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  • How do I make an ellipse blink?

    - by MedicineMan
    I am trying to make a custom control in WPF. I want it to simulate the behavior of a LED that can blink. There are three states to the control: On, Off, and Blinking. I know how to set On and Off through the code behind, but this WPF animation stuff is just driving me nuts!!!! I cannot get anything to animate whatsoever. The plan is to have a property called state. When the user sets the value to blinking, I want the control to alternate between green and grey. I'm assuming I need a dependency property here, but have no idea. I had more xaml before but just erased it all. it doesn't seem to do anything. I'd love to do this in the most best practice way possible, but at this point, I'll take anything. I'm half way to writing a thread that changes the color manually at this point. <UserControl x:Class="WpfAnimation.LED" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Height="300" Width="300"> <Grid> <Ellipse x:Name="MyLight" Height="Auto" Width="Auto"/> </Grid> </UserControl>

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  • GIT repository layout for server with multiple projects

    - by Paul Alexander
    One of the things I like about the way I have Subversion set up is that I can have a single main repository with multiple projects. When I want to work on a project I can check out just that project. Like this \main \ProductA \ProductB \Shared then svn checkout http://.../main/ProductA As a new user to git I want to explore a bit of best practice in the field before committing to a specific workflow. From what I've read so far, git stores everything in a single .git folder at the root of the project tree. So I could do one of two things. Set up a separate project for each Product. Set up a single massive project and store products in sub folders. There are dependencies between the products, so the single massive project seems appropriate. We'll be using a server where all the developers can share their code. I've already got this working over SSH & HTTP and that part I love. However, the repositories in SVN are already many GB in size so dragging around the entire repository on each machine seems like a bad idea - especially since we're billed for excessive network bandwidth. I'd imagine that the Linux kernel project repositories are equally large so there must be a proper way of handling this with Git but I just haven't figured it out yet. Are there any guidelines or best practices for working with very large multi-project repositories?

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  • ASP.NET MVC search box: use modal popup or inline div or redirect to another page?

    - by JK
    I have a view with a textbox and a search button, eg CustomerTextBox and CustomerSearchButton. The list of customers is too long to display in a dropdown, and there has to be advanced search functions anyway. What is the best practice in MVC to handle this case? When the user clicks on the search button, should it: A. Load another view into a modal popup (eg /customers/search)? How would you do this in MVC, just set popupWindow.location.href = '/customers/search'? How would you return the value to the main view? B. Have the search form in a hidden div that expands when the search button is clicked? How would be done? a partial view maybe? C. Redirect the user to a search page by means of RedirectTo("/customers/search")? How would you return the value to the main class? I've only been doing MVC for 3 days so thanks to those who answer my questions that might have quite obvious answers that I cant see yet. :)

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  • Model validation with enumerable properties in Asp.net MVC2 RTM

    - by Robert Koritnik
    I'm using DataAnnotations attributes to validate my model objects. My model class looks similar to this: public class MyModel { [Required] public string Title { get; set; } [Required] public List<User> Editors { get; set; } } public class User { public int Id { get; set; } [Required] public string FullName { get; set; } [Required] [DataType(DataType.Email)] public string Email { get; set; } } My controller action looks like: public ActionResult NewItem(MyModel data) { //... } User is presented with a view that has a form with: a text box with dummy name where users enter user's names. For each user they enter, there's a client script coupled with ajax that creates an <input type="hidden" name="data.Editors[0].Id" value="userId" /> for each user entered (enumeration index is therefore not always 0 as written here), so default model binder is able to consume and bind the form without any problems. a text box where users enter the title Since I'm using Asp.net MVC 2 RTM which does model validation instead of input validation I don't know how to avoid validation errors. The thing is I have to use BindAttribute on my controller action. I would have to either provide a white or a black list of properties. It's always a better practice to provide a white list. It's also more future proof. The problem My form works fine, but I get validation errors about user's FullName and Email properties since they are not provided. I also shouldn't feed them to the client (via ajax when user enters user data), because email is personal contact data and is not shared between users. If there was just a single user reference on MyModel I would write [Bind(Include = "Title, Editor.Id")] But I have an enumeration of them. How do I provide Bind white list to work with my model?

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  • Common vulnerabilities for WinForms applications

    - by David Stratton
    I'm not sure if this is on-topic or not here, but it's so specific to .NET WinForms that I believe it makes more sense here than at the Security stackexchange site. (Also, it's related strictly to secure coding, and I think it's as on-topic as any question asking about common website vulnerabiitles that I see all over the site.) For years, our team has been doing threat modeling on Website projects. Part of our template includes the OWASP Top 10 plus other well-known vulnerabilities, so that when we're doing threat modeling, we always make sure that we have a documented process to addressing each of those common vulnerabilities. Example: SQL Injection (Owasp A-1) Standard Practice Use Stored Parameterized Procedures where feasible for access to data where possible Use Parameterized Queries if Stored Procedures are not feasible. (Using a 3rd party DB that we can't modify) Escape single quotes only when the above options are not feasible Database permissions must be designed with least-privilege principle By default, users/groups have no access While developing, document the access needed to each object (Table/View/Stored Procedure) and the business need for access. [snip] At any rate, we used the OWASP Top 10 as the starting point for commonly known vulnerabilities specific to websites. (Finally to the question) On rare occasions, we develop WinForms or Windows Service applications when a web app doesn't meet the needs. I'm wondering if there is an equivalent list of commonly known security vulnerabilities for WinForms apps. Off the top of my head, I can think of a few.... SQL Injection is still a concern Buffer Overflow is normally prevented by the CLR, but is more possible if using non-managed code mixed in with managed code .NET code can be decompiled, so storing sensitive info in code, as opposed to encrypted in the app.config... Is there such a list, or even several versions of such a list, from which we can borrow to create our own? If so, where can I find it? I haven't been able to find it, but if there is one, it would be a great help to us, and also other WinForms developers.

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  • [PHP] Making a good singleton registry class structure which hold your objects

    - by Saif Bechan
    I am working on a web application in PHP. I have a singleton class called registry. This class will hold all the objects i need throughout my application, such as loader classes, template classes, database, classes, etc. When an object of the registry class is created I send it an array with the classes it need to load: // Create the registry $registry = registry::singleton(); // Store those core objects $registry->storeObjects(Array('session','db','page','template','errors')); In this example I only put some of the classes, to get the basic idea. Now I have some classes in the registry that use each other. For example the 'errors' object uses the 'page' object. Now I was wondering if it is a good practice to make an instance of the registry object in the errors object. Like this; class errors{ private $registry; public function __construct(){ $this->registry = registry::singleton(); } } So there is an instance of the registry object, inside an object of the registry object. This does not sound like a good idea to me. Anyone have a suggestion how to model such a thing?

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  • SQL Server Management Studio – tips for improving the TSQL coding process

    - by kristof
    I used to work in a place where a common practice was to use Pair Programming. I remember how many small things we could learn from each other when working together on the code. Picking up new shortcuts, code snippets etc. with time significantly improved our efficiency of writing code. Since I started working with SQL Server I have been left on my own. The best habits I would normally pick from working together with other people which I cannot do now. So here is the question: What are you tips on efficiently writing TSQL code using SQL Server Management Studio? Please keep the tips to 2 – 3 things/shortcuts that you think improve you speed of coding Please stay within the scope of TSQL and SQL Server Management Studio 2005/2008 If the feature is specific to the version of Management Studio please indicate: e.g. “Works with SQL Server 2008 only" Thanks EDIT: I am afraid that I could have been misunderstood by some of you. I am not looking for tips for writing efficient TSQL code but rather for advice on how to efficiently use Management Studio to speed up the coding process itself. The type of answers that I am looking for are: use of templates, keyboard-shortcuts, use of IntelliSense plugins etc. Basically those little things that make the coding experience a bit more efficient and pleasant. Thanks again

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  • What's the best way to refresh a UITableView within a UINavigationController hierarchy

    - by Steve Neal
    Hi, I'm pretty new to iPhone development and have struggled to find what I consider to be a neat way around this problem. I have a user interface where a summary of record data is displayed in a table inside a navigation controller. When the user clicks the accessory button for a row, a new view is pushed onto the navigation controller revealing a view where the user can edit the data in the corresponding record. Once done, the editing view is popped from the navigation controller's stack and the user is returned to the table view. My problem is that when the user returns to the table view, the table still shows the state of the data before the record was edited. I must therefore reload the table data to show the changes. It doesn't seem possible to reload the table data before it is displayed as the call only updates displayed records. Reloading it after the table has been displayed results in the old data changing before the user's eyes, which I'm not too happy with. This seems to me like a pretty normal thing to want to do in an iPhone app. Can anyone please suggest the best practice approach to doing this? I feel like I'm missing something. Cheers - Steve.

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  • Visual C# GUI Designer - Recommended way of removing generated event handler-code & basic tutorial

    - by cusack
    Hi, I'm new to the Visual C# designer so these are general and pretty basic question on how to work with the designer. When we for instance add a label to a form and then double-click on it in the Visual C# designer (I'm using Microsoft Visual C# 2008 Express Edition), the following things happen: The designer generates code within Form1.Designer.cs (assume default names for simplicity) to add the label, then with the double-click it will add the event handler label1_Click to the label within Form1.Designer.cs, using the following code this.label1.Click += new System.EventHandler(this.label1_Click); and it adds the event handler method to Form1.cs private void label1_Click(object sender, EventArgs e) { } If I now remove the label only the code within Form1.Designer.cs will be removed but the label1_Click method will stay within Form1.cs even if it isn't used by anything else. But if I'm using reset within Properties-Events for the Click-event from within the designer even the label1_Click method in Form1.cs will be removed. 1.) Isn't that a little inconsistent behavior? 2.) What is the recommended way of removing such generated event handler-code? 3.) What is the best "mental approach"/best practice for using the designer? I would approach it by mental separation in the way that Form1.cs is 100% my responsibility and that on the other hand I'm not touching the code in Form1.Designer.cs at all. Does that make sense or not? Since sometimes the designer removes sth. from Form1.cs I'm not sure about this. 4.) Can you recommend a simple designer tutorial that assumes no Visual C# designer knowledge but expects/doesn't explain C#. The following one is an example of what I would not want it explains what a c#-comment is and I'd prefer text over video as well: http://msdn.microsoft.com/en-us/beginner/bb964631.aspx

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  • Advice for last year college graduates

    - by Tomh
    Hey guys, I know there are many "advice" questions around this site. But I wanted to to narrow mine down to last year college students, in my case my last year as Master student in computer science. So far is a list of things I've done during my time in college (which I can recommend others to do aswell): Code a lot I've written several hobby projects, had part time jobs, entered the Imagine cup from Microsoft, took programming extensive courses and did freelance gigs. Read a lot I've bought most top books from the recommended book topics here, to be honest I have not read them all. learn different languages I've tried several languages including Haskell, Java, Python, Ruby, Lisp, Prolog, C#, PHP, JS, AS3 and possibly some more I forgot. Tried to start a blog Joel recommends to learn how to write, I tried starting a couple of blogs to improve upon this, I gave up on all instances after writing about three posts. It was just not my thing... Have a portfolio of launched projects/programs I'm busy with this, have a couple of finished, working projects I worked on to show to people. So this is my last year. Is there anything else you can recommend a last year college student to do before hitting the job market? Personally I'm tempted to spend my time on the following: Practice algorithm design Learn and memorize the usage of the low level API's of your favorite language Polish your portfolio Why? Because those first two will make sure you pass the majority of the interviews, here in Holland (I could be wrong). I rather not spend my time on those first two points, but I have to be realistic and thats just my experience on what kind of questions you'll get when you apply. The third point is my hope that I won't have to answer questions about the amount of standard types in c# for example if they can see I get projects done and launched. But I'm still graduating, so I don't know anything :), and many of you might be hiring grads on a recent base and could tell me and other interested people what you wish that the recent grads you interviewed would have done before they applied.

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  • Interoperability between Weblogic 10.3.1 and Oracle BPM 10.3.1

    - by alfredozn
    Hi, Im migrating an ALBPM 6.5 running on a WLS 10.0 to an Oracle BPM 10.3.1 running on WLS 10.3.1 I got some problems with the Oracle driver because the old driver (weblogic.jdbcx.oracle.OracleDataSource) was definitely removed from the server and is not longer supported. Instead I used the thin driver (oracle.jdbc.xa.OracleXADataSource), the database migration was executed succesfully but after that, when I try to deploy the engine ear in WebLogic I got exceptions asociated to the driver: [ (cont) ] Main: Caused by: weblogic.application.ModuleException: [HTTP:101216]Servlet: "engineStartup" failed to preload on startup in Web application: "/albpmServices/albpm_engine". [ (cont) ] Main: fuego.directory.DirectoryRuntimeException: Exception [java.sql.SQLException: Invalid column type]. [ (cont) ] Main: at fuego.directory.DirectoryRuntimeException.wrapException(DirectoryRuntimeException.java:85) [ (cont) ] Main: at fuego.directory.provider.jdbc.oracle.OraclePersistenceManager.mapSQLException(OraclePersistenceManager.java:145) [ (cont) ] Main: at fuego.directory.provider.jdbc.datadirect.oracle.DataDirectOraclePersistenceManager.mapSQLException(DataDirectOraclePersistenceManager.java:51) [ (cont) ] Main: at fuego.directory.provider.jdbc.JDBCServiceAccessor.mapSQLException(JDBCServiceAccessor.java:78) [ (cont) ] Main: at fuego.directory.provider.jdbc.JDBCObjectPropertiesAccessor.fetchAllDirectoryProperties(JDBCObjectPropertiesAccessor.java:442) [ (cont) ] Main: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) I was looking around for a solution but all is pointing to use the old driver, I think isn't a good practice to force the server to use this driver after Oracle remove it completely. Any suggestions or similar experiences??

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  • Conversion constructor vs. conversion operator: precedence

    - by GRB
    Reading some questions here on SO about conversion operators and constructors got me thinking about the interaction between them, namely when there is an 'ambiguous' call. Consider the following code: class A; class B { public: B(){} B(const A&) //conversion constructor { cout << "called B's conversion constructor" << endl; } }; class A { public: operator B() //conversion operator { cout << "called A's conversion operator" << endl; return B(); } }; int main() { B b = A(); //what should be called here? apparently, A::operator B() return 0; } The above code displays "called A's conversion operator", meaning that the conversion operator is called as opposed to the constructor. If you remove/comment out the operator B() code from A, the compiler will happily switch over to using the constructor instead (with no other changes to the code). My questions are: Since the compiler doesn't consider B b = A(); to be an ambiguous call, there must be some type of precedence at work here. Where exactly is this precedence established? (a reference/quote from the C++ standard would be appreciated) From an object-oriented philosophical standpoint, is this the way the code should behave? Who knows more about how an A object should become a B object, A or B? According to C++, the answer is A -- is there anything in object-oriented practice that suggests this should be the case? To me personally, it would make sense either way, so I'm interested to know how the choice was made. Thanks in advance

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  • IP address spoofing using Source Routing

    - by iamrohitbanga
    With IP options we can specify the route we want an IP packet to take while connecting to a server. If we know that a particular server provides some extra functionality based on the IP address can we not utilize this by spoofing an IP packet so that the source IP address is the privileged IP address and one of the hosts on the Source Routing is our own. So if the privileged IP address is x1 and server IP address is x2 and my own IP address is x3. I send a packet from x1 to x2 which is supposed to pass through x3. x1 does not actually send the packet. It is just that x2 thinks the packet came from x1 via x3. Now in response if x2 uses the same routing policy (as a matter of courtesy to x1) then all packets would be received by x3. Will the destination typically use the same IP address sequences as specified in the routing header so that packets coming from the server pass through my IP where I can get the required information? Can we not spoof a TCP connection in the above case? Is this attack used in practice?

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  • What are common anti-patterns when using VBA

    - by Ahmad
    I have being coding a lot in VBA lately (maintenance and new code), specifically with regards to Excel automation etc. = macros. Typically most of this has revolved around copy/paste, send some emails, import some files etc. but eventually just ends up as a Big ball of mud As a person who values clean code, I find it very difficult to produce 'decent' code when using VBA. I think that in most cases, this is a direct result of the macro-recorder. Very helpful to get you started, but most times, there are one too many lines of code that achieve the end result. Edit: The code from the macro-recorder is used as a base to get started, but is not used in its entirety in the end result I have already created a common addin that has my commonly used subroutines and some utility classes in an early attempt to enforce some DRYness - so this I think is a step in the right direction. But I feel as if it's a constant square peg, round hole situation. The wiki has an extensive list of common anti-patterns and what scared me the most was how many I have implemented in one way or another. The question Now considering, that my mindset is OO design, what some common anti-patterns and the possible solutions when designing a solution (think of this - how would designing a solution using Excel and VBA be different from say a .net/java/php/.../ etc solution) ; and when doing common tasks like copying data, emailing, data importing, file operations... etc An anti-pattern as defined by Wikipedia is: In software engineering, an anti-pattern (or antipattern) is a pattern that may be commonly used but is ineffective and/or counterproductive in practice

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  • Metaprogramming - self explanatory code - tutorials, articles, books

    - by elena
    Hello everybody, I am looking into improving my programming skils (actually I try to do my best to suck less each year, as our Jeff Atwood put it), so I was thinking into reading stuff about metaprogramming and self explanatory code. I am looking for something like an idiot's guide to this (free books for download, online resources). Also I want more than your average wiki page and also something language agnostic or preferably with Java examples. Do you know of such resources that will allow to efficiently put all of it into practice (I know experience has a lot to say in all of this but i kind of want to build experience avoiding the flow bad decisions - experience - good decisions)? EDIT: Something of the likes of this example from the Pragmatic Programmer: ...implement a mini-language to control a simple drawing package... The language consists of single-letter commands. Some commands are followed by a single number. For example, the following input would draw a rectangle: P 2 # select pen 2 D # pen down W 2 # draw west 2cm N 1 # then north 1 E 2 # then east 2 S 1 # then back south U # pen up Thank you!

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  • Moq: Unable to cast to interface

    - by Pickels
    Hello, earlier today I asked this question. So since moq creates it's own class from an interface I wasn't able to cast it to a different class. So it got me wondering what if I created a ICustomPrincipal and tried to cast to that. This is how my mocks look: var MockHttpContext = new Mock<HttpContextBase>(); var MockPrincipal = new Mock<ICustomPrincipal>(); MockHttpContext.SetupGet(h => h.User).Returns(MockPrincipal.Object); In the method I am trying to test the follow code gives the error(again): var user = (ICustomPrincipal)httpContext.User; The error is the following: Unable to cast object of type 'IPrincipalProxy4081807111564298854aabfc890edcc8' to type 'MyProject.Web.ICustomPrincipal'. I guess I still need some practice with interfaces and moq but shouldn't I be able to cast the class that moq created back to ICustomPrincipal? I know httpContext.User returns an IPrincipal so maybe something gets lost there? Well if anybody can help me I would appreciate that. Pickels Edit: As requested the full code of the method I am testing. It's still not finished but this is what I have so far: public bool AuthorizeCore(HttpContextBase httpContext) { if (httpContext == null) { throw new ArgumentNullException("httpContext"); } var user = (ICustomPrincipal)httpContext.User; if (!user.Identity.IsAuthenticated) { return false; } return true; }

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  • How do you prove your cleverness and programming skills?

    - by Sebi
    Lately, there were a lot of questions related to career planning and how to decide which languages to learn, how to learn new languages and so on. But I was thinking about a way, how do you will proof later that you're really learned something. Ok you can mentione it in your application for a job or in the interview, but by just stating that I was learning e.g. C++ at home, I don't think this will really be very sucessful. So some suggested to create something (homepage, application, whatsoever) to prove that you also can use these skills in practice. But still I'm not really sure if this will provide any benefit, because it would require a very special project to show all your skills and I don't think you can easily invent such a project (that sould also be useful). Others suggested to solve for example the Project Euler questions but still I'm not sure how this will be useful in career-planning. Are you going to mention at your job interview that you solved all this question in the company's favorite programming language?? :D I can't imagine. The reason why I'm asking is that I have some spare time and I would really like to learn some new programming languages (C++ and/or Python if this matters) and I'm looking for a smart way to do is while concurrently assure that it will be useful in my future career. (there are 3-4 companies id like to try to get a job andIi know all of them are using mainly C++/Pyhton...)

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  • Cast then check or check then cast?

    - by jamesrom
    Which method is regarded as best practice? Cast first? public string Describe(ICola cola) { var coke = cola as CocaCola; if (coke != null) { string result; // some unique coca-cola only code here. return result; } var pepsi = cola as Pepsi; if (pepsi != null) { string result; // some unique pepsi only code here. return result; } } Or should I check first, cast later? public string Describe(ICola cola) { if (cola is CocaCola) { coke = (CocaCola) cola; string result; // some unique coca-cola only code here. return result; } if (cola is Pepsi) { pepsi = (Pepsi) cola; string result; // some unique pepsi only code here. return result; } } Can you see any other way to do this?

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  • Structuring projects & dependencies of large winforms applications in C#

    - by Benjol
    UPDATE: This is one of my most-visited questions, and yet I still haven't really found a satisfactory solution for my project. One idea I read in an answer to another question is to create a tool which can build solutions 'on the fly' for projects that you pick from a list. I have yet to try that though. How do you structure a very large application? Multiple smallish projects/assemblies in one big solution? A few big projects? One solution per project? And how do you manage dependencies in the case where you don't have one solution. Note: I'm looking for advice based on experience, not answers you found on Google (I can do that myself). I'm currently working on an application which has upward of 80 dlls, each in its own solution. Managing the dependencies is almost a full time job. There is a custom in-house 'source control' with added functionality for copying dependency dlls all over the place. Seems like a sub-optimum solution to me, but is there a better way? Working on a solution with 80 projects would be pretty rough in practice, I fear. (Context: winforms, not web) EDIT: (If you think this is a different question, leave me a comment) It seems to me that there are interdependencies between: Project/Solution structure for an application Folder/File structure Branch structure for source control (if you use branching) But I have great difficulty separating these out to consider them individually, if that is even possible. I have asked another related question here.

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  • How to prove writing specifications beats code cowboys?

    - by Andrew Grant
    So I have a problem. Or rather my friend has a problem, since I would never write about my company on an internet forum. At my friend's company specification writing is, shall we say, a little underused. There's a deeply ingrained culture of writing code first and asking questions later, whether it's for a library routine or a new tool to inflict on their long suffering designers. This of course leads to situations where functionality is partially correct, incorrect, or just completely missing ("oh, just save before trying anything you may want to undo"). This usually results in a loss of productivity for those poor designers, or beta periods where bug-fixing is largely spent implementing things correctly. My friend's found his suggestions of writing (and testing against) specifications to be generally well received. Most of his colleagues have embraced the wonderful feeling of discovering false-assumptions on paper, instead of at 11pm on a Sunday in the middle of beta. Viva La Revolution! However there are a few who poo-poo anything that stands between their task and a keyboard. They laugh at the thought of actually designing anything, and write code with merry abandon. Mostly these are senior, long employed developers, reluctant to "waste time". The problem is that this second group of heretics invariably produce things (or at least something) quicker than the first. Subsequently this becomes justification along the lines of "It's pointless to write specifications for something as simple as an image resizer! Oh and those bugs where width!=height or the image uses RLE just need a few tweaks". And now the question :) Other than saying "told you so" at the end of a project, what are some good short-term ways to demonstrate how the practice of writing functional or technical specifications leads to better software in the long run? Cheers!

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  • What's the recommended implemenation for hashing OLE Variants?

    - by Barry Kelly
    OLE Variants, as used by older versions of Visual Basic and pervasively in COM Automation, can store lots of different types: basic types like integers and floats, more complicated types like strings and arrays, and all the way up to IDispatch implementations and pointers in the form of ByRef variants. Variants are also weakly typed: they convert the value to another type without warning depending on which operator you apply and what the current types are of the values passed to the operator. For example, comparing two variants, one containing the integer 1 and another containing the string "1", for equality will return True. So assuming that I'm working with variants at the underlying data level (e.g. VARIANT in C++ or TVarData in Delphi - i.e. the big union of different possible values), how should I hash variants consistently so that they obey the right rules? Rules: Variants that hash unequally should compare as unequal, both in sorting and direct equality Variants that compare as equal for both sorting and direct equality should hash as equal It's OK if I have to use different sorting and direct comparison rules in order to make the hashing fit. The way I'm currently working is I'm normalizing the variants to strings (if they fit), and treating them as strings, otherwise I'm working with the variant data as if it was an opaque blob, and hashing and comparing its raw bytes. That has some limitations, of course: numbers 1..10 sort as [1, 10, 2, ... 9] etc. This is mildly annoying, but it is consistent and it is very little work. However, I do wonder if there is an accepted practice for this problem.

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  • Ruby on rails generates tests for you. Do those give a false sense of a safety net?

    - by Hamish Grubijan
    Disclaimer: I have not used RoR, and I have not generated tests. But, I will still dare to post this question. Quality Assurance is theoretically impossible to get 100% right in general (Undecidable problem ;), and it is hard in practice. So many developers do not understand that writing good automated tests is an art, and it is hard. When I hear that RoR generates the tests for you, I get very skeptical. It cannot be that easy. Testing is a general concept; it applies across languages. So does the concept of code contracts, it is similar for languages that support it. Code contracts do not generate themselves. The programmer must add the requirements and the promises manually, after doing some thinking about the algorithm / function. If a human gets it wrong, then the tools will propagate the error. Similarly with testing - it takes human judgement about what should happen. Tests do not write themselves, and we are far from the day when a business analyst can just have a conversation with a computer and tell it informally what the requirements are and have the computer do all the work. There is no magic ... how can RoR generate good tests for you? Please shed some light on this. Opinions are ok, for this is a community wiki. Thanks!

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  • When to use custom exceptions vs. existing exceptions vs. generic exceptions

    - by Ryan Elkins
    I'm trying to figure out what the correct form of exceptions to throw would be for a library I am writing. One example of what I need to handle is logging a user in to a station. They do this by scanning a badge. Possible things that could go wrong include: Their badge is deactivated They don't have permission to work at this station The badge scanned does not exist in the system They are already logged in to another station elsewhere The database is down Internal DB error (happens sometimes if the badge didn't get set up correctly) An application using this library will have to handle these exceptions one way or another. It's possible they may decide to just say "Error" or they may want to give the user more useful information. What's the best practice in this situation? Create a custom exception for each possibility? Use existing exceptions? Use Exception and pass in the reason (throw new Exception("Badge is deactivated.");)? I'm thinking it's some sort of mix of the first two, using existing exceptions where applicable, and creating new ones where needed (and grouping exceptions where it makes sense).

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  • Help with converting foreach loop to while loop in c#

    - by James Dawson
    I had learnt by reading your great answers here, that it is not good practice deleting items from within a foreach loop, as it is (and I quote) "Sawing off the branch you're sitting on". My code currently removes the text from the dropdownlist, but the actual item remains (just without text displayed). In other words, it isn't deleting, and probably can't because you can't delete from within a foreach loop. After hours of trying I am unable to get my head around a way of doing it. //For each checked box, run the delete code for (int i = 0; i < this.organizeFav.CheckedItems.Count; i++) { //this is the foreach loop foreach (ToolStripItem mItem in favoritesToolStripMenuItem.DropDownItems) { //This rules out seperators if (mItem is ToolStripMenuItem) { ToolStripMenuItem menuItem = mItem as ToolStripMenuItem; //This matches the dropdownitems text to the CheckedItems String if (((ToolStripMenuItem)mItem).Text.ToString() == organizeFav.CheckedItems[i].ToString()) { //And deletes the item menuItem.DropDownItems.Remove(mItem); } } } } But it isn't deleting because it is within a foreach loop! I would greatly appreciate your help, and be truly amazed if anyone can get their head around this code :) Kind Regards

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  • XML Attributes or Element Nodes?

    - by Camsoft
    Example XML using element nodes: <?xml version="1.0" encoding="utf-8"?> <users> <user> <name>David Smith</name> <phone>0441 234443</phone> <email>[email protected]</email> <addresses> <address> <street>1 Some Street</street> <town>Toy Town</town> <country>UK</country> </address> <address> <street>5 New Street</street> <town>Lego City</town> <country>US</country> </address> </addresses> </user> </users> Example XML using attributes: <?xml version="1.0" encoding="utf-8"?> <users> <user name="David Smith" phone="0441 234443" email="[email protected]"> <addresses> <address street="1 Some Street" town="Toy Town" country="UK" /> <address street="5 New Street" town="Lego City" country="US" /> </addresses> </user> </users> I'm needing to build an XML file based on data from a relation database and can't work out whether I should use attributes or elements. What is best practice when building XML files?

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