Search Results

Search found 22007 results on 881 pages for 'variable reference'.

Page 276/881 | < Previous Page | 272 273 274 275 276 277 278 279 280 281 282 283  | Next Page >

  • Visual Studio 2010 Productivity Tips and Tricks&ndash;Part 1: Extensions

    - by ToStringTheory
    I don’t know about you, but when it comes to development, I prefer my environment to be as free of clutter as possible.  It may surprise you to know that I have tried ReSharper, and did not like it, for the reason that I stated above.  In my opinion, it had too much clutter.  Don’t get me wrong, there were a couple of features that I did like about it (inversion of if blocks, code feedback), but for the most part, I actually felt that it was slowing me down. Introduction Another large factor besides intrusiveness/speed in my choice to dislike ReSharper would probably be that I have become comfortable with my current setup and extensions.  I believe I have a good collection, and am quite happy with what I can accomplish in a short amount of time.  I figured that I would share some of my tips/findings regarding Visual Studio productivity here, and see what you had to say. The first section of things that I would like to cover, are Visual Studio Extensions.  In case you have been living under a rock for the past several years, Extensions are available under the Tools menu in Visual Studio: The extension manager enables integrated access to the Microsoft Visual Studio Gallery online with access to a few thousand different extensions.  I have tried many extensions, but for reasons of lack reliability, usability, or features, have uninstalled almost all of them.  However, I have come across several that I find I can not do without anymore: NuGet Package Manager (Microsoft) Perspectives (Adam Driscoll) Productivity Power Tools (Microsoft) Web Essentials (Mads Kristensen) Extensions NuGet Package Manager To be honest, I debated on whether or not to put this in here.  Most people seem to have it, however, there was a time when I didn’t, and was always confused when blogs/posts would say to right click and “Add Package Reference…” which with one of the latest updates is now “Manage NuGet Packages”.  So, if you haven’t downloaded the NuGet Package Manager yet, or don’t know what it is, I would highly suggest downloading it now! Features Simply put, the NuGet Package Manager gives you a GUI and command line to access different libraries that have been uploaded to NuGet. Some of its features include: Ability to search NuGet for packages via the GUI, with information in the detail bar on the right. Quick access to see what packages are in a solution, and what packages have updates available, with easy 1-click updating. If you download a package that requires references to work on other NuGet packages, they will be downloaded and referenced automatically. Productivity Tip If you use any type of source control in Visual Studio as well as using NuGet packages, be sure to right-click on the solution and click "Enable NuGet Package Restore". What this does is add a NuGet package to the solution so that it will be checked in along side your solution, as well as automatically grab packages from NuGet on build if needed. This is an extremely simple system to use to manage your package references, instead of having to manually go into TFS and add the Packages folder. Perspectives I can't stand developing with just one monitor. Especially if it comes to debugging. The great thing about Visual Studio 2010, is that all of the panels and windows are floatable, and can dock to other screens. The only bad thing is, I don't use the same toolset with everything that I am doing. By this, I mean that I don't use all of the same windows for debugging a web application, as I do for coding a WPF application. Only thing is, Visual Studio doesn't save the screen positions for all of the undocked windows. So, I got curious one day and decided to check and see if there was an extension to help out. This is where I found Perspectives. Features Perspectives gives you the ability to configure window positions across any or your monitors, and then to save the positions in a profile. Perspectives offers a Panel to manage different presets/favorites, and a toolbar to add to the toolbars at the top of Visual Studio. Ability to 'Favorite' a profile to add it to the perspectives toolbar. Productivity Tip Take the time to setup profiles for each of your scenarios - debugging web/winforms/xaml, coding, maintenance, etc. Try to remember to use the profiles for a few days, and at the end of a week, you may find that your productivity was never better. Productivity Power Tools Ah, the Productivity Power Tools... Quite possibly one of my most used extensions, if not my most used. The tool pack gives you a variety of enhancements ranging from key shortcuts, interface tweaks, and completely new features to Visual Studio 2010. Features I don't want to bore you with all of the features here, so here are my favorite: Quick Find - Unobtrusive search box in upper-right corner of the code window. Great for searching in general, especially in a file. Solution Navigator - The 'Solution Explorer' on steroids. Easy to search for files, see defined members/properties/methods in files, and my favorite feature is the 'set as root' option. Updated 'Add Reference...' Dialog - This is probably my favorite enhancement period... The 'Add Reference...' dialog redone in a manner that resembles the Extension/Package managers. I especially love the ability to search through all of the references. "Ctrl - Click" for Definition - I am still getting used to this as I usually try to use my keyboard for everything, but I love the ability to hold Ctrl and turn property/methods/variables into hyperlinks, that you click on to see their definitions. Great for travelling down a rabbit hole in an application to research problems. While there are other commands/utilities, I find these to be the ones that I lean on the most for the usefulness. Web Essentials If you have do any type of web development in ASP .Net, ASP .Net MVC, even HTML, I highly suggest grabbing the Web Essentials right NOW! This extension alone is great for productivity in web development, and greatly decreases my development time on new features. Features Some of its best features include: CSS Previews - I say 'previews' because of the multiple kinds of previews in CSS that you get font-family, color, background/background-image previews. This is great for just tweaking UI slightly in different ways and seeing how they look in the CSS window at a glance. Live Preview - One word - awesome! This goes well with my multi-monitor setup. I put the site on one monitor in a Live Preview panel, and then as I make changes to CSS/cshtml/aspx/html, the preview window will update with each save/build automatically. For CSS, you can even turn on live-update, so as you are tweaking CSS, the style changes in real time. Great for tweaking colors or font-sizes. Outlining - Small, but I like to be able to collapse regions/declarations that are in the way of new work, or are just distracting. Commenting Shortcuts - I don't know why it wasn't included by default, but it is nice to have the key shortcuts for commenting working in the CSS editor as well. Productivity Tip When working on a site, hit CTRL-ALT-ENTER to launch the Live Preview window. Dock it to another monitor. When you make changes to the document/css, just save and glance at the other monitor. No need to alt tab, then alt tab before continuing editing. Conclusion These extensions are only the most useful and least intrusive - ones that I use every day. The great thing about Visual Studio 2010 is the extensibility options that it gives developers to utilize. Have an extension that you use that isn't intrusive, but isn't listed here? Please, feel free to comment. I love trying new things, and am always looking for new additions to my toolset of the most useful. Finally, please keep an eye out for Part 2 on key shortcuts in Visual Studio. Also, if you are visiting my site (http://tostringtheory.com || http://geekswithblogs.net/tostringtheory) from an actual browser and not a feed, please let me know what you think of the new styling!

    Read the article

  • Business layer access to the data layer

    - by rerun
    I have a Business layer (BL) and a Data layer (DL). I have an object o with a child objects collection of Type C. I would like to provide a semantics like the following o.Children.Add("info"). In the BL I would like to have a static CLASS that all of business layer classes uses to get a reference to the current datalayer instance. Is there any issue with that or must I use the factory pattern to limit creation to A class in the BL that knows the DL instance.

    Read the article

  • Security-related database settings are not restored when a DB is restored

    - by Greg Low
    A question came up today about whether it was a bug that the TRUSTWORTHY database setting isn't restored to its previous value when a database is restored. TRUSTWORTHY is a very powerful setting for a database. By design, it's not restored when a database is. We actually documented this behavior when writing the Upgrade Technical Reference for 2008: http://www.microsoft.com/downloads/en/confirmation.aspx?familyId=66d3e6f5-6902-4fdd-af75-9975aea5bea7&displayLang=en The other settings that are...(read more)

    Read the article

  • Use of c89 in GNU software

    - by Federico Culloca
    In GNU coding standard it is said that free software developer should use C89 because C99 is not widespread yet. 1999 Standard C is not widespread yet, so please do not require its features in programs. Reference here. Are they talking about developers knowledge of C99, or about compilers supporting it? Also, is this statement plausible as of today or is it somewhat "obsolete" or at least obsolescent.

    Read the article

  • Joomla!, le guide officiel, un livre de Jennifer Marriott et Elin Waring, critique de Thibaut Cuvelier

    Le Guide officiel Joomla! est l'ouvrage de référence pour tout administrateur, blogueur, éditeur de contenus, développeur ou designer, débutant ou utilisateur averti. Grâce à des explications simples et des exemples pratiques, il vous permettra de mettre en place un site web de qualité, en accord avec vos cibles et le public que vous visez. Si vous débutez avec Joomla!, vous apprendrez dans ce livre à créer et mettre en ligne des sites de qualité immédiatement opérationnels et entièrement personnalisables....

    Read the article

  • SQLAuthority News Win MS Office License Last 2 days

    Just a note for everybody who is from India and want to win FREE Office License, participate in very easy contest here. SQLAuthority News Virtual Launch Event for Office 2010 Contest Win MS Office License Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, [...]...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.

    Read the article

  • Running Objects – Associations and Relationships

    - by edurdias
    After the introduction to the Running Objects with the tutorial Movie Database in 2 Minutes (available here), I would like to demonstrate how Running Objects interprets the Associations where we will cover: Direct Association – A reference to another complex object. Aggregation – A collection of another complex object. For those coming with a database perspective, by demonstrating these associations we will also exemplify the underline relationships such as 1 to Many and Many to Many relationships...(read more)

    Read the article

  • Looping in Python and keeping current line after sub routine [migrated]

    - by Brendan
    I've been trying to nut out an issue when looping in python 3. When returning from sub routine the "line" variable has not incremented. How do I get the script to return the latest readline from the subsroutine? Code below def getData(line): #print(line) #while line in sTSDP_data: while "/service/content/test" not in line: line = sTSDP_data.readline() import os, sys sFileTSDP = "d:/ess/redo/Test.log" sTSDP_data = open(sFileTSDP, "r") for line in sTSDP_data: if "MOBITV" in line: getData(line) #call sub routine print(line)

    Read the article

  • Understanding clojure keywords

    - by tjb1982
    I'm taking my first steps with Clojure. Otherwise, I'm somewhat competent with JavaScript, Python, Java, and a little C. I was reading this artical that describes destructuring vectors and maps. E.g. => (def point [0 0]) => (let [[x y] point] => (println "the coordinates are:" x y)) the coordinates are: 0 0 but I'm having a difficult time understanding keywords. At first glance, they seem really simple, as they just evaluate to themselves: => :test :test But they seem to be used is so many different ways and I don't understand how to think about them. E.g., you can also do stuff like this: => (defn full-name [& {first :first last :last}] => (println first last)) => (full-name :first "Tom" :last "Brennan") Tom Brennan nil This doesn't seem intuitive to me. I would have guessed the arguments should have been something more like: (full-name {:first "Tom" :last "Brennan"}) because it looks like in the function definition that you're saying "no required arguments, but a variable number of arguments comes in the form of a single map". But it seems more like you're saying "no required arguments, but a variable number of arguments comes which should be a list of alternating keywords and values... ?" I'm not really sure how to wrap my brain around this. Also, things like this confuse me too: => (def population {:humans 5 :zombies 1000}) => (:zombies population) 1000 => (population :zombies) 1000 How do maps and keywords suddenly become functions? If I could get some clarification on the use of keywords in these two examples, that would be really helpful. Update I've also seen http://stackoverflow.com/questions/3337888/clojure-named-arguments and while the accepted answer is a great demonstration of how to use keywords with destructuring and named arguments, I'm really looking more for understanding how to think about them--why the language is designed this way and how I can best internalize their use.

    Read the article

  • How does a "Variables introduce state"?

    - by kunj2aan
    I was reading the "C++ Coding Standards" and this line was there: Variables introduce state, and you should have to deal with as little state as possible, with lifetimes as short as possible. Doesn't anything that mutates eventually manipulate state? What does "you should have to deal with little state as possible" mean? In an impure language such as C++, isn't state management really what you are doing? And what are other ways to "deal with as little state as possible" other than limiting variable lifetime?

    Read the article

  • Simple collision detection in Unity 2D

    - by N1ghtshade3
    I realise other posts exist with this topic yet none have gone into enough detail for me. I am attempting to create a 2D game in Unity using C# as my scripting language. Basically I have two objects, player and bomb. Both were created simply by dragging the respective PNG to the stage. I have set up touch controls to move player left and right; gravity of any kind is not needed as I only require it to move x units when I tap either the left or right side of the screen. This movement is stored in a script called playerController.cs and works just fine. I also have a variable health = 3 for player, which is stored in healthScript.cs. I am now at a point where I am stuck. I would like it so that when player collides with bomb, health decreases by one and the bomb object is destroyed. So what I tried doing is using a new script called playerPhysics.cs, I added the following: void OnCollisionEnter2D(Collision2D coll){ if(coll.gameObject.name=="bomb") GameObject.Destroy("bomb"); healthScript.health -= 1; } While I'm fairly sure I don't know the proper way to reference a variable in another script and that's why the health didn't decrease when I collided, bomb never disappeared from the stage so I'm thinking there's also a problem with my collision. Initially, I had simply attached playerPhysics.cs to player. After searching around though, it appeared as though player also needed a rigidBody attached to it, so I did that. Still no luck. I tried using a circleCollider (player is a circle), using a rigidBody2D, and using all manner of colliders on one and/or both of the objects. If you could please explain what colliders (if any) should be attached to which objects and whether I need to change my script(s), that would be much more helpful than pointing me to one of the generic documentation examples I've already read. Also, if it would be simple to fix the health thing not working that would be an added bonus but not exactly the focus of this question. Bear in mind that this game is 2D; I'm not sure if that changes anything. Thanks!

    Read the article

  • Combining javascript files

    - by Michael Freidgeim
    I’ve read Combining Client Scripts into a Composite Script and wanted to use it. Then I’ve read Julian Jelfs concerns ScriptManager.CompositeScript issues However the article Combining javascript files with Ajax toolkit library describes workarounds, that make the solution workable. You also can use Script reference profiler: http://aspnet.codeplex.com/releases/view/13356 Related posts: Using ScriptManager with other frameworks MSDN documentation: CompositeScriptReference he older implementations, that has been superseded by CompositeScript class: ToolkitScriptManager Combining, Compressing, Minifying ASP.NET ScriptResource and HTML Markups

    Read the article

  • how to enable opengl 2.0 and webgl on gma 3150 ?

    - by mahmoudelbadry
    hi, i have a dell mini 1012 which has an intel n450 processor and gma 3150 integrated graphics card running ubuntu 10.10 according to the intel website the graphics card support opengl 2.0 http://software.intel.com/en-us/articles/quick-reference-guide-to-intel-integrated-graphics/#9 but when i type glxinfo in terminal the opengl version string gives me the following OpenGL version string: 1.4 Mesa 7.9-devel i installed the latest drivers but it didn't work. so, how can i enable opengl 2.0 on this card?? thanks

    Read the article

  • Free eBooks - SQL Server and other Microsoft Technologies

    - by Greg Low
    Great to see the advice from Gail Erickson about the release of a number of SQL Server related eBooks on the new Microsoft eBook Gallery site. It's good to see this sort of content moving over to eBook formats.The e-books that are currently available include: SQL Server 2012 Transact-SQL DML Reference Master Data Services Capacity Guidelines Microsoft SQL Server AlwaysOn Solutions Guide for High Availability and Disaster Recovery QuickStart: Learn DAX Basics in 30 Minutes Microsoft SQL Server Analysis Services Multidimensional Performance and Operations Guide You'll find details of them here: http://social.technet.microsoft.com/wiki/contents/articles/11608.e-book-gallery-for-microsoft-technologies.aspx

    Read the article

  • Math > Logic for a Logarithmic Score Meter

    - by oodavid
    I'm trying to implement a score meter whereby I specify a maximum value (say 15,000) and I can render values on it in a logarithmic manner ie: +------+---+--+-++ +------+---+--+-++ |== | |====== | +------+---+--+-++ +------+---+--+-++ 200 pts 1,000 pts +------+---+--+-++ +------+---+--+-++ |============= | |================| +------+---+--+-++ +------+---+--+-++ 5,000 pts 15,000 pts + The upper bound needs to be variable, and need to be able to convert a score to a percentage, using the above mockup as an example: score2pct(15000, 200) = 0.2 score2pct(15000, 1000) = 0.4 score2pct(15000, 5000) = 0.8 score2pct(15000, 15000) = 1 Does anyone have any pointers for me?

    Read the article

  • Resolving data redundancy up front

    - by okeofs
    Introduction As all of us do when confronted with a problem, the resource of choice is to ‘Google it’. This is where the plot thickens. Recently I was asked to stage data from numerous databases which were to be loaded into a data warehouse. To make a long story short, I was looking for a manner in which to obtain the table names from each database, to ascertain potential overlap.   As the source data comes from a SQL database created from dumps of a third party product,  one could say that there were +/- 95 tables for each database.   Yes I know that first instinct is to use the system stored procedure “exec sp_msforeachdb 'select "?" AS db, * from [?].sys.tables'”. However, if one stops to think about this, it would be nice to have all the results in a temporary or disc based  table; which in itself , implies additional labour. This said,  I decided to ‘re-invent’ the wheel. The full code sample may be found at the bottom of this article.   Define a few temporary tables and variables   declare @SQL varchar(max); declare @databasename varchar(75) /* drop table ##rawdata3 drop table #rawdata1 drop table #rawdata11 */ -- A temp table to hold the names of my databases CREATE TABLE #rawdata1 (    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) )     --A temp table with the same database names as above, HOWEVER using an --Identity number (recNO) as a loop variable. --You will note below that I loop through until I reach 25 (see below) as at --that point the system databases, the reporting server database etc begin. --1- 24 are user databases. These are really what I was looking for. --Whilst NOT the best solution,it works and the code was meant as a quick --and dirty. CREATE TABLE #rawdata11 (    recNo int identity(1,1),    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) )   --My output table showing the database name and table name CREATE TABLE ##rawdata3 (    database_name varchar(75) ,    table_name varchar(75), )   Insert the database names into a temporary table I pull the database names using the system stored procedure sp_databases   INSERT INTO #rawdata1 EXEC sp_databases Go   Insert the results from #rawdata1 into a table containing a record number  #rawdata11 so that I can LOOP through the extract   INSERT into #rawdata11 select * from  #rawdata1   We now declare 3 more variables:  @kounter is used to keep track of our position within the loop. @databasename is used to keep track of the’ current ‘ database name being used in the current pass of the loop;  as inorder to obtain the tables for that database we  need to issue a ‘USE’ statement, an insert command and other related code parts. This is the challenging part. @sql is a varchar(max) variable used to contain the ‘USE’ statement PLUS the’ insert ‘ code statements. We now initalize @kounter to 1 .   declare @kounter int; declare @databasename varchar(75); declare @sql varchar(max); set @kounter = 1   The Loop The astute reader will remember that the temporary table #rawdata11 contains our  database names  and each ‘database row’ has a record number (recNo). I am only interested in record numbers under 25. I now set the value of the temporary variable @DatabaseName (see below) .Note that I used the row number as a part of the predicate. Now, knowing the database name, I can create dynamic T-SQL to be executed using the sp_sqlexec stored procedure (see the code in red below). Finally, after all the tables for that given database have been placed in temporary table ##rawdata3, I increment the counter and continue on. Note that I used a global temporary table to ensure that the result set persists after the termination of the run. At some stage, I plan to redo this part of the code, as global temporary tables are not really an ideal solution.    WHILE (@kounter < 25)  BEGIN  select @DatabaseName = database_name from #rawdata11 where recNo = @kounter  set @SQL = 'Use ' + @DatabaseName + ' Insert into ##rawdata3 ' + + ' SELECT table_catalog,Table_name FROM information_schema.tables' exec sp_sqlexec  @Sql  SET @kounter  = @kounter + 1  END   The full code extract   Here is the full code sample.   declare @SQL varchar(max); declare @databasename varchar(75) /* drop table ##rawdata3 drop table #rawdata1 drop table #rawdata11 */ CREATE TABLE #rawdata1 (    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) ) CREATE TABLE #rawdata11 (    recNo int identity(1,1),    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) ) CREATE TABLE ##rawdata3 (    database_name varchar(75) ,    table_name varchar(75), )   INSERT INTO #rawdata1 EXEC sp_databases go INSERT into #rawdata11 select * from  #rawdata1 declare @kounter int; declare @databasename varchar(75); declare @sql varchar(max); set @kounter = 1 WHILE (@kounter < 25)  BEGIN  select @databasename = database_name from #rawdata11 where recNo = @kounter  set @SQL = 'Use ' + @DatabaseName + ' Insert into ##rawdata3 ' + + ' SELECT table_catalog,Table_name FROM information_schema.tables' exec sp_sqlexec  @Sql  SET @kounter  = @kounter + 1  END    select * from ##rawdata3  where table_name like '%SalesOrderHeader%'

    Read the article

  • Game state management (Game, Menu, Titlescreen, etc)

    - by munchor
    Basically, in every single game I've made so far, I always have a variable like "current_state", which can be "game", "titlescreen", "gameoverscreen", etc. And then on my Update function I have a huge: if current_state == "game" game stuf ... else if current_state == "titlescreen" ... However, I don't feel like this is a professional/clean way of handling states. Any ideas on how to do this in a better way? Or is this the standard way?

    Read the article

  • Configuring Full-Text Search for pdf and docx files

    - by Lukasz Kurylo
    I think in may I was creating a little filters module based on Full Text-Search. I have configured my dev machine, the same for two testing servers – in our company for internal testing before we deployed it to client, and then on the testing client server. Until last week this build  was still on the testing server and finally we got feedback that we can deploy it on the production one. I only say that, I lost half a day because I had not correctly remembered what I was doing to configure the FTS on the previous servers and I had no notes for that. I foolishly believed in my memory. Lesson learned.   For future reference a bunch of steps to configure the FTS for searching in *.pdf and *.docx files (and by the way in other Office files like *.xlsx).   1. From the page (link) download and install the *.pdf IFilter for FTS. 2. To the PATH global system variable add path to the catalog, where you installed the plugin. Default for this version is: C:\Program Files\Adobe\Adobe PDF iFilter 9 for 64-bit platforms\bin 3. From the page (link) download a FilterPackx64.exe and install it. 4. Now from SSMS execute the following procedures: -sp_fulltext_service 'load_os_resources',1 -sp_fulltext_service 'verify_signature', 0 5. Restart the server 6. Now we must check if the plugins are visible: -select document_type, path from sys.fulltext_document_types where document_type = '.pdf' -select document_type, path from sys.fulltext_document_types where document_type = '.docx' 7. If we see a result, then we can assume that everything is ok*. 8. Right now we can create a catalog for FTS and indexes on appropriate columns.     *I lost a lot of hours to find out, why the plugin for the *.pdf files wasn’t indexed any file in the database, but in the sys.fulltext_document_types table there was available a line for this plugin. After the deeper investigation I found that the *.pdf files actually were indexed. At least the EOF sign was added to the indexes and nothing more for each file. In the end the problem was that, I forgot to add the /bin in the path to the plugin in PATH variable..

    Read the article

  • When Is It Acceptable to NOT Fix Broken Windows?

    - by Bullines
    In reference to broken windows... Are there times when refactoring is best left for a future activity? For example, if a project to add some new features to an existing internal system is assigned to a team that has not worked with the system until now, and is given a short timeline in which to work with - can it be ever be justifiable to defer major refactorings to existing code for the sake of making the deadline in this scenario?

    Read the article

  • Stop a rotating object at a specified angle?

    - by Krummelz
    I'm working in JavaScript with HTML5 and the canvas. I have an object which is rotating at a certain speed, and I need the object's rotation to slow down gradually and the front of the object to stop at a specified angle. (I'm using radians, not degrees.) I have a variable to keep track of the angle which the object is facing, as it rotates. How would I go about getting the object to come to rest, facing the direction I want it to?

    Read the article

  • We've completed the first iteration

    - by CliveT
    There are a lot of features in C# that are implemented by the compiler and not by the underlying platform. One such feature is a lambda expression. Since local variables cannot be accessed once the current method activation finishes, the compiler has to go out of its way to generate a new class which acts as a home for any variable whose lifetime needs to be extended past the activation of the procedure. Take the following example:     Random generator = new Random();     Func func = () = generator.Next(10); In this case, the compiler generates a new class called c_DisplayClass1 which is marked with the CompilerGenerated attribute. [CompilerGenerated] private sealed class c__DisplayClass1 {     // Fields     public Random generator;     // Methods     public int b__0()     {         return this.generator.Next(10);     } } Two quick comments on this: (i)    A display was the means that compilers for languages like Algol recorded the various lexical contours of the nested procedure activations on the stack. I imagine that this is what has led to the name. (ii)    It is a shame that the same attribute is used to mark all compiler generated classes as it makes it hard to figure out what they are being used for. Indeed, you could imagine optimisations that the runtime could perform if it knew that classes corresponded to certain high level concepts. We can see that the local variable generator has been turned into a field in the class, and the body of the lambda expression has been turned into a method of the new class. The code that builds the Func object simply constructs an instance of this class and initialises the fields to their initial values.     c__DisplayClass1 class2 = new c__DisplayClass1();     class2.generator = new Random();     Func func = new Func(class2.b__0); Reflector already contains code to spot this pattern of code and reproduce the form containing the lambda expression, so this is example is correctly decompiled. The use of compiler generated code is even more spectacular in the case of iterators. C# introduced the idea of a method that could automatically store its state between calls, so that it can pick up where it left off. The code can express the logical flow with yield return and yield break denoting places where the method should return a particular value and be prepared to resume.         {             yield return 1;             yield return 2;             yield return 3;         } Of course, there was already a .NET pattern for expressing the idea of returning a sequence of values with the computation proceeding lazily (in the sense that the work for the next value is executed on demand). This is expressed by the IEnumerable interface with its Current property for fetching the current value and the MoveNext method for forcing the computation of the next value. The sequence is terminated when this method returns false. The C# compiler links these two ideas together so that an IEnumerator returning method using the yield keyword causes the compiler to produce the implementation of an Iterator. Take the following piece of code.         IEnumerable GetItems()         {             yield return 1;             yield return 2;             yield return 3;         } The compiler implements this by defining a new class that implements a state machine. This has an integer state that records which yield point we should go to if we are resumed. It also has a field that records the Current value of the enumerator and a field for recording the thread. This latter value is used for optimising the creation of iterator instances. [CompilerGenerated] private sealed class d__0 : IEnumerable, IEnumerable, IEnumerator, IEnumerator, IDisposable {     // Fields     private int 1__state;     private int 2__current;     public Program 4__this;     private int l__initialThreadId; The body gets converted into the code to construct and initialize this new class. private IEnumerable GetItems() {     d__0 d__ = new d__0(-2);     d__.4__this = this;     return d__; } When the class is constructed we set the state, which was passed through as -2 and the current thread. public d__0(int 1__state) {     this.1__state = 1__state;     this.l__initialThreadId = Thread.CurrentThread.ManagedThreadId; } The state needs to be set to 0 to represent a valid enumerator and this is done in the GetEnumerator method which optimises for the usual case where the returned enumerator is only used once. IEnumerator IEnumerable.GetEnumerator() {     if ((Thread.CurrentThread.ManagedThreadId == this.l__initialThreadId)               && (this.1__state == -2))     {         this.1__state = 0;         return this;     } The state machine itself is implemented inside the MoveNext method. private bool MoveNext() {     switch (this.1__state)     {         case 0:             this.1__state = -1;             this.2__current = 1;             this.1__state = 1;             return true;         case 1:             this.1__state = -1;             this.2__current = 2;             this.1__state = 2;             return true;         case 2:             this.1__state = -1;             this.2__current = 3;             this.1__state = 3;             return true;         case 3:             this.1__state = -1;             break;     }     return false; } At each stage, the current value of the state is used to determine how far we got, and then we generate the next value which we return after recording the next state. Finally we return false from the MoveNext to signify the end of the sequence. Of course, that example was really simple. The original method body didn't have any local variables. Any local variables need to live between the calls to MoveNext and so they need to be transformed into fields in much the same way that we did in the case of the lambda expression. More complicated MoveNext methods are required to deal with resources that need to be disposed when the iterator finishes, and sometimes the compiler uses a temporary variable to hold the return value. Why all of this explanation? We've implemented the de-compilation of iterators in the current EAP version of Reflector (7). This contrasts with previous version where all you could do was look at the MoveNext method and try to figure out the control flow. There's a fair amount of things we have to do. We have to spot the use of a CompilerGenerated class which implements the Enumerator pattern. We need to go to the class and figure out the fields corresponding to the local variables. We then need to go to the MoveNext method and try to break it into the various possible states and spot the state transitions. We can then take these pieces and put them back together into an object model that uses yield return to show the transition points. After that Reflector can carry on optimising using its usual optimisations. The pattern matching is currently a little too sensitive to changes in the code generation, and we only do a limited analysis of the MoveNext method to determine use of the compiler generated fields. In some ways, it is a pity that iterators are compiled away and there is no metadata that reflects the original intent. Without it, we are always going to dependent on our knowledge of the compiler's implementation. For example, we have noticed that the Async CTP changes the way that iterators are code generated, so we'll have to do some more work to support that. However, with that warning in place, we seem to do a reasonable job of decompiling the iterators that are built into the framework. Hopefully, the EAP will give us a chance to find examples where we don't spot the pattern correctly or regenerate the wrong code, and we can improve things. Please give it a go, and report any problems.

    Read the article

  • Confusion about inheritance

    - by Samuel Adam
    I know I might get downvoted for this, but I'm really curious. I was taught that inheritance is a very powerful polymorphism tool, but I can't seem to use it well in real cases. So far, I can only use inheritance when the base class is an abstract class. Examples : If we're talking about Product and Inventory, I quickly assumed that a Product is an Inventory because a Product must be inventorized as well. But a problem occured when user wanted to sell their Inventory item. It just doesn't seem to be right to change an Inventory object to it's subtype (Product), it's almost like trying to convert a parent to it's child. Another case is Customer and Member. It is logical (at least for me) to think that a Member is a Customer with some more privileges. Same problem occurred when user wanted to upgrade an existing Customer to become a Member. A very trivial case is the Employee case. Where Manager, Clerk, etc can be derived from Employee. Still, the same upgrading issue. I tried to use composition instead for some cases, but I really wanted to know if I'm missing something for inheritance solution here. My composition solution for those cases : Create a reference of Inventory inside a Product. Here I'm making an assumption about that Product and Inventory is talking in a different context. While Product is in the context of sales (price, volume, discount, etc), Inventory is in the context of physical management (stock, movement, etc). Make a reference of Membership instead inside Customer class instead of previous inheritance solution. Therefor upgrading a Customer is only about instantiating the Customer's Membership property. This example is keep being taught in basic programming classes, but I think it's more proper to have those Manager, Clerk, etc derived from an abstract Role class and make it a property in Employee. I found it difficult to find an example of a concrete class deriving from another concrete class. Is there any inheritance solution in which I can solve those cases? Being new in this OOP thing, I really really need a guidance. Thanks!

    Read the article

  • Pointers in C vs No pointers in PHP

    - by AnnaBanana
    Both languages have the same syntax. Why does C have the weird * character that denotes pointers (which is some kind of memory address of the variable contents?), when PHP doesn't have it and you can do pretty much the same things in PHP that you can do in C, without pointers? I guess the PHP compiler handles this internally, why doesn't C do the same? Doesn't this add unneeded complexity in C? For example I don't understand them :)

    Read the article

  • See you at OSCON!

    - by darcy
    In just under a month, I'll be speaking at the OSCON Java conference about various OpenJDK and JDK 7 matters: JDK 7 in a Nutshell The State of JDK and OpenJDK More detailed talks on those topics include Stuart's session on Coin in Action: Using New Java SE 7 Language Features in Real Code and Dalibor's OpenJDK – When And How To Contribute To The Java SE Reference Implementation. See you in Portland!

    Read the article

< Previous Page | 272 273 274 275 276 277 278 279 280 281 282 283  | Next Page >