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• Control to Control Binding in WPF/Silverlight

  - by psheriff

  In the past if you had two controls that you needed to work together, you would have to write code. For example, if you want a label control to display any text a user typed into a text box you would write code to do that. If you want turn off a set of controls when a user checks a check box, you would also have to write code. However, with XAML, these operations become very easy to do. Bind Text Box to Text Block As a basic example of this functionality, let’s bind a TextBlock control to a TextBox. When the user types into a TextBox the value typed in will show up in the TextBlock control as well. To try this out, create a new Silverlight or WPF application in Visual Studio. On the main window or user control type in the following XAML. <StackPanel>  <TextBox Margin="10" x:Name="txtData" />  <TextBlock Margin="10"              Text="{Binding ElementName=txtData,                             Path=Text}" /></StackPanel> Now run the application and type into the TextBox control. As you type you will see the data you type also appear in the TextBlock control. The {Binding} markup extension is responsible for this behavior. You set the ElementName attribute of the Binding markup to the name of the control that you wish to bind to. You then set the Path attribute to the name of the property of that control you wish to bind to. That’s all there is to it! Bind the IsEnabled Property Now let’s apply this concept to something that you might use in a business application. Consider the following two screen shots. The idea is that if the Add Benefits check box is un-checked, then the IsEnabled property of the three “Benefits” check boxes will be set to false (Figure 1). If the Add Benefits check box is checked, then the IsEnabled property of the “Benefits” check boxes will be set to true (Figure 2). Figure 1: Uncheck Add Benefits and the Benefits will be disabled. Figure 2: Check Add Benefits and the Benefits will be enabled. To accomplish this, you would write XAML to bind to each of the check boxes in the “Benefits To Add” section to the check box named chkBenefits. Below is a fragment of the XAML code that would be used. <CheckBox x:Name="chkBenefits" /> <CheckBox Content="401k"           IsEnabled="{Binding ElementName=chkBenefits,                               Path=IsChecked}" /> Since the IsEnabled property is a boolean type and the IsChecked property is also a boolean type, you can bind these two together. If they were different types, or if you needed them to set the IsEnabled property to the inverse of the IsChecked property then you would need to use a ValueConverter class. SummaryOnce you understand the basics of data binding in XAML, you can eliminate a lot code. Connecting controls together is as easy as just setting the ElementName and Path properties of the Binding markup extension. NOTE: You can download the complete sample code at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "SL – Basic Control Binding" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free eBook on "Fundamentals of N-Tier".

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• Take Control Of Web Control ClientID Values in ASP.NET 4.0

  Each server-side Web control in an ASP.NET Web Forms application has an <code>ID</code> property that identifies the Web control and is name by which the Web control is accessed in the code-behind class. When rendered into HTML, the Web control turns its server-side <code>ID</code> value into a client-side <code>id</code> attribute. Ideally, there would be a one-to-one correspondence between the value of the server-side <code>ID</code> property and the generated client-side <code>id</code>, but in reality things aren't so simple. By default, the rendered client-side <code>id</code> is formed by taking the Web control's <code>ID</code> property and prefixed it with the <code>ID</code>

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• Ajax Control Toolkit and Superexpert

  - by Stephen Walther

  Microsoft has asked my company, Superexpert Consulting, to take ownership of the development and maintenance of the Ajax Control Toolkit moving forward. In this blog entry, I discuss our strategy for improving the Ajax Control Toolkit. Why the Ajax Control Toolkit? The Ajax Control Toolkit is one of the most popular projects on CodePlex. In fact, some have argued that it is among the most successful open-source projects of all time. It consistently receives over 3,500 downloads a day (not weekends -- workdays). A mind-boggling number of developers use the Ajax Control Toolkit in their ASP.NET Web Forms applications. Why does the Ajax Control Toolkit continue to be such a popular project? The Ajax Control Toolkit fills a strong need in the ASP.NET Web Forms world. The Toolkit enables Web Forms developers to build richly interactive JavaScript applications without writing any JavaScript. For example, by taking advantage of the Ajax Control Toolkit, a Web Forms developer can add modal dialogs, popup calendars, and client tabs to a web application simply by dragging web controls onto a page. The Ajax Control Toolkit is not for everyone. If you are comfortable writing JavaScript then I recommend that you investigate using jQuery plugins instead of the Ajax Control Toolkit. However, if you are a Web Forms developer and you don’t want to get your hands dirty writing JavaScript, then the Ajax Control Toolkit is a great solution. The Ajax Control Toolkit is Vast The Ajax Control Toolkit consists of 40 controls. That’s a lot of controls (For the sake of comparison, jQuery UI consists of only 8 controls – those slackers J). Furthermore, developers expect the Ajax Control Toolkit to work on browsers both old and new. For example, people expect the Ajax Control Toolkit to work with Internet Explorer 6 and Internet Explorer 9 and every version of Internet Explorer in between. People also expect the Ajax Control Toolkit to work on the latest versions of Mozilla Firefox, Apple Safari, and Google Chrome. And, people expect the Ajax Control Toolkit to work with different operating systems. Yikes, that is a lot of combinations. The biggest challenge which my company faces in supporting the Ajax Control Toolkit is ensuring that the Ajax Control Toolkit works across all of these different browsers and operating systems. Testing, Testing, Testing Because we wanted to ensure that we could easily test the Ajax Control Toolkit with different browsers, the very first thing that we did was to set up a dedicated testing server. The dedicated server -- named Schizo -- hosts 4 virtual machines so that we can run Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and Internet Explorer 9 at the same time (We also use the virtual machines to host the latest versions of Firefox, Chrome, Opera, and Safari). The five developers on our team (plus me) can each publish to a separate FTP website on the testing server. That way, we can quickly test how changes to the Ajax Control Toolkit affect different browsers. QUnit Tests for the Ajax Control Toolkit Introducing regressions – introducing new bugs when trying to fix existing bugs – is the concern which prevents me from sleeping well at night. There are so many people using the Ajax Control Toolkit in so many unique scenarios, that it is difficult to make improvements to the Ajax Control Toolkit without introducing regressions. In order to avoid regressions, we decided early on that it was extremely important to build good test coverage for the 40 controls in the Ajax Control Toolkit. We’ve been focusing a lot of energy on building automated JavaScript unit tests which we can use to help us discover regressions. We decided to write the unit tests with the QUnit test framework. We picked QUnit because it is quickly becoming the standard unit testing framework in the JavaScript world. For example, it is the unit testing framework used by the jQuery team, the jQuery UI team, and many jQuery UI plugin developers. We had to make several enhancements to the QUnit framework in order to test the Ajax Control Toolkit. For example, QUnit does not support tests which include postbacks. We modified the QUnit framework so that it works with IFrames so we could perform postbacks in our automated tests. At this point, we have written hundreds of QUnit tests. For example, we have written 135 QUnit tests for the Accordion control. The QUnit tests are included with the Ajax Control Toolkit source code in a project named AjaxControlToolkit.Tests. You can run all of the QUnit tests contained in the project by opening the Default.aspx page. Automating the QUnit Tests across Multiple Browsers Automated tests are useless if no one ever runs them. In order for the QUnit tests to be useful, we needed an easy way to run the tests automatically against a matrix of browsers. We wanted to run the unit tests against Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, Firefox, Chrome, and Safari automatically. Expecting a developer to run QUnit tests against every browser after every check-in is just too much to expect. It takes 20 seconds to run the Accordion QUnit tests. We are testing against 8 browsers. That would require the developer to open 8 browsers and wait for the results after each change in code. Too much work. Therefore, we built a JavaScript Test Server. Our JavaScript Test Server project was inspired by John Resig’s TestSwarm project. The JavaScript Test Server runs our QUnit tests in a swarm of browsers (running on different operating systems) automatically. Here’s how the JavaScript Test Server works: 1. We created an ASP.NET page named RunTest.aspx that constantly polls the JavaScript Test Server for a new set of QUnit tests to run. After the RunTest.aspx page runs the QUnit tests, the RunTest.aspx records the test results back to the JavaScript Test Server. 2. We opened the RunTest.aspx page on instances of Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, FireFox, Chrome, Opera, Google, and Safari. Now that we have the JavaScript Test Server setup, we can run all of our QUnit tests against all of the browsers which we need to support with a single click of a button. A New Release of the Ajax Control Toolkit Each Month The Ajax Control Toolkit Issue Tracker contains over one thousand five hundred open issues and feature requests. So we have plenty of work on our plates J At CodePlex, anyone can vote for an issue to be fixed. Originally, we planned to fix issues in order of their votes. However, we quickly discovered that this approach was inefficient. Constantly switching back and forth between different controls was too time-consuming. It takes time to re-familiarize yourself with a control. Instead, we decided to focus on two or three controls each month and really focus on fixing the issues with those controls. This way, we can fix sets of related issues and avoid the randomization caused by context switching. Our team works in monthly sprints. We plan to do another release of the Ajax Control Toolkit each and every month. So far, we have competed one release of the Ajax Control Toolkit which was released on April 1, 2011. We plan to release a new version in early May. Conclusion Fortunately, I work with a team of smart developers. We currently have 5 developers working on the Ajax Control Toolkit (not full-time, they are also building two very cool ASP.NET MVC applications). All the developers who work on our team are required to have strong JavaScript, jQuery, and ASP.NET MVC skills. In the interest of being as transparent as possible about our work on the Ajax Control Toolkit, I plan to blog frequently about our team’s ongoing work. In my next blog entry, I plan to write about the two Ajax Control Toolkit controls which are the focus of our work for next release.

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• How to Install vaio-control-center from source?

  - by KasiyA

  I have a problem about turning off keyboard backlight that I asked here with no useful answers. After searching on internet I find a package for vaio control center and downloaded it from here, I don't know how to install it. This is the output of trying one solution: USER@XXXXpc:~/vaio-control-center-0.1$ ls compile Makefile run vaio-control-center vcc COPYING moc_main_window.cpp ui_main_window.h vaio-control-center.pro USER@XXXXpc:~/vaio-control-center-0.1$ ./compile make: *** No rule to make target `/usr/share/qt/mkspecs/linux-g++-64/qmake.conf', needed by `Makefile'. Stop. USER@XXXXpc:~/vaio-control-center-0.1$ ./run ./run: 3: ./run: ./vaio-control-center: not found USER@XXXXpc:~/vaio-control-center-0.1$ Updated I tried also with @pandya's suggestion from here. and the output is as follows: root@user-pc:/# cd /home/user/vaio-f11-linux.control-center root@user-pc:/home/user/vaio-f11-linux.control-center# ls compile COPYING resource.qrc run sony-acpid vaio-control-center.pro vcc root@user-pc:/home/user/vaio-f11-linux.control-center# ./compile -su: ./compile: Permission denied root@user-pc:/home/user/vaio-f11-linux.control-center# sudo ./compile sudo: ./compile: command not found root@user-pc:/home/user/vaio-f11-linux.control-center# gksudo ./compile root@user-pc:/home/user/vaio-f11-linux.control-center# <----- nothing happened here root@user-pc:/home/user/vaio-f11-linux.control-center# ./run -su: ./run: Permission denied root@user-pc:/home/user/vaio-f11-linux.control-center# sudo ./run sudo: ./run: command not found root@user-pc:/home/user/vaio-f11-linux.control-center# gksudo ./run root@user-pc:/home/user/vaio-f11-linux.control-center# <----- nothing happened here root@user-pc:/home/user/vaio-f11-linux.control-center# and after running that I didn't see any affect on keyboard backlight.

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• Why does NUnit ignore datapoints when using generics in a theory

  - by The Chairman

  I'm trying to make use of the TheoryAttribute, introduced in NUnit 2.5. Everything works fine as long as the arguments are of a defined type: [Datapoint] public double[,] Array2X2 = new double[,] { { 1, 0 }, { 0, 1 } }; [Theory] public void TestForArbitraryArray(double[,] array) { // ... } It does not work, when I use generics: [Datapoint] public double[,] Array2X2 = new double[,] { { 1, 0 }, { 0, 1 } }; [Theory] public void TestForArbitraryArray<T>(T[,] array) { // ... } NUnit gives a warning saying No arguments were provided. Why is that?

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• How to setup Secure SemiPublic Revision Control System

  - by user24912

  I have a windows server with a project configured with a revision control system. Suppose it's GIT or SVN or .... Suppose there are 10 people around the globe working on this project. The first thing that comes in to mind is to secure the connection between these programmer and the server with SSH. but my problem is that the a hacker can destroy the server if he gets the SSH username and password user account (tell me if i'm wrong). So I need a secure way to let thoes programmers push their revision to the server. Any ideas would be lovely

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• How to access a named element in a control that inherits from a templated control

  - by Mrt

  Hello this is similar to http://stackoverflow.com/questions/2620165/how-to-access-a-named-element-of-a-derived-user-control-in-silverlight with the difference is inheriting from a templated control, not a user control. I have a templated control called MyBaseControl <Style TargetType="Problemo:MyBaseControl"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="Problemo:MyBaseControl"> <Grid x:Name="LayoutRoot" Background="White"> <Border Name="HeaderControl" Background="Red" /> </Grid> </ControlTemplate> </Setter.Value> </Setter> </Style> public class MyBaseControl : Control { public UIElement Header { get; set; } public MyBaseControl() { DefaultStyleKey = typeof(MyBaseControl); } public override void OnApplyTemplate() { base.OnApplyTemplate(); var headerControl = GetTemplateChild("HeaderControl") as ContentPresenter; if (headerControl != null) headerControl.Content = Header; } } I have another control called myControl which inherits from MyBaseControl Control <me:MyBaseControl x:Class="Problemo.MyControl" 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" mc:Ignorable="d" xmlns:me="clr-namespace:Problemo" d:DesignHeight="300" d:DesignWidth="400"> <me:MyBaseControl.Header> <TextBlock Name="xxx" /> </me:MyBaseControl.Header> </me:MyBaseControl> public partial class MyControl : MyBaseControl { public string Text { get; set; } public MyControl(string text) { InitializeComponent(); Text = text; Loaded += MyControl_Loaded; } void MyControl_Loaded(object sender, RoutedEventArgs e) { base.ApplyTemplate(); xxx.Text = Text; } } The issue is xxx is null. How do I access the xxx control in the code behind ?

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• Development processes, the use of version control, and unit-testing

  - by ct01

  Preface I've worked at quite a few "flat" organizations in my time. Most of the version control policy/process has been "only commit after it's been tested". We were constantly committing at each place to "trunk" (cvs/svn). The same was true with unit-testing - it's always been a "we need to do this" mentality but it never really materializes in a substantive form b/c there is no institutional knowledge base to do it - no mentorship. Version Control The emphasis for version control management at one place was a very strict protocol for commit messages (format & content). The other places let employees just do "whatever". The branching, tagging, committing, rolling back, and merging aspect of things was always ill defined and almost never used. This sort of seems to leave the version control system in the position of being a fancy file-storage mechanism with a meta-data component that never really gets accessed/utilized. (The same was true for unit testing and committing code to the source tree) Unit tests It seems there's a prevailing "we must/should do this" mentality in most places I've worked. As a policy or standard operating procedure it never gets implemented because there seems to be a very ill-defined understanding about what that means, what is going to be tested, and how to do it. Summary It seems most places I've been to think version control and unit testing is "important" b/c the trendy trade journals say it is but, if there's very little mentorship to use these tools or any real business policies, then the full power of version control/unit testing is never really expressed. So grunts, like myself, never really have a complete understanding of the point beyond that "it's a good thing" and "we should do it". Question I was wondering if there are blogs, books, white-papers, or online journals about what one could call the business process or "standard operating procedures" or uses cases for version control and unit testing? I want to know more than the trade journals tell me and get serious about doing these things. PS: @Henrik Hansen had a great comment about the lack of definition for the question. I'm not interested in a specific unit-testing/versioning product or methodology (like, XP) - my interest is more about work-flow at the individual team/developer level than evangelism. This is more-or-less a by product of the management situation I've operated under more than a lack of reading software engineering books or magazines about development processes. A lot of what I've seen/read is more marketing oriented material than any specifically enumerated description of "well, this is how our shop operates".

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• Is there a good example of the difference between practice and theory?

  - by a_person

  There has been a lot of posters advising that the best way to retain knowledge is to apply it practically. After ignoring said advice for several years in a futile attempt to accumulate enough theoretical knowledge to be prepared for every possible case scenario, the process which lead me to assembling a library that's easily worth ~6K, I finally get it. I would like to share my story in the hopes that others will avoid taking the same route that was taken by me. I've selected graphical format (photos with caption to be exact) as my media. Help me with your ideas, maybe a fragment of code, or other imagery that would convey a message of the inherent difference between practice and theory.

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• Stairway to Database Source Control Level 2: Getting a Database into Source Control

  In this level, we're going to continue the philosophy of learning by example, and get a database into our SVN repository. We will also consider our overall approach to source control for databases, and the manner in which our team will develop these databases, concurrently. 24% of devs don’t use database source control – make sure you aren’t one of themVersion control is standard for application code, but databases haven’t caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out…

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• Is it possible to test a theory?

  - by user363295

  We are a group of students who are working on a theory in software engineering (talking about the theory takes a lot of time so I just skip that). Implementing the theory is impossible, due to technical limitations, but it can be proven on a paper logically. We've been pushed to do a testing on it, so it can be proved that way too (although we bleieve that's not possible!), now: Basically, is it possible to test something like this? If it is, what type of testing should we use? I heard,its possible to handout a brief about it to some experts and asking about their opinion (not sure if that's true), is that a testing method? if it is, what does it called? and how exactly can be done?

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• making control in user control visible=false on mouse over

  - by Mohan

  Hi Everybody, More I have this datalist in a user control i want when i keep mouse over "More", it should be invisible. it is working on .aspx page not on user control. How to do this. This control is placed on master page. Plz Help.

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• [Update] RedGate SQL Source Control and TFSPreview

  - by andyleonard

  31 Oct 2012 Update: SQL Source Control 3.1 is available! - Andy 12 Oct 2012 Update: The SQL Source Control 3.1 update is currently unavailable. I will provide additional updates when this version is re-released. - Andy I am excited that RedGate ’s SQL Source Control now supports connectivity to TFSPreview , Microsoft ’s cloud-based Application Life Cycle Management portal. Buck Woody ( Blog | @buckwoody ) and I have written about TFSPreview at SQLBlog already: Team Foundation Server (TFS) in the...(read more)

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• A design pattern for data binding an object (with subclasses) to asp.net user control

  - by Rohith Nair

  I have an abstract class called Address and I am deriving three classes ; HomeAddress, Work Address, NextOfKin address. My idea is to bind this to a usercontrol and based on the type of Address it should bind properly to the ASP.NET user control. My idea is the user control doesn't know which address it is going to present and based on the type it will parse accordingly. How can I design such a setup, based on the fact that, the user control can take any type of address and bind accordingly. I know of one method like :- Declare class objects for all the three types (Home,Work,NextOfKin). Declare an enum to hold these types and based on the type of this enum passed to user control, instantiate the appropriate object based on setter injection. As a part of my generic design, I just created a class structure like this :- I know I am missing a lot of pieces in design. Can anybody give me an idea of how to approach this in proper way.

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• Database source control

  - by Bojan Skrchevski

  Should database files(scripts etc.) be on source control? If so, what is the best method to keep it and update it there? Is there even a need for database files to be on source control since we can put it on a development server where everyone can use it and make changes to it if needed. But, then we can't get it back if someone messes it up. What approach is best used for databases on source-control?

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• What version control system can manage all aspects?

  - by Andy Canfield

  A few months ago I dug into Subversion and GIT and was disappointed. They handle SOURCE CODE fine but not other aspects. For example, a web site under version control needs to manage file/directory ownership, file/directory read & write access, Access Control Lists, timestamps, database contents. and external links. Is there a version control system that can do as perfect a reversion as reloading from a month-old backup?

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• Are There Realistic/Useful Solutions for Source Control for Ladder Logic Programs

  - by Steven A. Lowe

  Version control for ladder logic (LL) programs for programmable logic controllers (PLCs) seems to be virtually non-existent. It may be because LL is a visual language and tends to be stored in binary files, or it may be because source code control hasn't "caught on" in process control engineering circles - or perhaps my Google-Fu is weak tonight. Do you know of any realistic and useful solutions for version control for such systems? Definitions: realistic = changes to the programs are tracked by user and subject to reversion and merges useful = the system integrates with visual LL designers, is not limited to LL from a single PLC manufacturer, and does not cost a ridiculous amount of money? Note: I have heard of people using SVN or Mercurial et al to track the binary files, but I don't think the diff/merge capabilities would display readable differences.

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• Choosing the right version control system for .NET projects [closed]

  - by madxpol

  I'm getting ready for my first "bigger" .NET project (ASP.NET MVC 3/4) on which I'm going to lead another 2 programmers and right now I'm choosing the right version control system for the job (plus I'm gonna use it for my future development too). My problem is that I did't use any version control system before, so I would like it to have as fast learning curve and intuitive merging as possible. So far I quickly looked at VisualSVN (I like the Visual Studio integration in it), but I'm reading everywhere how Git is awesome and dunno which one to choose (not limited to these two).. Maybe I'm ovethinking this but I like when everything goes smoothly:) I'd like to hear some opinions from people who used multiple version control systems (preferably on VS projects) what do you think is the less complicated and effective version control system for such a use (one to 5 man projects)?

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• You know you're a "version control avoider" if [closed]

  - by kmote

  I'm in the process of trying to introduce Version/Revision Control to a team of developers who have never used it. I'll be giving a presentation that I hope will be a persuasive explanation of the importance of Version Control -- the benefits of using it and the liabilities of avoiding it. I'd like to kick it off with an amusing but instructive list modelled after the "redneck" line of jokes. Can anyone help me add to this list? "You know you're a Version Control Avoider if..." You have a bunch of files or folders with names like Engine_05212012_works_old[2].cpp You've had to explain to your boss how you accidentally overwrote production code. I don't consider myself terribly witty, but I think a little humor could be helpful in this situation. Any ideas for how to extend this list? [Bonus points if you can suggest a better moniker than "Version Control Avoider"]

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• Graph theory in python

  - by Dan

  I was wondering how people deal with graph theory in python? How is a graph stored? Are there libraries for this? For example how would I input a graph and then find its Chromatic polynomial? Or its girth? Or the number of unique spanning trees? How about problems that involve edge weight like salesman problems? I don't need all of these answered, I'm just looking for a method or tool set that will be able to help me approach solve problems like this. Thanks, Dan

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• What is the relaxation condition in graph theory

  - by windopal

  Hi, I'm trying to understand the main concepts of graph theory and the algorithms within it. Most algorithms seem to contain a "Relaxation Condition" I'm unsure about what this is. Could some one explain it to me please. An example of this is dijkstras algorithm, here is the pseudo-code. 1 function Dijkstra(Graph, source): 2 for each vertex v in Graph: // Initializations 3 dist[v] := infinity // Unknown distance function from source to v 4 previous[v] := undefined // Previous node in optimal path from source 5 dist[source] := 0 // Distance from source to source 6 Q := the set of all nodes in Graph // All nodes in the graph are unoptimized - thus are in Q 7 while Q is not empty: // The main loop 8 u := vertex in Q with smallest dist[] 9 if dist[u] = infinity: 10 break // all remaining vertices are inaccessible from source 11 remove u from Q 12 for each neighbor v of u: // where v has not yet been removed from Q. 13 alt := dist[u] + dist_between(u, v) 14 if alt < dist[v]: // Relax (u,v,a) 15 dist[v] := alt 16 previous[v] := u 17 return dist[] Thanks

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• Set Theory and .NET

  - by MasterMax1313

  Recently I came across a situation where set theory and set math fit what I was doing to the letter (granted there was an easier way to accomplish what I needed - i.e. LINQ - but I didn't think of that at the time). However I didn't know of any generic set libraries. Granted IEnumerables provide some set operations (Union, etc.), but nothing like Intersection or set comparison. Can anyone point out something that fits here? Something that implements set math using a generic type?

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• Is there a theory for "transactional" sequences of failing and no-fail actions?

  - by Ross Bencina

  My question is about writing transaction-like functions that execute sequences of actions, some of which may fail. It is related to the general C++ principle "destructors can't throw," no-fail property, and maybe also with multi-phase transactions or exception safety. However, I'm thinking about it in language-neutral terms. My concern is with correctly designing error handling in C++ functions that must be reliable. I would like to know what the concepts below are called so that I can learn more about them. I'm sorry that I can't ask the question more directly. Since I don't know this area I have provided an example to explain my question. The question is at the end. Here goes: Consider a sequence of steps or actions executed sequentially, where actions belong to one of two classes: those that always succeed, and those that may fail. In the examples below: S stands for an action that always succeeds (called "no-fail" in some settings). F stands for an action that may fail (for example, it might fail to allocate memory or do I/O that could fail). Consider a sequences of actions (executed sequentially from left to right): S->S->S->S Since each action in the sequence above succeeds, the whole sequence succeeds. On the other hand, the following sequence may fail because the last action may fail: S->S->S->F So, claim: a sequence has the no-fail (S) property if and only if all of its actions are no-fail. Now, I'm interested in action sequences that form "atomic transactions", with "failure atomicity," i.e. where either the whole sequence completes successfully, or there is no effect. I.e. if some action fails, the earlier ones must be rolled back. This requires that any successfully executed actions prior to a failing action must always be able to be rolled back. Consider the sequence: S->S->S->F S<-S<-S In the example above, the first row is the forward path of the transaction, and the second row are inverse actions (executed from right to left) that can be used to roll back if the final top row actions fails. It seems to me that for a transaction to support failure atomicity, the following invariant must hold: Claim: To support failure atomicity (either completion or complete roll-back on failure) all actions preceding the latest failable (F) action on the forward path (marked * in the example below) must have no-fail (S) inverses. The following is an example of a sequence that supports failure atomicity: * S->F->F->F S<-S<-S Further, if we want the transaction to be able to attempt cancellation mid-way through, but still guarantee either full completion or full rollback then we need the following property: Claim: To support failure atomicity and cancellation mid-way through execution, in the face of errors in the inverse (cancellation) path, all actions following the earliest failable (F) inverse on the reverse path (marked *) must be no-fail (S). F->F->F->S->S S<-S<-F<-F * I believe that these two conditions guarantee that an abortable/cancelable transaction will never get "stuck". My questions are: What is the study and theory of these properties called? are my claims correct? and what else is there to know? UPDATE 1: Updated terminology: what I previously called "robustness" is called atomicity in the database literature. UPDATE 2: Added explicit reference to failure atomicity, which seems to be a thing.

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• How to replace the SharePoint date calendar control with more user friendly jQuery calendar control

  - by ybbest

  When you use the SharePoint date and time type for date of birth field, you will notice that the calendar control is extremely non-user-friendly. You can only navigate month by month as shown below. To resolve the issue, you can customize the list form page using SharePoint designer and replace the OOB calendar control with popular jQuery control. The solution works for both SharePoint 2010,2013 and office365. Here are the steps for how to achieve this. 1. Open SharePoint designer and create a New List Form called customNew and set as default form for the selected type. 2. Open style library in file explorer and copy jQuery and jQuery UI files into the style library in SharePoint site. You can download the jQuery and jQuery UI from the web and the content of the contactPersonCustomNewForm.js is as below. I use the dd/mm/yy format as my locale in Regional Settings is English(New Zealand). You need to change this if you live in another country with different date format $(document).ready(function() { $("img#ctl00_m_g_540b9a50_52dc_4400_a58d_1db99555fddf_ff41_ctl00_ctl00_DateTimeField_DateTimeFieldDateDatePickerImage").parent().hide(); $("img#ctl00_m_g_540b9a50_52dc_4400_a58d_1db99555fddf_ff41_ctl00_ctl00_DateTimeField_DateTimeFieldDateDatePickerImage").hide(); $("input#ctl00_m_g_540b9a50_52dc_4400_a58d_1db99555fddf_ff41_ctl00_ctl00_DateTimeField_DateTimeFieldDate").datepicker({ changeMonth:true, changeYear:true, showOn: "button", buttonImage: "/_layouts/images/calendar.gif", buttonImageOnly: true, defaultDate:"01/01/1970", yearRange: "c-20:c+20", dateFormat: "dd/mm/yy" }); }); In order to get the image and textbox selector above , you can open IE developer toolbar(click F12) and find the control ID as below: 3. Open SharePoint designer and edit the newly created New List Form customNew.aspx in advance mode. Then copy and paste the following links in the PlaceHolderAdditionalPageHead. <SharePoint:CssRegistration name="<%$SPUrl:~SiteCollection/Style Library/themes/ui-lightness/jquery-ui.css%>" runat="server"/> <SharePoint:ScriptLink language="javascript" name="~sitecollection/Style Library/jquery-1.10.2.js" Defer="false" runat="server"/> <SharePoint:ScriptLink language="javascript" name="~sitecollection/Style Library/jquery-ui-1.10.4.custom.min.js" Defer="false" runat="server"/> <SharePoint:ScriptLink language="javascript" name="~sitecollection/Style Library/contactPersonCustomNewForm.js" Defer="false" runat="server"/>   4. Now go to the list and click add, you will see the new calendar control as shown below

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• Version Control for developers new to source control

  - by Daisetsu

  I've been writing code for a few years now and our backup strategy has been to zip the entire code directory up every few days and put it somewhere else on your hard drive, or occasionally upload it to some online file hosting service. Unfortunately the file hosting service got canceled without telling me and we lost years of backups. It's come down to the point where I finally have to learn to use version control. The only problems are My boss really doesn't like SVN, he tried it and it had a high learning curve (at least his client). We need a reliable place to host it (we can pay a reasonable amount). Can someone suggest what may be the best version control system and client for a newbie which won't be too annoying. Second what is a good remote version control service?

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