articles on Java.  First is an editorial from Editor-in-Chief Tom Haunert who shares some insight into the long-standing relationship that Oracle has had with Java. Next up is a Oracle Technology Network Chief Justin Kestelyn's Community Bulletin entitled: Java Evolves.  And finally, Java Champion Adam Bien's feature on Java EE 6: Simplicity by DesignEnjoy!

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  • Handy ASP.NET MVC 2 Extension Methods &ndash; Where am I?

    - by Bobby Diaz
    Have you ever needed to detect what part of the application is currently being viewed?  This might be a bigger issue if you write a lot of shared/partial views or custom display or editor templates.  Another scenario, which is the one I encountered when I first started down this path, is when you have some type of menu and you’d like to be able to determine which item represents the current page so you can highlight it in some way.  A simple example is the menu that is created as part of the default ASP.NET MVC 2 Application template.   <div id="menucontainer">       <ul id="menu">         <li><%= Html.ActionLink("Home", "Index", "Home") %></li>         <li><%= Html.ActionLink("About", "About", "Home") %></li>     </ul>   </div>   The part that got me at first, however, was the following entry in the default style sheet (Site.css):   ul#menu li.selected a {     background-color: #fff;     color: #000; }   I assumed that the .selected class would automatically get applied to the active menu item.  After trying a few different things, including the MvcContrib MenuBuilder, I decided to write my own extension methods so I would have more control over the output.  First, I needed a way to determine what view the user has navigated to based on the requested URL and route configuration.  Now, I am sure there are many ways to do this, but this is what I came up with:   public static class RequestExtensions {     public static bool IsCurrentRoute(this RequestContext context, String areaName,         String controllerName, params String[] actionNames)     {         var routeData = context.RouteData;         var routeArea = routeData.DataTokens["area"] as String;         var current = false;           if ( ((String.IsNullOrEmpty(routeArea) && String.IsNullOrEmpty(areaName)) ||               (routeArea == areaName)) &&              ((String.IsNullOrEmpty(controllerName)) ||               (routeData.GetRequiredString("controller") == controllerName)) &&              ((actionNames == null) ||                actionNames.Contains(routeData.GetRequiredString("action"))) )         {             current = true;         }           return current;     }       // additional overloads omitted... }   With that in place, I was able to write several UrlHelper methods that check if the supplied values map to the current view.   public static class UrlExtensions {     public static bool IsCurrent(this UrlHelper urlHelper, String areaName,         String controllerName, params String[] actionNames)     {         return urlHelper.RequestContext.IsCurrentRoute(areaName, controllerName, actionNames);     }       public static string Selected(this UrlHelper urlHelper, String areaName,         String controllerName, params String[] actionNames)     {         return urlHelper.IsCurrent(areaName, controllerName, actionNames)             ? "selected" : String.Empty;     }       // additional overloads omitted... }   Now I can re-work the original menu to utilize these new methods.  Note: be sure to import the proper namespace so the extension methods become available inside your views!   <div id="menucontainer">       <ul id="menu">         <li class="<%= Url.Selected(null, "Home", "Index") %>">             <%= Html.ActionLink("Home", "Index", "Home")%></li>           <li class="<%= Url.Selected(null, "Home", "About") %>">             <%= Html.ActionLink("About", "About", "Home")%></li>     </ul>   </div>   If we take it one step further, we can clean up the markup even more.  Check out the Html.ActionMenuItem() extension method and the refined menu:   public static class HtmlExtensions {     public static MvcHtmlString ActionMenuItem(this HtmlHelper htmlHelper, String linkText,         String actionName, String controllerName)     {         var html = new StringBuilder("<li");           if ( htmlHelper.ViewContext.RequestContext                 .IsCurrentRoute(null, controllerName, actionName) )         {             html.Append(" class=\"selected\"");         }           html.Append(">")             .Append(htmlHelper.ActionLink(linkText, actionName, controllerName))             .Append("</li>");           return MvcHtmlString.Create(html.ToString());     }       // additional overloads omitted... }   <div id="menucontainer">       <ul id="menu">         <%= Html.ActionMenuItem("Home", "Index", "Home") %>         <%= Html.ActionMenuItem("About", "About", "Home") %>     </ul>   </div>   Which generates the following HTML:   <div id="menucontainer">       <ul id="menu">         <li class="selected"><a href="/">Home</a></li>         <li><a href="/Home/About">About</a></li>     </ul>   </div>     I have created a codepaste of these extension methods if you are interested in using them in your own projects.  Enjoy!

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  • Tween Animation Cannot Start

    - by David Dimalanta
    Do you have any reasons why my tween code didn't run or work? I already add the tween engine onto the library folder under LibGDX project folder and "Order and Export" it under Java Build Path at the Properties menu. My first two classes ran correctly and workly but my third class didn't work. Here's the sequence: First class is the first screen. Fade animation works on the company's logo. Second class is the second screen. Fade animation for the loading screen works. Third class is the third screen. After the second screen, now calls for the third screen. Animation stopped or won't run since I want the black screen to fade out at the start when the menu is here. Can you check if I did right? Look carefully by comment lines for explanation. //-----[ Animation Setup ]----- Tween.registerAccessor(Sprite.class, new Tween_Animation()); // --> Tween_Animation.java Tween_Manager = new TweenManager(); // --> I initialized it the TweenManager and seems okay. cb_start = new TweenCallback() // --> I'll use this when I choose START and the menu will fade in black. { @Override public void onEvent(int arg0, BaseTween<?> arg1) { goTo(); } }; Tween // --> This is where I focused the problem. .to(black_Sprite, Tween_Animation.ALPHA, 3f) .target(1) .ease(TweenEquations.easeInQuad) .repeatYoyo(200, 2.5f) // --> I set the repeat for 200 times when I noticed that the animation won't work! .start(Tween_Manager);

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  • Editing Routes in ASP.NET MVC

    - by imran_ku07
    Introduction :        Phil Haack's had written two great articles about Editable Routes, Editable Routes or Editable Routes Using App_Code.These Article are great. But if you not need to unit test your Routes and don't care about restart Application Domian during editing your Routes then global.asax file is the fastest and easiest to achieve the same. In this Article I will use Global.asax file instead of Global.asax.cs file for defining Routes and you will also see how this whole process will works.   Description :          You just need to Cut (or Copy) the code inside Global.asax.cs and paste it in Global.asax inside runat server tag.          You can simply do this by cutting the code of Global.asax.cs,          and paste it inside Global.asax,               Easy and quick ,Now you can change Global.asax without compiling the application. How this works :        I think it is worth here to see what is happening here.        Actually, ASP.NET will use Global.asax file to create a class named global_asax within ASP namespace and place all the code in Global.asax inside the class global_asax class which is created at runtime,                namespace ASP               {                    public class global_asax: NerdDinner.MvcApplication                    {                         //Any definitions defined in Global.asax like Application_Start method                                     }               }         Which inherits from class defined in Application tag,      <%@ Application Codebehind="Global.asax.cs" Inherits="NerdDinner.MvcApplication" Language="C#" %>          Actually ASP.NET creates a pool of application objects of this class, which varies from 1 to 100. Every request take one of these application objects to a serve incoming requests. After receiving an application object then it will call application specific events, like Application_Start(for only firstRequest), Application_BeginRequest(for every request), and so on. Therefore if these methods are defined in global_asax class then ASP.NET will call these method from global_asax, if not then it will use base class methods may be defined in Global.asax.cs(the concept known as shadowing or hiding). Summary :        In this article, I showed how easily and quickly you can make your Routes Editable. But also note that any change in global.asax results in Application Domain restart and this technique also makes your Route Unit Test difficult.

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  • Box2D Joints in entity components system

    - by Johnmph
    I search a way to have Box2D joints in an entity component system, here is what i found : 1) Having the joints in Box2D/Body component as parameters, we have a joint array with an ID by joint and having in the other body component the same joint ID, like in this example : Entity1 - Box2D/Body component { Body => (body parameters), Joints => { Joint1 => (joint parameters), others joints... } } // Joint ID = Joint1 Entity2 - Box2D/Body component { Body => (body parameters), Joints => { Joint1 => (joint parameters), others joints... } } // Same joint ID than in Entity1 There are 3 problems with this solution : The first problem is the implementation of this solution, we must manage the joints ID to create joints and to know between which bodies they are connected. The second problem is the parameters of joint, where are they got ? on the Entity1 or Entity2 ? If they are the same parameters for the joint, there is no problem but if they are differents ? The third problem is that we can't limit number of bodies to 2 by joint (which is mandatory), a joint can only link 2 bodies, in this solution, nothing prevents to create more than 2 entities with for each a body component with the same joint ID, in this case, how we know the 2 bodies to joint and what to do with others bodies ? 2) Same solution than the first solution but by having entities ID instead of Joint ID, like in this example : Entity1 - Box2D/Body component { Body => (body parameters), Joints => { Entity2 => (joint parameters), others joints... } } Entity2 - Box2D/Body component { Body => (body parameters), Joints => { Entity1 => (joint parameters), others joints... } } With this solution, we fix the first problem of the first solution but we have always the two others problems. 3) Having a Box2D/Joint component which is inserted in the entities which contains the bodies to joint (we share the same joint component between entities with bodies to joint), like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } - Box2D/Joint component { Joint => (Joint parameters) } // Shared, same as in Entity2 Entity2 - Box2D/Body component { Body => (body parameters) } - Box2D/Joint component { Joint => (joint parameters) } // Shared, same as in Entity1 There are 2 problems with this solution : The first problem is the same problem than in solution 1 and 2 : We can't limit number of bodies to 2 by joint (which is mandatory), a joint can only link 2 bodies, in this solution, nothing prevents to create more than 2 entities with for each a body component and the shared joint component, in this case, how we know the 2 bodies to joint and what to do with others bodies ? The second problem is that we can have only one joint by body because entity components system allows to have only one component of same type in an entity. So we can't put two Joint components in the same entity. 4) Having a Box2D/Joint component which is inserted in the entity which contains the first body component to joint and which has an entity ID parameter (this entity contains the second body to joint), like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } - Box2D/Joint component { Entity2 => (Joint parameters) } // Entity2 is the entity ID which contains the other body to joint, the first body being in this entity Entity2 - Box2D/Body component { Body => (body parameters) } There are exactly the same problems that in the third solution, the only difference is that we can have two differents joints by entity instead of one (by putting one joint component in an entity and another joint component in another entity, each joint referencing to the other entity). 5) Having a Box2D/Joint component which take in parameter the two entities ID which contains the bodies to joint, this component can be inserted in any entity, like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } Entity2 - Box2D/Body component { Body => (body parameters) } Entity3 - Box2D/Joint component { Joint => (Body1 => Entity1, Body2 => Entity2, others parameters of joint) } // Entity1 is the ID of the entity which have the first body to joint and Entity2 is the ID of the entity which have the second body to joint (This component can be in any entity, that doesn't matter) With this solution, we fix the problem of the body limitation by joint, we can only have two bodies per joint, which is correct. And we are not limited by number of joints per body, because we can create an another Box2D/Joint component, referencing to Entity1 and Entity2 and put this component in a new entity. The problem of this solution is : What happens if we change the Body1 or Body2 parameter of Joint component at runtime ? We need to add code to sync the Body1/Body2 parameters changes with the real joint object. 6) Same as solution 3 but in a better way : Having a Box2D/Joint component Box2D/Joint which is inserted in the entities which contains the bodies to joint, we share the same joint component between these entities BUT the difference is that we create a new entity to link the body component with the joint component, like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity3 Entity2 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity4 Entity3 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity1 - Box2D/Joint component { Joint => (joint parameters) } // Shared, same as in Entity4 Entity4 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity2 - Box2D/Joint component { Joint => (joint parameters) } // Shared, same as in Entity3 With this solution, we fix the second problem of the solution 3, because we can create an Entity5 which will have the shared body component of Entity1 and an another joint component so we are no longer limited in the joint number per body. But the first problem of solution 3 remains, because we can't limit the number of entities which have the shared joint component. To resolve this problem, we can add a way to limit the number of share of a component, so for the Joint component, we limit the number of share to 2, because we can only joint 2 bodies per joint. This solution would be perfect because there is no need to add code to sync changes like in the solution 5 because we are notified by the entity components system when components / entities are added to/removed from the system. But there is a conception problem : How to know easily and quickly between which bodies the joint operates ? Because, there is no way to find easily an entity with a component instance. My question is : Which solution is the best ? Is there any other better solutions ? Sorry for the long text and my bad english.

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  • Find a Hash Collision, Win $100

    - by Mike C
    Margarity Kerns recently published a very nice article at SQL Server Central on using hash functions to detect changes in rows during the data warehouse load ETL process. On the discussion page for the article I noticed a lot of the same old arguments against using hash functions to detect change. After having this same discussion several times over the past several months in public and private forums, I've decided to see if we can't put this argument to rest for a while. To that end I'm going to...(read more)

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  • Sorting Algorithms

    - by MarkPearl
    General Every time I go back to university I find myself wading through sorting algorithms and their implementation in C++. Up to now I haven’t really appreciated their true value. However as I discovered this last week with Dictionaries in C# – having a knowledge of some basic programming principles can greatly improve the performance of a system and make one think twice about how to tackle a problem. I’m going to cover briefly in this post the following: Selection Sort Insertion Sort Shellsort Quicksort Mergesort Heapsort (not complete) Selection Sort Array based selection sort is a simple approach to sorting an unsorted array. Simply put, it repeats two basic steps to achieve a sorted collection. It starts with a collection of data and repeatedly parses it, each time sorting out one element and reducing the size of the next iteration of parsed data by one. So the first iteration would go something like this… Go through the entire array of data and find the lowest value Place the value at the front of the array The second iteration would go something like this… Go through the array from position two (position one has already been sorted with the smallest value) and find the next lowest value in the array. Place the value at the second position in the array This process would be completed until the entire array had been sorted. A positive about selection sort is that it does not make many item movements. In fact, in a worst case scenario every items is only moved once. Selection sort is however a comparison intensive sort. If you had 10 items in a collection, just to parse the collection you would have 10+9+8+7+6+5+4+3+2=54 comparisons to sort regardless of how sorted the collection was to start with. If you think about it, if you applied selection sort to a collection already sorted, you would still perform relatively the same number of iterations as if it was not sorted at all. Many of the following algorithms try and reduce the number of comparisons if the list is already sorted – leaving one with a best case and worst case scenario for comparisons. Likewise different approaches have different levels of item movement. Depending on what is more expensive, one may give priority to one approach compared to another based on what is more expensive, a comparison or a item move. Insertion Sort Insertion sort tries to reduce the number of key comparisons it performs compared to selection sort by not “doing anything” if things are sorted. Assume you had an collection of numbers in the following order… 10 18 25 30 23 17 45 35 There are 8 elements in the list. If we were to start at the front of the list – 10 18 25 & 30 are already sorted. Element 5 (23) however is smaller than element 4 (30) and so needs to be repositioned. We do this by copying the value at element 5 to a temporary holder, and then begin shifting the elements before it up one. So… Element 5 would be copied to a temporary holder 10 18 25 30 23 17 45 35 – T 23 Element 4 would shift to Element 5 10 18 25 30 30 17 45 35 – T 23 Element 3 would shift to Element 4 10 18 25 25 30 17 45 35 – T 23 Element 2 (18) is smaller than the temporary holder so we put the temporary holder value into Element 3. 10 18 23 25 30 17 45 35 – T 23   We now have a sorted list up to element 6. And so we would repeat the same process by moving element 6 to a temporary value and then shifting everything up by one from element 2 to element 5. As you can see, one major setback for this technique is the shifting values up one – this is because up to now we have been considering the collection to be an array. If however the collection was a linked list, we would not need to shift values up, but merely remove the link from the unsorted value and “reinsert” it in a sorted position. Which would reduce the number of transactions performed on the collection. So.. Insertion sort seems to perform better than selection sort – however an implementation is slightly more complicated. This is typical with most sorting algorithms – generally, greater performance leads to greater complexity. Also, insertion sort performs better if a collection of data is already sorted. If for instance you were handed a sorted collection of size n, then only n number of comparisons would need to be performed to verify that it is sorted. It’s important to note that insertion sort (array based) performs a number item moves – every time an item is “out of place” several items before it get shifted up. Shellsort – Diminishing Increment Sort So up to now we have covered Selection Sort & Insertion Sort. Selection Sort makes many comparisons and insertion sort (with an array) has the potential of making many item movements. Shellsort is an approach that takes the normal insertion sort and tries to reduce the number of item movements. In Shellsort, elements in a collection are viewed as sub-collections of a particular size. Each sub-collection is sorted so that the elements that are far apart move closer to their final position. Suppose we had a collection of 15 elements… 10 20 15 45 36 48 7 60 18 50 2 19 43 30 55 First we may view the collection as 7 sub-collections and sort each sublist, lets say at intervals of 7 10 60 55 – 20 18 – 15 50 – 45 2 – 36 19 – 48 43 – 7 30 10 55 60 – 18 20 – 15 50 – 2 45 – 19 36 – 43 48 – 7 30 (Sorted) We then sort each sublist at a smaller inter – lets say 4 10 55 60 18 – 20 15 50 2 – 45 19 36 43 – 48 7 30 10 18 55 60 – 2 15 20 50 – 19 36 43 45 – 7 30 48 (Sorted) We then sort elements at a distance of 1 (i.e. we apply a normal insertion sort) 10 18 55 60 2 15 20 50 19 36 43 45 7 30 48 2 7 10 15 18 19 20 30 36 43 45 48 50 55 (Sorted) The important thing with shellsort is deciding on the increment sequence of each sub-collection. From what I can tell, there isn’t any definitive method and depending on the order of your elements, different increment sequences may perform better than others. There are however certain increment sequences that you may want to avoid. An even based increment sequence (e.g. 2 4 8 16 32 …) should typically be avoided because it does not allow for even elements to be compared with odd elements until the final sort phase – which in a way would negate many of the benefits of using sub-collections. The performance on the number of comparisons and item movements of Shellsort is hard to determine, however it is considered to be considerably better than the normal insertion sort. Quicksort Quicksort uses a divide and conquer approach to sort a collection of items. The collection is divided into two sub-collections – and the two sub-collections are sorted and combined into one list in such a way that the combined list is sorted. The algorithm is in general pseudo code below… Divide the collection into two sub-collections Quicksort the lower sub-collection Quicksort the upper sub-collection Combine the lower & upper sub-collection together As hinted at above, quicksort uses recursion in its implementation. The real trick with quicksort is to get the lower and upper sub-collections to be of equal size. The size of a sub-collection is determined by what value the pivot is. Once a pivot is determined, one would partition to sub-collections and then repeat the process on each sub collection until you reach the base case. With quicksort, the work is done when dividing the sub-collections into lower & upper collections. The actual combining of the lower & upper sub-collections at the end is relatively simple since every element in the lower sub-collection is smaller than the smallest element in the upper sub-collection. Mergesort With quicksort, the average-case complexity was O(nlog2n) however the worst case complexity was still O(N*N). Mergesort improves on quicksort by always having a complexity of O(nlog2n) regardless of the best or worst case. So how does it do this? Mergesort makes use of the divide and conquer approach to partition a collection into two sub-collections. It then sorts each sub-collection and combines the sorted sub-collections into one sorted collection. The general algorithm for mergesort is as follows… Divide the collection into two sub-collections Mergesort the first sub-collection Mergesort the second sub-collection Merge the first sub-collection and the second sub-collection As you can see.. it still pretty much looks like quicksort – so lets see where it differs… Firstly, mergesort differs from quicksort in how it partitions the sub-collections. Instead of having a pivot – merge sort partitions each sub-collection based on size so that the first and second sub-collection of relatively the same size. This dividing keeps getting repeated until the sub-collections are the size of a single element. If a sub-collection is one element in size – it is now sorted! So the trick is how do we put all these sub-collections together so that they maintain their sorted order. Sorted sub-collections are merged into a sorted collection by comparing the elements of the sub-collection and then adjusting the sorted collection. Lets have a look at a few examples… Assume 2 sub-collections with 1 element each 10 & 20 Compare the first element of the first sub-collection with the first element of the second sub-collection. Take the smallest of the two and place it as the first element in the sorted collection. In this scenario 10 is smaller than 20 so 10 is taken from sub-collection 1 leaving that sub-collection empty, which means by default the next smallest element is in sub-collection 2 (20). So the sorted collection would be 10 20 Lets assume 2 sub-collections with 2 elements each 10 20 & 15 19 So… again we would Compare 10 with 15 – 10 is the winner so we add it to our sorted collection (10) leaving us with 20 & 15 19 Compare 20 with 15 – 15 is the winner so we add it to our sorted collection (10 15) leaving us with 20 & 19 Compare 20 with 19 – 19 is the winner so we add it to our sorted collection (10 15 19) leaving us with 20 & _ 20 is by default the winner so our sorted collection is 10 15 19 20. Make sense? Heapsort (still needs to be completed) So by now I am tired of sorting algorithms and trying to remember why they were so important. I think every year I go through this stuff I wonder to myself why are we made to learn about selection sort and insertion sort if they are so bad – why didn’t we just skip to Mergesort & Quicksort. I guess the only explanation I have for this is that sometimes you learn things so that you can implement them in future – and other times you learn things so that you know it isn’t the best way of implementing things and that you don’t need to implement it in future. Anyhow… luckily this is going to be the last one of my sorts for today. The first step in heapsort is to convert a collection of data into a heap. After the data is converted into a heap, sorting begins… So what is the definition of a heap? If we have to convert a collection of data into a heap, how do we know when it is a heap and when it is not? The definition of a heap is as follows: A heap is a list in which each element contains a key, such that the key in the element at position k in the list is at least as large as the key in the element at position 2k +1 (if it exists) and 2k + 2 (if it exists). Does that make sense? At first glance I’m thinking what the heck??? But then after re-reading my notes I see that we are doing something different – up to now we have really looked at data as an array or sequential collection of data that we need to sort – a heap represents data in a slightly different way – although the data is stored in a sequential collection, for a sequential collection of data to be in a valid heap – it is “semi sorted”. Let me try and explain a bit further with an example… Example 1 of Potential Heap Data Assume we had a collection of numbers as follows 1[1] 2[2] 3[3] 4[4] 5[5] 6[6] For this to be a valid heap element with value of 1 at position [1] needs to be greater or equal to the element at position [3] (2k +1) and position [4] (2k +2). So in the above example, the collection of numbers is not in a valid heap. Example 2 of Potential Heap Data Lets look at another collection of numbers as follows 6[1] 5[2] 4[3] 3[4] 2[5] 1[6] Is this a valid heap? Well… element with the value 6 at position 1 must be greater or equal to the element at position [3] and position [4]. Is 6 > 4 and 6 > 3? Yes it is. Lets look at element 5 as position 2. It must be greater than the values at [4] & [5]. Is 5 > 3 and 5 > 2? Yes it is. If you continued to examine this second collection of data you would find that it is in a valid heap based on the definition of a heap.

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  • Is CodeFirst intended for large scale applications?

    - by RoboShop
    I've been reading up on Entity Framework, in particular, EF 4.1 and following this link ( http://weblogs.asp.net/scottgu/archive/2010/07/16/code-first-development-with-entity-framework-4.aspx) and it's guide on Code First. I find it neat but I was wondering, is Code First supposed to be just a solution for rapid development where you can just jump right in without much planning or is it actually intended to be used for large scale applications?

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  • Dynamic XAP loading in Task-It - Part 1

    Download Source Code NOTE 1: The source code provided is running against the RC versions of Silverlight 4 and VisualStudio 2010, so you will need to update to those bits to run it. NOTE 2: After downloading the source, be sure to set the .Web project as the StartUp Project, and Default.aspx as the Start Page In my MEF into post, MEF to the rescue in Task-It, I outlined a couple of issues I was facing and explained why I chose MEF (the Managed Extensibility Framework) to solve these issues. Other posts to check out There are a few other resources out there around dynamic XAP loading that you may want to review (by the way, Glenn Block is the main dude when it comes to MEF): Glenn Blocks 3-part series on a dynamically loaded dashboard Glenn and John Papas Silverlight TV video on dynamic xap loading These provide some great info, but didnt exactly cover the scenario I wanted to achieve in Task-Itand that is dynamically loading each of the apps pages the first time the user enters a page. The code In the code I provided for download above, I created a simple solution that shows the technique I used for dynamic XAP loading in Task-It, but without all of the other code that surrounds it. Taking all that other stuff away should make it easier to grasp. Having said that, there is still a fair amount of code involved. I am always looking for ways to make things simpler, and to achieve the desired result with as little code as possible, so if I find a better/simpler way I will blog about it, but for now this technique works for me. When I created this solution I started by creating a new Silverlight Navigation Application called DynamicXAP Loading. I then added the following line to my UriMappings in MainPage.xaml: <uriMapper:UriMapping Uri="/{assemblyName};component/{path}" MappedUri="/{assemblyName};component/{path}"/> In the section of MainPage.xaml that produces the page links in the upper right, I kept the Home link, but added a couple of new ones (page1 and page 2). These are the pages that will be dynamically (lazy) loaded: <StackPanel x:Name="LinksStackPanel" Style="{StaticResource LinksStackPanelStyle}">      <HyperlinkButton Style="{StaticResource LinkStyle}" NavigateUri="/Home" TargetName="ContentFrame" Content="home"/>      <Rectangle Style="{StaticResource DividerStyle}"/>      <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 1" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage1}"/>      <Rectangle Style="{StaticResource DividerStyle}"/>      <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 2" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage2}"/>  </StackPanel> In App.xaml.cs I added a bit of MEF code. In Application_Startup I call a method called InitializeContainer, which creates a PackageCatalog (a MEF thing), then I create a CompositionContainer and pass it to the CompositionHost.Initialize method. This is boiler-plate MEF stuff that allows you to do 'composition' and import 'packages'. You're welcome to do a bit more MEF research on what is happening here if you'd like, but for the purpose of this example you can just trust that it works. :-) private void Application_Startup(object sender, StartupEventArgs e) {     InitializeContainer();     this.RootVisual = new MainPage(); }   private static void InitializeContainer() {     var catalog = new PackageCatalog();     catalog.AddPackage(Package.Current);     var container = new CompositionContainer(catalog);     container.ComposeExportedValue(catalog);     CompositionHost.Initialize(container); } Infrastructure In the sample code you'll notice that there is a project in the solution called DynamicXAPLoading.Infrastructure. This is simply a Silverlight Class Library project that I created just to move stuff I considered application 'infrastructure' code into a separate place, rather than cluttering the main Silverlight project (DynamicXapLoading). I did this same thing in Task-It, as the amount of this type of code was starting to clutter up the Silverlight project, and it just seemed to make sense to move things like Enums, Constants and the like off to a separate place. In the DynamicXapLoading.Infrastructure project you'll see 3 classes: Enums - There is only one enum in here called ModuleEnum. We'll use these later. PageMetadata - We will use this class later to add metadata to a new dynamically loaded project. ViewModelBase - This is simply a base class for view models that we will use in this, as well as future samples. As mentioned in my MVVM post, I will be using the MVVM pattern throughout my code for reasons detailed in the post. By the way, the ViewModelExtension class in there allows me to do strongly-typed property changed notification, so rather than OnPropertyChanged("MyProperty"), I can do this.OnPropertyChanged(p => p.MyProperty). It's just a less error-prown approach, because if you don't spell "MyProperty" correctly using the first method, nothing will break, it just won't work. Adding a new page We currently have a couple of pages that are being dynamically (lazy) loaded, but now let's add a third page. 1. First, create a new Silverlight Application project: In this example I call it Page3. In the future you may prefer to use a different name, like DynamicXAPLoading.Page3, or even DynamicXAPLoading.Modules.Page3. It can be whatever you want. In my Task-It application I used the latter approach (with 'Modules' in the name). I do think of these application as 'modules', but Prism uses the same term, so some folks may not like that. Use whichever naming convention you feel is appropriate, but for now Page3 will do. When you change the name to Page3 and click OK, you will be presented with the Add New Project dialog: It is important that you leave the 'Host the Silverlight application in a new or existing Web site in the solution' checked, and the .Web project will be selected in the dropdown below. This will create the .xap file for this project under ClientBin in the .Web project, which is where we want it. 2. Uncheck the 'Add a test page that references the application' checkbox, and leave everything else as is. 3. Once the project is created, you can delete App.xaml and MainPage.xaml. 4. You will need to add references your new project to the following: DynamicXAPLoading.Infrastructure.dll (this is a Project reference) DynamicNavigation.dll (this is in the Libs directory under the DynamicXAPLoading project) System.ComponentModel.Composition.dll System.ComponentModel.Composition.Initialization.dll System.Windows.Controls.Navigation.dll If you have installed the latest RC bits you will find the last 3 dll's under the .NET tab in the Add Referenced dialog. They live in the following location, or if you are on a 64-bit machine like me, it will be Program Files (x86).       C:\Program Files\Microsoft SDKs\Silverlight\v4.0\Libraries\Client Now let's create some UI for our new project. 5. First, create a new Silverlight User Control called Page3.dyn.xaml 6. Paste the following code into the xaml: <dyn:DynamicPageShim xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:dyn="clr-namespace:DynamicNavigation;assembly=DynamicNavigation"     xmlns:my="clr-namespace:Page3;assembly=Page3">     <my:Page3Host /> </dyn:DynamicPageShim> This is just a 'shim', part of David Poll's technique for dynamic loading. 7. Expand the icon next to Page3.dyn.xaml and delete the code-behind file (Page3.dyn.xaml.cs). 8. Next we will create a control that will 'host' our page. Create another Silverlight User Control called Page3Host.xaml and paste in the following XAML: <dyn:DynamicPage x:Class="Page3.Page3Host"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"     xmlns:dyn="clr-namespace:DynamicNavigation;assembly=DynamicNavigation"     xmlns:Views="clr-namespace:Page3.Views"      mc:Ignorable="d"     d:DesignHeight="300" d:DesignWidth="400"     Title="Page 3">       <Views:Page3/>   </dyn:DynamicPage> 9. Now paste the following code into the code-behind for this control: using DynamicXAPLoading.Infrastructure;   namespace Page3 {     [PageMetadata(NavigateUri = "/Page3;component/Page3.dyn.xaml", Module = Enums.Page3)]     public partial class Page3Host     {         public Page3Host()         {             InitializeComponent();         }     } } Notice that we are now using that PageMetadata custom attribute class that we created in the Infrastructure project, and setting its two properties. NavigateUri - This tells it that the assembly is called Page3 (with a slash beforehand), and the page we want to load is Page3.dyn.xaml...our 'shim'. That line we added to the UriMapper in MainPage.xaml will use this information to load the page. Module - This goes back to that ModuleEnum class in our Infrastructure project. However, setting the Module to ModuleEnum.Page3 will cause a compilation error, so... 10. Go back to that Enums.cs under the Infrastructure project and add a 3rd entry for Page3: public enum ModuleEnum {     Page1,     Page2,     Page3 } 11. Now right-click on the Page3 project and add a folder called Views. 12. Right-click on the Views folder and create a new Silverlight User Control called Page3.xaml. We won't bother creating a view model for this User Control as I did in the Page 1 and Page 2 projects, just for the sake of simplicity. Feel free to add one if you'd like though, and copy the code from one of those other projects. Right now those view models aren't really doing anything anyway...though they will in my next post. :-) 13. Now let's replace the xaml for Page3.xaml with the following: <dyn:DynamicPage x:Class="Page3.Views.Page3"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"     xmlns:dyn="clr-namespace:DynamicNavigation;assembly=DynamicNavigation"     mc:Ignorable="d"     d:DesignHeight="300" d:DesignWidth="400"     Style="{StaticResource PageStyle}">       <Grid x:Name="LayoutRoot">         <ScrollViewer x:Name="PageScrollViewer" Style="{StaticResource PageScrollViewerStyle}">             <StackPanel x:Name="ContentStackPanel">                 <TextBlock x:Name="HeaderText" Style="{StaticResource HeaderTextStyle}" Text="Page 3"/>                 <TextBlock x:Name="ContentText" Style="{StaticResource ContentTextStyle}" Text="Page 3 content"/>             </StackPanel>         </ScrollViewer>     </Grid>   </dyn:DynamicPage> 14. And in the code-behind remove the inheritance from UserControl, so it should look like this: namespace Page3.Views {     public partial class Page3     {         public Page3()         {             InitializeComponent();         }     } } One thing you may have noticed is that the base class for the last two User Controls we created is DynamicPage. Once again, we are using the infrastructure that David Poll created. 15. OK, a few last things. We need a link on our main page so that we can access our new page. In MainPage.xaml let's update our links to look like this: <StackPanel x:Name="LinksStackPanel" Style="{StaticResource LinksStackPanelStyle}">     <HyperlinkButton Style="{StaticResource LinkStyle}" NavigateUri="/Home" TargetName="ContentFrame" Content="home"/>     <Rectangle Style="{StaticResource DividerStyle}"/>     <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 1" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage1}"/>     <Rectangle Style="{StaticResource DividerStyle}"/>     <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 2" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage2}"/>     <Rectangle Style="{StaticResource DividerStyle}"/>     <HyperlinkButton Style="{StaticResource LinkStyle}" Content="page 3" Command="{Binding NavigateCommand}" CommandParameter="{Binding ModulePage3}"/> </StackPanel> 16. Next, we need to add the following at the bottom of MainPageViewModel in the ViewModels directory of our DynamicXAPLoading project: public ModuleEnum ModulePage3 {     get { return ModuleEnum.Page3; } } 17. And at last, we need to add a case for our new page to the switch statement in MainPageViewModel: switch (module) {     case ModuleEnum.Page1:         DownloadPackage("Page1.xap");         break;     case ModuleEnum.Page2:         DownloadPackage("Page2.xap");         break;     case ModuleEnum.Page3:         DownloadPackage("Page3.xap");         break;     default:         break; } Now fire up the application and click the page 1, page 2 and page 3 links. What you'll notice is that there is a 2-second delay the first time you hit each page. That is because I added the following line to the Navigate method in MainPageViewModel: Thread.Sleep(2000); // Simulate a 2 second initial loading delay The reason I put this in there is that I wanted to simulate a delay the first time the page loads (as the .xap is being downloaded from the server). You'll notice that after the first hit to the page though that there is no delay...that's because the .xap has already been downloaded. Feel free to comment out this 2-second delay, or remove it if you'd like. I just wanted to show how subsequent hits to the page would be quicker than the initial one. By the way, you may want to display some sort of BusyIndicator while the .xap is loading. I have that in my Task-It appplication, but for the sake of simplicity I did not include it here. In the future I'll blog about how I show and hide the BusyIndicator using events (I'm currently using the eventing framework in Prism for that, but may move to the one in the MVVM Light Toolkit some time soon). Whew, that felt like a lot of steps, but it does work quite nicely. As I mentioned earlier, I'll try to find ways to simplify the code (I'd like to get away from having things like hard-coded .xap file names) and will blog about it in the future if I find a better way. In my next post, I'll talk more about what is actually happening with the code that makes this all work.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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  • Can static methods be called using object/instance in .NET

    Ans is Yes and No   Yes in C++, Java and VB.NET No in C#   This is only compiler restriction in c#. You might see in some websites that we can break this restriction using reflection and delegates, but we can’t, according to my little research J I shall try to explain you…   Following is code sample to break this rule using reflection, it seems that it is possible to call a static method using an object, p1 using System; namespace T {     class Program     {         static void Main()         {             var p1 = new Person() { Name = "Smith" };             typeof(Person).GetMethod("TestStatMethod").Invoke(p1, new object[] { });                     }         class Person         {             public string Name { get; set; }             public static void TestStatMethod()             {                 Console.WriteLine("Hello");             }         }     } } but I do not think so this method is being called using p1 rather Type Name “Person”. I shall try to prove this… look at another example…  Test2 has been inherited from Test1. Let’s see various scenarios… Scenario1 using System; namespace T {     class Program     {         static void Main()         {             Test1 t = new Test1();            typeof(Test2).GetMethod("Method1").Invoke(t,                                  new object[] { });         }     }     class Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method1");         }     }       class Test2 : Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method2");         }     } } Output:   At test1::Method2 Scenario2         static void Main()         {             Test2 t = new Test2();            typeof(Test2).GetMethod("Method1").Invoke(t,                                          new object[] { });         }   Output:   At test1::Method2   Scenario3         static void Main()         {             Test1 t = new Test2();            typeof(Test2).GetMethod("Method1").Invoke(t,                             new object[] { });         }   Output: At test1::Method2 In all above scenarios output is same, that means, Reflection also not considering the object what you pass to Invoke method in case of static methods. It is always considering the type which you specify in typeof(). So, what is the use passing instance to “Invoke”. Let see below sample using System; namespace T {     class Program     {         static void Main()         {            typeof(Test2).GetMethod("Method1").                Invoke(null, new object[] { });         }     }       class Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method1");         }     }     class Test2 : Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method2");         }     } }   Output is   At test1::Method2   I was able to call Invoke “Method1” of Test2 without any object.  Yes, there no wonder here as Method1 is static. So we may conclude that static methods cannot be called using instances (only in c#) Why Microsoft has restricted it in C#? Ans: Really there Is no use calling static methods using objects because static methods are stateless. but still Java and C++ latest compilers allow calling static methods using instances. Java sample class Test {      public static void main(String str[])      {            Person p = new Person();            System.out.println(p.GetCount());      } }   class Person {   public static int GetCount()   {      return 100;   } }   Output          100 span.fullpost {display:none;}

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  • Mocking the Unmockable: Using Microsoft Moles with Gallio

    - by Thomas Weller
    Usual opensource mocking frameworks (like e.g. Moq or Rhino.Mocks) can mock only interfaces and virtual methods. In contrary to that, Microsoft’s Moles framework can ‘mock’ virtually anything, in that it uses runtime instrumentation to inject callbacks in the method MSIL bodies of the moled methods. Therefore, it is possible to detour any .NET method, including non-virtual/static methods in sealed types. This can be extremely helpful when dealing e.g. with code that calls into the .NET framework, some third-party or legacy stuff etc… Some useful collected resources (links to website, documentation material and some videos) can be found in my toolbox on Delicious under this link: http://delicious.com/thomasweller/toolbox+moles A Gallio extension for Moles Originally, Moles is a part of Microsoft’s Pex framework and thus integrates best with Visual Studio Unit Tests (MSTest). However, the Moles sample download contains some additional assemblies to also support other unit test frameworks. They provide a Moled attribute to ease the usage of mole types with the respective framework (there are extensions for NUnit, xUnit.net and MbUnit v2 included with the samples). As there is no such extension for the Gallio platform, I did the few required lines myself – the resulting Gallio.Moles.dll is included with the sample download. With this little assembly in place, it is possible to use Moles with Gallio like that: [Test, Moled] public void SomeTest() {     ... What you can do with it Moles can be very helpful, if you need to ‘mock’ something other than a virtual or interface-implementing method. This might be the case when dealing with some third-party component, legacy code, or if you want to ‘mock’ the .NET framework itself. Generally, you need to announce each moled type that you want to use in a test with the MoledType attribute on assembly level. For example: [assembly: MoledType(typeof(System.IO.File))] Below are some typical use cases for Moles. For a more detailed overview (incl. naming conventions and an instruction on how to create the required moles assemblies), please refer to the reference material above.  Detouring the .NET framework Imagine that you want to test a method similar to the one below, which internally calls some framework method:   public void ReadFileContent(string fileName) {     this.FileContent = System.IO.File.ReadAllText(fileName); } Using a mole, you would replace the call to the File.ReadAllText(string) method with a runtime delegate like so: [Test, Moled] [Description("This 'mocks' the System.IO.File class with a custom delegate.")] public void ReadFileContentWithMoles() {     // arrange ('mock' the FileSystem with a delegate)     System.IO.Moles.MFile.ReadAllTextString = (fname => fname == FileName ? FileContent : "WrongFileName");       // act     var testTarget = new TestTarget.TestTarget();     testTarget.ReadFileContent(FileName);       // assert     Assert.AreEqual(FileContent, testTarget.FileContent); } Detouring static methods and/or classes A static method like the below… public static string StaticMethod(int x, int y) {     return string.Format("{0}{1}", x, y); } … can be ‘mocked’ with the following: [Test, Moled] public void StaticMethodWithMoles() {     MStaticClass.StaticMethodInt32Int32 = ((x, y) => "uups");       var result = StaticClass.StaticMethod(1, 2);       Assert.AreEqual("uups", result); } Detouring constructors You can do this delegate thing even with a class’ constructor. The syntax for this is not all  too intuitive, because you have to setup the internal state of the mole, but generally it works like a charm. For example, to replace this c’tor… public class ClassWithCtor {     public int Value { get; private set; }       public ClassWithCtor(int someValue)     {         this.Value = someValue;     } } … you would do the following: [Test, Moled] public void ConstructorTestWithMoles() {     MClassWithCtor.ConstructorInt32 =            ((@class, @value) => new MClassWithCtor(@class) {ValueGet = () => 99});       var classWithCtor = new ClassWithCtor(3);       Assert.AreEqual(99, classWithCtor.Value); } Detouring abstract base classes You can also use this approach to ‘mock’ abstract base classes of a class that you call in your test. Assumed that you have something like that: public abstract class AbstractBaseClass {     public virtual string SaySomething()     {         return "Hello from base.";     } }      public class ChildClass : AbstractBaseClass {     public override string SaySomething()     {         return string.Format(             "Hello from child. Base says: '{0}'",             base.SaySomething());     } } Then you would set up the child’s underlying base class like this: [Test, Moled] public void AbstractBaseClassTestWithMoles() {     ChildClass child = new ChildClass();     new MAbstractBaseClass(child)         {                 SaySomething = () => "Leave me alone!"         }         .InstanceBehavior = MoleBehaviors.Fallthrough;       var hello = child.SaySomething();       Assert.AreEqual("Hello from child. Base says: 'Leave me alone!'", hello); } Setting the moles behavior to a value of  MoleBehaviors.Fallthrough causes the ‘original’ method to be called if a respective delegate is not provided explicitly – here it causes the ChildClass’ override of the SaySomething() method to be called. There are some more possible scenarios, where the Moles framework could be of much help (e.g. it’s also possible to detour interface implementations like IEnumerable<T> and such…). One other possibility that comes to my mind (because I’m currently dealing with that), is to replace calls from repository classes to the ADO.NET Entity Framework O/R mapper with delegates to isolate the repository classes from the underlying database, which otherwise would not be possible… Usage Since Moles relies on runtime instrumentation, mole types must be run under the Pex profiler. This only works from inside Visual Studio if you write your tests with MSTest (Visual Studio Unit Test). While other unit test frameworks generally can be used with Moles, they require the respective tests to be run via command line, executed through the moles.runner.exe tool. A typical test execution would be similar to this: moles.runner.exe <mytests.dll> /runner:<myframework.console.exe> /args:/<myargs> So, the moled test can be run through tools like NCover or a scripting tool like MSBuild (which makes them easy to run in a Continuous Integration environment), but they are somewhat unhandy to run in the usual TDD workflow (which I described in some detail here). To make this a bit more fluent, I wrote a ReSharper live template to generate the respective command line for the test (it is also included in the sample download – moled_cmd.xml). - This is just a quick-and-dirty ‘solution’. Maybe it makes sense to write an extra Gallio adapter plugin (similar to the many others that are already provided) and include it with the Gallio download package, if  there’s sufficient demand for it. As of now, the only way to run tests with the Moles framework from within Visual Studio is by using them with MSTest. From the command line, anything with a managed console runner can be used (provided that the appropriate extension is in place)… A typical Gallio/Moles command line (as generated by the mentioned R#-template) looks like that: "%ProgramFiles%\Microsoft Moles\bin\moles.runner.exe" /runner:"%ProgramFiles%\Gallio\bin\Gallio.Echo.exe" "Gallio.Moles.Demo.dll" /args:/r:IsolatedAppDomain /args:/filter:"ExactType:TestFixture and Member:ReadFileContentWithMoles" -- Note: When using the command line with Echo (Gallio’s console runner), be sure to always include the IsolatedAppDomain option, otherwise the tests won’t use the instrumentation callbacks! -- License issues As I already said, the free mocking frameworks can mock only interfaces and virtual methods. if you want to mock other things, you need the Typemock Isolator tool for that, which comes with license costs (Although these ‘costs’ are ridiculously low compared to the value that such a tool can bring to a software project, spending money often is a considerable gateway hurdle in real life...).  The Moles framework also is not totally free, but comes with the same license conditions as the (closely related) Pex framework: It is free for academic/non-commercial use only, to use it in a ‘real’ software project requires an MSDN Subscription (from VS2010pro on). The demo solution The sample solution (VS 2008) can be downloaded from here. It contains the Gallio.Moles.dll which provides the here described Moled attribute, the above mentioned R#-template (moled_cmd.xml) and a test fixture containing the above described use case scenarios. To run it, you need the Gallio framework (download) and Microsoft Moles (download) being installed in the default locations. Happy testing…

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  • Sybase ASE

    - by Linchi Shea
    I sat in a Sybase ASE class last week for five days. Although it didn't cover the more advanced features introduced in the more recent versions of Sybase ASE, the class did touch all the basics of administering Sybase ASE. While I was successful in suppressing any urge to openly compare Sybase ASE with Microsoft SQL Server in the class, I could not help making mental notes on the differences between the two database platforms. It's always interesting to look at how two DBMS platforms that share the...(read more)

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  • Building extensions for Expression Blend 4 using MEF

    - by Timmy Kokke
    Introduction Although it was possible to write extensions for Expression Blend and Expression Design, it wasn’t very easy and out of the box only one addin could be used. With Expression Blend 4 it is possible to write extensions using MEF, the Managed Extensibility Framework. Until today there’s no documentation on how to build these extensions, so look thru the code with Reflector is something you’ll have to do very often. Because Blend and Design are build using WPF searching the visual tree with Snoop and Mole belong to the tools you’ll be using a lot exploring the possibilities.  Configuring the extension project Extensions are regular .NET class libraries. To create one, load up Visual Studio 2010 and start a new project. Because Blend is build using WPF, choose a WPF User Control Library from the Windows section and give it a name and location. I named mine DemoExtension1. Because Blend looks for addins named *.extension.dll  you’ll have to tell Visual Studio to use that in the Assembly Name. To change the Assembly Name right click your project and go to Properties. On the Application tab, add .Extension to name already in the Assembly name text field. To be able to debug this extension, I prefer to set the output path on the Build tab to the extensions folder of Expression Blend. This means that everything that used to go into the Debug folder is placed in the extensions folder. Including all referenced assemblies that have the copy local property set to false. One last setting. To be able to debug your extension you could start Blend and attach the debugger by hand. I like it to be able to just hit F5. Go to the Debug tab and add the the full path to Blend.exe in the Start external program text field. Extension Class Add a new class to the project.  This class needs to be inherited from the IPackage interface. The IPackage interface can be found in the Microsoft.Expression.Extensibility namespace. To get access to this namespace add Microsoft.Expression.Extensibility.dll to your references. This file can be found in the same folder as the (Expression Blend 4 Beta) Blend.exe file. Make sure the Copy Local property is set to false in this reference. After implementing the interface the class would look something like: using Microsoft.Expression.Extensibility; namespace DemoExtension1 { public class DemoExtension1:IPackage { public void Load(IServices services) { } public void Unload() { } } } These two methods are called when your addin is loaded and unloaded. The parameter passed to the Load method, IServices services, is your main entry point into Blend. The IServices interface exposes the GetService<T> method. You will be using this method a lot. Almost every part of Blend can be accessed thru a service. For example, you can use to get to the commanding services of Blend by calling GetService<ICommandService>() or to get to the Windowing services by calling GetService<IWindowService>(). To get Blend to load the extension we have to implement MEF. (You can get up to speed on MEF on the community site or read the blog of Mr. MEF, Glenn Block.)  In the case of Blend extensions, all that needs to be done is mark the class with an Export attribute and pass it the type of IPackage. The Export attribute can be found in the System.ComponentModel.Composition namespace which is part of the .NET 4 framework. You need to add this to your references. using System.ComponentModel.Composition; using Microsoft.Expression.Extensibility;   namespace DemoExtension1 { [Export(typeof(IPackage))] public class DemoExtension1:IPackage { Blend is able to find your addin now. Adding UI The addin doesn’t do very much at this point. The WPF User Control Library came with a UserControl so lets use that in this example. I just drop a Button and a TextBlock onto the surface of the control to have something to show in the demo. To get the UserControl to work in Blend it has to be registered with the WindowService.  Call GetService<IWindowService>() on the IServices interface to get access to the windowing services. The UserControl will be used in Blend on a Palette and has to be registered to enable it. This is done by calling the RegisterPalette on the IWindowService interface and passing it an identifier, an instance of the UserControl and a caption for the palette. public void Load(IServices services) { IWindowService windowService = services.GetService<IWindowService>(); UserControl1 uc = new UserControl1(); windowService.RegisterPalette("DemoExtension", uc, "Demo Extension"); } After hitting F5 to start debugging Expression Blend will start. You should be able to find the addin in the Window menu now. Activating this window will show the “Demo Extension” palette with the UserControl, style according to the settings of Blend. Now what? Because little is publicly known about how to access different parts of Blend adding breakpoints in Debug mode and browsing thru objects using the Quick Watch feature of Visual Studio is something you have to do very often. This demo extension can be used for that purpose very easily. Add the click event handler to the button on the UserControl. Change the contructor to take the IServices interface and store this in a field. Set a breakpoint in the Button_Click method. public partial class UserControl1 : UserControl { private readonly IServices _services;   public UserControl1(IServices services) { _services = services; InitializeComponent(); }   private void button1_Click(object sender, RoutedEventArgs e) { } } Change the call to the constructor in the load method and pass it the services property. public void Load(IServices services) { IWindowService service = services.GetService<IWindowService>(); UserControl1 uc = new UserControl1(services); service.RegisterPalette("DemoExtension", uc, "Demo Extension"); } Hit F5 to compile and start Blend. Got to the window menu and start show the addin. Click on  the button to hit the breakpoint. Now place the carrot text _services text in the code window and hit Shift+F9 to show the Quick Watch window. Now start exploring and discovering where to find everything you need.  More Information The are no official resources available yet. Microsoft has released one extension for expression Blend that is very useful as a reference, the Microsoft Expression Blend® Add-in Preview for Windows® Phone. This will install a .extension.dll file in the extension folder of Blend. You can load this file with Reflector and have a peek at how Microsoft is building his addins. Conclusion I hope this gives you something to get started building extensions for Expression Blend. Until Microsoft releases the final version, which hopefully includes more information about building extensions, we’ll have to work on documenting it in the community.

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  • Power supply triggered to start by another power supply

    - by steampowered
    I am building a raid array in a separate enclosure. I will be putting an empty tower case next to an existing tower computer, and this second tower case will only hold hard drives. There are many solutions for connecting the drives in the second case to the raid card in the first case (SFF-8088 and SFF-8087 cables). But I prefer not to run power from the first case to the second case. Can I use a power supply in the first tower case and cause it to start the power supply in the second case based on an indication from power in the first tower case's power supply? Maybe run a 12 volt cable from the first case to the power supply on the second case only for the purpose of initiating the second power supply.

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  • Why’s (Poignant) Guide to Ruby

    - by Ben Griswold
    You’re familiar with O’Reilly’s brilliant Head First Series, right?  Great.  Then you know how every book begins with an explanation of the Head First teaching style and you know the teaching format which Kathy Sierra and Bert Bates developed is based on research in cognitive science, neurobiology and educational psychology and it’s all about making learning visual and conversational and attractive and emotional and it’s highly effective.  Anyway, it’s a great series and you should read every last one of the books. Moving on… I’ve been wanting to learn more about Ruby and Why’s (Poignant) Guide to Ruby has been on my reading list for a while and there was talk about cartoon foxes and other silliness and I figured Why’s (Poignant) Guide to Ruby probably takes the same unorthodox teaching style as the Head First books – and that’s great – so I read the book, in piecemeal, over the last couple of weeks and, well, I figured wrong. Now having read the book, here’s my take on Why’s (Poignant) Guide – it’s very creative and clever and it does a darn good job of introducing one to Ruby.  If you’re interested in Ruby or simply interested, the online book is worth your time.  If you’re thinking (like me) that cartoon foxes will be doing the teaching, that’s simple not the case.  However, the cartoons and the random stories in the sidebar may serve a purpose. Unlike the Head First books where images and captions are used to further explain the teachings, the cartoons and stories in Why’s Guide serve as intermission and offer your brain a brief moment of rest before the next Ruby concept is explained.  It’s not a bad strategy, but definitely not as effective as the Head First techniques.  

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  • How do I get information about the level to the player object?

    - by pangaea
    I have a design problem with my Player and Level class in my game. So below is a picture of the game. The problem is I don't want to move on the black space and only the white space. I know how to do this as all I need to do is get the check for the sf::Color::Black and I have methods to do this in the Level class. The problem is this piece of code void Game::input() { player.input(); } void Game::update() { (*level).update(); player.update(); } void Game::render() { (*level).render(); player.render(); } So as you there is a problem in that how do I get the map information from the Level class to the Player class. Now I was thinking if I made the Player position static and pass it into the Level as parameter in update I could do it. The problem is interaction. I don't know what to do. I could maybe make player go into the Level class. However, what if I want multiple levels? So I have big design problems that I'm trying to solve.

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  • Dynamic Code for type casting Generic Types 'generically' in C#

    - by Rick Strahl
    C# is a strongly typed language and while that's a fundamental feature of the language there are more and more situations where dynamic types make a lot of sense. I've written quite a bit about how I use dynamic for creating new type extensions: Dynamic Types and DynamicObject References in C# Creating a dynamic, extensible C# Expando Object Creating a dynamic DataReader for dynamic Property Access Today I want to point out an example of a much simpler usage for dynamic that I use occasionally to get around potential static typing issues in C# code especially those concerning generic types. TypeCasting Generics Generic types have been around since .NET 2.0 I've run into a number of situations in the past - especially with generic types that don't implement specific interfaces that can be cast to - where I've been unable to properly cast an object when it's passed to a method or assigned to a property. Granted often this can be a sign of bad design, but in at least some situations the code that needs to be integrated is not under my control so I have to make due with what's available or the parent object is too complex or intermingled to be easily refactored to a new usage scenario. Here's an example that I ran into in my own RazorHosting library - so I have really no excuse, but I also don't see another clean way around it in this case. A Generic Example Imagine I've implemented a generic type like this: public class RazorEngine<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase, new() You can now happily instantiate new generic versions of this type with custom template bases or even a non-generic version which is implemented like this: public class RazorEngine : RazorEngine<RazorTemplateBase> { public RazorEngine() : base() { } } To instantiate one: var engine = new RazorEngine<MyCustomRazorTemplate>(); Now imagine that the template class receives a reference to the engine when it's instantiated. This code is fired as part of the Engine pipeline when it gets ready to execute the template. It instantiates the template and assigns itself to the template: var template = new TBaseTemplateType() { Engine = this } The problem here is that possibly many variations of RazorEngine<T> can be passed. I can have RazorTemplateBase, RazorFolderHostTemplateBase, CustomRazorTemplateBase etc. as generic parameters and the Engine property has to reflect that somehow. So, how would I cast that? My first inclination was to use an interface on the engine class and then cast to the interface.  Generally that works, but unfortunately here the engine class is generic and has a few members that require the template type in the member signatures. So while I certainly can implement an interface: public interface IRazorEngine<TBaseTemplateType> it doesn't really help for passing this generically templated object to the template class - I still can't cast it if multiple differently typed versions of the generic type could be passed. I have the exact same issue in that I can't specify a 'generic' generic parameter, since there's no underlying base type that's common. In light of this I decided on using object and the following syntax for the property (and the same would be true for a method parameter): public class RazorTemplateBase :MarshalByRefObject,IDisposable { public object Engine {get;set; } } Now because the Engine property is a non-typed object, when I need to do something with this value, I still have no way to cast it explicitly. What I really would need is: public RazorEngine<> Engine { get; set; } but that's not possible. Dynamic to the Rescue Luckily with the dynamic type this sort of thing can be mitigated fairly easily. For example here's a method that uses the Engine property and uses the well known class interface by simply casting the plain object reference to dynamic and then firing away on the properties and methods of the base template class that are common to all templates:/// <summary> /// Allows rendering a dynamic template from a string template /// passing in a model. This is like rendering a partial /// but providing the input as a /// </summary> public virtual string RenderTemplate(string template,object model) { if (template == null) return string.Empty; // if there's no template markup if(!template.Contains("@")) return template; // use dynamic to get around generic type casting dynamic engine = Engine; string result = engine.RenderTemplate(template, model); if (result == null) throw new ApplicationException("RenderTemplate failed: " + engine.ErrorMessage); return result; } Prior to .NET 4.0  I would have had to use Reflection for this sort of thing which would have a been a heck of a lot more verbose, but dynamic makes this so much easier and cleaner and in this case at least the overhead is negliable since it's a single dynamic operation on an otherwise very complex operation call. Dynamic as  a Bailout Sometimes this sort of thing often reeks of a design flaw, and I agree that in hindsight this could have been designed differently. But as is often the case this particular scenario wasn't planned for originally and removing the generic signatures from the base type would break a ton of other code in the framework. Given the existing fairly complex engine design, refactoring an interface to remove generic types just to make this particular code work would have been overkill. Instead dynamic provides a nice and simple and relatively clean solution. Now if there were many other places where this occurs I would probably consider reworking the code to make this cleaner but given this isolated instance and relatively low profile operation use of dynamic seems a valid choice for me. This solution really works anywhere where you might end up with an inheritance structure that doesn't have a common base or interface that is sufficient. In the example above I know what I'm getting but there's no common base type that I can cast to. All that said, it's a good idea to think about use of dynamic before you rush in. In many situations there are alternatives that can still work with static typing. Dynamic definitely has some overhead compared to direct static access of objects, so if possible we should definitely stick to static typing. In the example above the application already uses dynamics extensively for dynamic page page templating and passing models around so introducing dynamics here has very little additional overhead. The operation itself also fires of a fairly resource heavy operation where the overhead of a couple of dynamic member accesses are not a performance issue. So, what's your experience with dynamic as a bailout mechanism? © Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • URL Routing in ASP.NET 4.0

    In the .NET Framework 3.5 SP1, Microsoft introduced ASP.NET Routing, which decouples the URL of a resource from the physical file on the web server. With ASP.NET Routing you, the developer, define routing rules map route patterns to a class that generates the content. For example, you might indicate that the URL Categories/CategoryName maps to a class that takes the CategoryName and generates HTML that lists that category's products in a grid. With such a mapping, users could view products for the Beverages category by visiting www.yoursite.com/Categories/Beverages. In .NET 3.5 SP1, ASP.NET Routing was primarily designed for ASP.NET MVC applications, although as discussed in Using ASP.NET Routing Without ASP.NET MVC it is possible to implement ASP.NET Routing in a Web Forms application, as well. However, implementing ASP.NET Routing in a Web Forms application involves a bit of seemingly excessive legwork. In a Web Forms scenario we typically want to map a routing pattern to an actual ASP.NET page. To do so we need to create a route handler class that is invoked when the routing URL is requested and, in a sense, dispatches the request to the appropriate ASP.NET page. For instance, to map a route to a physical file, such as mapping Categories/CategoryName to ShowProductsByCategory.aspx - requires three steps: (1) Define the mapping in Global.asax, which maps a route pattern to a route handler class; (2) Create the route handler class, which is responsible for parsing the URL, storing any route parameters into some location that is accessible to the target page (such as HttpContext.Items), and returning an instance of the target page or HTTP Handler that handles the requested route; and (3) writing code in the target page to grab the route parameters and use them in rendering its content. Given how much effort it took to just read the preceding sentence (let alone write it) you can imagine that implementing ASP.NET Routing in a Web Forms application is not necessarily the most straightforward task. The good news is that ASP.NET 4.0 has greatly simplified ASP.NET Routing for Web Form applications by adding a number of classes and helper methods that can be used to encapsulate the aforementioned complexity. With ASP.NET 4.0 it's easier to define the routing rules and there's no need to create a custom route handling class. This article details these enhancements. Read on to learn more! Read More >

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  • Workarounds for supporting MVVM in the Silverlight TreeView Control

    - by cibrax
    MVVM (Model-View-ViewModel) is the pattern that you will typically choose for building testable user interfaces either in WPF or Silverlight. This pattern basically relies on the data binding support in those two technologies for mapping an existing model class (the view model) to the different parts of the UI or view. Unfortunately, MVVM was not threated as first citizen for some of controls released out of the box in the Silverlight runtime or the Silverlight toolkit. That means that using data binding for implementing MVVM is not always something trivial and usually requires some customization in the existing controls. In ran into different problems myself trying to fully support data binding in controls like the tree view or the context menu or things like drag & drop.  For that reason, I decided to write this post to show how the tree view control or the tree view items can be customized to support data binding in many of its properties. In first place, you will typically use a tree view for showing hierarchical data so the view model somehow must reflect that hierarchy. An easy way to implement hierarchy in a model is to use a base item element like this one, public abstract class TreeItemModel { public abstract IEnumerable<TreeItemModel> Children; } You can later derive your concrete model classes from that base class. For example, public class CustomerModel { public string FullName { get; set; } public string Address { get; set; } public IEnumerable<OrderModel> Orders { get; set; } }   public class CustomerTreeItemModel : TreeItemModel { public CustomerTreeItemModel(CustomerModel customer) { }   public override IEnumerable<TreeItemModel> Children { get { // Return orders } } } The Children property in the CustomerTreeItem model implementation can return for instance an ObservableCollection<TreeItemModel> with the orders, so the tree view will automatically subscribe to all the changes in the collection. You can bind this model to the tree view control in the UI by using a Hierarchical data template. <e:TreeView x:Name="TreeView" ItemsSource="{Binding Customers}"> <e:TreeView.ItemTemplate> <sdk:HierarchicalDataTemplate ItemsSource="{Binding Children}"> <!-- TEMPLATE --> </sdk:HierarchicalDataTemplate> </e:TreeView.ItemTemplate> </e:TreeView> An interesting behavior with the Children property and the Hierarchical data template is that the Children property is only invoked before the expansion, so you can use lazy load at this point (The tree view control will not expand the whole tree in the first expansion). The problem with using MVVM in this control is that you can not bind properties in model with specific properties of the TreeView item such as IsSelected or IsExpanded. Here is where you need to customize the existing tree view control to support data binding in tree items. public class CustomTreeView : TreeView { public CustomTreeView() { }   protected override DependencyObject GetContainerForItemOverride() { CustomTreeViewItem tvi = new CustomTreeViewItem(); Binding expandedBinding = new Binding("IsExpanded"); expandedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsExpandedProperty, expandedBinding); Binding selectedBinding = new Binding("IsSelected"); selectedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsSelectedProperty, selectedBinding); return tvi; } }   public class CustomTreeViewItem : TreeViewItem { public CustomTreeViewItem() { }   protected override DependencyObject GetContainerForItemOverride() { CustomTreeViewItem tvi = new CustomTreeViewItem(); Binding expandedBinding = new Binding("IsExpanded"); expandedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsExpandedProperty, expandedBinding); Binding selectedBinding = new Binding("IsSelected"); selectedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsSelectedProperty, selectedBinding); return tvi; } } You basically need to derive the TreeView and TreeViewItem controls to manually add a binding for the properties you need. In the example above, I am adding a binding for the “IsExpanded” and “IsSelected” properties in the items. The model for the tree items now needs to be extended to support those properties as well, public abstract class TreeItemModel : INotifyPropertyChanged { bool isExpanded = false; bool isSelected = false;   public abstract IEnumerable<TreeItemModel> Children { get; }   public bool IsExpanded { get { return isExpanded; } set { isExpanded = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsExpanded")); } }   public bool IsSelected { get { return isSelected; } set { isSelected = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsSelected")); } }   public event PropertyChangedEventHandler PropertyChanged; } However, as soon as you use this custom tree view control, you lose all the automatic styles from the built-in toolkit themes because they are tied to the control type (TreeView in this case).  The only ugly workaround I found so far for this problem is to copy the styles from the Toolkit source code and reuse them in the application.

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  • Anatomy of a serialization killer

    - by Brian Donahue
    As I had mentioned last month, I have been working on a project to create an easy-to-use managed debugger. It's still an internal tool that we use at Red Gate as part of product support to analyze application errors on customer's computers, and as such, should be easy to use and not require installation. Since the project has got rather large and important, I had decided to use SmartAssembly to protect all of my hard work. This was trivial for the most part, but the loading and saving of results was broken by SA after using the obfuscation, rendering the loading and saving of XML results basically useless, although the merging and error reporting was an absolute godsend and definitely worth the price of admission. (Well, I get my Red Gate licenses for free, but you know what I mean!)My initial reaction was to simply exclude the serializable results class and all of its' members from obfuscation, and that was just dandy, but a few weeks on I decided to look into exactly why serialization had broken and change the code to work with SA so I could write any new code to be compatible with SmartAssembly and save me some additional testing and changes to the SA project.In simple terms, SA does all that it can to prevent serialization problems, for instance, it will not obfuscate public members of a DLL and it will exclude any types with the Serializable attribute from obfuscation. This prevents public members and properties from being made private and having the name changed. If the serialization is done inside the executable, however, public members have the access changed to private and are renamed. That was my first problem, because my types were in the executable assembly and implemented ISerializable, but did not have the Serializable attribute set on them!public class RedFlagResults : ISerializable        {        }The second problem caused by the pruning feature. Although RedFlagResults had public members, they were not truly properties, and used the GetObjectData() method of ISerializable to serialize the members. For that reason, SA could not exclude these members from pruning and further broke the serialization. public class RedFlagResults : ISerializable        {                public List<RedFlag.Exception> Exceptions;                 #region ISerializable Members                 public void GetObjectData(SerializationInfo info, StreamingContext context)                {                                info.AddValue("Exceptions", Exceptions);                }                 #endregionSo to fix this, it was necessary to make Exceptions a proper property by implementing get and set on it. Also, I added the Serializable attribute so that I don't have to exclude the class from obfuscation in the SA project any more. The DoNotPrune attribute means I do not need to exclude the class from pruning.[Serializable, SmartAssembly.Attributes.DoNotPrune]        public class RedFlagResults        {                public List<RedFlag.Exception> Exceptions {get;set;}        }Similarly, the Exception class gets the Serializable and DoNotPrune attributes applied so all of its' properties are excluded from obfuscation.Now my project has some protection from prying eyes by scrambling up the code so it's harder to reverse-engineer, without breaking anything. SmartAssembly has also provided the benefit of merging so that the end-user doesn't need to extract all of the DLL files needed by RedFlag into a directory, and can be run directly from the .zip archive. When an error occurs (hey, I'm only human!), an exception report can be sent to me so I can see what went wrong without having to, er, debug the debugger.

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  • How to handle "circular dependency" in dependency injection

    - by Roel
    The title says "Circular Dependency", but it is not the correct wording, because to me the design seems solid. However, consider the following scenario, where the blue parts are given from external partner, and orange is my own implementation. Also assume there is more then one ConcreteMain, but I want to use a specific one. (In reality, each class has some more dependencies, but I tried to simplify it here) I would like to instanciate all of this with Depency Injection (Unity), but I obviously get a StackOverflowException on the following code, because Runner tries to instantiate ConcreteMain, and ConcreteMain needs a Runner. IUnityContainer ioc = new UnityContainer(); ioc.RegisterType<IMain, ConcreteMain>() .RegisterType<IMainCallback, Runner>(); var runner = ioc.Resolve<Runner>(); How can I avouid this? Is there any way to structure this so that I can use it with DI? The scenario I'm doing now is setting everything up manually, but that puts a hard dependency on ConcreteMain in the class which instantiates it. This is what i'm trying to avoid (with Unity registrations in configuration). All source code below (very simplified example!); public class Program { public static void Main(string[] args) { IUnityContainer ioc = new UnityContainer(); ioc.RegisterType<IMain, ConcreteMain>() .RegisterType<IMainCallback, Runner>(); var runner = ioc.Resolve<Runner>(); Console.WriteLine("invoking runner..."); runner.DoSomethingAwesome(); Console.ReadLine(); } } public class Runner : IMainCallback { private readonly IMain mainServer; public Runner(IMain mainServer) { this.mainServer = mainServer; } public void DoSomethingAwesome() { Console.WriteLine("trying to do something awesome"); mainServer.DoSomething(); } public void SomethingIsDone(object something) { Console.WriteLine("hey look, something is finally done."); } } public interface IMain { void DoSomething(); } public interface IMainCallback { void SomethingIsDone(object something); } public abstract class AbstractMain : IMain { protected readonly IMainCallback callback; protected AbstractMain(IMainCallback callback) { this.callback = callback; } public abstract void DoSomething(); } public class ConcreteMain : AbstractMain { public ConcreteMain(IMainCallback callback) : base(callback){} public override void DoSomething() { Console.WriteLine("starting to do something..."); var task = Task.Factory.StartNew(() =>{ Thread.Sleep(5000);/*very long running task*/ }); task.ContinueWith(t => callback.SomethingIsDone(true)); } }

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  • CLR via C# 3rd Edition is out

    - by Abhijeet Patel
    Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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  • Gvim GLib-GObject-WARNING in ubuntu 13.10

    - by naveen.panwar
    I upgraded from ubuntu 13.04 to ubuntu 13.10 this afternoon. And when I try starting vim form the terminal after the upgrade, I get these warnings (gvim:4054): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::sm-connect after class was initialised (gvim:4054): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::show-crash-dialog after class was initialised (gvim:4054): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::display after class was initialised (gvim:4054): GLib-GObject-WARNING **: Attempt to add property GnomeProgram::default-icon after class was initialised` How can I fix these and what exectly are these warnings about

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