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  • Confused about "override" vs. "new" in C#

    - by iTayb
    I'm having the following classes: class Base { public virtual void Print() { Console.WriteLine("Base"); } } class Der1 : Base { public new virtual void Print() { Console.WriteLine("Der1"); } } class Der2 : Der1 { public override void Print() { Console.WriteLine("Der2"); } } This is my main method: Base b = new Der2(); Der1 d1 = new Der2(); Der2 d2 = new Der2(); b.Print(); d1.Print(); d2.Print(); The output is Base, Der2, Der2. As far as I know, Override won't let previous method to run, even if the pointer is pointing to them. So the first line should output Der2 as well. However Base came out. How is it possible? How the override didn't work there?

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  • bulk update/delete entities of different kind in db.run_in_transaction

    - by Ray Yun
    Here goes pseudo code of bulk update/delete entities of different kind in single transaction. Note that Album and Song entities have AlbumGroup as root entity. class AlbumGroup: pass class Album: group = db.ReferenceProperty(reference_class=AlbumGroup,collection_name="albums") class Song: album = db.ReferenceProperty(reference_class=Album,collection_name="songs") def bulk_update_album_group(album_group): updated = [album_group] deleted = [] for album in album_group.albums: updated.append(album) for song in album.songs: if song.is_updated: updated.append(song) if song.is_deleted: deleted.append(song) db.put(updated) db.delete(deleted) a = AlbumGroup.all().filter("...").get() # bulk update/delete album group. for simplicity, album cannot be deleted. db.run_in_transaction(bulk_update_album_group,a) But I met a famous "Only Ancestor Queries in Transactions" error at the iterating reference properties like album.songs or album_group.albums. I guess ancestor() filter does not help because those entities are modified in memory. Should I not to iterate reference property in transaction function and always provide them as function parameters like def bulk_update_album_group(updated,deleted): ??? Is there any good coding pattern for this situation?

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  • Polymorphic classes in templates

    - by soxarered
    Let's say we have a class hierarchy where we have a generic Animal class, which has several classes directly inherit from it (such as Dog, Cat, Horse, etc..). When using templates on this inheritance hierarchy, is it legal to just use SomeTemplateClass<Animal> and then shove in Dogs and Cats and Horses into this templated object? For example, assume we have a templated Stack class, where we want to host all sorts of animals. Can I simply state Stack<Animal> s; Dog d; s.push(d); Cat c; s.push(c);

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  • having trouble with a mysql query

    - by chuck akers
    this keeps saying Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in directory here the error is near the login_query variable, can someone help me fix it. <?php if (isset($_POST['login_username'], $_POST['login_password'])) { $login_username = trim(mysql_real_escape_string(htmlentities($_POST['login_username']))); $login_password = md5(trim(mysql_real_escape_string(htmlentities($_POST['login_password'])))); if (!empty($login_username) && !empty($login_password)) { $login_query = mysql_query("SELECT user_id FROM username WHERE username='".$login_username."' AND password='".$login_password."'"); if (mysql_num_rows($login_query)==1) { $user_id = mysql_result($login_query, 0, 'user_id'); $_SESSION['user_id'] = $user_id; header('Location: index.php'); die(); } }} ?

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  • Dynamically load a type from an external assembly

    - by Water Cooler v2
    From managed code, how do I load a managed type from another assembly at runtime, assuming the calling code does not have a static reference to the assembly? To clarify, let's say I have class Lib in Lib.cs compiled into Lib.dll. I want to write a class Foo in a separate assembly called Foo.dll, that does not have a reference to Lib.dll statically, but instead loads Lib.dll and then reflects on for the presence of the class Lib and then calls a method on it. Sorry for such an obvious question on Reflection. I figure it'll take much lesser time to get the answer on a forum that to read a few articles.

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  • Best way to test instance methods without running __init__

    - by KenFar
    I've got a simple class that gets most of its arguments via init, which also runs a variety of private methods that do most of the work. Output is available either through access to object variables or public methods. Here's the problem - I'd like my unittest framework to directly call the private methods called by init with different data - without going through init. What's the best way to do this? So far, I've been refactoring these classes so that init does less and data is passed in separately. This makes testing easy, but I think the usability of the class suffers a little. EDIT: Example solution based on Ignacio's answer: import types class C(object): def __init__(self, number): new_number = self._foo(number) self._bar(new_number) def _foo(self, number): return number * 2 def _bar(self, number): print number * 10 #--- normal execution - should print 160: ------- MyC = C(8) #--- testing execution - should print 80 -------- MyC = object.__new__(C) MyC._bar(8)

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  • Can't run the ActionBarCompat sample

    - by David Miler
    I am having trouble compiling and running the ActionBarCompat sample of Android 16. I have API level 16 as the build target selected, which seems to build fine, but when I try to debug these errors pop up. Of course I could change the min API level in the manifest, but what would be the point of that? I have made no changes to the sample, so how come it is not working properly? Class requires API level 14 (current min is 3): android.view.ActionProvider SimpleMenuItem.java /ActionBarCompat/src/com/example/android/actionbarcompat line 129 Android Lint Problem Class requires API level 14 (current min is 3): android.view.ActionProvider SimpleMenuItem.java /ActionBarCompat/src/com/example/android/actionbarcompat line 134 Android Lint Problem Class requires API level 14 (current min is 3): android.view.MenuItem.OnActionExpandListener SimpleMenuItem.java /ActionBarCompat/src/com/example/android/actionbarcompat line 155 Android Lint Problem I am thoroughly confused, any help would be appreciated.

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  • Receive messages for derived types in MVVMLight

    - by Hrvoje
    Shouldn't this test pass: [TestMethod] public void derived_message_subscription() { bool handled = false; Messenger.Default.Register<GenericMessage<baseClass>>(this, true, (msg) => handled = true); Messenger.Default.Send(new GenericMessage<testClass>(new testClass())); Assert.IsTrue(handled); } public abstract class baseClass { } public class testClass : baseClass { } I have to receive all messages for classes that inherits from one base class. MVVMLight has bool property receiveDerivedMessagesToo in Register method, but it seems to me that it isn't working.

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  • indicate tuncation in ToolTipStatusLabel automatically

    - by harper
    I have a .NET application with a StatusStrip holding three ToolTipStatusLabels. The Text of the labels are filled from the application as they show the status. For some circumstances they can hold an empty text. When I resize the window, the ToolTipStatusLabels are hidden when they cannot be fit in the StatusStrip. I would like to have the text truncated when the label cannot be fit in the StatusStrip. The default behavior to hide the label makes it difficult to distinguish between empty text or hidden label. To indicate that the text is truncated automatically, this should be indicated with an ellipsis (...). How can this be done?

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  • Does AsEnumerable() cache all result (LINQ)

    - by Akshay
    When we call a query operator on a sequence, a sequence-specific operator gets called. I mean if i call Where<>() operator on IEnumerable<>, the operator that will be called will be defined in Enumerable class and if it's called on IQueryable<>, the one defined in Queryable class will be called. Consider the operator Reverse, defined in the Enumerable class. If i want to call it on Iqueryable<> then I must use the AsEnumerable<>() operator to first convert it into IEnumerable<>. db.Countries.OrderBy(cntry=>cntry.CountryName).AsEnumerable().Reverse() But the Reverse operator got to have all records at the same time so that it can reverse them. In the above code do all the records get loaded in memory first and then the Reverse() operator is reversing it ?

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  • undefined reference to static member variable

    - by Max
    Hi. I have this class that has a static member. it is also a base class for several other classes in my program. Here's its header file: #ifndef YARL_OBJECT_HPP #define YARL_OBJECT_HPP namespace yarlObject { class YarlObject { // Member Variables private: static int nextID; // keeps track of the next ID number to be used int ID; // the identifier for a specific object // Member Functions public: YarlObject(): ID(++nextID) {} virtual ~YarlObject() {} int getID() const {return ID;} }; } #endif and here's its implementation file. #include "YarlObject.hpp" namespace yarlObject { int YarlObject::nextID = 0; } I'm using g++, and it returns three undefined reference to 'yarlObject::YarlObject::nextID linker errors. If I change the ++nextID phrase in the constructor to just nextID, then I only get one error, and if I change it to 1, then it links correctly. I imagine it's something simple, but what's going on?

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  • Problem overridding virtual function

    - by William
    Okay, I'm writing a game that has a vector of a pairent class (enemy) that s going to be filled with children classes (goomba, koopa, boss1) and I need to make it so when I call update it calls the childclasses respective update. I have managed to create a example of my problem. #include <stdio.h> class A{ public: virtual void print(){printf("Hello from A");} }; class B : public A{ public: void print(){printf("Hello from B");} }; int main(){ A ab = B(); ab.print(); while(true){} } Output wanted: "Hello from B" Output got: "Hello from A" How do I get it to call B's print function?

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  • JQuery Validation Plugin not working when used on page that includes another page via AJAX

    - by droidy
    We have a long page that contains a bunch of different form elements. One part of the form is called remotely via AJAX and is populated in an empty div. This is the part which JQuery Validation plugin is not working correctly on. We have class="required" on the elements on this page, but they do not show up as required. I'm guessing it's because the Validation plugin is looking for class="required" on our main page, and since the content from the AJAX page is put into the empty div behind the scenes, it's not detected the required fields. Any help is greatly appreciated.

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  • what the java command's -jar option really does

    - by JBoy
    Does the -jar option of the java command also compile the sources before running the main method? I believe so but i would like to have a better understanding of the internal process, from the man page you can clearly see a small workflow sequence: -jar Execute a program encapsulated in a JAR file. The first argument is the name of a JAR file instead of a startup class name. In order for this option to work, the manifest of the JAR file must contain a line of the form Main-Class: classname. Here, classname identifies the class having the public static void main(String[] args) method that serves as your application's starting point. See the Jar tool reference page and the Jar trail of the Java Tutorial @ But it does not mention that it compiles the sources.

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  • scroll bar in textareas

    - by Hulk
    Int the following code, The scroll bar appears in IE and in mozilla it doesnt,how is this to be fixed,scroll bar should not appear where there is not much of data. <script> var row= '<table><tr>'; row = '<tr class="display_row"">'; row += '<td class="display_col" wrap width="75"><b><textarea rows = "8" cols = "18" border ="1" class="input" style="border: none;overflow:visible;width:95%;" readonly maxlength="5">Name selected is Tom </textarea>'; row+='</td></tr></table>'; </script>

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  • jsp update request happens to be invoked by a link

    - by Akshatha
    <tr class="bg-row1"> <td class="td-highlighted-2"> <div align="left"><a href="<%=contextPath%>/jsp/admin/UpdateProject.jsp"><%=searchList1.getProjid()%></a></div> </td> <td class="td-highlighted-2"> <div align="left"><%=searchList1.getProjname()%></div> </td> </tr> here jsp update request happens to be invoked by a link in updateproject.jsp how can i refer projid and projname value in a text box

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  • When is it safe to do a Response.Redirect() without throwing an exception?

    - by DDechant
    I have an intermediary class extending System.Web.UI.Page for all of my pages that require authentication. The class mostly does custom authentication handling. When a user with insufficient access attempts to visit a page, I try to redirect the user back to the login page while preventing any further page events from being executed (ie. Page_load). The first solution that came to mind was the default implementation of Response.Redirect. Of course the downside to this is the possibility of ThreadAbortExceptions being thrown. So my question is this: When (if at all) during the page life cycle is it actually safe to execute Response.Redirect() without ThreadAbortException ever being thrown? public class CustomPage : System.Web.UI.Page { protected override void OnInit(EventArgs e) { base.OnInit(e); if (!IsValid()) Response.Redirect("login.aspx", true); } }

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  • how to use multiple $_name using extends Zend_Db_Table_Abstract in zend frame work.

    - by karthik
    we tried to give our tables(users,messages) like this in two different abstract classes but it is not working. This is included in a file childconnect1.php ,is there any relation between the file name(childconnect1.php) and the class(Application_Model_childconnect1). class Application_Model_childconnect1 extends Zend_Db_Table_Abstract { protected $_name = 'users'; public function loginvalidation($username,$pwd) { $row = $this->fetchRow('UserName = \'' . $username . '\'and UserPW = \''. $pwd . '\''); if (!$row) { $msg="invalid"; return $msg; } else { return $row->toArray(); } } } class Application_Model_childconnect2 extends Zend_Db_Table_Abstract { protected $_name = 'messages'; public function replymessage($message) { $data=array( 'MessageText'=>$message ); $this->insert($data); } }

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  • has_many relation doesn't seems right or logical, some thing like belongs_to_many looks right

    - by Vijendra
    My situation is like this. Company has many users and users may belongs to many companies. And current implementation is something like below. class Company has_many :employments has_many :users, :through = :employments end class Employment belongs_to :company belongs_to :user end class User has_many :employments has_many :companies, :through = :employments #This doesn't looks correct end User has many companies doesn't looks logically meaningful.It must be some thing like belongs_to_many companies. Do I need to use has_and_belongs_to_many? But that also will gives the same meaning. Can some one please suggest the right way for representing these relationships?

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  • How to make pytest display a custom string representation for fixture parameters?

    - by Björn Pollex
    When using builtin types as fixture parameters, pytest prints out the value of the parameters in the test report. For example: @fixture(params=['hello', 'world'] def data(request): return request.param def test_something(data): pass Running this with py.test --verbose will print something like: test_example.py:7: test_something[hello] PASSED test_example.py:7: test_something[world] PASSED Note that the value of the parameter is printed in square brackets after the test name. Now, when using an object of a user-defined class as parameter, like so: class Param(object): def __init__(self, text): self.text = text @fixture(params=[Param('hello'), Param('world')] def data(request): return request.param def test_something(data): pass pytest will simply enumerate the number of values (p0, p1, etc.): test_example.py:7: test_something[p0] PASSED test_example.py:7: test_something[p1] PASSED This behavior does not change even when the user-defined class provides custom __str__ and __repr__ implementations. Is there any way to make pytest display something more useful than just p0 here? I am using pytest 2.5.2 on Python 2.7.6 on Windows 7.

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  • Why my WCF Service returns xml serialized objects?

    - by user294554
    Hi, I'm new here and I hope anyonte can help me. I have WCF Service and Windows Forms working with this client written in VB.NET. The Service class started to return xml serialized objects, but all my classes on Service side are DataContract-s and the service class is DataContractFormat. I googled everywhere about serializations and I couldn't find reason why it started to do that. I checked my classes and service, app.config file, but I couldn't find anything. I checked Reference.vb class, and it's System.Xml.Serialization.XmlElementAttribute everywhere. The question may seem dummy, but I really don't know what to do. I just want to know what can cause the service to act like that. Thank you.

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  • Pattern for database-wrapper in java

    - by Space_C0wb0y
    I am currently writing a java-class that wraps an SQLite database. This class has two ways to be instantiated: Open an existing database. Create a new database. This is what I cam up with: public class SQLiteDatabaseWrapper { public static SQLiteDatabaseWrapper openExisting(File PathToDB) { return new SQLiteDatabaseWrapper(PathToDB); } public static SQLiteDatabaseWrapper createNew(File PathToDB) { CreateAndInitializeNewDatabase(PathToDB); return new SQLiteDatabaseWrapper(PathToDB); } private SQLiteDatabaseWrapper(File PathToDB) { // Open connection and setup wrapper } } Is this the way to go in Java, or is there any other best practice for this situation?

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  • frameworks for coding a php library?

    - by ajsie
    there are plenty of frameworks for coding MVC web applications. this time im going to code a library (think of Doctrine or Solr) with a bunch of class files. u just include a bootstrap or a class file and you are ready to use my classes. i have never tried to code a library before and intend to code one for learning purpose so that i can use various design patterns i have learned. are there any great frameworks for this, how i should organize the different class files, where i can put configuration files and so on? tutorials or other information would be great too. thanks

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  • Casting objects to Integer,string ,...

    - by Milan
    Hello everybody! I have one small problem. I have list of types(int,string,..) ArrayList<Class> typeList; and I have some input values; ArrayList<Object> values; How to cast some value to some type if I know which type from the typeList is the values; typeList.get(i).cast(values.get(i)); <- this is not working??? Actualy I generate dynamic form in runtime. With Java reflection I get parameterTypes from methods from some class, I generate form with input fields and then i want to cast the text from the input fields to specific types from the paramterTypes that I got with Java reflection from some class.

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  • C++ operator overloading doubt

    - by avd
    I have a code base, in which for Matrix class, these two definitions are there for () operator: template <class T> T& Matrix<T>::operator() (unsigned row, unsigned col) { ...... } template <class T> T Matrix<T>::operator() (unsigned row, unsigned col) const { ...... } One thing I understand is that the second one does not return the reference but what does const mean in the second declaration. Also which function is called when I do say mat(i,j)

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