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  • Seam @Factory in abstract base class?

    - by Shadowman
    I've got a series of web actions I'm implementing in Seam to perform create, read, update, etc. operations. For my read/update/delete actions, I'd like to have individual action classes that all extend an abstract base class. I'd like to put the @Factory method in the abstract base class to retrieve the item that is to be acted upon. For example, I have this as the base class: public abstract class BaseAction { @In(required=false)@Out(required=false) private MyItem item=null; public MyItem getItem(){...} public void setItem(...){...} @Factory("item") public void initItem(){...} } My subclasses would extend BaseAction, so that I don't have to repeat the logic to load the item that is to be viewed, deleted, updated, etc. However, when I start my application, Seam throws errors saying I have declared multiple @Factory's for the same object. Is there any way around this? Is there any way to provide the @Factory in the base class without encoutnering these errors?

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  • Work around for MessageNotReadableException in Java

    - by Hari
    Hi, I am building a small api around the JMS API for a project of mine. Essentially, we are building code that will handle the connection logic, and will simplify publishing messages by providing a method like Client.send(String message). One of the ideas being discussed right now is that we provide a means for the users to attach interceptors to this client. We will apply the interceptors after preparing the JMS message and before publishing it. For example, if we want to timestamp a message and wrote an interceptor for that, then this is how we would apply that ...some code ... Message message = session.createMessage() ..do all the current processing on the message and set the body for(interceptor:listOfInterceptors){ interceptor.apply(message) } One of the intrerceptors we though of was to compress the message body. But when we try to read the body of the message in the interceptor, we are getting a MessageNotReadableException. In the past, I normally compressed the content before setting it as the body of the message - so never had to worry about this exception. Is there any way of getting around this exception?

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  • Wnat is the preferred method of building extremely lightweight business object / DAL now that I have

    - by Seth Spearman
    Hello, I have completed a simple database for a project. Only 6tables. Of the 6, one is a "lookup" table. There is one "master" table that is the driver for the system. It is referenced as a foreign key by the other four tables. Give that this step is completed. What is the FASTEST, EASIEST way to create POCOs/BizObjects that can load load the data and the child data. Here are my CAVEATS. *I don't want to spend more than 30-60 minutes learning how? *There is very little biz logic needed in the POCOs. They will pretty much load data. Don't even really need to write back data. *I already know CSLA (up to version 3) but I feel that is overkill for this little project. *Nevertheless, I would love it if it ROOT objects could have collection classes that contain the CHILD objects as in CSLA...but again, without using CSLA. *Please give the answer for .NET 35 but also if I was restricted to only use .NET 20. *Ideally I could just point a tool at the database and the POCOs would be genn'ed. *FREE Just curious what you guys use for this kind of scenario. I understand that this question is subjective but I want to hear a variety of answers. Seth

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  • C++ iterators, default initialization and what to use as an uninitialized sentinel.

    - by Hassan Syed
    The Context I have a custom template container class put together from a map and vector. The map resolves a string to an ordinal, and the vector resolves an ordinal (only an initial string to ordinal lookup is done, future references are to the vector) to the entry. The entries are modified intrusively to contain a a bool "assigned" and an iterator_type which is a const_iterator to the container class's map. My container class will use RCF's serialization code (which models boost::serialization) to serialize my container classes to nodes in a network. Serializing iterator's is not possible, or a can of worms, and I can easily regenerate them onces the vectors and maps are serialized on the remote site. The Question I need to default initialize, and be able to test that the iterator has not been assigned to (if it is assigned it is valid, if not it is invalid). Since map iterators are not invalidated upon operations performed on it (unless of course items are removed :D) am I to assume that map<x,y>::end() is a valid sentinel (regardless of the state of the map -- i.e., it could be empty) to initialize to ? I will always have access to the parent map, I'm just unsure wheather end() is the same as the map contents change. I don't want to use another level of indirection (--i.e., boost::optional) to achieve my goal, I'd rather forego compiler checks to correct logic, but it would be nice if I didn't need to. Misc This question exists, but most of its content seems non-sense. Assigning a NULL to an iterator is invalid according to g++ and clang++. This is another similar question, but it focuses on the common use-cases of iterators, which generally tends to be using the iterator to iterate, ofcourse in this use-case the state of the container isn't meant to change whilst iteration is going on.

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  • How can I split my conkeror-rc config over multiple files?

    - by Ryan Thompson
    Short version: can you help me fill in this code? var conkeror_settings_dir = ".conkeror.mozdev.org/settings"; function load_all_js_files_in_dir (dir) { var full_path = get_home_directory().appendRelativePath(dir); // YOUR CODE HERE } load_all_js_files_in_dir(conkeror_settings_dir); Background I'm trying out Conkeror for web browsing. It's an emacs-like browser running on Mozilla's rendering engine, using javascript as configuration language (filling the role that elisp plays for emacs). In my emacs config, I have split my customizations into a series of files, where each file is a single unit of related options (for example, all my perl-related settings might be in perl-settings.el. All these settings files are loaded automatically by a function in my .emacs that simply loads every elisp file under my "settings" directory. I am looking to structure my Conkeror config in the same way, with my main conkeror-rc file basically being a stub that loads all the js files under a certain directory relative to my home directory. Unfortunately, I am much less literate in javascript than I am in elisp, so I don't even know how to "source" a file.

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  • What can i use to journal writes to file system

    - by Dmitry
    Hello, all I need to track all writes to files in order to have synchronized version of files on different place (server or just other directory, not considerable). Let it: all files located in same directory feel free to create some system files (e.g. SomeFileName.Ext~temp-data) no one have concurrent access to synced directory; nobody spoil ours meta-files or change real-files before we do postponed writes (like a commits) do not to care recovering "local" changes in case of crash; system can just rolled back to state of "server" by simple copy from it significant to have it transparent to use (so programmer must just call ordinary fopen(), read(), write()) It must be guaranteed that copy of files which "server" have is consistent. That is whole files scope existed in some moment of time. They may be sufficiently outdated but it must be fair snapshot of all files at some time. As i understand i should overload writing logic to collect data in order sent changes to "server". For example writing to temporary File~tmp. And so i have to overload reads in order program could read actual data of file. It would be great if you suggest some existing library (java or c++, it is unimportant) or solution (VCS customizing?). Or give hints how should i write it by myself. edit: After some reading i have more precision requirements: I need COW (Copy-on-write) wrapper for fopen(),fwrite(),.. or interceptor (hook) WriteFile() and other FS api system calls. Log-structured file system in userspace would be a alternative too.

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  • autologin component doesn't work on remote server

    - by user606521
    I am using autologin component from http://milesj.me/code/cakephp/auto-login (v 3.5.1). It works on my localhost WAMP server but fails on remote server. I am using this settings in beforeFilter() callback: $this->AutoLogin->settings = array( // Model settings 'model' => 'User', 'username' => 'username', 'password' => 'password', // Controller settings 'plugin' => '', 'controller' => 'users', // Cookie settings 'cookieName' => 'rememberMe', 'expires' => '+1 month', // Process logic 'active' => true, 'redirect' => true, 'requirePrompt' => true ); On remote server it simply doesn't autolog users after the browser was closed. I can't figure out what may cause the problem. -------------------- edit I figured out what is causing the problem but I don't know how to fix this. First of all cookie is set like this: $this->Cookie->write('key',array('username' => 'someusername', 'hash' => 'somehash', ...) ); Then it's readed like this: $cookie = $this->Cookie->read('key'); On my WAMP server $cookie is array('username' => 'someusername', 'hash' => 'somehash', ...) and on remote server returned $cookie is string(159) "{\"username\":\"YWxlay5iYXJzsdsdZXdza2ldssd21haWwuY29t\",\"password\":\"YWxlazc3ODEy\",\"hash\":\"aa15bffff9ca12cdcgfgb351d8bfg2f370bf458\",\"time\":1339923926}" and it should be: array( 'username' => "YWxlay5iYXJzsdsdZXdza2ldssd21haWwuY29t", 'password' => "YWxlazc3ODEy", ...) Why the retuned cookie is string not array?

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  • get Random in ArrayList has error of java.lang.IllegalArgumentException: n must be positive

    - by gabrielle fregil
    In my ArrayList, i have get a random Item from my ArrayList for the equip method. Whenever i use my tester, the terminal window prints java.lang.IllegalArgumentException: n must be positive when I try to call random for the size. I tried to change the value of totalElements to the integer size of the elements, then the error would be an OutOfBoundsExeption import java.util.*; import java.util.Scanner; import java.util.Random; public class GameMaster { private int turn, totalElements; private boolean winner; private Avatar x1; private Avatar x2; private ArrayList<Item> inventory; public GameMaster(Avatar a1, Avatar a2) { x2 = a1; x1 = a2; turn = 1; winner = false; inventory = new ArrayList<Item>(); totalElements = 0; } private void fillInventory() { inventory.add( new Item( "Zealot Blades", true, 8 ) ); inventory.add( new Item( "BFG", true, 13 ) ); inventory.add( new Item( "Synthetic Cloth", false, 7 ) ); // more items inventory.add( new Item( "Gauss Rifle", true, 9 ) ); inventory.add( new Item( "Flight Unit", false, 6 ) ); totalElements = inventory.size(); } public String equip() { Avatar w; String a; if (turn%2==1) w=x2; else w=x1; if (w.beltIsFull()) { a = w.getName() + "'s belt is full. \n"; } else { turn++; Random generator = new Random(); Item rand = inventory.get(generator.nextInt(totalElements)); //terminal window in blueJ: java.lang.IllegalArgumentException: n must be positive a = w.getName()+" is equiped with "+rand.getName()+"."; } return a; }

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  • structDelete doesn't affect the shallow copy?

    - by Travis
    I was playing around onError so I tried to create an error using a large xml document object. <cfset XMLByRef = variables.parsedXML.XMLRootElement.XMLChildElement> <cfset structDelete(variables.parsedXML, "XMLRootElement")> <cfset startXMLShortLoop = getTickCount()> <cfloop from = "1" to = "#arrayLen(variables.XMLByRef)#" index = "variables.i"> <cfoutput>#variables.XMLByRef[variables.i].id.xmltext#</cfoutput><br /> </cfloop> <cfset stopXMLShortLoop = getTickCount()> I expected to get an error because I deleted the structure I was referencing. From LiveDocs: Variable Assignment - Creates an additional reference, or alias, to the structure. Any change to the data using one variable name changes the structure that you access using the other variable name. This technique is useful when you want to add a local variable to another scope or otherwise change a variable's scope without deleting the variable from the original scope. instead I got 580df1de-3362-ca9b-b287-47795b6cdc17 25a00498-0f68-6f04-a981-56853c0844ed ... ... ... db49ed8a-0ba6-8644-124a-6d6ebda3aa52 57e57e28-e044-6119-afe2-aebffb549342 Looped 12805 times in 297 milliseconds <cfdump var = "#variables#"> Shows there's nothing in the structure, just parsedXML.xmlRoot.xmlName with the value of XMLRootElement. I also tried <cfset structDelete(variables.parsedXML.XMLRootElement, "XMLChildElement")> as well as structClear for both. More information on deleting from the xml document object. http://help.adobe.com/en_US/ColdFusion/9.0/Developing/WSc3ff6d0ea77859461172e0811cbec22c24-78e3.html Can someone please explain my faulty logic? Thanks.

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  • How should I organize complex SQL views in Rails?

    - by Benjamin Oakes
    I manage a research database with Ruby on Rails. The data that is entered is primarily used by scientists who prefer to have all the relevant information for a study in one single massive table for use in their statistics software of choice. I'm currently presenting it as CSV, as it's very straightforward to do and compatible with the tools people want to use. I've written many views (the SQL kind, not the Rails HTML/ERB kind) to make the output they expect a reality. Some of these views are quite large and have a fair amount of complexity behind them. I wrote them in SQL because there are many calculations and comparisons that are more easily done with SQL. They're currently loaded into the database straight from a file named views.sql. To get the requested data, I do a select * from my_view;. The views.sql file is getting quite large. Part of the problem is that we're still figuring out what the data we collect means, so there's a lot of changes being made to the views all the time -- and a ton of them are being created. Many of them need to be repeatable. I've recently run into issues organizing and testing these views. Rails works great for user interface stuff and business logic, but I'm not aware of much existing structure for handling the reporting we require. Some options I've thought of: Should I move them into the most relevant models somehow? Several of the views interact with each other, which makes this situation more complex than just doing a single find_by_sql, so I don't know if they should only be part of the model. Perhaps they should be treated as a "view" in the MVC sense? (That is, they could be moved into app/views/ and live alongside the HTML, perhaps as files named something like my_view.csv.sql which return CSV.) How would you deal with a complex reporting problem like this?

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  • Interchange structured data between Haskell and C

    - by Eonil
    First, I'm a Haskell beginner. I'm planning integrating Haskell into C for realtime game. Haskell does logic, C does rendering. To do this, I have to pass huge complexly structured data (game state) from/to each other for each tick (at least 30 times per second). So the passing data should be lightweight. This state data may laid on sequential space on memory. Both of Haskell and C parts should access every area of the states freely. In best case, the cost of passing data can be copying a pointer to a memory. In worst case, copying whole data with conversion. I'm reading Haskell's FFI(http://www.haskell.org/haskellwiki/FFICookBook#Working_with_structs) The Haskell code look specifying memory layout explicitly. I have a few questions. Can Haskell specify memory layout explicitly? (to be matched exactly with C struct) Is this real memory layout? Or any kind of conversion required? (performance penalty) If Q#2 is true, Any performance penalty when the memory layout specified explicitly? What's the syntax #{alignment foo}? Where can I find the document about this? If I want to pass huge data with best performance, how should I do that? *PS Explicit memory layout feature which I said is just C#'s [StructLayout] attribute. Which is specifying in-memory position and size explicitly. http://www.developerfusion.com/article/84519/mastering-structs-in-c/ I'm not sure Haskell has matching linguistic construct matching with fields of C struct.

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  • Circular dependency with generics

    - by devoured elysium
    I have defined the following interface: public interface IStateSpace<State, Action> where State : IState where Action : IAction<State, Action> // <-- this is the line that bothers me { void SetValueAt(State state, Action action); Action GetValueAt(State state); } Basically, an IStateSpace interface should be something like a chess board, and in each position of the chess board you have a set of possible movements to do. Those movements here are called IActions. I have defined this interface this way so I can accommodate for different implementations: I can then define concrete classes that implement 2D matrix, 3D matrix, graphs, etc. public interface IAction<State, Action> { IStateSpace<State, Action> StateSpace { get; } } An IAction, would be to move up(this is, if in (2, 2) move to (2, 1)), move down, etc. Now, I'll want that each action has access to a StateSpace so it can do some checking logic. Is this implementation correct? Or is this a bad case of a circular dependence? If yes, how to accomplish "the same" in a different way? Thanks

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  • MVVM: where is the best place to integrate an id counter, in ViewModel or Repository or... ?

    - by msfanboy
    Hello, I am using http://loungerepo.codeplex.com/ this library needs a unique id when I persist my entities to the repository. I decided for integer not Guid. The question is now where do I retrieve a new integer and how do I do it? This is my current approach in the SchoolclassAdministrationViewModel.cs: public SchoolclassAdministrationViewModel() { _schoolclassRepo = new SchoolclassRepository(); _pupilRepo = new PupilRepository(); _subjectRepo = new SubjectRepository(); _currentSchoolclass = new SchoolclassModel(); _currentPupil = new PupilModel(); _currentSubject = new SubjectModel(); ... } private void AddSchoolclass() { // get the last free id for a schoolclass entity _currentSchoolclass.SchoolclassID = _schoolclassRepo.LastID; // add the new schoolclass entity to the repository _schoolclassRepo.Add(SchoolclassModel.SchoolclassModelToSchoolclass(_currentSchoolclass)); // add the new schoolclass entity to the ObservableCollection bound to the View Schoolclasses.Add(_currentSchoolclass); // Create a new schoolclass entity and the bound UI controls content gets cleaned CurrentSchoolclass = new SchoolclassModel(); } public class SchoolclassRepository : IRepository<Schoolclass> { private int _lastID; public SchoolclassRepository() { _lastID = FetchLastId(); } public void Add(Schoolclass entity) { //repo.Store(entity); } private int FetchLastId() { return // repo.GetIDOfLastEntryAndDoInc++ } public int LastID { get { return _lastID; } } } Explanation: Every time the user switches to the SchoolclassAdministrationViewModel which is datatemplated with a UserControl the saVM Ctor is called and the schoolclass repository is created wherein the FetchLastId() is called and I am up to date with the last ID doing a inc++ on it to get the free one... Do you have any better ideas? What I do not like about my current apporach: -Having a private method in repositry class because a repositry is to fetch data only not "entity logic" like the counter - Having to access from the ViewModel a public property - located in the repository -, actually its not the ViewModel concern to get a entity id and assign it. Actually the ViewModel should ask for a schoolclass POCO and get a SchoolclassModel to bind to the UI. But then I have again to re-read the Schoolclass properties into the SchoolclassModel properties what I want to avoid.

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  • Closures in Ruby

    - by Isaac Cambron
    I'm kind of new to Ruby and some of the closure logic has me a confused. Consider this code: array = [] for i in (1..5) array << lambda {j} end array.map{|f| f.call} => [5, 5, 5, 5, 5] This makes sense to me because i is bound outside the loop, so the same variable is captured by each trip through the loop. It also makes sense to me that using an each block can fix this: array = [] (1..5).each{|i| array << lambda {i}} array.map{|f| f.call} => [1, 2, 3, 4, 5] ...because i is now being declared separately for each time through. But now I get lost: why can't I also fix it by introducing an intermediate variable? array = [] for i in 1..5 j = i array << lambda {j} end array.map{|f| f.call} => [5, 5, 5, 5, 5] Because j is new each time through the loop, I'd think a different variable would be captured on each pass. For example, this is definitely how C# works, and how -- I think-- Lisp behaves with a let. But in Ruby not so much. It almost looks like = is aliasing the variable instead of copying the reference, but that's just speculation on my part. What's really happening?

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  • Which languages and techniques can I use to improve my coding practices?

    - by Danjah
    I've been offered the opportunity upskill through study, while at work which is great. My background I am mostly self-taught, but have worked with many excellent people over the years - both self-taught and fully educated, and on many decent projects. I have mild experience in Actionscript, I'm getting better every day with my Javascript, and my CSS is angled at best practice, but needs a bit of modernising. I'm a traditional interface developer, I'm not stupid and I like a challenge. My goal I need to start seeing ways of applying better logic, optimising code, refactoring, different styles of development (agile, others?), and.. well I need to try and start thinking like.. a more solid programmer. Its hard to describe, I have good solutions and I'm efficient - but I KNOW that there's a bunch I am missing. I am already employed with a solid career, but I feel the need to fill gaps. My question/s Are there a set of guiding principles you can recommend I focus on to improve the points above? Are there particular programming languages which I might focus on to get a broader overview? Do you think I should avoid particular styles of development, or even languages, while solidifying what might end up being part 'the basics' but hopefully 'advanced programming'? -- Sorry if this appears off topic or something but I figure you're probably some of the best people to ask.

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  • Is the size of a struct required to be an exact multiple of the alignment of that struct?

    - by Steve314
    Once again, I'm questioning a longstanding belief. Until today, I believed that the alignment of the following struct would normally be 4 and the size would normally be 5... struct example { int m_Assume_32_Bits; char m_Assume_8_Bit_Bytes; }; Because of this assumption, I have data structure code that uses offsetof to determine the distance in bytes between two adjacent items in an array. Today, I spotted some old code that was using sizeof where it shouldn't, couldn't understand why I hadn't had bugs from it, coded up a unit test - and the test surprised me by passing. A bit of investigation showed that the sizeof the type I used for the test (similar to the struct above) was an exact multiple of the alignment - ie 8 bytes. It had padding after the final member. Here is an example of why I never expected this... struct example2 { example m_Example; char m_Why_Cant_This_Be_At_Offset_6_Bytes; }; A bit of Googling showed examples that make it clear that this padding after the final member is allowed - for example http://en.wikipedia.org/wiki/Data_structure_alignment#Data_structure_padding (the "or at the end of the structure" bit). This is a bit embarrassing, as I recently posted this comment - Use of struct padding (my first comment to that answer). What I can't seem to determine is whether this padding to an exact multiple of the alignment is guaranteed by the C++ standard, or whether it is just something that is permitted and that some (but maybe not all) compilers do. So - is the size of a struct required to be an exact multiple of the alignment of that struct according to the C++ standard? If the C standard makes different guarantees, I'm interested in that too, but the focus is on C++.

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  • How to find an embedded platform?

    - by gmagana
    I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, custom boards, a zillion option for each board, volume discounts, devel kits, ahhh!!) I am asking here for some direction. Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do: Required: 2 RS232 serial ports (one used all the time for primary UI, the second one not continuous) 1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices, so interrupt sharing with one serial port is OK, but not both] Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files) RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable. Nice to have: USB port(s) Ethernet network port Wireless network Implementation languages (any O/S I will adapt to): First choice Java/C# (Mono ok) Second choice is C/Pascal Third is BASIC Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are). The #1 constraint is cost, #2 is size. Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-). EDIT: A bit of background: This is a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to reimplement this in a modern platform. I can only change the programming and the motherboard hardware.

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  • Spring security - same page to deliver different content based on user role

    - by Ramesh
    Hello, i tried to search for any previous post related to my issue but couldnt find any. I have a scenario where in page handles 3 different scenarios and one of them not working. This page returns different content depending on if the user is authenticated or anonymous. localhost:8080/myApp/muUrl?test=authenticatedContent - used for Scenario 1 & 2 localhost:8080/myApp/muUrl?test=anonymousContent - used for Scenario 3 Scenario: 1) Authenticated user accesing the page url - the user gets displayed correct information. Works fine 2) Anonymous user accesing page URL with parameters that requires authentication - If anonymous, there is second level of check on the content they are accessing. for example, based on the GET parameters, there is custom logic to determine if the user has to be authenticated. In which case the page gets redirected to login page (WORKS fine). 3) Anonymous user accessing page URL with parameters that doesnt need authentication - in this case i get the SAvedRequest and redirect to the URL which is taking me to an infinite loop. Am i missing something very obvious or is there a way in AuthenticationProcessFilterEntryPoint to say "DON'T redirect to LOGIN page but process it" ? thanks.

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  • find contiguous stretches of equal data in a vector

    - by mariotomo
    I have a numeric vector, it contains patches of elements that are repeating, something like: R> data <- c(1,1,1,2,2,2,3,3,2,2,2,2,2,3,3,1,1,1,1,1) R> data [1] 1 1 1 2 2 2 3 3 2 2 2 2 2 3 3 1 1 1 1 1 R> I need to extract contiguous patches of elements equals to a specific value... but I'm only interested in the patch around a specific position. so, my input is: (1) the numeric vector, (2) the desired value, (3) the position. I want to return a logic vector indicating which positions satisfy the request. if at that position the data does not equal the value, I return all FALSE. possible outcomes that are not all F would be: [1] 1 1 1 2 2 2 3 3 2 2 2 2 2 3 3 1 1 1 1 1 [1] T T T F F F F F F F F F F F F F F F F F [2] F F F T T T F F F F F F F F F F F F F F [3] F F F F F F T T F F F F F F F F F F F F [4] F F F F F F F F T T T T T F F F F F F F [5] F F F F F F F F F F F F F T T F F F F F [6] F F F F F F F F F F F F F F F T T T T T

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  • Encapsulating user input of data for a class (C++)

    - by Dr. Monkey
    For an assignment I've made a simple C++ program that uses a superclass (Student) and two subclasses (CourseStudent and ResearchStudent) to store a list of students and print out their details, with different details shown for the two different types of students (using overriding of the display() method from Student). My question is about how the program collects input from the user of things like the student name, ID number, unit and fee information (for a course student) and research information (for research students): My implementation has the prompting for user input and the collecting of that input handled within the classes themselves. The reasoning behind this was that each class knows what kind of input it needs, so it makes sense to me to have it know how to ask for it (given an ostream through which to ask and an istream to collect the input from). My lecturer says that the prompting and input should all be handled in the main program, which seems to me somewhat messier, and would make it trickier to extend the program to handle different types of students. I am considering, as a compromise, to make a helper class that handles the prompting and collection of user input for each type of Student, which could then be called on by the main program. The advantage of this would be that the student classes don't have as much in them (so they're cleaner), but also they can be bundled with the helper classes if the input functionality is required. This also means more classes of Student could be added without having to make major changes to the main program, as long as helper classes are provided for these new classes. Also the helper class could be swapped for an alternative language version without having to make any changes to the class itself. What are the major advantages and disadvantages of the three different options for user input (fully encapsulated, helper class or in the main program)?

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  • PHP Overloading, singleton instance

    - by jamalali81
    I've sort of created my own MVC framework and am curious as to how other frameworks can send properties from the "controller" to the "view". Zend does something along the lines of $this->view->name = 'value'; My code is: file: services_hosting.php class services_hosting extends controller { function __construct($sMvcName) { parent::__construct($sMvcName); $this->setViewSettings(); } public function setViewSettings() { $p = new property; $p->banner = '/path/to/banners/home.jpg'; } } file: controller.php class controller { public $sMvcName = "home"; function __construct($sMvcName) { if ($sMvcName) { $this->sMvcName = $sMvcName; } include('path/to/views/view.phtml'); } public function renderContent() { include('path/to/views/'.$this->sMvcName.'.phtml'); } } file: property.php class property { private $data = array(); protected static $_instance = null; public static function getInstance() { if (null === self::$_instance) { self::$_instance = new self(); } return self::$_instance; } public function __set($name, $value) { $this->data[$name] = $value; } public function __get($name) { if (array_key_exists($name, $this->data)) { return $this->data[$name]; } } public function __isset($name) { return isset($this->data[$name]); } public function __unset($name) { unset($this->data[$name]); } } In my services_hosting.phtml "view" file I have: <img src="<?php echo $this->p->banner ?>" /> This just does not work. Am I doing something fundamentally wrong or is my logic incorrect? I seem to be going round in circles at the moment. Any help would be very much appreciated.

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  • Bulletin board - Database optimisation

    - by andrew
    This question is a follow on from this Question The project and problem The project I am currently working on is a bulletin board for a large non-profit organisation. The bulletin board will be used to allow inter-office communication within the organisation. I am building the application and have been having trouble extracting the results that I need from my database because I don't think it is properly normalized and because of limitations in my knowledge of relational database theory and mysql. I would appreciate input into the design of the board in general and in particular, ways that the database structure can be improved to facilitate efficient queries and help me develop this application and future application faster Business Logic The bulletin board will be used in the following way Posting bulletins and responses to bulletins Employees or 'users' in offices around the country will be able to post messages to the bulletin board.Bulletins must be posted to a location and categorised- i'll call these "bulletins". Users will be able to post any number of replies to any one bulletin and users will be able to reply to their own bulletin - i'll call these 'replies'. Rating bulletins and replies Users will be able to either 'like' or 'dislike' a bulletin or a reply and the total number of likes or dislikes will be shown for each bulletin or reply. Viewing the bulletin board and responses Bulletins can be displayed chronologically. Users can sort bulletins chronologically or chronologically by the latest reply to that bulletin(let me know if you need more explanation) When a particular bulletin is selected, replies to that bulletin will be displayed chronologically @PerformanceDBA - edited 10:34 est 28/12/10I have begun implementing the data model. I assume that the 6th data model is the physical model because it contains the associative tables. I am going to post any questions that I have below. I will put up a database dump once I am done. I will then put up a list of all the queries that I need to run on the database and begin writing them. I hope you had a good Christmas. I'm in Canada and there's snow! Implementation of Physical model

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  • Rails - Help scoring an online quiz in RoR

    - by ChrisWesAllen
    I'm trying to grade a quiz application I would like to make. I have a questions model with and ask(the actual question), 4 choices(a-d), and a correct answer(string). In the view I have the 4 question being diplayed then the correct answer choice (This is just a test for functionality) and then I created a text_field to accept the users answer choice and a button to refresh the index action which has the scoring logic, for now.. --Do I need to put the text_field within a form_tag? <p>1. <%= h @question.q1 %></p> <p>2. <%= h @question.q2 %></p> <p>3. <%= h @question.q3 %></p> <p>4. <%= h @question.q4 %></p> <p>Answer: <%= h @question.correct %></p> <%= text_field_tag :choice, params[:choice] %> <%= button_to "Grade", {:controller => 'site', :action => "index"} %> <p> <%= @answer %></p> Heres the index controller action def index @question = Question.find(1) if @question.correct == params[:choice] @answer = 'right' else @answer = 'wrong' end end Its not really working. The textfield is supposed to take a letter choice like 'a' or 'c' and compare it with the correct answer in the database. I would love this to work by radiobuttons, but I'm a newbie to rails so I thought I'd take baby steps. So if anyone can help me with how to fix this by string, or preferably by radiobuttons, I'd really appreciate it.

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  • XML Schema: Can I make some of an attribute's values be required but still allow other values?

    - by scrotty
    (Note: I cannot change structure of the XML I receive, I am only able to change how I validate it.) Let's say I can get XML like this: <Address Field="Street" Value="123 Main"/> <Address Field="StreetPartTwo" Value="Unit B"/> <Address Field="State" Value="CO"/> <Address Field="Zip" Value="80020"/> <Address Field="SomeOtherCrazyValue" Value="Foo"/> I need to create an XSD schema that validates that "Street", "State" and "Zip" must be present. But I don't care if "StreetPartTwo" or "SomeOTherCrazyValue" is present. If I knew that only the three I care about could be included, I could do this: <xs:element name="Address" type="addressType" maxOccurs="unbounded" minOccurs="3"/> <xs:complexType name="addressType"> <xs:attribute name="Field" use="required"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:enumeration value="Street"/> <xs:enumeration value="State"/> <xs:enumeration value="Zip"/> </xs:restriction> </xs:simpleType> </xs:attribute> </xs:complexType> But this won't work with my case because I may also receive those other Address elements (that also have "Field" attributes) that I don't care about. Any ideas how I can ensure the stuff I care about is present but let the other stuff in too? TIA! Sean

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  • Reversible numerical calculations in Prolog

    - by user8472
    While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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