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  • Pattern for UI configuration

    - by TERACytE
    I have a Win32 C++ program that validates user input and updates the UI with status information and options. Currently it is written like this: void ShowError() { SetIcon(kError); SetMessageString("There was an error"); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } void ShowSuccess() { SetIcon(kError); std::String statusText (GetStatusText()); SetMessageString(statusText); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } // plus several more methods to update the UI using similar mechanisms I do not likes this because it duplicates code and causes me to update several methods if something changes in the UI. I am wondering if there is a design pattern or best practice to remove the duplication and make the functionality easier to understand and update. I could consolidate the code inside a config function and pass in flags to enable/disable UI items, but I am not convinced this is the best approach. Any suggestions and ideas?

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  • PHP Form Validation

    - by JM4
    This question will undoubtedly be difficult to answer and ask in a way that makes sense but I'll try my best: I have a form which uses PHP to display certain sections of the form such as: <?php if ($_SESSION['EnrType'] == "Individual") { display only form information for individual enrollment } ?> and <?php if ($_SESSION['Num_Enrs'] > 6) { display only form information for 7 total members enrollment } ?> In each form piece, unique information is collected about each enrollee but the basic criteria for each enrollee is the same, i.e. All enrollee's must use have a value in the FirstName field. Each field is named according to the enrollee number, i.e. Num1FirstName; Num2FirstName. I have a PHP validation script which is absolutely fantastic and am not looking to change it but the issue I am running into is duplication of the script in order to validate ALL fields in one swoop. On submission, all POSTED items are run through my validation script and based on the rules set return an error if they do not equal true. Sample code: if (isset($_POST['submit'])) { // import the validation library require("validation.php"); $rules = array(); // stores the validation rules //All Enrollee Rules $rules[] = "required,Num1FirstName,Num2FirstName,The First Name field is required."; The script above does the following, $rules[] ="REQUIREMENT,fieldname,error message" where requirement gives criteria (in this case, simply that a value is passed), fieldname is the name of the field being validated, and error message returns the error used. My Goal is to use the same formula above and have $rules[] run through ALL firstnames and return the error posted ONLY if they exist (i.e. dont check for member #7's first name if it doesnt exist on the screen). If I simply put a comma between the 'fieldnames' this only checks for the first, then second, and so on so this wont work. Any ideas?

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  • Ogre material scripts; how do I give a technique multiple lod_indexes?

    - by BlueNovember
    I have an Ogre material script that defines 4 rendering techniques. 1 using GLSL shaders, then 3 others that just use textures of different resolutions. I want to use the GLSL shader unconditionally if the graphics card supports it, and the other 3 textures depending on camera distance. At the moment my script is; material foo { lod_distances 1600 2000 technique shaders { lod_index 0 lod_index 1 lod_index 2 //various passes here } technique high_res { lod_index 0 //various passes here } technique medium_res { lod_index 1 //various passes here } technique low_res { lod_index 2 //various passes here } Extra information The Ogre manual says; Increasing indexes denote lower levels of detail You can (and often will) assign more than one technique to the same LOD index, what this means is that OGRE will pick the best technique of the ones listed at the same LOD index. OGRE determines which one is 'best' by which one is listed first. Currently, on a machine supporting the GLSL version I am using, the script behaves as follows; Camera 2000 : Shader technique Camera 1600 <= 2000 : Medium Camera <= 1600 : High If I change the lod order in shader technique to { lod_index 2 lod_index 1 lod_index 0 } The behaviour becomes; Camera 2000 : Low Camera 1600 <= 2000 : Medium Camera <= 1600 : Shader implying only the latest lod_index is used. If I change it to lod_index 0 1 2 It shouts at me Compiler error: fewer parameters expected in foo.material(#): lod_index only supports 1 argument So how do I specify a technique to have 3 lod_indexes? Duplication works; technique shaders { lod_index 0 //various passes here } technique shaders1 { lod_index 1 //passes repeated here } technique shaders2 { lod_index 2 //passes repeated here } ...but it's ugly.

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  • Have you considered doing revenue sharing to fund development of a mobile app? How would you do it?

    - by Brennan
    I am looking to build multiple mobile apps which leverage existing content and resources by enabling these mobile apps with web services. I will duplication much of the same features which are also in place and add more features that are possible on a mobile device like address book, maps and calendar integration to make the service much more useful. To fund these projects I see that I have 2 options. First I could simply quote them for the project based on my hourly rate and the estimate in hours that I will take the to complete the job. That may be a high number. The second option would be to do shared revenue with ads placed in the app. I could then take a percentage of any revenue that is generated from the app. There is also a hybrid where I might charge for a percentage of the estimated quote and then take a percentage of the revenue sharing. So my question is how much should I propose for the revenue sharing? Should it be 30%? Or maybe I should make it 70% up to a point that a certain dollar amount is reached? And should the revenue sharing agreement be for 12 months, 24 months or more? Should I include in the proposal an agreement that they will help promote this app with their content and resources? Ultimately this system will benefit both sides because it extends their reach into the mobile space instead of where they are currently with just print and web. I have tried to find some examples with a few Google searches but I keep hitting content about the Google and Apple revenue sharing models. I would like to get some solid examples that are working to compare against so that my proposal do build these apps is not completely off base.

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  • What would you write in a Constitution (law book) for a programmers' country? [closed]

    - by Developer Art
    After we have got our great place to talk about professional matters and sozialize online - on SO, I believe the next logical step would be to found our own country! I invite you all to participate and bring together your available resources. We will buy an island, better even a group of islands so that we could establish states like .NET territories, Java land, Linux republic etc. We will build a society of programmers (girls - we need you too). To the organizational side, we're going to need some sort of a Constitution or a law book. I suggest we write it together. I make it a wiki as it should be a cooperative effort. I'll open the work. Section 1. Programmers' rights. Every citizen has a right to an Internet connection 24/7. Every citizen can freely choose the field of interest Section 2. Programmers' obligations. Every citizen must embrace the changing nature of the profession and constanly educate himself Section 3. Law enforcement. Code duplication when can be avoided is punished by limiting the bandwith speed to 64Kbit for a period of one week. Using ugly hacks instead of refactoring code is punished by cutting the Internet connection for a period of one month. Usage of technologies older than 5/10 years is punished by restricting the web access to the sites last updated 5/10 years ago for a period of one month. Please feel free to modify and extend the list. We'll need to have it ready before we proceed formally with the country foundation. A purchase fund will be established shortly. Everyone is invited to participate.

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  • How can I use a single-table inheritance and single controller to make this more DRY?

    - by Angela
    I have three models, Calls, Emails, and Letters and those are basically templates of what gets sent to individuals, modeled as Contacts. When a Call is made, a row in model in ContactCalls gets created. If an Email is sent, an entry in ContactEmails is made. Each has its own controller: contact_calls_controller.rb and contact_emails_controller.rb. I would like to create a single table inheritance called ContactEvents which has types Calls, Emails, and Letters. But I'm not clear how I pass the type information or how to consolidate the controllers. Here's the two controllers I have, as you can see, there's alot of duplication, but some differences that needs to be preserved. In the case of letter and postcards (another Model), it's even more so. class ContactEmailsController < ApplicationController def new @contact_email = ContactEmail.new @contact_email.contact_id = params[:contact] @contact_email.email_id = params[:email] @contact = Contact.find(params[:contact]) @company = Company.find(@contact.company_id) contacts = @company.contacts.collect(&:full_name) contacts.each do |contact| @colleagues = contacts.reject{ |c| [email protected]_name } end @email = Email.find(@contact_email.email_id) @contact_email.subject = @email.subject @contact_email.body = @email.message @email.message.gsub!("{FirstName}", @contact.first_name) @email.message.gsub!("{Company}", @contact.company_name) @email.message.gsub!("{Colleagues}", @colleagues.to_sentence) @email.message.gsub!("{NextWeek}", (Date.today + 7.days).strftime("%A, %B %d")) @contact_email.status = "sent" end def create @contact_email = ContactEmail.new(params[:contact_email]) @contact = Contact.find_by_id(@contact_email.contact_id) @email = Email.find_by_id(@contact_email.email_id) if @contact_email.save flash[:notice] = "Successfully created contact email." # send email using class in outbound_mailer.rb OutboundMailer.deliver_campaign_email(@contact,@contact_email) redirect_to todo_url else render :action => 'new' end end AND: class ContactCallsController < ApplicationController def new @contact_call = ContactCall.new @contact_call.contact_id = params[:contact] @contact_call.call_id = params[:call] @contact_call.status = params[:status] @contact = Contact.find(params[:contact]) @company = Company.find(@contact.company_id) @contact = Contact.find(@contact_call.contact_id) @call = Call.find(@contact_call.call_id) @contact_call.title = @call.title contacts = @company.contacts.collect(&:full_name) contacts.each do |contact| @colleagues = contacts.reject{ |c| [email protected]_name } end @contact_call.script = @call.script @call.script.gsub!("{FirstName}", @contact.first_name) @call.script.gsub!("{Company}", @contact.company_name ) @call.script.gsub!("{Colleagues}", @colleagues.to_sentence) end def create @contact_call = ContactCall.new(params[:contact_call]) if @contact_call.save flash[:notice] = "Successfully created contact call." redirect_to contact_path(@contact_call.contact_id) else render :action => 'new' end end

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  • Generic ASP.NET MVC Route Conflict

    - by Donn Felker
    I'm working on a Legacy ASP.NET system. I say legacy because there are NO tests around 90% of the system. I'm trying to fix the routes in this project and I'm running into a issue I wish to solve with generic routes. I have the following routes: routes.MapRoute( "DefaultWithPdn", "{controller}/{action}/{pdn}", new { controller = "", action = "Index", pdn = "" }, null ); routes.MapRoute( "DefaultWithClientId", "{controller}/{action}/{clientId}", new { controller = "", action = "index", clientid = "" }, null ); The problem is that the first route is catching all of the traffic for what I need to be routed to the second route. The route is generic (no controller is defined in the constraint in either route definition) because multiple controllers throughout the entire app share this same premise (sometimes we need a "pdn" sometimes we need a "clientId"). How can I map these generic routes so that they go to the proper controller and action, yet not have one be too greedy? Or can I at all? Are these routes too generic (which is what I'm starting to believe is the case). My only option at this point (AFAIK) is one of the following: In the contraints, apply a regex to match the action values like: (foo|bar|biz|bang) and the same for the controller: (home|customer|products) for each controller. However, this has a problem in the fact that I may need to do this: ~/Foo/Home/123 // Should map to "DefaultwithPdn" ~/Foo/Home/abc // Should map to "DefaultWithClientId" Which means that if the Foo Controller has an action that takes a pdn and another action that takes a clientId (which happens all the time in this app), the wrong route is chosen. To hardcode these contstraints into each possible controller/action combo seems like a lot of duplication to me and I have the feeling I've been looking at the problem for too long so I need another pair of eyes to help out. Can I have generic routes to handle this scenario? Or do I need to have custom routes for each controller with constraints applied to the actions on those routes? Thanks

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  • Help me clean up this crazy lambda with the out keyword

    - by Sarah Vessels
    My code looks ugly, and I know there's got to be a better way of doing what I'm doing: private delegate string doStuff( PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt ); private bool tryEncryptPassword( doStuff encryptPassword, out string errorMessage ) { ...get some variables... string encryptedPassword = encryptPassword(encrypter, publicKey, privateKey, out salt); ... } This stuff so far doesn't bother me. It's how I'm calling tryEncryptPassword that looks so ugly, and has duplication because I call it from two methods: public bool method1(out string errorMessage) { string rawPassword = "foo"; return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 1 rawPassword, publicKey, privateKey, out salt ), out errorMessage ); } public bool method2(SecureString unencryptedPassword, out string errorMessage) { return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 2 unencryptedPassword, publicKey, privateKey, out salt ), out errorMessage ); } Two parts to the ugliness: I have to explicitly list all the parameter types in the lambda expression because of the single out parameter. The two overloads of EncryptPasswordAndDoStuff take all the same parameters except for the first parameter, which can either be a string or a SecureString. So method1 and method2 are pretty much identical, they just call different overloads of EncryptPasswordAndDoStuff. Any suggestions? Edit: if I apply Jeff's suggestions, I do the following call in method1: return tryEncryptPassword( (encrypter, publicKey, privateKey) => { var result = new EncryptionResult(); string salt; result.EncryptedValue = encrypter.EncryptPasswordAndDoStuff( rawPassword, publicKey, privateKey, out salt ); result.Salt = salt; return result; }, out errorMessage ); Much the same call is made in method2, just with a different first value to EncryptPasswordAndDoStuff. This is an improvement, but it still seems like a lot of duplicated code.

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  • boost::python string-convertible properties

    - by Checkers
    I have a C++ class, which has the following methods: class Bar { ... const Foo& getFoo() const; void setFoo(const Foo&); }; where class Foo is convertible to std::string (it has an implicit constructor from std::string and an std::string cast operator). I define a Boost.Python wrapper class, which, among other things, defines a property based on previous two functions: class_<Bar>("Bar") ... .add_property( "foo", make_function( &Bar::getFoo, return_value_policy<return_by_value>()), &Bar::setFoo) ... I also mark the class as convertible to/from std::string. implicitly_convertible<std::string, Foo>(); implicitly_convertible<Foo, std::string>(); But at runtime I still get a conversion error trying to access this property: TypeError: No to_python (by-value) converter found for C++ type: Foo How to achieve the conversion without too much boilerplate of wrapper functions? (I already have all the conversion functions in class Foo, so duplication is undesirable.

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  • Generate and download a text file in javascript

    - by Mark B
    All my research so far suggests this can't be done, but I'm hoping someone here has some cunning ideas. I have a form on a website which allows users to bulk upload lots of URLs to add to a list on the server. There's quite a lot of server-side processing to do on each URL, so to avoid timeouts and to display progress, I've implemented the upload using jQuery to submit the URLs one at a time using ajax. This is all working nicely. However, part of the processing on each URL is deduplicating it against the complete list. The ajax call returns a status indicating either a successful upload or a rejection due to duplication. As the upload progresses, I tell the user how many URLs have been rejected as duplicates (along with overall progress and ETA). The problem now is how to give the user a complete list of the failed duplicate URLs. I've kept them in an array in my jQuery, and would like the user to be able to click on a link on the form to download a text file containing those URLs. Is this possible just using client-side processing? The server-side processing basically handles a single keyword at a time. I'd rather not have to store the duplicates in a database table with some kind of session key which gets sent with every ajax call, and is then used at the end to generate the text file server-side (and then gets cleaned up some time later). I can see how to do this, but it seems very clunky and a bit 20th century.

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  • Using pointers to adjust global objects in objective-c

    - by Rob
    Ok, so I am working with two sets of data that are extremely similar, and at the same time, these data sets are both global NSMutableArrays within the object. data_set_one = [[NSMutableArray alloc] init]; data_set_two = [[NSMutableArray alloc] init]; Two new NSMutableArrays are loaded, which need to be added to the old, existing data. These Arrays are also global. xml_dataset_one = [[NSMutableArray alloc] init]; xml_dataset_two = [[NSMutableArray alloc] init]; To reduce code duplication (and because these data sets are so similar) I wrote a void method within the class to handle the data combination process for both Arrays: -(void)constructData:(NSMutableArray *)data fromDownloadArray:(NSMutableArray *)down withMatchSelector:(NSString *)sel_str Now, I have a decent understanding of object oriented programming, so I was thinking that if I were to invoke the method with the global Arrays in the data like so... [self constructData:data_set_one fromDownloadArray:xml_dataset_one withMatchSelector:@"id"]; Then the global NSMutableArrays (data_set_one) would reflect the changes that happen to "array" within the method. Sadly, this is not the case, data_set_one doesn't reflect the changes (ex: new objects within the Array) outside of the method. Here is a code snippet of the problem // data_set_one is empty // xml_dataset_one has a few objects [constructData:(NSMutableArray *)data_set_one fromDownloadArray:(NSMutableArray *)xml_dataset_one withMatchSelector:(NSString *)@"id"]; // data_set_one should now be xml_dataset_one, but when echoed to screen, it appears to remain empty And here is the gist of the code for the method, any help is appreciated. -(void)constructData:(NSMutableArray *)data fromDownloadArray:(NSMutableArray *)down withMatchSelector:(NSString *)sel_str { if ([data count] == 0) { data = down; // set data equal to downloaded data } else if ([down count] == 0) { // download yields no results, do nothing } else { // combine the two arrays here } } This project is not ARC enabled. Thanks for the help guys! Rob

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  • How can I limit asp.net control actions based on user role?

    - by Duke
    I have several pages or views in my application which are essentially the same for both authenticated users and anonymous users. I'd like to limit the insert/update/delete actions in formviews and gridviews to authenticated users only, and allow read access for both authed and anon users. I'm using the asp.net configuration system for handling authentication and roles. This system limits access based on path so I've been creating duplicate pages for authed and anon paths. The solution that comes to mind immediately is to check roles in the appropriate event handlers, limiting what possible actions are displayed (insert/update/delete buttons) and also limiting what actions are performed (for users that may know how to perform an action in the absence of a button.) However, this solution doesn't eliminate duplication - I'd be duplicating security code on a series of pages rather than duplicating pages and limiting access based on path; the latter would be significantly less complicated. I could always build some controls that offered role-based configuration, but I don't think I have time for that kind of commitment right now. Is there a relatively easy way to do this (do such controls exist?) or should I just stick to path-based access and duplicate pages? Does it even make sense to use two methods of authorization? There are still some pages which are strictly for either role so I'll be making use of path-based authorization anyway. Finally, would using something other than path-based authorization be contrary to typical asp.net design practices, at least in the context of using the asp.net configuration system?

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  • MSMQ - Message Queue Abstraction and Pattern

    - by Maxim Gershkovich
    Hi All, Let me define the problem first and why a messagequeue has been chosen. I have a datalayer that will be transactional and EXTREMELY insert heavy and rather then attempt to deal with these issues when they occur I am hoping to implement my application from the ground up with this in mind. I have decided to tackle this problem by using the Microsoft Message Queue and perform inserts as time permits asynchronously. However I quickly ran into a problem. Certain inserts that I perform may need to be recalled (ie: retrieved) immediately (imagine this is for POS system and what happens if you need to recall the last transaction - one that still hasn’t been inserted). The way I decided to tackle this problem is by abstracting the MessageQueue and combining it in my data access layer thereby creating the illusion of a single set of data being returned to the user of the datalayer (I have considered the other issues that occur in such a scenario (ie: essentially dirty reads and such) and have concluded for my purposes I can control these issues). However this is where things get a little nasty... I’ve worked out how to get the messages back and such (trivial enough problem) but where I am stuck is; how do I create a generic (or at least somewhat generic) way of querying my message queue? One where I can minimize the duplication between the SQL queries and MessageQueue queries. I have considered using LINQ (but have very limited understanding of the technology) and have also attempted an implementation with Predicates which so far is pretty smelly. Are there any patterns for such a problem that I can utilize? Am I going about this the wrong way? Does anyone have an of their own ideas about how I can tackle this problem? Does anyone even understand what I am talking about? :-) Any and ALL input would be highly appreciated and seriously considered… Thanks again.

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  • Omit return type in C++0x

    - by Clinton
    I've recently found myself using the following macro with gcc 4.5 in C++0x mode: #define RETURN(x) -> decltype(x) { return x; } And writing functions like this: template <class T> auto f(T&& x) RETURN (( g(h(std::forward<T>(x))) )) I've been doing this to avoid the inconvenience having to effectively write the function body twice, and having keep changes in the body and the return type in sync (which in my opinion is a disaster waiting to happen). The problem is that this technique only works on one line functions. So when I have something like this (convoluted example): template <class T> auto f(T&& x) -> ... { auto y1 = f(x); auto y2 = h(y1, g1(x)); auto y3 = h(y1, g2(x)); if (y1) { ++y3; } return h2(y2, y3); } Then I have to put something horrible in the return type. Furthermore, whenever I update the function, I'll need to change the return type, and if I don't change it correctly, I'll get a compile error if I'm lucky, or a runtime bug in the worse case. Having to copy and paste changes to two locations and keep them in sync I feel is not good practice. And I can't think of a situation where I'd want an implicit cast on return instead of an explicit cast. Surely there is a way to ask the compiler to deduce this information. What is the point of the compiler keeping it a secret? I thought C++0x was designed so such duplication would not be required.

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  • Using IAM for user authentication

    - by mdavis6890
    I've read lots and lots of posts that touch on what I think should be a very common use case - but without finding exactly what I want, or a simple reason why it can't be done. I have some files on S3. I want to be able to grant certain users access to certain files, via a front end that I build. So far, I've made it work this way: I built the front end in Django, using it's built-in Users and Groups I have a model for Buckets, in which I mirror my S3 buckets. I have a m2m relationship from groups to buckets representing the S3 permissions. The user logs in and authenticates against Django's users. I grab from Django the list of buckets that the user is allowed to see I use boto to grab a list of links to files from those buckets and display to user. This works, but isn't ideal, and also just doesn't feel right. I've got to keep a mirror of the buckets, and I also have to maintain my own list of user/passwords and permissions, when AWS already has all that built in. What I really want is to simply create the users in IAM and use group permissions in IAM to control access to the S3 buckets. No duplication of data or function. My app would request a UN/PW from the user and use that to connect to IAM/S3 to pull the list of buckets and files, then display links to the user. Simple. How can I, or why can't I? Am I looking at this the wrong way? What's the "right" way to address this (I assume) very common use case?

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  • unknown exception error in php

    - by fayer
    i wanna catch all exceptions thrown in a script and then check if they have a error code 23000. if they don't i want to rethrow the exception. here is my code: function myException($exception) { /*** If it is a Doctrine Connection Mysql Duplication Exception ***/ if(get_class($exception) === 'Doctrine_Connection_Mysql_Exception' && $exception->getCode() === 23000) { echo "Duplicate entry"; } else { throw $exception; } } set_exception_handler('myException'); $contact = new Contact(); $contact->email = 'peter'; $contact->save(); but i get this error message and i dont know what it means: Fatal error: Exception thrown without a stack frame in Unknown on line 0 i want to be able to rethrow the original error message if it has not the error code 23000. even when i deleted the check errorcode i still get the same message: function myException($exception) { throw $exception; } set_exception_handler('myException'); $contact = new Contact(); $contact->email = 'peter'; $contact->save(); how could i solve this? thanks

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  • JSF 2 - clearing component attributes on page load?

    - by jamiebarrow
    Hi, The real question: Is there a way to clear certain attributes for all components on an initial page load? Background info: In my application, I have a JSF 2.0 frontend layer that speaks to a service layer (the service layer is made up of Spring beans that get injected to the managed beans). The service layer does its own validation, and I do the same validation in the frontend layer using my own validator classes to try and avoid code duplication somehow. These validator classes aren't JSF validators, they're just POJOs. I'm only doing validation on an action, so in the action method, I perform validation, and only if it's valid do I call through to the service layer. When I do my validation, I set the styleClass and title on the UIComponents using reflection (so if the UIComponent has the setStyleClass(:String) or setTitle(:String) methods, then I use them). This works nicely, and on a validation error I see a nicely styled text box with a popup containing the error message if I hover over it. However, since the component is bound to a Session Scoped Managed Bean, it seems that these attributes stick. So if I navigate away and come back to the same page, the styleClass and title are still in the error state. Is there a way to clear the styleClass and title attributes on each initial page load? Thanks, James P.S. I'm using the action method to validate because of some issues I had before with JSF 1.2 and it's validation methods, but can't remember why... so that's why I'm using the action method to validate.

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  • How to design data storage for partitioned tagging system?

    - by Morgan Cheng
    How to design data storage for huge tagging system (like digg or delicious)? There is already discussion about it, but it is about centralized database. Since the data is supposed to grow, we'll need to partition the data into multiple shards soon or later. So, the question turns to be: How to design data storage for partitioned tagging system? The tagging system basically has 3 tables: Item (item_id, item_content) Tag (tag_id, tag_title) TagMapping(map_id, tag_id, item_id) That works fine for finding all items for given tag and finding all tags for given item, if the table is stored in one database instance. If we need to partition the data into multiple database instances, it is not that easy. For table Item, we can partition its content with its key item_id. For table Tag, we can partition its content with its key tag_id. For example, we want to partition table Tag into K databases. We can simply choose number (tag_id % K) database to store given tag. But, how to partition table TagMapping? The TagMapping table represents the many-to-many relationship. I can only image to have duplication. That is, same content of TagMappping has two copies. One is partitioned with tag_id and the other is partitioned with item_id. In scenario to find tags for given item, we use partition with tag_id. If scenario to find items for given tag, we use partition with item_id. As a result, there is data redundancy. And, the application level should keep the consistency of all tables. It looks hard. Is there any better solution to solve this many-to-many partition problem?

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  • Java: using generic wildcards with subclassing

    - by gibberish
    Say I have a class Foo, a class A and some subclass B of A. Foo accepts A and its sublclasses as the generic type. A and B both require a Foo instance in their constructor. I want A's Foo to be of type A , and B's Foo to be of type B or a superclass of B. So in effect, So I only want this: Foo<X> bar = new Foo<X>; new B(bar); to be possible if X is either A, B, or a both subclass of A and superclass of B. So far this is what I have: class Foo<? extends A>{ //construct } class A(Foo<A> bar){ //construct } class B(Foo<? super B> bar){ super(bar); //construct } The call to super(...) doesn't work, because <A> is stricter than <? super B>. Is it somehow possible to use the constructor (or avoid code duplication by another means) while enforcing these types? Edit: Foo keeps a collection of elements of the generic parameter type, and these elements and Foo have a bidirectional link. It should therefore not be possible to link an A to a Foo.

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  • Argument type deduction, references and rvalues

    - by uj2
    Consider the situation where a function template needs to forward an argument while keeping it's lvalue-ness in case it's a non-const lvalue, but is itself agnostic to what the argument actually is, as in: template <typename T> void target(T&) { cout << "non-const lvalue"; } template <typename T> void target(const T&) { cout << "const lvalue or rvalue"; } template <typename T> void forward(T& x) { target(x); } When x is an rvalue, instead of T being deduced to a constant type, it gives an error: int x = 0; const int y = 0; forward(x); // T = int forward(y); // T = const int forward(0); // Hopefully, T = const int, but actually an error forward<const int>(0); // Works, T = const int It seems that for forward to handle rvalues (without calling for explicit template arguments) there needs to be an forward(const T&) overload, even though it's body would be an exact duplicate. Is there any way to avoid this duplication?

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  • C# Debug.Assert-s use the same error message. Should I promote it to a static variable?

    - by Hamish Grubijan
    I love Asserts but not code duplication, and in several places I use a Debug.Assert which checks for the same condition like so: Debug.Assert(kosherBaconList.SelectedIndex != -1, "An error message along the lines - you should not ever be able to click on edit button without selecting a kosher bacon first."); This is in response to an actual bug, although the actual list does not contain kosher bacon. Anyhow, I can think of two approaches: private static readonly mustSelectKosherBaconBeforeEditAssertMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; ... Debug.Assert( kosherBaconList.SelectedIndex != -1, mustSelectKosherBaconBeforeEditAssertMessage) or: if (kosherBaconList.SelectedIndex == -1) { AssertMustSelectKosherBaconBeforeEdit(); } ... [Conditional("DEBUG")] private void AssertMustSelectKosherBaconBeforeEdit() { // Compiler will optimize away this variable. string errorMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; Debug.Assert(false, errorMessage); } or is there a third way which sucks less than either one above? Please share. General helpful relevant tips are also welcome.

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  • Custom Image Button and Radio/Toggle Button from Common Base Class

    - by Wonko the Sane
    Hi All, I would like to create a set of custom controls that are basically image buttons (it's a little more complex than that, but that's the underlying effect I'm going for) that I've seen a few different examples for. However, I would like to further extend that to also allow radio/toggle buttons. What I'd like to do is have a common abstract class called ImageButtonBase that has default implementations for ImageSource and Text, etc. That makes a regular ImageButton implementation pretty easy. The issue I am having is creating the RadioButton flavor of it. As I see it, there are at least three options: It would be easy to create something that derives from RadioButton, but then I can't use the abstract class I've created. I could change the abstract class to an interface, but then I lose the abstract implementations, and will in fact have duplication of code. I could derive from my abstract class, and re-implement the RadioButton-type properties and events (IsChecked, GroupName, etc.), but that certainly doesn't seem like a great idea. Note: I have seen http://stackoverflow.com/questions/2362641/how-to-get-a-group-of-toggle-buttons-to-act-like-radio-buttons-in-wpf, but what I want to do is a little more complex. I'm just wondering if anybody has an example of an implementation, or something that might be adapted to this kind of scenario. I can see pros and cons of each of the ideas above, but each comes with potential pitfalls. Thanks, wTs

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  • How to duplicate all data in a table except for a single column that should be changed.

    - by twiga
    I have a question regarding a unified insert query against tables with different data structures (Oracle). Let me elaborate with an example: tb_customers ( id NUMBER(3), name VARCHAR2(40), archive_id NUMBER(3) ) tb_suppliers ( id NUMBER(3), name VARCHAR2(40), contact VARCHAR2(40), xxx, xxx, archive_id NUMBER(3) ) The only column that is present in all tables is [archive_id]. The plan is to create a new archive of the dataset by copying (duplicating) all records to a different database partition and incrementing the archive_id for those records accordingly. [archive_id] is always part of the primary key. My problem is with select statements to do the actual duplication of the data. Because the columns are variable, I am struggling to come up with a unified select statement that will copy the data and update the archive_id. One solution (that works), is to iterate over all the tables in a stored procedure and do a: CREATE TABLE temp as (SELECT * from ORIGINAL_TABLE); UPDATE temp SET archive_id=something; INSERT INTO temp (select * from temp); DROP TABLE temp; I do not like this solution very much as the DDL commands muck up all restore points. Does anyone else have any solution?

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  • Why does mobile first responsive design tend to not use max-width queries alongside the min-width queries?

    - by Sam
    First off, I understand the basic principles behind mobile first responsive web design, and totally agree with them. But one thing I don't understand: In my experience, not all styles for small screens can be used for the larger version of a website. For example, usually smaller versions tend to have larger clickable areas, hamburger navigation, etc. So I sometimes have to override these specific styles, aside from just progressively enhancing the base styles. So I was wondering: why is max-width rarely mentioned (or used) in the context of mobile-first responsive web design? Because it looks like it could be used to isolate styles for smaller screens that are not useful for larger screens, and would thus prevent unnecessary duplication of code. A quote which mentions min-width as typically mobile-first, but not max-width: Mobile first, from a coding perspective, means that your base style is typically a single-column, fully-fluid layout. You use @media (min-width: whatever) to add a grid-based layout on top of that. from: http://gomakethings.com/mobile-first-and-internet-explorer/ EDIT: So to be more specific: I was wondering if there is a reason to exclude max-width from a mobile-first responsive design (as it seems like it can be useful for writing your css as DRY as possible, as some styles for small screens will not be used for bigger screens).

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  • TDD approach for complex function

    - by jamie
    I have a method in a class for which they are a few different outcomes (based upon event responses etc). But this is a single atomic function which is to used by other applications. I have broken down the main blocks of the functionality that comprise this function into different functions and successfully taken a Test Driven Development approach to the functionality of each of these elements. These elements however aren't exposed for other applications would use. And so my question is how can/should i easily approach a TDD style solution to verifying that the single method that should be called does function correctly without a lot of duplication in testing or lots of setup required for each test? I have considered / looked at moving the blocks of functionality into a different class and use Mocking to simulate the responses of the functions used but it doesn't feel right and the individual methods need to write to variables within the main class (it felt really heath robinson). The code roughly looks like this (i have removed a lot of parameters to make things clearer along with a fair bit of irrelevant code). public void MethodToTest(string parameter) { IResponse x = null; if (function1(parameter)) { if (!function2(parameter,out x)) { function3(parameter, out x); } } // ... // more bits of code here // ... if (x != null) { x.Success(); } }

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