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  • Scope of Connection Object for a Website using Connection Pooling (Local or Instance)

    - by Danny
    For a web application with connection polling enabled, is it better to work with a locally scoped connection object or instance scoped connection object. I know there is probably not a big performance improvement between the two (because of the pooling) but would you say that one follows a better pattern than the other. Thanks ;) public class MyServlet extends HttpServlet { DataSource ds; public void init() throws ServletException { ds = (DataSource) getServletContext().getAttribute("DBCPool"); } protected void doGet(HttpServletRequest arg0, HttpServletResponse arg1) throws ServletException, IOException { SomeWork("SELECT * FROM A"); SomeWork("SELECT * FROM B"); } void SomeWork(String sql) { Connection conn = null; try { conn = ds.getConnection(); // execute some sql ..... } finally { if(conn != null) { conn.close(); // return to pool } } } } Or public class MyServlet extends HttpServlet { DataSource ds; Connection conn;* public void init() throws ServletException { ds = (DataSource) getServletContext().getAttribute("DBCPool"); } protected void doGet(HttpServletRequest arg0, HttpServletResponse arg1) throws ServletException, IOException { try { conn = ds.getConnection(); SomeWork("SELECT * FROM A"); SomeWork("SELECT * FROM B"); } finally { if(conn != null) { conn.close(); // return to pool } } } void SomeWork(String sql) { // execute some sql ..... } }

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  • cocoa - making a UIImageView class act like a UIButton

    - by Mike
    For some reason that will take too much time to explain, I have to create a UIImageView based class that has some properties of a button. Imagine a class like the UISwitch (no I cannot base my class on the UISwitch) with two states, on and off. WHen the user selects one state, it runs a method like a button that was clicked and the method receives the sender id. I have already the class more or less working. The class is based on UIImageView. I am having difficulties to understand the following. WHen I create a new button I have a line that is like [myButton addTarget:self action:NSSelectorFromString(myMethod) forControlEvents:UIControlEventTouchUpInside]; This line defines a target and an action to run when the button is triggered. I my case I would need something like [myObject addTarget:self action:myMethod ifState:1] //or another thing ifState:2 I have no idea what kind of code I should put on the class to make this work. Remember that as a button the class should send the "sender" information to identify the object which triggered the action... Can you guys, transcendental gurus help? thanks for any help!

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  • Jackson object mapping - map incoming JSON field to protected property in base class

    - by Pete
    We use Jersey/Jackson for our REST application. Incoming JSON strings get mapped to the @Entity objects in the backend by Jackson to be persisted. The problem arises from the base class that we use for all entities. It has a protected id property, which we want to exchange via REST as well so that when we send an object that has dependencies, hibernate will automatically fetch these dependencies by their ids. Howevery, Jackson does not access the setter, even if we override it in the subclass to be public. We also tried using @JsonSetter but to no avail. Probably Jackson just looks at the base class and sees ID is not accessible so it skips setting it... @MappedSuperclass public abstract class AbstractPersistable<PK extends Serializable> implements Persistable<PK> { @Id @GeneratedValue(strategy = GenerationType.AUTO) private PK id; public PK getId() { return id; } protected void setId(final PK id) { this.id = id; } Subclasses: public class A extends AbstractPersistable<Long> { private String name; } public class B extends AbstractPersistable<Long> { private A a; private int value; // getter, setter // make base class setter accessible @Override @JsonSetter("id") public void setId(Long id) { super.setId(id); } } Now if there are some As in our database and we want to create a new B via the REST resource: @POST @Consumes(MediaType.APPLICATION_JSON) @Produces(MediaType.APPLICATION_JSON) @Transactional public Response create(B b) { if (b.getA().getId() == null) cry(); } with a JSON String like this {"a":{"id":"1","name":"foo"},"value":"123"}. The incoming B will have the A reference but without an ID. Is there any way to tell Jackson to either ignore the base class setter or tell it to use the subclass setter instead? I've just found out about @JsonTypeInfo but I'm not sure this is what I need or how to use it. Thanks for any help!

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  • cocoa - making a class like UIButton

    - by Mike
    For some reason that will take too much time to explain, I have to create a UIImageView based class that has some properties of a button. Imagine a class like the UISwitch (no I cannot base my class on the UISwitch) with two states, on and off. WHen the user selects one state, it runs a method like a button that was clicked and the method receives the sender id. I have already the class more or less working. The class is based on UIImageView. I am having difficulties to understand the following. WHen I create a new button I have a line that is like [myButton addTarget:self action:NSSelectorFromString(myMethod) forControlEvents:UIControlEventTouchUpInside]; This line defines a target and an action to run when the button is triggered. I my case I would need something like [myObject addTarget:self action:myMethod ifState:1] //or another thing ifState:2 I have no idea what kind of code I should put on the class to make this work. Remember that as a button the class should send the "sender" information to identify the object which triggered the action... Can you guys, transcendental gurus help? thanks.

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  • Accessing a class's containing namespace from within a module

    - by SFEley
    I'm working on a module that, among other things, will add some generic 'finder' type functionality to the class you mix it into. The problem: for reasons of convenience and aesthetics, I want to include some functionality outside the class, in the same scope as the class itself. For example: class User include MyMagicMixin end # Should automagically enable: User.name('Bob') # Returns first user named Bob Users.name('Bob') # Returns ALL users named Bob User(5) # Returns the user with an ID of 5 Users # Returns all users I can do the functionality within these methods, no problem. And case 1 (User.name('Bob')) is easy. Cases 2–4, however, require being able to create new classes and methods outside User. The Module.included method gives me access to the class, but not to its containing scope. There is no simple "parent" type method that I can see on Class nor Module. (For namespace, I mean, not superclass nor nested modules.) The best way I can think to do this is with some string parsing on the class's #name to break out its namespace, and then turn the string back into a constant. But that seems clumsy, and given that this is Ruby, I feel like there should be a more elegant way. Does anyone have ideas? Or am I just being too clever for my own good?

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  • Accessing type members outside the class in Scala

    - by Pekka Mattila
    Hi, I am trying to understand type members in Scala. I wrote a simple example that tries to explain my question. First, I created two classes for types: class BaseclassForTypes class OwnType extends BaseclassForTypes Then, I defined an abstract type member in trait and then defined the type member in a concerete class: trait ScalaTypesTest { type T <: BaseclassForTypes def returnType: T } class ScalaTypesTestImpl extends ScalaTypesTest { type T = OwnType override def returnType: T = { new T } } Then, I want to access the type member (yes, the type is not needed here, but this explains my question). Both examples work. Solution 1. Declaring the type, but the problem here is that it does not use the type member and the type information is duplicated (caller and callee). val typeTest = new ScalaTypesTestImpl val typeObject:OwnType = typeTest.returnType // declare the type second time here true must beTrue Solution 2. Initializing the class and using the type through the object. I don't like this, since the class needs to be initialized val typeTest = new ScalaTypesTestImpl val typeObject:typeTest.T = typeTest.returnType // through an instance true must beTrue So, is there a better way of doing this or are type members meant to be used only with the internal implementation of a class?

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  • JQuery collapse table cells based on class

    - by H4mm3rHead
    Hi i have a table strcture for my menu, and i need to be able to collapse/expand the menu from level2, so that all level3 cells becone visible. My HTML is like this: <table> <tr><td class="level1"><a href="abc.html">First Item</a></td></tr> <tr><td class="level2"><a href="def.html">SecondItem</a></td></tr> <tr><td class="level3"><a href="ghi.html">Third Item</a></td></tr> <tr><td class="level3"><a href="jkl.html">Fourth Item</a></td></tr> <tr><td class="level3"><a href="mno.html">Fifth Item</a></td></tr> <tr><td class="level2"><a href="pqr.html">Sixth Item</a></td></tr> <tr><td class="level2"><a href="stu.html">Seventh Item</a></td></tr> </table> How do i, when i press the level2 item i only collapse/expand the level3 items following the level2 i pushed? I only want to do this for level2, not for level 1.

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  • OnContextMenu() not working in view class

    - by Anu
    Hi, i have a popup menu for contextmenu.And i wrote the function for each menu in CMainframe. I have OnContextMenu() in each view class and in one dialog class.Its works fine in Dialog class.But not in View class.Codings are below: CMainframe funciton: void CMainFrame::OnUpdateFptrend(CCmdUI* pCmdUI) { ((CMainFrame *)AfxGetMainWnd())->SendMessage(WM_COMMAND,ID_TRENDVIEW,NULL); } void CMainFrame::OnUpdateFptuning(CCmdUI* pCmdUI) { ((CMainFrame *)AfxGetMainWnd())->SendMessageWM_COMMAND,ID_TUNINGVIEW,NULL); } Dialog class Contextmenu: void CFacePlate::OnContextMenu(CWnd* pWnd, CPoint point) { CMenu mnuPopup; mnuPopup.LoadMenu(IDR_FPMENU); CRect rBarRect; rBarRect.left = rBarRect.top = 0; rBarRect.right = 1000;rBarRect.bottom = 300; CMenu *mnuPopupMenu = mnuPopup.GetSubMenu(0); ASSERT(mnuPopupMenu); if( rBarRect.PtInRect(point) ) mnuPopupMenu->TrackPopupMenu(TPM_LEFTALIGN | TPM_RIGHTBUTTON, point.x, point.y, this); } View class: void CGroupView::OnContextMenu(CWnd* pWnd, CPoint point) { CMenu mnuPopup; mnuPopup.LoadMenu(IDR_FPMENU); CRect rBarRect; rBarRect.left = rBarRect.top = 0; rBarRect.right = 1150;rBarRect.bottom = 390; CMenu *mnuPopupMenu = mnuPopup.GetSubMenu(0); ASSERT(mnuPopupMenu); if( rBarRect.PtInRect(point) ) mnuPopupMenu->TrackPopupMenu(TPM_LEFTALIGN | TPM_RIGHTBUTTON, point.x, point.y, this); } When i press popup menu from Faceplate(Dialogclass),it goes to Mainframe function.At the same time when i press menu from any view class,it doesnot go to Mainframe function.Why its like that?

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  • Embedding Lua functions as member variables in Java

    - by Zarion
    Although the program I'm working on is in Java, answering this from a C perspective is also fine, considering that most of this is either language-agnostic, or happens on the Lua side of things. In the outline I have for the architecture of a game I'm programming, individual types of game objects within a particular class (eg: creatures, items, spells, etc.) are loaded from a data file. Most of their properties are simple data types, but I'd like a few of these members to actually contain simple scripts that define, for example, what an item does when it's used. The scripts will be extremely simple, since all fundamental game actions will be exposed through an API from Java. The Lua is simply responsible for stringing a couple of these basic functions together, and setting arguments. The question is largely about the best way to store a reference to a specific Lua function as a member of a Java class. I understand that if I store the Lua code as a string and call lua_dostring, Lua will compile the code fresh every time it's called. So the function needs to be defined somehow, and a reference to this specific function wrapped in a Java function object. One possibility that I've considered is, during the data loading process, when the loader encounters a script definition in a data file, it extracts this string, decorates the function name using the associated object's unique ID, calls lua_dostring on the string containing a full function definition, and then wraps the generated function name in a Java function object. A function declared in script run with lua_dostring should still be added to the global function table, correct? I'm just wondering if there's a better way of going about this. I admit that my knowledge of Lua at this point is rather superficial and theoretical, so it's possible that I'm overlooking something obvious.

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  • c++ passing unknown type to a function and any Class type definition

    - by user259789
    I am trying to create a generic class to write and read Objects to/from file. Called it ActiveRecord class only has one method, which saves the class itself: void ActiveRecord::saveRecord(){ string fileName = "data.dat"; ofstream stream(fileName.c_str(), ios::out); if (!stream) { cerr << "Error opening file: " << fileName << endl; exit(1); } stream.write(reinterpret_cast<const char *> (this), sizeof(ActiveRecord)); stream.close(); } now I'm extending this class with User class: class User : public ActiveRecord { public: User(void); ~User(void); string name; string lastName; }; to create and save the user I would like to do something like: User user = User(); user.name = "John"; user.lastName = "Smith" user.save(); how can I get this ActiveRecord::saveRecord() method to take any object, and class definition so it writes whatever i send it: to look like: void ActiveRecord::saveRecord(foo_instance, FooClass){ string fileName = "data.dat"; ofstream stream(fileName.c_str(), ios::out); if (!stream) { cerr << "Error opening file: " << fileName << endl; exit(1); } stream.write(reinterpret_cast<const char *> (foo_instance), sizeof(FooClass)); stream.close(); } and while we're at it, what is the default Object type in c++. eg. in objective-c it's id in java it's Object in AS3 it's Object what is it in C++??

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  • jQuery element with multiple classes: storing one class as a var

    - by Aaron
    I'm trying to create a standardized show/hide element system, like so: <div class="opener popup_1">Click Me</div> <div class="popup popup_1">I'm usually hidden</div> Clicking on the div with the opener class should show() the div with the popup class. I don't know how many opener/popup combinations I'm going to have on any given page, I don't know where on any given page the opener and the popup are going to be displayed, and I don't know how many popups a given opener should call show() for. Both the opener and the popup have to be able to have more classes than just what's used by jQuery. What I'd like to do is something like this: $(".opener").click(function() { var openerTarget = $(this).attr("class").filter(function() { return this.class.match(/^popup_([a-zA-Z0-9-_\+]*) ?$/); }); $(".popup." + openerTarget).show(); The idea is that when you click on an opener, it filters out "popup_whatever" from opener's classes and stores that as openerTarget. Then anything with class=popup and openerTarget will be shown.

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  • Get instance of type inheriting from base class, implementing interface, using StructureMap

    - by Ben
    Continuing on my quest for a good plugin implementation I have been testing the StructureMap assembly scanning features. All plugins will inherit from abstract class PluginBase. This will provide access to common application services such as logging. Depending on it's function, each plugin may then implement additional interfaces, for example, IStartUpTask. I am initializing my plugins like so: Scan(x => { x.AssembliesFromPath(HttpContext.Current.Server.MapPath("~/Plugins"), assembly => assembly.GetName().Name.Contains("Extension")); x.AddAllTypesOf<PluginBase>(); }); The difficulty I am then having is how to work against the interface (not the PluginBase) in code. It's easy enough to work with PluginBase: var plugins = ObjectFactory.GetAllInstances<PluginBase>(); foreach (var plugin in plugins) { } But specific functionality (e.g. IStartUpTask.RunTask) is tied to the interface, not the base class. I appreciate this may not be specific to structuremap (perhaps more a question of reflection). Thanks, Ben

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  • Correct way of setting a custom FileInfo class to an Iterator

    - by Gordon
    I am trying to set a custom class to an Iterator through the setInfoClass method: Use this method to set a custom class which will be used when getFileInfo and getPathInfo are called. The class name passed to this method must be derived from SplFileInfo. My class is like this (simplified example): class MyFileInfo extends SplFileInfo { public $props = array( 'foo' => '1', 'bar' => '2' ); } The iterator code is this: $rit = new RecursiveIteratorIterator( new RecursiveDirectoryIterator('/some/file/path/'), RecursiveIteratorIterator::SELF_FIRST); Since RecursiveDirectoryIterator is by inheritance through DirectoryIterator also an SplFileInfo object, it provides the setInfoClass method (it's not listed in the manual, but reflection shows it's there). Thus I can do: $rit->getInnerIterator()->setInfoClass('MyFileInfo'); All good up to here, but when iterating over the directory with foreach($rit as $file) { var_dump( $file ); } I get the following weird result object(MyFileInfo)#4 (3) { ["props"]=>UNKNOWN:0 ["pathName":"SplFileInfo":private]=>string(49) "/some/file/path/someFile.txt" ["fileName":"SplFileInfo":private]=>string(25) "someFile.txt" } So while MyFileInfo is picked up, I cannot access it's properties. If I add custom methods, I can invoke them fine, but any properties are UNKNOWN. If I don't set the info class to the iterator, but to the SplFileInfo object (like shown in the example in the manual), it will give the same UNKNOWN result: foreach($rit as $file) { // $file is a SplFileInfo instance $file->setInfoClass('MyFileInfo'); var_dump( $file->getFileInfo() ); } However, it will work when I do foreach($rit as $file) { $file = new MyFileInfo($file); var_dump( $file ); } Unfortunately, the code I a want to use this in is somewhat more complicated and stacks some more iterators. Creating the MyFileInfo class like this is not an option. So, does anyone know how to get this working or why PHP behaves this weird? Thanks.

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  • How to delete a QProcess instance correctly?

    - by Kopfschmerzen
    Hi everyone! I have a class looking like this: class FakeRunner : public QObject { Q_OBJECT private: QProcess* proc; public: FakeRunner(); int run() { if (proc) return -1; proc = new QProcess(); QStringList args; QString programName = "fake.exe"; connect(comp, SIGNAL(started()), this, SLOT(procStarted())); connect(comp, SIGNAL(error(QProcess::ProcessError)), this, SLOT(procError(QProcess::ProcessError))); connect(comp, SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(procFinished(int, QProcess::ExitStatus))); proc->start(programName, args); return 0; }; private slots: void procStarted() {}; void procFinished(int, QProcess::ExitStatus) {}; void procError(QProcess::ProcessError); } Since "fake.exe" does not exist on my system, proc emits the error() signal. If I handle it like following, my program crashes: void FakeRunner::procError(QProcess::ProcessError rc) { delete proc; proc = 0; } It works well, though, if I don't delete the pointer. So, the question is how (and when) should I delete the pointer to QProcess? I believe I have to delete it to avoid a memory leak. FakeRunner::run() can be invoked many times, so the leak, if there is one, will grow. Thanks!

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  • How to control CSS class applied to ASP.NET 4 Menu with RenderingMode=List

    - by Joe
    I am using an ASP.NET 4.0 Menu control with RenderingMode=List and am struggling with creating the appropriate CSS. Each menu item is represented by an <li tag that contains a nested <a tag with what appear to be fixed class names: <a class="level1" for unselected level 1 menu items <a class="level2" for unselected level 2 menu items <a class="level1 selected" for the selected level 1 menu item ... etc... What I want to do is to is to prevent the currently selected menu item from being "clickable". To do so I tried using: if (menuItem.Selected) menuItem.Selectable = false; This has the desired effect of removing the href attribute from the <a tag but also removes the class attribute - and as a result my CSS can not identify what level the menu item belongs to! Looks to me like a possible bug, but in any case I can't find any documentation describing what CSS class names are used, nor whether there is any way to control this (the old Style properties don't appear to have any effect). Ideally I would like to have "level" class attributes on the <li tags, not just the nested <a tags.

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  • NoClassDefFoundError without any class name

    - by Safder
    Hello, I am trying to run a java task from ant. I am trying to run the "org.apache.tools.ant.launch.Launcher" class. I keep on getting the "NoClassDefFoundError" without any class name being specified. I am also getting a "ClassNotFoundException" along with that displaying a message "Could not find the main class: . Program will exit". Here's a snippet of the error [java] Exception in thread "main" java.lang.NoClassDefFoundError: [java] Caused by: java.lang.ClassNotFoundException: [java] at java.net.URLClassLoader$1.run(URLClassLoader.java:200) [java] at java.security.AccessController.doPrivileged(Native Method) [java] at java.net.URLClassLoader.findClass(URLClassLoader.java:188) [java] at java.lang.ClassLoader.loadClass(ClassLoader.java:307) [java] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) [java] at java.lang.ClassLoader.loadClass(ClassLoader.java:252) [java] at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) [java] Could not find the main class: . Program will exit. [java] Java Result: 1 Now I am trying to run an ant class from an ant jar and i specifiy the classpath where this class file resides using the "classpathref" attribute, however I still get this message. I checked the ant jar to check the Manifest and the "main" class is specified properly (it's "org.apache.tools.ant.launch.Launcher") . I have exhausted all my resources. Please help ! ! ! ps: My environment is Eclipse on Ubuntu 9.04

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  • Using unset member variables within a class or struct

    - by Doug Kavendek
    It's pretty nice to catch some really obvious errors when using unset local variables or when accessing a class or struct's members directly prior to initializing them. In visual studio 2008 you get an "uninitialized local variable used" warning at compile-time and get a run-time check failure at the point of access when debugging. However, if you access an uninitialized struct's member variable through one of its functions, you don't get any warnings or assertions. Obviously the easiest solution is don't do that, but nobody's perfect. For example: struct Test { float GetMember() const { return member; } float member; }; Test test; float f1 = test.member; // Raises warning, asserts in VS debugger at runtime float f2 = test.GetMember(); // No problem, just keeps on going This surprised me, but it makes some sense -- the compiler can't assume calling a function on an unused struct is an error, or how else would you initialize or construct it? And anything fancier just quickly brings up so many other complications that it makes sense that it wouldn't bother classifying which functions are ok to call and when, especially just as a debugging help. I know I can set up my own assertions or error checking within the class itself, but that can complicate some simpler structs. Still, it would seem like within the context of the function call, wouldn't it know insides GetMember() that member wasn't initialized yet? I'm assuming it's not only relying on static compile-time deduction, given the Run-Time Check Failure #3 it raises during execution, so based on my current understanding of it it would seem reasonable for the same checks to apply. Is this just a limitation of this specific compiler/debugger (Visual Studio 2008), or more tied to how C++ works?

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  • c# delegate and abstract class

    - by BeraCim
    Hi all: I currently have 2 concrete methods in 2 abstract classes. One class contains the current method, while the other contains the legacy method. E.g. // Class #1 public abstract class ClassCurrent<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllRootNodes(int i) { //some code } } // Class #2 public abstract class MyClassLegacy<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllLeafNodes(int j) { //some code } } I want the corresponding method to run in their relative scenarios in the app. I'm planning to write a delegate to handle this. The idea is that I can just call the delegate and write logic in it to handle which method to call depending on which class/project it is called from (at least thats what I think delegates are for and how they are used). However, I have some questions on that topic (after some googling): 1) Is it possible to have a delegate that knows the 2 (or more) methods that reside in different classes? 2) Is it possible to make a delegate that spawns off abstract classes (like from the above code)? (My guess is a no, since delegates create concrete implementation of the passed-in classes) 3) I tried to write a delegate for the above code. But I'm being technically challenged: public delegate List GetAllNodesDelegate(int k); GetAllNodesDelegate del = new GetAllNodesDelegate(ClassCurrent.GetAllRootNodes); I got the following error: An object reference is required for the non-static field, method, property ClassCurrent<BaseNode>.GetAllRootNodes(int) I might have misunderstood something... but if I have to manually declare a delegate at the calling class, AND to pass in the function manually as above, then I'm starting to question whether delegate is a good way to handle my problem. Thanks.

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  • Ruby on rails form variables as array items

    - by Francois
    I have a simple form with text input and text area, but when I submit it the variables seems to be array items instead of just string values? the form <%= form_tag(home_kontak_path, :remote => true) do %> <label>Jou epos adres</label> <%= text_field(:epos, "", :placeholder => "Jou epos adres", :id => "epos", :class => "input-block-level") %> <label>Boodskap hier</label> <%= text_area(:boodskap, "", :rows => "5", :placeholder => "Boodskap hier...", :id => "boodskap", :class => "input-block-level") %> <%= submit_tag "submit" %> <% end %> console output Started POST "/home/kontak" for 127.0.0.1 at 2012-11-23 11:53:03 +0200 Processing by HomeController#kontak as JS Parameters: {"utf8"=>"?", "authenticity_token"=>"i+5UWaQeBu7LYGPFBNAbum+67VzyyC82JN2wMlLc/UU=", "epos"=>["text box value"], "boodskap"=>["text area value"], "commit"=>""} what i would like it to be instead of "epos"=["text box value"] i want it to return "epos"="text box value"

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  • templete class c++

    - by inna karpasas
    hi! i try to design a templete for my universty project. i wrote the follwing cod: #ifndef _LinkedList_H_ #define _LinkedList_H_ #include "Link.h" #include <ostream> template <class L>//error one class LinkedList { private: Link<L> *pm_head; Link<L> * pm_tail; int m_numOfElements; Link<L>* FindLink(L * dataToFind); public: LinkedList(); ~LinkedList(); int GetNumOfElements(){return m_numOfElements;} bool Add( L * data); L *FindData(L * data); template <class L> friend ostream & operator<<(ostream& os,const LinkedList<L> listToprint);//error two L* GetDataOnTop(); bool RemoveFromHead(); L* Remove(L * toRemove); this templete uses the link class templete #ifndef _Link_H_ #define _Link_H_ template <class T>//error 3 class Link { private: T* m_data; Link* m_next; Link* m_prev; public: Link(T* data); ~Link(void); bool Link::operator ==(const Link& other)const; /*getters*/ Link* GetNext()const {return m_next;} Link* GetPrev()const {return m_prev;} T* GetData()const {return m_data;} //setters void SetNext(Link* next) {m_next = next;} void SetPrev(Link* prev) {m_prev = prev;} void SetData(T* data) {m_data = data;} }; error one: shadows template parm class L' error two:declaration ofclass L' error three: shadows template parm `class T' i dont understand what is the problem. i can relly usr your help thank you :)

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  • Passing variables to a Custom Zend Form Element

    - by user322003
    Hi, I'm trying to create a custom form element which extends Zend_Form_Element_Text with a validator (so I don't have to keep setting up the validator when I use certain elements). Anyway, I'm having trouble passing $maxChars variable to it when I instantiate it in my Main form. I've provided my shortened code below This is my custom element below class My_Form_Custom_Element extends Zend_Form_Element_Text { public $maxChars public function init() { $this->addValidator('StringLength', true, array(0, $this->maxChars)) } public function setProperties($maxChars) { $this->maxChars= $maxChars; } } This is where I instantiate my custom form element. class My_Form_Abc extends Zend_Form { public function __construct($options = null) { parent::__construct($options); $this->setName('abc'); $customElement = new My_Form_Custom_Element('myCustomElement'); $customElement->setProperties(100); //**<----This is where i set the $maxChars** $submit = new Zend_Form_Element_Submit('submit'); $submit -> setAttrib('id', 'submitbutton'); $this->addElements(array($customElement ,$submit)); } } When I try to pass '100' using $customElement-setProperties(100) in my Form, it doesnt get passed properly to my StringLength validator. I assume it's because the validator is getting called in Init? How can I fix this?

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  • Choosing between instance methods and separate functions?

    - by StackedCrooked
    Adding functionality to a class can be done by adding a method or by defining a function that takes an object as its first parameter. Most programmers that I know would choose for the solution of adding a instance method. However, I sometimes prefer to create a separate function. For example, in the example code below Area and Diagonal are defined as separate functions instead of methods. I find it better this way because I think these functions provide enhancements rather than core functionality. Is this considered a good/bad practice? If the answer is "it depends", then what are the rules for deciding between adding method or defining a separate function? class Rect { public: Rect(int x, int y, int w, int h) : mX(x), mY(y), mWidth(w), mHeight(h) { } int x() const { return mX; } int y() const { return mY; } int width() const { return mWidth; } int height() const { return mHeight; } private: int mX, mY, mWidth, mHeight; }; int Area(const Rect & inRect) { return inRect.width() * inRect.height(); } float Diagonal(const Rect & inRect) { return std::sqrt(std::pow(static_cast<float>(inRect.width()), 2) + std::pow(static_cast<float>(inRect.height()), 2)); }

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  • Class unloading in java

    - by java_geek
    When a classloader is garbage collected, are the classes loaded by it unloaded? When the JVM is running is verbose mode, all the loaded classes are o/p. Similarly will the JVM log when it unloads a class? I wrote a custom class loader to test this, but could not see any verbose log for unloading of the classes. CustomClassLoader loader = new CustomClassLoader(new URL[]{}, CustomClassLoader.class.getClassLoader()); loader.addURL("D:\workspace\ClassLoaderTest\implementation.jar"); Class c = null; try { c = Class.forName("Horse",false,loader); if (c != null) { try { Animal animal = (Animal)c.newInstance(); animal.eat(); } catch(Exception ex) { ex.printStackTrace(); } } } catch(Exception e) { e.printStackTrace(); } loader = null; byte[] b = new byte[58*1024*1024]; System.gc(); ClassLoadingMXBean clBean = ManagementFactory.getClassLoadingMXBean(); System.out.println("Number of classes currently loaded " + clBean.getLoadedClassCount()); System.out.println("Number of classes loaded totally " + clBean.getTotalLoadedClassCount()); System.out.println("Number of classes unloaded " + clBean.getUnloadedClassCount()); Even the ClassLoadingMXBean gives number of unloaded classes as 0. How can i know that a class is unloaded when the class loader is GCed?

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  • The new operator in C# isn't overriding base class member

    - by Dominic Zukiewicz
    I am confused as to why the new operator isn't working as I expected it to. Note: All classes below are defined in the same namespace, and in the same file. This class allows you to prefix any content written to the console with some provided text. public class ConsoleWriter { private string prefix; public ConsoleWriter(string prefix) { this.prefix = prefix; } public void Write(string text) { Console.WriteLine(String.Concat(prefix,text)); } } Here is a base class: public class BaseClass { protected static ConsoleWriter consoleWriter = new ConsoleWriter(""); public static void Write(string text) { consoleWriter.Write(text); } } Here is an implemented class: public class NewClass : BaseClass { protected new static ConsoleWriter consoleWriter = new ConsoleWriter("> "); } Now here's the code to execute this: class Program { static void Main(string[] args) { BaseClass.Write("Hello World!"); NewClass.Write("Hello World!"); Console.Read(); } } So I would expect the output to be Hello World! > Hello World! But the output is Hello World Hello World I do not understand why this is happening. Here is my thought process as to what is happening: The CLR calls the BaseClass.Write() method The CLR initialises the BaseClass.consoleWriter member. The method is called and executed with the BaseClass.consoleWriter variable Then The CLR calls the NewClass.Write() The CLR initialises the NewClass.consoleWriter object. The CLR sees that the implementation lies in BaseClass, but the method is inherited through The CLR executes the method locally (in NewClass) using the NewClass.consoleWriter variable I thought this is how the inheritance structure works? Please can someone help me understand why this is not working?

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  • Unit Testing Private Method in Resource Managing Class (C++)

    - by BillyONeal
    I previously asked this question under another name but deleted it because I didn't explain it very well. Let's say I have a class which manages a file. Let's say that this class treats the file as having a specific file format, and contains methods to perform operations on this file: class Foo { std::wstring fileName_; public: Foo(const std::wstring& fileName) : fileName_(fileName) { //Construct a Foo here. }; int getChecksum() { //Open the file and read some part of it //Long method to figure out what checksum it is. //Return the checksum. } }; Let's say I'd like to be able to unit test the part of this class that calculates the checksum. Unit testing the parts of the class that load in the file and such is impractical, because to test every part of the getChecksum() method I might need to construct 40 or 50 files! Now lets say I'd like to reuse the checksum method elsewhere in the class. I extract the method so that it now looks like this: class Foo { std::wstring fileName_; static int calculateChecksum(const std::vector<unsigned char> &fileBytes) { //Long method to figure out what checksum it is. } public: Foo(const std::wstring& fileName) : fileName_(fileName) { //Construct a Foo here. }; int getChecksum() { //Open the file and read some part of it return calculateChecksum( something ); } void modifyThisFileSomehow() { //Perform modification int newChecksum = calculateChecksum( something ); //Apply the newChecksum to the file } }; Now I'd like to unit test the calculateChecksum() method because it's easy to test and complicated, and I don't care about unit testing getChecksum() because it's simple and very difficult to test. But I can't test calculateChecksum() directly because it is private. Does anyone know of a solution to this problem?

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