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  • Define an empty array in Perl class new()

    - by Laimoncijus
    Hi, I am just beginner with Perl, so if it sounds stupid - sorry for that :) My problem is - I am trying to write a class, which has an empty array, defined in constructor of a class. So I am doing this like this: package MyClass; use strict; sub new { my ($C) = @_; my $self = { items => () }; bless $self, ref $C || $C; } sub get { return $_[0]->{items}; } 1; Later I am testing my class with simple script: use strict; use Data::Dumper; use MyClass; my $o = MyClass->new(); my @items = $o->get(); print "length = ", scalar(@items), "\n", Dumper(@items); And while running the script I get following: $ perl my_test.pl length = 1 $VAR1 = undef; Why am I doing wrong what causes that I get my items array filled with undef? Maybe someone could show me example how the class would need to be defined so I would not get any default values in my array? Thanks!

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  • Passing a string when starting a class in PHP

    - by Francesc
    Hi. First I have to say: Happy Christmas to All! I'm starting learning classes in PHP. I coded that: class User { function getFbId($authtoken) { } function getFbFirstName ($authtoken) { } } What I want to do is something like that: $user=new User($authtoken); And pass the $authtoken to the class. It's possible to define that when starting the class. It's possible to retrive that value inside a function of that class?

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  • Object reference not set to an instance of an object.....?

    - by jamal
    Hi guys I always got this error from my site and it keeps bugging me.I've been trying to figure out the cause of this error but I can't really figure it out. Here's the stacktrace: at BasePage.Page_PreInit(Object sender, EventArgs e) at System.EventHandler.Invoke(Object sender, EventArgs e) at System.Web.UI.Page.OnPreInit(EventArgs e) at System.Web.UI.Page.PerformPreInit() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) And on my basepage I only got this code: Imports Microsoft.VisualBasic Public Class BasePage Inherits System.Web.UI.Page Private Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit Page.Theme = "Something" If (Request.UserAgent.IndexOf("AppleWebKit") 0) Then Request.Browser.Adapters.Clear() End If End Sub Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender If Me.Title = "Untitled Page" Then Throw New Exception("Page title cannot be ""Untitled Page"".") End If End Sub End Class According to the stacktrace this always happens on my basepage preinit event.What do you think is the problem here guys?

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  • java protected method accessibility

    - by JavaUser
    In the below code the Consumer class can access the protected method of Parent class.How is it possible since there is no relation between Parent and Consumer class.Please explain class Parent { public void method1(){ System.out.println("PUBLIC METHOD"); } private void method2(){ System.out.println("PRIVATE METHOD"); } protected void method3(){ System.out.println("PROTECTED METHOD"); } } public class Consumer { public static void main(String[] args){ Parent parentObj = new Parent(); parentObj.method1(); //parentObj.method2(); parentObj.method3(); } } Thanks

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  • How do I correct feature envy in this case?

    - by RMorrisey
    I have some code that looks like: class Parent { private Intermediate intermediateContainer; public Intermediate getIntermediate(); } class Intermediate { private Child child; public Child getChild() {...} public void intermediateOp(); } class Child { public void something(); public void somethingElse(); } class Client { private Parent parent; public void something() { parent.getIntermediate().getChild().something(); } public void somethingElse() { parent.getIntermediate().getChild().somethingElse(); } public void intermediate() { parent.getIntermediate().intermediateOp(); } } I understand that is an example of the "feature envy" code smell. The question is, what's the best way to fix it? My first instinct is to put the three methods on parent: parent.something(); parent.somethingElse(); parent.intermediateOp(); ...but I feel like this duplicates code, and clutters the API of the Parent class (which is already rather busy). Do I want to store the result of getIntermediate(), and/or getChild(), and keep my own references to these objects?

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  • Java generics question

    - by user247866
    So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = methodCall(); // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void someMethod(List<A> a) However, when I do: C c = new C(); c.someMethod(b); I get an error that some-method is not applicable for the argument List<B>, instead it's expecting to get List<A>. Is there a good way to fix this problem? Many thanks!

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  • UI Design Tips and Tutorials for Android

    - by Omega
    Does anyone have any good pointers on designing the UI for an android application and some good practises? Obviously I'm aware of the basic principles involved with designing the layout in XML. Also, that you have a stack of activities. But I'm interested in some approaches to creating the interfaces and also how to design an application around those intentions.

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  • Unserializing an API return object (PHP/Ebay API)

    - by DavidYell
    I have been working with the Ebay api for a project and have found it great. I have however found a problem now, more PHP related. When I read my items from Ebay, I store a bunch of details in the database. Currently, just for the sake of it really, I serialize the whole return object and store it in the database in a related table. The idea being, that when I display my information, I have all the details to hand should I need them. The problem arises in that the pricing information is always in a sub object. [ConvertedAdjustmentAmount] => __PHP_Incomplete_Class Object ( [__PHP_Incomplete_Class_Name] => eBayAmountType [_] => 0 [currencyID] => USD ) As you can see when I unserialize my object, my cunning plan falls foul of the Incomplete class problem. I have checked the following question, without success. http://stackoverflow.com/questions/965611/forcing-access-to-php-incomplete-class-object-properties The main issue lies, as far as I can see, in that the price class is stored in the Ebay api, so how do I recreate it? I have been reading this page, http://uk3.php.net/manual/en/function.unserialize.php and trying to figure out, unserialize_callback_func which I can't figure out either, so any help would be appreciated!

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  • Reading object tree from file into Python

    - by jjkparker
    I have a Python app that contains an object structure that the user can manipulate. What I want to do is allow the user to create a file declaring how the object structure should be created. For example, I would like the user to be able to create the following file: foo.bar.baz = true x.y.z = 12 and for my app to then create that object tree automatically. What's the best way to do something like this?

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  • when to make a method static

    - by Don
    Hi, I'd like to know how people decide whether to define a method as static. I'm aware that a method can only be defined as static if it doesn't require access to instance fields. So lets say we have a method that does not access instance fields, do you always define such a method as static, or only if you need to call it statically (without a reference to an instance). Perhaps another way of asking the same question, is whether you use static or non-static as the default? Thanks, Don

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  • How to call virtual function of an object in C++

    - by SoonDead
    I'm struggling with calling a virtual function in C++. I'm not experienced in C++, I mainly use C# and Java so I might have some delusions, but bear with me. I have to write a program where I have to avoid dynamic memory allocation if possible. I have made a class called List: template <class T> class List { public: T items[maxListLength]; int length; List() { length = 0; } T get(int i) const { if (i >= 0 && i < length) { return items[i]; } else { throw "Out of range!"; } }; // set the value of an already existing element void set(int i, T p) { if (i >= 0 && i < length) { items[i] = p; } else { throw "Out of range!"; } } // returns the index of the element int add(T p) { if (length >= maxListLength) { throw "Too many points!"; } items[length] = p; return length++; } // removes and returns the last element; T pop() { if (length > 0) { return items[--length]; } else { throw "There is no element to remove!"; } } }; It just makes an array of the given type, and manages the length of it. There is no need for dynamic memory allocation, I can just write: List<Object> objects; MyObject obj; objects.add(obj); MyObject inherits form Object. Object has a virtual function which is supposed to be overridden in MyObject: struct Object { virtual float method(const Input& input) { return 0.0f; } }; struct MyObject: public Object { virtual float method(const Input& input) { return 1.0f; } }; I get the elements as: objects.get(0).method(asdf); The problem is that even though the first element is a MyObject, the Object's method function is called. I'm guessing there is something wrong with storing the object in an array of Objects without dynamically allocating memory for the MyObject, but I'm not sure. Is there a way to call MyObject's method function? How? It's supposed to be a heterogeneous collection btw, so that's why the inheritance is there in the first place. If there is no way to call the MyObject's method function, then how should I make my list in the first place?

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  • Force an object to be allocated on the heap

    - by Warren Seine
    A C++ class I'm writing uses shared_from_this() to return a valid boost::shared_ptr<>. Besides, I don't want to manage memory for this kind of object. At the moment, I'm not restricting the way the user allocates the object, which causes an error if shared_from_this() is called on a stack-allocated object. I'd like to force the object to be allocated with new and managed by a smart pointer, no matter how the user declares it. I thought it could be done through a proxy or an overloaded new operator, but I can't find a proper way of doing that. Is there a common design pattern for such usage? If it's not possible, how can I test it at compile time?

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  • Return an object after parsing xml with SAX

    - by sentimental_turtle
    I have some large XML files to parse and have created an object class to contain my relevant data. Unfortunately, I am unsure how to return the object for later processing. Right now I pickle my data and moments later depickle the object for access. This seems wasteful, and there surely must be a way of grabbing my data without hitting the disk. def endElement(self, name): if name == "info": # done collecting this iteration self.data.setX(self.x) self.data.setY(self.y) elif name == "lastTagOfInterest": # done with file # want to return my object from here filehandler = open(self.outputname + ".pi", "w") pickle.dump(self.data, filehandler) filehandler.close() I have tried putting a return statement in my endElement tag, but that does not seem to get passed up the chain to where I call the SAX parser. Thanks for any tips.

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  • Convert an ArrayList to an object array

    - by marionmaiden
    Hello, Is there a command in java for conversion of an ArrayList into a object array. I know how to do this copying each object from the arrayList into the object array, but I was wondering if would it be done automatically. I want something like this: ArrayList<TypeA> a; // Let's imagine "a" was filled with TypeA objects TypeA[] array = MagicalCommand(a);

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  • How to determine if object in another AppDomain has gone

    - by Dmitry Lobanov
    I instantiate an object of some class in other ApDomain using CreateInstanceAndUnwrap(). I can determine if this object resides in other domain by using RemotingServices.IsTransparentProxy(). But can I determine if the real remote object has gone away (e.g. was garbage collected) without probing a call on proxy and catching RemotingException? Is it possible?

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  • PHP5: restrict access to function to certain classes

    - by Tim
    Is there a way in PHP5 to only allow a certain class or set of classes to call a particular function? For example, let's say I have three classes ("Foo", "Bar", and "Baz"), all with similarly-named methods, and I want Bar to be able to call Foo::foo() but deny Baz the ability to make that call: class Foo { static function foo() { print "foo"; } } class Bar { static function bar() { Foo::foo(); print "bar"; } // Should work } class Baz { static function baz() { Foo::foo; print "baz"; } // Should fail } Foo::foo(); // Should also fail There's not necessarily inheritance between Foo, Bar, and Baz, so the use of protected or similar modifiers won't help; however, the methods aren't necessarily static (I made them so here for the simplicity of the example).

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  • Domain object validation vs view model validation

    - by Brendan Vogt
    I am using ASP.NET MVC 3 and I am using FluentValidation to validate my view models. I am just a little concerned that I might not be on the correct track. As far as what I know, model validation should be done on the domain object. Now with MVC you might have multiple view models that are similar that needs validation. What happens if a property from a domain object occurs in more than one view model? Now you are validating the same property twice, and they might not even be in sync. So if I have a User domain object then I would like to do validation on this object. Now what happens if I have UserAViewModel and UserBViewModel, so now it is multiple validations that needs to be done. The scenario above is just an example, so please don't critise on it.

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  • Modifying object in AfterInsert / AfterUpdate

    - by Jean Barmash
    I have a domain object that holds results of a calculation based on parameters that are properties of the same domain object. I'd like to make sure that any time parameters get changed by the user, it recalculates and gets saved properly into the database. I am trying to do that with afterInsert (to make sure calculation is correct in the first place), and afterUpdate. However, since my calculation is trying to modify the object itself, it's not working - throwing various hibernate exceptions. I tried to put the afterUpdate code into a transaction, but that didn't help. I am afraid I am getting into a circular dependency issues here. The exception I am getting right now is: org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [esc.scorecard.PropertyScorecard#27] Are the GORM events designed for simpler use cases? I am tempted to conclude that modifying the object you are in the middle of saving is not the way to go.

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