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  • Is inheritance bad nowadays?

    - by mafutrct
    Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

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  • How To Write Selenium Xpath

    - by user3690563
    I am Struck here. I am Trying a write Xpath for the Code in the image. I am Trying to click Browse TAB. Where the ID is changing every time. Help me guys. Thanks you in Advance I have tried this as my Xpath //*[@id='ext-gen43']/em/span/span <a id="ext-gen43" class="x-tab-right" href="#"> <em class="x-tab-left"> <span class="x-tab-strip-inner"> <span class="x-tab-strip-text ">Browse</span> </span> </em> </a>

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  • C++ interview question

    - by benjamin button
    as i am not an expert in c++,i was not aware of the answer to this question asked in one of the interviews. lets say there is a base class pointer which is pointing to a base class object: baseclass *bptr; bptr= new baseclass; now if i do bptr= new derived; what is the problem here?

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  • ZF2 namespace and file system

    - by user1918648
    I have standard Application module in ZF2. It's configured by default, I didn't change anything. I just added some stuff: module/ Application/ src/ Application/ Entity/ Product/ **Product.php** Controller/ **IndexController.php** Product.php namespace Application\Entity; class Product { } IndexController.php namespace Application\Controller; use Zend\Mvc\Controller\AbstractActionController; use Zend\View\Model\ViewModel; use Application\Entity\Product; class IndexController extends AbstractActionController { public function indexAction() { $product = new Product(); } } and I get following error: Fatal error: Class 'Application\Entity\Product' not found in \module\Application\src\Application\Controller\IndexController.php on line 20 I use the same namespace, but it doesn't see it. Why? P.S: If I will change Product.php to be the following: namespace Application\Entity\Product; class Product { } then in the IndexController.php the following code will be working: namespace Application\Controller; use Zend\Mvc\Controller\AbstractActionController; use Zend\View\Model\ViewModel; use Application\Entity\Product\Product; class IndexController extends AbstractActionController { public function indexAction() { $product = new Product(); } }

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  • Inferring type from method generics

    - by ng
    I am from a Java background and I am looking from the equivalent in c# for the following. public interface Reader { <T> T read(Class<? extends T> type); } Such that I can do the following, constraining the parameter and inferring the return type. Cat cat = reader.read(Cat.class); Dog dog = reader.read(Dog.class); I was hoping something like this would work in c# but I am not sure it will. public interface Reader { T Read<T>(); } And and do this. public class TypeReader : Reader { public T Read<T>() { Type type = T.GetType(); ... } } Is something like this even possible in c#?

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  • Listening to PHP function calls to intercept the returned value

    - by Lansen Q
    I am working on making use of a Web Services API offered by the hosts of our internal system. I am accessing it via PHP with the built-in SOAP offering. The API session is initiated by a remote call to a function that returns some session tokens; every call to any function thereafter will return a new session token, which must accompany the next request. I have an API Client class that is doing the bulk of the work; what I would like to do is to set something up whereby any SOAP call that is made will make sure to update the API Client class' $session variable with the new session details, and then pass the data along. So far the only way I can think of doing this is creating a new class extending the SoapClient class, with a __call function wrapper to execute the function, update the new session token, and return the results nonetheless. I'm not sure that this will a) work b) be the best way to go about this. The wrapper class would be identical to making a SOAP call, and it would return an identical result, just it would update the session token before you get your result back. Thanks! Hope I explained myself properly.

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  • PHP preg_match image between html tags

    - by Alvins
    I've got an html template like this: <div class="cont"> <div class="..."> <p>...<p> <img alt="" class="popup" src="DESIRED IMAGE LINK" style="..." /></p><p>...</p> .... And i want to extract "DESIRED IMAGE LINK" inside the "" tag, currently i'm using this: $pattern = '<div class="cont">.*?src=["\']?([^"\']?.*?(png|jpg|jpeg|gif))["\']?/i'; if (preg_match($pattern, $content, $image)) ..... But it doesn't work, the error is: warning: preg_match() [function.preg-match]: Unknown modifier '.' How can i fix it? Thanks

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  • Activerecord default accessors & unusual requirements

    - by JP
    I have an ActiveRecord::Base class which needs to have a field that is automatically generated when a new instance is made. How should I go about doing this? By defining an initialize function? class Thing < ActiveRecord::Base # 'special' (integer) needs to be set to lowest unused number (above 0) # considering that random rows will be removed via other processes end This is as far as I've got! Any ideas?

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  • "Add another item" form functionality

    - by GSTAR
    I have a form that lets a user enter their career history - it's a very simple form with only 3 fields - type (dropdown), details (textfield) and year (dropdown). Basically I want to include some dynamic functionality whereby the user can enter multiple items on the same page and then submit them all in one go. I had a search on Google and found some examples but they were all based on tables - my markup is based on DIV tags: <div class="form-fields"> <div class="row"> <label for="type">Type</label> <select id="type" name="type"> <option value="Work">Work</option> </select> </div> <div class="row"> <label for="details">Details</label> <input id="details" type="text" name="details" /> </div> <div class="row"> <label for="year">Year</label> <select id="year" name="year"> <option value="2010">2010</option> </select> </div> </div> So basically the 3 DIV tags with class "row" need to be duplicated, or to simplify things - the div "form-fields" could just be duplicated. I am also aware that the input names would have to converted to array format. Additionally each item will require a "remove" button. There will be a main submit button at the bottom which submits all the data. Anyone got an elegant solution for this?

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  • NHibernate not dropping foreign key constraints.

    - by Kendrick
    I'm new to NHibernate, so this is probably my mistake, but when I use: schema.Create(true, true); I get: SchemaExport [(null)]- There is already an object named 'XXX' in the database. System.Data.SqlClient.SqlException: There is already an object named 'XXX' in the database. I grabbed the SQL code nHibernate was using, ran it directly from MSSMS, and recieved similar errors. Looking into it, the generated code is not properly dropping the foreign key constraints. The drop looks like this: if exists (select 1 from sysobjects where id = OBJECT_ID(N'dbo[FK22212EAFBFE4C58]') AND parent_obj = OBJECT_ID('YYY')) alter table dbo.YYY drop constraint FK22212EAFBFE4C58 Doing a "select OBJECT_ID(N'dbo[FK22212EAFBFE4C58]')" I get null. If I take out the "dbo" (i.e. "select OBJECT_ID(N'[FK22212EAFBFE4C58]')") then the ID is returned. So, my question is, why is nHibernate adding the dbo, and why does that prevent the object from being returned (since the table owning the constraint is dbo.XXX) One of my mapping files: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping namespace="CanineApp.Model" assembly="CanineApp.Model" xmlns="urn:nhibernate-mapping-2.2"> <class name="MedicalLog" table="MedicalLog" schema="dbo"> <id name="MedicalLogID" type="Int64"> <generator class="identity" /> </id> <property name="InvoiceAmount" type="Decimal" not-null="true" /> ... <many-to-one name="Canine" class="Canine" column="CanineID" not-null="true" fetch="join" /> <many-to-one name="TreatmentCategory" class="TreatmentCategory" column="TreatmentCategoryID" not-null="true" access="field.camelcase-underscore" /> </class> </hibernate-mapping>

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  • A strange error in java generic.

    - by ???
    This is ok: Class<? extends String> stringClass = "a".getClass(); But this gets error: <T> void f(T obj) { Class<? extends T> objClass = obj.getClass(); } I know I can cast it like: <T> void f(T obj) { @SuppressWarnings("unchecked") Class<? extends T> objClass = (Class<? extends T>) obj.getClass(); } But why the previous error? Will the next release of Java 7 will support such usage?

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  • How do I wrap a repeatbale set of elements in jQuery?

    - by Globalz
    In jQuery how would I go about wrapping a repeatable set of elements with a div? For example I have: img h4 p img h4 p img h4 p I need to wrap each img, h4, p set with a div class="container". So it will look like: <div> class="container" img h4 p </div> <div> class="container" img h4 p </div> <div> class="container" img h4 p </div> Any ideas on how I can achieve this as its driving me nuts! I keep getting nested div.containers! Thanks!

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  • [C#] How do I make hierarchy of objects from two alternating classes?

    - by Millicent
    Here's the scenario: I have two classes ("Page" and "Field"), that are descended from a common class ("Pield"). They represent tags in an XML file and are in the following hierarchy: <page> <field> <page> ... </page> ... </field> ... </page> I.e.: Page and Field objects are in a hierarchy of alternating type (there may be more than one Page or Field to each rung of the hierarchy). Every Field and Page object has a parent property, which points to the respective parent object of the other type. This is not a problem unless the parent-child mechanism is controlled by the base class (Pield), which is shared by the two descended classes (Page and Field). Here is one try, that fails at the line "Pield child = new Pield(pchild, this);": class Pield<T> { private T _pield_parent; ... private void get_children() { ... Pield<Page> child = new Pield<Page>(pchild, this); ... } ... } class Page : Pield<Field> { ... } class Field : Pield<Page> { ... } Any ideas about how to solve this elegantly? Best, Millicent

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  • jQuery : how to apply effect on a child element

    - by Tristan
    Hello, instead of re-writting the same function, i want to optimise my code : <div class="header"> <h3>How to use the widget</h3> <span id="idwidget" ></span> </div> <div class="content" id="widget"> the JS : <script type="text/javascript"> $(document).ready(function() { var showText="Show"; var hideText="Hide"; $("#idwidget").before("<a href='#' class='button' id='toggle_link'>"+showText+"</a>"); $('#widget').hide(); $('a#toggle_link').click(function() { if ($('a#toggle_link').text()==showText) { $('a#toggle_link').text(hideText); } else { $('a#toggle_link').text(showText); } $('#widget').toggle('slow'); return false; }); }); This is working just with the div which is called widget and the button called idwidget. But on this page i have also : <div class="header"> <h3>How to eat APPLES</h3> <span id="IDsomethingelse" ></span> </div> <div class="content" id="somethingelse"> And i want it to be compatible with the code. I heard about children attribute, do you have an idea how to do that please ? Thank you

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  • How to check if TypeIdenitifier(T) is an Object?

    - by John
    I'm creating a generic list class that has a member of type Array(Array of ). The problem is the class descruction,because the class is supposed to be used for types from byte to types inheriting TObject. Specifically: destructor Destroy; var elem:T; begin /*if(T is Tobject) then //Check if T inherits TObject {Compiler error!} for elem in FData do TObject(elem).Free;*/ // do not know how to do it SetLength(FItems,0); //FItems : Array of T inherited Destroy; end; How do I check if T is TObject so I can free every member if the typeidenitifier is a class,for example?

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  • Determining where a function is defined in C#?

    - by templatetypedef
    Hey all - I am a complete novice at C# (I've never used it before) and recently needed to look over some code written in it. I spent the longest time trying to track down a nonexistent method in a class that didn't seem to be defined anywhere in the class that was using it. I later found out it was an "extension method," which I gather is a method grafted onto another class by some source. I completely understand the rationale behind this language feature and actually think it's quite nice. However, as someone without much experience in the language, it makes it harder to look up unfamiliar methods, since the method in question could be defined anywhere. My question is this: given an unfamiliar method call in C#, what's the best way for me to look up more info on it, given that it could be an extension method defined in an entirely separate class? Thanks!

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  • How to override jquery's show() and hide() functions

    - by Max Williams
    hi all Short version of question: see title Long version of question: I've used jquery's show() and hide() functions extensively in my code and just encountered a bit of a problem: they work by changing the display attribute of the element to 'block' or 'none' respectively, so that if you have somethin that has display: inline and then hide and show it, you've changed its display to block, which screws up the layout in a couple of cases. In my code, whenever i want something to be hidden initially i give it a class 'hidden'. This class is simply {display: none}. I'd like the change show and hide to remove or add this class, instead of directly changing the display attribute, so that if you add the hidden class and then remove it again (ie hide and show something) then it's back to exactly how it was to start off with (since adding a class overrides the attributes rather than directly changing them). Something like this (this is a little pseucodey as i don't know how to set the function up properly - let's assume that 'this' is the object that show/hide was called on) function show(){ this.removeClass("hidden"); } function hide(){ this.addClass("hidden"); } how and where would i go about overriding the jquery methods? (I'm not a javascript expert) thanks - max

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  • Django - Problem with models/manager to organise a query...

    - by user296644
    Hi, I have an application to count the number of access to an object for each website in a same database. class SimpleHit(models.Model): """ Hit is the hit counter of a given object """ content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') site = models.ForeignKey(Site) hits_total = models.PositiveIntegerField(default=0, blank=True) [...] class SimpleHitManager(models.Manager): def get_query_set(self): print self.model._meta.fields qset = super(SimpleHitManager, self).get_query_set() qset = qset.filter(hits__site=settings.SITE_ID) return qset class SimpleHitBase(models.Model): hits = generic.GenericRelation(SimpleHit) objects = SimpleHitManager() _hits = None def _db_get_hits(self, only=None): if self._hits == None: try: self._hits = self.hits.get(site=settings.SITE_ID) except SimpleHit.DoesNotExist: self._hits = SimpleHit() return self._hits @property def hits_total(self): return self._db_get_hits().hits_total [...] class Meta: abstract = True And I have a model like: class Model(SimpleHitBase): name = models.CharField(max_length=255) url = models.CharField(max_length=255) rss = models.CharField(max_length=255) creation = AutoNowAddDateTimeField() update = AutoNowDateTimeField() So, my problem is this one: when I call Model.objects.all(), I would like to have one request for the SQL (not two). In this case: one for Model in order to have information and one for the hits in order to have the counter (hits_total). This is because I cannot call directly hits.hits_total (due to SITE_ID?). I have tried select_related, but it seems to do not work... Question: - How can I add column automatically like (SELECT hits.hits_total, model.* FROM [...]) to the queryset? - Or use a functional select_related with my models? I want this model could be plugable on all other existing model. Thank you, Best regards.

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  • Tracking changed (unsaved) objects

    - by Eric
    I have a class which is serialized to and from an XML file when the user decided to open or save. I'm trying to add the typical functionality where when they try to close the form with un-saved changes the form warns them and gives them the option of saving before closing. I've added a HasUnsavedChanges property to my class, which my form checks before closing. However, it's a little annoying that my properties have changed from something like this .. public string Name { get; set; } to this... private string _Name; public string Name { get { return _Name; } set { this._Name = value; this.HasUnsavedChanges = true; } } Is there a better way to track changes to an instance of a class? For example is there some standard way I can "hash" an instance of a class into a value that I can use to compare the most recent version with the saved version without mucking up every property in the class?

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  • Quick question regarding MVC framework for a java game

    - by Jason
    I have a question regarding the use of the MVC framework for a blackjack game im writing in java. As I understand, my model would be a class that stores the state of the game, and more specifically, each players hand. Within the model class, I would have an array of listeners, which would be notified each time the game state changes (ie a player has drawn a new card). These listeners would be my viewer, which is the class that handles the display of the game. This class would implement the ActionListener interface, and each time the model changes, it would call/"notify" my viewer's actionPerformed method. My question is as follows: I intend to have two JPanels, each devoted to displaying the respective player's hand. As a player draws a new card, a new ImageIcon would be added to the panel. My question is how would the viewer class know what card has been added to the player's hand? I suppose I could store the player's hand before a notify event, and then upon the notification event, compare the new state with the old, to find out what has changed. I'm a complete novice here, so I could be completely wrong, but it seems a bit tedious to do this. Is there a more efficient/common way of detecting what has changed in the model between the before and after state? Another solution would be to redraw the entire panel each time the notification occurs? Would this be a better idea?

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  • Why do we need a private constructor?

    - by isthatacode
    if a class has a private constructor then it cant be instantiated. so, if i dont want my class to be instantiated and still use it, then i can make it static. what is the use of a private constructor ? Also its used in singleton class, except that, is there any othe use ? (Note : The reason i am excuding the singleton case above is because I dont understand why do we need a singleton at all ? when there is a static class availble. You may not answer for my this confusion in the question. )

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  • C++: Is there a way to limit access to certain methods to certain classes without exposing other pri

    - by dadads
    I have a class with a protected method Zig::punt() and I only want it to be accessible to the class "Avocado". In C++, you'll normally do this using the "friend Avocado" specifier, but this will cause all of the other variables to become accessible to "Avocado" class; I don't want this because this breaks encapsulation. Is what I want impossible, or does there already exist an obscure trick out there that I can use to achieve what I want? Or possibly alternative class design patterns that'll achieve the same thing? Thanks in advance for any ideas!

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