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  • Homemaking a 2d soft body physics engine

    - by Griffin
    hey so I've decided to Code my own 2D soft-body physics engine in C++ since apparently none exist and I'm starting only with a general idea/understanding on how physics work and could be simulated: by giving points and connections between points properties such as elasticity, density, mass, shape retention, friction, stickiness, etc. What I want is a starting point: resources and helpful examples/sites that could give me the specifics needed to actually make this such as equations and required physics knowledge. It would be great if anyone out there also would give me their attempts or ideas. finally I was wondering if it was possible to... use the source code of an existing 3D engine such as Bullet and transform it to be 2D based? use the source code of a 2D Rigid body physics engine such as box2d as a starting point?

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  • How to load with "simplegame" mode after cooking?

    - by Emran Bayati
    i got a problem after i cook my game in Frontend (udk) ! Every thing is ok during the Cook operation i mean i compiled my scripts,it's ok there's no problem in this step,and i cooked my packages it's ok too ! no problem just like last step. so before i package the whole game;i'll lunch it and see if every thing is ok ! but when i load the game it'll load whit the Unreal tournament default game type ! i mean i don't want it to load with this type ! i want it to load with the "simplegame" game type ! i need to say that i set game type to "simplegame" in the Editor from View world Properties Game Type! but still it's loading with Ut game mode when i cook the game ! I just want load my game in "Simplegame" mode after cooked. if any one can help ! plz help ! Tnx Alot Emran Bayati

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  • How to Create Steel Wool Light Paintings [Video]

    - by Jason Fitzpatrick
    Steel Wool Light Paintings are like regular long-exposure light paintings but they replace LEDs with flaming balls of steel; watch this video to see how to safely and successfully light paint with steal wool. In this video Benjamin Von Wong explains how to set up a steel wool light painting photoshoot, how to create your steel wool light source, and how to do it all safely without burning down your neighborhood or lighting nearby pedestrians on fire. [via DIYPhotography] What’s the Difference Between Sleep and Hibernate in Windows? Screenshot Tour: XBMC 11 Eden Rocks Improved iOS Support, AirPlay, and Even a Custom XBMC OS How To Be Your Own Personal Clone Army (With a Little Photoshop)

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  • How can I add a bash script to the Unity launcher?

    - by hippyjim
    I open my favourite IDE (PhpStorm) using a custom bash script. I would like to add the script to the Unity launcher. I thought I could add it by clicking the "keep in launcher" option, and sure enough, the icon stays on the launcher after I close the app. But clicking the icon doesn't reopen the IDE - the launcher just sits there, flashing. When I relogin in, the launcher icon is gone. Anyone got any ideas how I can make this work?

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  • Junior software developer - How to understand web aplications in depth?

    - by nat_gr
    I am currently a junior developer in web applications and specifically in asp.net mvc technology. My problem is that the c# senior developer in the company has no experience with this technology and I try to learn without any guidance. I went through all tutorials (e.g music store), codeplex projects and also read pro asp.net mvc 4. However, most of the examples are about crud and e-commerce applications. What I don't understand is how dependency injection fits in web applications (I have realized that is not only used for facilitating unit testing) or when i should use a custom model binder or how to model the business logic when there is already a database schema in place. I read the forum quite often and it would very helpful if some experienced developers could give me an insight about how to proceed. Do I need to read some books to understand the overall idea behind web applications? And what kind of application should I start building myself - I don't think it would be useful to create similar examples with the tutorials.

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  • How to setup SyntaxHighlighter with GeeksWithBlogs in about 10 minutes.

    - by mbcrump
    SyntaxHighlighter is a fully functional self-contained code syntax highlighter developed in JavaScript. Below is a sample of what it looks like in your blog. class Test { static void Main() { System.Console.WriteLine("Sample SyntaxHighlighter"); } } This tutorial will help you setup SyntaxHighlighter with GeeksWithBlogs.net in about 10 minutes. Even though this guide is specifically for GWB, you can use it on any other hosting provider that does not allow you to upload custom CSS/JavaScript. It is recommended that if you are using LiveWriter to go ahead and download Code Snippet with SyntaxHighlighter Support to integrate this functionality within Live Writer. 1) Log into GWB and select Options->Configure Now under the Custom CSS insert the following code at the top of the textbox: @import url("http://alexgorbatchev.com/pub/sh/current/styles/shCore.css"); @import url("http://alexgorbatchev.com/pub/sh/current/styles/shThemeDefault.css"); Please note that you can change the default theme by changing the shThemeDefault.css to one listed below: shThemeDefault.css shThemeDjango.css shThemeEmacs.css shThemeFadeToGrey.css shThemeMidnight.css shThemeRDark.css 2) Under the Static News/Announcements insert the following code at the top: <script type="text/javascript" src="http://alexgorbatchev.com/pub/sh/current/scripts/shCore.js"></script> <script type="text/javascript" language="javascript" src="http://alexgorbatchev.com/pub/sh/current/scripts/shBrushCSharp.js"></script> <script type="text/javascript" language="javascript" src="http://alexgorbatchev.com/pub/sh/current/scripts/shBrushJScript.js"></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushJava.js' type='text/javascript'></script> <script language='javascript'> SyntaxHighlighter.config.bloggerMode = true; SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/current/scripts/clipboard.swf'; SyntaxHighlighter.all(); </script> Please note that this will only give you support for Java, JavaScript and C Sharp. If you want more languages like Ruby and SQL. Then add the proper tags listed below. The reason that I didn’t add them is because I do not want to load languages that I will not be blogging about. <link href='http://alexgorbatchev.com/pub/sh/current/styles/shCore.css' rel='stylesheet' type='text/css'/> <link href='http://alexgorbatchev.com/pub/sh/current/styles/shThemeDefault.css' rel='stylesheet' type='text/css'/> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shCore.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushCpp.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushCSharp.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushCss.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushJava.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushJScript.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushPhp.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushPython.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushRuby.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushSql.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushVb.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushXml.js' type='text/javascript'></script> <script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushPerl.js' type='text/javascript'></script> <script language='javascript'> SyntaxHighlighter.config.bloggerMode = true; SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/current/scripts/clipboard.swf'; SyntaxHighlighter.all(); </script> 3) Now install Code Snippet with SyntaxHighlighter Support and launch Windows Live Writer. Click on the PreCode Snippet plugin add copy/paste your code into the windows. Make sure you select “PRE” and the Language that you are using. It should look similar to the following screenshot.  After you finish editing the post, hit publish and your code should look nice and neat like the example shown earlier.

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  • Hosting a web application on discountasp.net using sql ce 5

    - by David Stanley
    I am hoping that someone may have experience with this, since the discountasp site is very lacking in straightforward answers. I am building a lightweight web application and have decided to have sql ce as the database for it. Two questions regarding this: Do i need to get an actual database hosted as well as the site, in order for it to work? Do you know if discountasp supports the use of sql ce (not with webmatrix or any cms builds, completely custom)? If they don't, do you have any experience/recommendations with getting this done?

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  • adverising servers / advert delivery solutions for C#/Asp.Net

    - by Karl Cassar
    We have a website which we want to show adverts in - However, these are custom adverts uploaded by the webmaster, not the Google adverts, or any adverts the network chooses. Ideally, there would be both options. We were considering developing our own advert-management system, but looking at the big picture, it might be better to consider other alternatives. Website is currently developed in C# / ASP.Net (Web Forms) Are there any recommendations to some open-source delivery networks and/or external hosted advert delivery networks? Personally I've used Google's DFP, however sometimes it is not so easy to get a Google AdSense account approved, especially while developing a new website and it not yet being launched. Not sure if this is the best place to ask this kind of question!

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  • Multi database link and mix and match email alert

    - by menardmam
    I have a site which is a large database of people that have different knowledge in different domains, such as teaching (maths, french, science etc...) On the site there is a page where you can search people base on different request, such as distance from home, grade, sex. Now, I would like to add a page where people that are looking for mentor will fill a request, and when a tutor in his area of search will match request, a email will be send to this researcher. Because I know for sure, that when in January you look for a math teacher for your 10 year old son, and you find none, you won't go again in February, March... and on and on just to see. Maybe there is one now, you want to be informed when the tutor will get into database automatically (more or less like www.jobboom.com) So the question is, what CMS do I need to be able to do that ? Wordpress, drupal or something custom made?

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  • Changing email application in Preferred Applications to GMail?

    - by grm
    I'm trying to change the Preferred Application for email. I have installed the package desktop-webmail, but there is no new option under System - Preferences - Preferred Application as you would expect, infact, there is only one option there, only Evolution. According to this post it should be possible to set a custom application, but no option is available. Is it possible to setup GMail as Preferred email app so that File - Send by email works in gnome apps? This seems to be a dup of another post here, Thing is that this works fine in 10.10, but in 11.04 this method no longer work. My post above is meant for 11.04 and the question is still valid.

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  • Customizing configuration with Dependency Injection

    - by mathieu
    I'm designing a small application infrastructure library, aiming to simplify development of ASP.NET MVC based applications. Main goal is to enforce convention over configuration. Hovewer, I still want to make some parts "configurable" by developpers. I'm leaning towards the following design: public interface IConfiguration { SomeType SomeValue; } // this one won't get registered in container protected class DefaultConfiguration : IConfiguration { public SomeType SomeValue { get { return SomeType.Default; } } } // declared inside 3rd party library, will get registered in container protected class CustomConfiguration : IConfiguration { public SomeType SomeValue { get { return SomeType.Custom; } } } And the "service" class : public class Service { private IConfiguration conf = new DefaultConfiguration(); // optional dependency, if found, will be set to CustomConfiguration by DI container public IConfiguration Conf { get { return conf; } set { conf = value; } } public void Configure() { DoSomethingWith( Conf ); } } There, the "configuration" part is clearly a dependency of the service class, but it this an "overuse" of DI ?

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  • Sort method versus OrderBy LINQ extension method

    - by nmarun
    I have a class Product with an Id and a Name as properties. There are multiple ways of getting a list of products to display in sorted/ordered fashion, say, by the Name of the product. The two I’m concerned about here are the Sort and the OrderBy extension method through LINQ and the difference between them. 1: public class Product 2: { 3: public int Id { get; set; } 4: public string Name { get; set; } 5: } Below is the list of products that I’ll be using and is defined somewhere in the Program.cs...(read more)

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  • Redirecting a CSS file based on .htaccess rules.

    - by Anthony Hiscox
    I'm trying to hack the css files on OSTicket by replacing them with my own custom ones when a specific URL is accessed. The URL that is accessed for this example is http://osticket.cts/helpdesk/scp/css/main.css and I would like it to use the css file at http://osticket.cts/test.css why won't this .htaccess file (in web root, not /helpdesk/scp/) work? Is there an easy way to debug these rules, some way to find out what apache did when the URL was accessed and where it's failing? error.log doesn't show anything useful. RewriteEngine On RewriteCond %{HTTP_HOST} ^osticket\.cts$ [NC] RewriteRule ^(.*)main\.css$ /test.css [NC, L]

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  • How is this site so fast?

    - by user8628
    how is the website http://dftba.com/ so fast? when i click a link it loads right then? what makes it work like this? how do i make it work like this on my site? some of the objects on the site are being hosted by a website called ecogeek-cdn.net? who is this company and why do they host the images of this site? i have been looking into this site some time because i want this site to be like mine site they site use Apache they site use Python (when asked the developer told me this) they site use jquery and jqueryui they site is custom built not using wordpress they site is ownedhosted by liquidweb they site gets a million users a month they site launched in january they site uses cpanel they site does not have SSH or FTP (i tried to connect but it denied me all) they does have SSH and FTP but only allowed by their addresses Please; my english is not as good as yours

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  • Help me classify this type of software architecture

    - by Alex Burtsev
    I read some books about software architecture as we are using it in our project but I can't classify the architecture properly. It's some kind of Enterprise Architecture, but what exactly... SOA, ESB (Enterprise Service Bus), Message Bus, Event Driven SOA, there are so many terms in Enterprise software.... The system is based on custom XML messages exchanges between services. (it's not SOAP, nor any other XML based standard, just plain XML). These messages represent notifications (state changes) that are applied to the Domain model, (it's not like CRUD when you serialize the whole domain object, and pass it to service for persistence). The system is centralized, and system participants use different programming languages and frameworks (c++, c#, java). Also, messages are not processed at the moment they are received as they are stored first and the treatment begins on demand. It's called SOA+EDA -:)

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  • apt changelog for to-be installed packages

    - by ithkuil
    GUI update-manager is able to show the "changelog" of packages to-be installed (not downloaded yet). I also found out how to provide the .changelog files in the right place for update-manager to show them, and now I'm happy since I'm able to tell my clients that they can see changelogs of my custom packages directly from their gui. Unfortunately I'm not able to find any command line tool to do the same thing and that would be more useful on servers. From what I saw it seems that this convention (putting .changelog files directly alongside the .deb files in the apt repo) is a ubuntu specific extension. There are some debian resources (the reprepro man page for example) which point on a different way to store changelogs online, http://packages.debian.org/changelogs Does anybody know if there already exists a tool like apt-cache to show the changelogs from packages which are not yet installed (nor downloaded) ?

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  • Business Logic Layer in MVC Application

    - by Subin Jacob
    In my ASP MVC application I decided to add another Business Layer and made the model only to have properties. All other functionality like save to db, get from db is done on this new Business layer. So now the controller will be calling this business layer and model for various operations. Is it a good approach to design like this? I decided not to use model for this purpose because I would need a number of models for different actions. (for eg, one for edit and other for create)

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  • How does Blizzard manage to support Mac OS and Windows in their games?

    - by begray
    I've always thought, that using Direct X for Windows was the most powerful, easy and modern method to create games with modern graphics nowdays. And knowing, that it's only Windows I thinks it's pretty difficult to make something similar on other platforms (Mac OS to be exact). But Blizzard somehow managed to deliver Starcraft 2 for Mac OS, and Diablo 3 will be available for Mac too. So what I'm interested in is information about: what technologies are they using for their game engines? are they using one engine for both games (Starcraft 2 and Diablo 3)? Or develop custom for each game? what are they paying in terms of time and money for Mac OS support? Thanks

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  • Simple Scripting for your Exalogic Storage

    - by Trond Strømme
    As part of my job in Oracle ACS (Advanced Customer Services) I'm handling lots of different systems and customers. Among the recent systems I worked with have been Oracle's Exalogic engineered systems. One of the things I'd never had much exposure to as a system developer/architect/middleware guy/Java dude has been storage; outside of consuming it for my photography needs.. Well, I'm always ready for a new challenge... I'd downloaded the 7000 series storage simulator when it was released in the good old Sun days, found it fun and instructive to play around with, but as I never touched storage in any way (besides consuming it..) I forgot about it. A couple of years ago when I started working with Exalogic engineered systems it again came into light as an invaluable learning and testing tool for the embedded storage in an Exalogic;  Oracle's Sun ZFS Storage 7320 Appliance.  aaaanyway... I've been "booted" into a part-time role as the interim storage/system admin/middleware/Java guy for a client and found I needed to create the occasional report or summary or whatever.. of what's using the storage in the 7320 (as default configured for an Exalogic, 40T of disk in a mirrored configuration, yielding 18T of actual space.) Reading the nice documentation and some articles on the Oracle Technology Network I saw great possibilities with the embedded ECMAScript3/JavaScript engine in the 7000 series.  In my personal opinion anyone who's dealing with Exalogic administration, or exposed to any of the 7000 series of storage appliances and servers that Oracle offers should have a VirtualBox instance of it kicking around. For development and testing it's a fantastic tool. (It can save you from explaining (most) of the embarrassing FAILS you can do if you test something in a production system to your management...) So download, and install.  A small sidestep, if after firing up the 7000 series simulator in VirtualBox you've forgotten what it's IP address is, the following will sort you out if you log in directly via the running VirtualBox VM. So in my case I can ssh to 192.168.56.101 or point a browser to https://192.168.56.101:215 to log into the storage appliance. One simple way of executing a script on the 7320 is to ssh to the device and redirecting a file with the script in it to ssh. ssh [email protected] < myscript.js One question I got from my client and the people who will take over the systems was: "how can we see the quotas and allocations for all projects/shares in one easy go so we don't have to go navigating around in the BUI for all the hundreds of shares the 7320 is hosting just to check if anything is running dry?" Easy! JavaScript time, VirtualBox and emacs! //NOTE! this script is available 'as is' It has ben run on a couple of 7320's, (running 2010.08.17.3.0,1-1.25 & // 2011.04.24.1.0,1-1.8) a 7420 and the VB image, but I personally //offer no guarantee whatsoever that it won't make your server topple, catch fire or in any way go pear shaped.. //run at your own risk or learn from my code and or mistakes.. script run('cd /'); run('shares'); //get all projects: proj = list(); function spaceToGig(bytes){ return bytes/1073741824; //convert bytes to GB } function fullInPercent(quota, space_data){ tmp = (space_data/quota)*100; return tmp; } //print header, slightly good looking printf(" %s/%-15s %8s(GB) %7s(GB) %5s(GB) %7s(GB) %3s\n","Project", "Share","Quota","Ref", "Snap", "Total","%full"); printf("-------------------------------------------------------------------------------\n") //for each project, get all shares. check for quota and calculate percentage and human readable figures.. for (i=0;i<proj.length;i++){ run('select ' + proj[i]); //get all shares for a project var pshares = list(); //for each share get quota properties for (j=0;j<pshares.length;j++){ run('select ' + pshares[j]); quota = get('quota'); //properties associated with a share or inherited from a project spaceData = get('space_data'); spaceSnap = get('space_snapshots'); spaceTotal = get('space_total'); if(quota>0){ //has quota printf(" %s/%-15s \t%4.2fGB\t%.2fGB\t%.2fGB\t%.2fGB\t%5.2f%%\n",proj[i], pshares[j],spaceToGig(quota),spaceToGig(spaceData),spaceToGig(spaceSnap),spaceToGig(spaceTotal),fullInPercent(quota,spaceTotal)); }else{ //no quota printf(" %s/%-15s \t%8s\t%.2fGB\t%.2fGB\t%.2fGB\t%s\n",proj[i],pshares[j], "N/A", spaceToGig(spaceData),spaceToGig(spaceSnap),spaceToGig(spaceTotal),"N/A"); } run('cd ..'); } run('done'); } The resulting output should look something like this: Project/Share Quota(GB) Ref(GB) Snap(GB) Total(GB) %full ------------------------------------------------------------------------------- ACSExalogicSystem/domains N/A 0.04GB 0.00GB 0.04GB N/A ACSExalogicSystem/logs N/A 0.01GB 0.00GB 0.01GB N/A ACSExalogicSystem/nodemgrs N/A 0.00GB 0.00GB 0.00GB N/A ACSExalogicSystem/stores N/A 0.04GB 0.00GB 0.04GB N/A ***_dev/FMW_***_1 133GB 4.24GB 0.01GB 4.25GB 3.19% ***_dev/FMW_***_2 N/A 4.25GB 0.01GB 4.26GB N/A ***_dev/applications 10GB 0.00GB 0.00GB 0.00GB 0.00% ***_dev/domains 50GB 10.75GB 3.55GB 14.30GB 28.61% ***_dev/logs 20GB 0.32GB 0.01GB 0.33GB 1.66% ***_dev/softwaredepot 20GB 4.15GB 0.00GB 4.15GB 20.73% ***_dev/stores 20GB 0.01GB 0.00GB 0.01GB 0.05% ###_dev/FMW_###_1 400GB 17.63GB 0.12GB 17.75GB 4.44% ###_dev/applications N/A 0.00GB 0.00GB 0.00GB N/A ###_dev/domains 120GB 14.21GB 5.53GB 19.74GB 16.45% ###_dev/logs 15GB 0.00GB 0.00GB 0.00GB 0.00% ###_dev/softwaredepot 250GB 73.55GB 0.02GB 73.57GB 29.43% …snip My apologies if the output is a bit mis-aligned here and there, I only bothered making it look good, not perfect :/ I also removed some of the project names (*,#)

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  • Smart Grid Gateway and New Meter Data Management released

    - by Anthony Shorten
    Two products have just been released and are available from edlivery.oracle.com. Smart Grid Gateway 2.0.0 - A new product to integrate to Smart Grid networks Meter Data Management 2.0.1 - A new version of the Meter Data Management product. These products are the first products to use the brand new version of the Oracle Utilities Applicaton Framework (V4.1). The new framework builds up on FW2.2 and FW4.0.2 to add exciting new features (this is just a subset): Support for Database Vault Enhancements to Business Object Maintenance Batch Statistics Portal for benchmarking Custom template user exit support File permissions now consistent with other Oracle products Use of Universal Connection Pool for all database pool access Ability to manage the batch data cache Over the next few weeks I will be publishing articles and updates to existing whitepapers to highlight all the new features.

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  • How to Transfer Files Between Your PC and Android Phone Wirelessly

    - by Zainul Franciscus
    Mounting your Android phone to transfer files is fast and efficient, but nothing beats the convenience of a wireless file transfer. Today, we’ll show you how to transfer files between Android and your computer without a USB cable Latest Features How-To Geek ETC How To Colorize Black and White Vintage Photographs in Photoshop How To Get SSH Command-Line Access to Windows 7 Using Cygwin The How-To Geek Video Guide to Using Windows 7 Speech Recognition How To Create Your Own Custom ASCII Art from Any Image How To Process Camera Raw Without Paying for Adobe Photoshop How Do You Block Annoying Text Message (SMS) Spam? Change Your MAC Address to Avoid Free Internet Restrictions Battlestar Galactica – Caprica Map of the 12 Colonies (Wallpaper Also Available) View Enlarged Versions of Thumbnail Images with Thumbnail Zoom for Firefox IntoNow Identifies Any TV Show by Sound Walk Score Calculates a Neighborhood’s Pedestrian Friendliness Factor Fantasy World at Twilight Wallpaper

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  • Is there a IRC Client which can use or emulate mIRC scripts

    - by fred.bear
    I've used mIRC (Windows) for years, and have some custom scripts, written in mIRC's own scripting language. Is there an Ubuntu/Linux IRC Client which will allow me to use my scripts as-is? Failing that, is there a "functions a lot like mIRC" Client available? I've just tried Pidgin's IRC client, but it seems to be quite basic. I couldn't see any way for it to tap into channel activity via scripts. I don't want to use Wine... WineHQ reports it as having too many bugs for my liking, and anyhow, I try to avoid using Wine like I do Windows :)

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  • Breaking through the class sealing

    - by Jason Crease
    Do you understand 'sealing' in C#?  Somewhat?  Anyway, here's the lowdown. I've done this article from a C# perspective, but I've occasionally referenced .NET when appropriate. What is sealing a class? By sealing a class in C#, you ensure that you ensure that no class can be derived from that class.  You do this by simply adding the word 'sealed' to a class definition: public sealed class Dog {} Now writing something like " public sealed class Hamster: Dog {} " you'll get a compile error like this: 'Hamster: cannot derive from sealed type 'Dog' If you look in an IL disassembler, you'll see a definition like this: .class public auto ansi sealed beforefieldinit Dog extends [mscorlib]System.Object Note the addition of the word 'sealed'. What about sealing methods? You can also seal overriding methods.  By adding the word 'sealed', you ensure that the method cannot be overridden in a derived class.  Consider the following code: public class Dog : Mammal { public sealed override void Go() { } } public class Mammal { public virtual void Go() { } } In this code, the method 'Go' in Dog is sealed.  It cannot be overridden in a subclass.  Writing this would cause a compile error: public class Dachshund : Dog { public override void Go() { } } However, we can 'new' a method with the same name.  This is essentially a new method; distinct from the 'Go' in the subclass: public class Terrier : Dog { public new void Go() { } } Sealing properties? You can also seal seal properties.  You add 'sealed' to the property definition, like so: public sealed override string Name {     get { return m_Name; }     set { m_Name = value; } } In C#, you can only seal a property, not the underlying setters/getters.  This is because C# offers no override syntax for setters or getters.  However, in underlying IL you seal the setter and getter methods individually - a property is just metadata. Why bother sealing? There are a few traditional reasons to seal: Invariance. Other people may want to derive from your class, even though your implementation may make successful derivation near-impossible.  There may be twisted, hacky logic that could never be second-guessed by another developer.  By sealing your class, you're protecting them from wasting their time.  The CLR team has sealed most of the framework classes, and I assume they did this for this reason. Security.  By deriving from your type, an attacker may gain access to functionality that enables him to hack your system.  I consider this a very weak security precaution. Speed.  If a class is sealed, then .NET doesn't need to consult the virtual-function-call table to find the actual type, since it knows that no derived type can exist.  Therefore, it could emit a 'call' instead of 'callvirt' or at least optimise the machine code, thus producing a performance benefit.  But I've done trials, and have been unable to demonstrate this If you have an example, please share! All in all, I'm not convinced that sealing is interesting or important.  Anyway, moving-on... What is automatically sealed? Value types and structs.  If they were not always sealed, all sorts of things would go wrong.  For instance, structs are laid-out inline within a class.  But what if you assigned a substruct to a struct field of that class?  There may be too many fields to fit. Static classes.  Static classes exist in C# but not .NET.  The C# compiler compiles a static class into an 'abstract sealed' class.  So static classes are already sealed in C#. Enumerations.  The CLR does not track the types of enumerations - it treats them as simple value types.  Hence, polymorphism would not work. What cannot be sealed? Interfaces.  Interfaces exist to be implemented, so sealing to prevent implementation is dumb.  But what if you could prevent interfaces from being extended (i.e. ban declarations like "public interface IMyInterface : ISealedInterface")?  There is no good reason to seal an interface like this.  Sealing finalizes behaviour, but interfaces have no intrinsic behaviour to finalize Abstract classes.  In IL you can create an abstract sealed class.  But C# syntax for this already exists - declaring a class as a 'static', so it forces you to declare it as such. Non-override methods.  If a method isn't declared as override it cannot be overridden, so sealing would make no difference.  Note this is stated from a C# perspective - the words are opposite in IL.  In IL, you have four choices in total: no declaration (which actually seals the method), 'virtual' (called 'override' in C#), 'sealed virtual' ('sealed override' in C#) and 'newslot virtual' ('new virtual' or 'virtual' in C#, depending on whether the method already exists in a base class). Methods that implement interface methods.  Methods that implement an interface method must be virtual, so cannot be sealed. Fields.  A field cannot be overridden, only hidden (using the 'new' keyword in C#), so sealing would make no sense.

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  • Why is there no generic implementation of OrderedDictionary in .net?

    - by nonot1
    Why did Microsoft not provide generic implementation of OrderedDictionary? There are a few custom implementations I've seen, including: http://www.codeproject.com/KB/recipes/GenericOrderedDictionary.aspx But why did Microsoft not include it in the base .net library? Surely they had a reason for not building a generic.... but what is it? Prior to posting this message, I did see: http://stackoverflow.com/questions/2629027/no-generic-implementation-of-ordereddictionary But that just confirms that it does not exist. Not why it does not exist. Thanks

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  • Which online form builders offer conditional logic/branching?

    - by Hari Sundararajan
    I have a survey with the following form fields: Country Age Male/Female Undergraduate/Graduate Question? Yes No If No, what about this and that? Yes No Google Forms and SurveyMonkey don't seem to allow things like the above. For question one I could ask, "What country are you from?" with a textbox as an answer section and work around it. But how do I go about creating questions five and six? I am not able to figure out how to do it except for having one more question that says "If your answer to the previous question was No, then blah blah (else skip this question)". Any suggestions, apart from creating my own custom website with JavaScript and a backend database?

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