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  • Should we avoid to use Object as the input parameter/ output value of a method?

    - by developer.cyrus
    Take Java syntax as an example, though the question itself is language independent. If the following snippet takes an object MyAbstractEmailTemplate as input argument in the method setTemplate, the class MyGateway will then become tightly-coupled with the object MyAbstractEmailTemplate, which lessens the re-usability of the class MyGateway. A compromise is to use dependency-injection to ease the instantiation of MyAbstractEmailTemplate. This might solve the coupling problem to some extent, but the interface is still rigid, hardly providing enough ?exibility to other developers/ applications. So if we only use primitive data type (or even plain XML in web service) as the input/ output of a method, it seems the coupling problem no longer exists. So what do you think? public class MyGateway { protected MyAbstractEmailTemplate template; publoc void setTemplate(MyAbstractEmailTemplate template) { this.template = template; } }

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  • non-scalar type requested

    - by lego69
    can somebody please help me with an error conversion from `A' to non-scalar type `B' requested I have class A and derived from it B, but I have problems with these rows: A a(1); A *pb = new B(a); B b = *pb; //here I have an error thanks in advance for any help class A { protected: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); virtual ~A(){}; virtual void foo(); void foo() const; operator int(); }; class B: public A { public: B(int initPlayer): A(initPlayer){}; ~B(){}; virtual void foo(); };

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  • C# - Why can't I enforce derived classes to have parameterless constructors?

    - by FrisbeeBen
    I am trying to do the following: public class foo<T> where T : bar, new { _t = new T(); private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

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  • Compiling C++ when two classes references one another

    - by Omry
    I am trying to write a simple wrapper around a connection pointer that will return it to the pool when the wrapper is destroyed. but it wont compile because the ConnectionPool and AutoConn need each other to be declared. I tried to use forward deceleration but it didn't work. how do I solve this? (using g++) class Connection {}; class ConnectionPool { Connection *m_c; public: AutoConn getConn() { return AutoConn(this, m_c); // by value } void releaseConnection(Connection *c) { } }; class AutoConn { ConnectionPool* m_pool; Connection *m_connection; public: AutoConn(ConnectionPool* pool, Connection *c) : m_pool(pool), m_connection(c) {} ~AutoConn() { m_pool->releaseConnection(m_connection); } };

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  • Django Forms: TimeField Validation

    - by Tom
    I feel like I'm missing something obvious here. I have a Django form with a TimeField on it. I want to be able to allow times like "10:30AM", but I cannot get it to accept that input format or to use the "%P" format (which has a note attached saying it's a "Proprietary extension", but doesn't say where it comes from). Here's the gist of my form code: calendar_widget = forms.widgets.DateInput(attrs={'class': 'date-pick'}, format='%m/%d/%Y') time_widget = forms.widgets.TimeInput(attrs={'class': 'time-pick'}) valid_time_formats = ['%P', '%H:%M%A', '%H:%M %A', '%H:%M%a', '%H:%M %a'] class EventForm(forms.ModelForm): start_date = forms.DateField(widget=calendar_widget) start_time = forms.TimeField(required=False, widget=time_widget, help_text='ex: 10:30AM', input_formats=valid_time_formats) end_date = forms.DateField(required=False, widget=calendar_widget) end_time = forms.TimeField(required=False, widget=time_widget, help_text='ex: 10:30AM', input_formats=valid_time_formats) description = forms.CharField(widget=forms.Textarea) Any time I submit "10:30AM", I get a validation error. The underlying model has two fields, event_start and event_end, no time fields, so I don't think the problem is in there. What stupid thing am I missing?

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  • Constructors for C++ objects

    - by sasquatch
    I have class Person as following : class Person { char* name; int age; }; Now I need to add two contructors. One taking no arguments, that inserts field values to dynamically allocated resources. Second taking (char*, int) arguments initialized by initialization list. Last part is to define a destructor showing information about destroying objects and deallocating dynamically allocated resources. How to perform this task ? That's what I already have : class Person { char* name; int age; public: Person(){ this->name = new *char; this->age = new int; } Person(char* c, int i){ } };

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  • how XSLT convert tag inside tag?

    - by cc96ai
    I have the following XML <title> This is a <highlight>test</highlight> thanks. </title> and want to convert into <span class="title">this is a <span class="highlight">test</span> thanks.</span> I try this xslt, only can ge the text inside title tag, how can I also convert the highlight tag? <span class="title"><xsl:value-of select="title"/></span>

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  • Hold border and Resize two or more DIV simultaneously in the same container

    - by Manu
    Code : <div id="widget1"> <div class="part blue">this is the part</div> <div class="part white">of the genial</div> <div class="part red">and good widget</div> </div> Let's say that div#widget1 is 99px width and div.part are 33px by default. How can I easily resize div.blue by increasing its width and deacreasing width of other div.part proportionnaly ? http://jqueryui.com/demos/resizable/#synchronous-resize : give an example which show element increase in the same time. Thanks,

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  • Beginning with Datampper, Association question

    - by Ian
    I'm just diving into Datamapper (and Sinatra) and have a question about associations. Below are some models I have. This is what I want to implemented. I'm having an issue with Workoutitems and Workout. Workout will be managed separately, but Workoutitems has a single workout associated with each row. Workout - just a list of types of workouts (run, lift, situps, etc) Selected workout - this is the name of a set of workouts, along with notes by the user and trainer. It has a collection of N workoutitems Workoutitems - this takes a workout and a number of repetitions to it that go in the workout set. class Workout include DataMapper::Resource property :id, Serial #PK id property :name, String, :length=50,:required=true # workout name property :description, String, :length=255 #workout description end class Selectedworkout include DataMapper::Resource property :id, Serial property :name, String, :length=50, :required=true property :workout_time, String, :length=20 property :user_notes, String, :length=255 property :coach_notes, String, :length=255 has n, :workoutitems end class Workoutitem include DataMapper::Resource property :id, Serial property :reps, String, :length=50, :required=true belongs_to :selectedworkout end

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  • MVVM Binding To Property == Null

    - by LnDCobra
    I want to show some elements when a property is not null. What is the best way of achieving this? The following is my ViewModel: class ViewModel : ViewModelBase { public Trade Trade { get { return _trade; } set { SetField(ref _trade, value, () => Trade); } } private Trade _trade; } ViewModelBase inherits INotifyPropertyChanged and contains SetField() The Following is the Trade class: public class Trade : INotifyPropertyChaged { public virtual Company Company { get { return _company; } set { SetField(ref _company, value, () => Company); } } private Company _company; ...... } This is part of my View.xaml <GroupBox Visibility="{Binding Path=Trade.Company, Converter={StaticResource boolToVisConverter}}" /> I would like this groupbox to show only if Trade.Company is not null (so when a user selects a company). Would I need to create a custom converter to check for null and return the correct visibility or is there one in .NET?

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  • maintain user login status in express.js

    - by chenliang
    when user login the app the username will be display in the header, this is my header.jade div#header_content input(type='text',name='search',id='globle_search') span#user_status if(req.isAuthenticated()) a(class='user_menu_btn',href='home', target='_blank' ) req.user.username a(class='user_menu_btn',href='logout') Logout else a(id='login_btn',href='login',class='user_status_btn') login run the app i get the error says ReferenceError: F:\shopping\views\includes\header.jade:4 req is not defined this is my index route: app.get('/',index.index); exports.index = function(req, res){ res.render('index', { title: 'Express' }); }; how to maintain login ststus in the heaedr? by the way am using passport to login user

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  • Inheritance: possible to change base reference to something else?

    - by fred
    For example I have two classes, Base and Derived as shown below: class Base { public string Name { get; set; } public Base() { } } class Derived : Base { public Derived(Base b) { base = b; // doesn't compile, but is there any way to do something similar? } } So that they behave like this: Base b = new Base(); b.Name = "Bob"; Derived d = new Derived(b); d.Name = "John"; // b.Name is now "John" also Is this possible? I guess one way would be to keep the Base b reference in Derived and override Derived.Name to point to b.Name? Is there an easier way though, for example if I have like 50 properties to override? class Derived : Base { Base b; public override string Name { get { return b.Name; } set { b.Name = value; } } public Derived(Base b) { this.b = b; } }

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  • going to build a php MVC, what naming conventions do i need to be aware of?

    - by Haroldo
    I'm pretty new to OO PHP, however i get how it all works and am ready to start building an MVC for a big site i'm working on. I know it isnt necessary written that you must do it like this but there's gotta be some normal practises.... class names - camelcase? underscores? class files - same as class? url/post/get controll name - router.php? any other things i should be aware of before i embark?

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  • IRepository with Inherited Classes

    - by Stacey
    In keeping with the Repository pattern of data input, I've a question in regards to using inherited classes. For instance, suppose I would have the class... class Employee IEmployeeRepository { Add(Employee employee); } This works fine, nothing wrong with it so far... but now let's say I continue on.. class Manager : Employee Okay, now let's assume that I never need to enter a manager different than an Employee? What's the best approach here? Would a scenario such as .. IEmployeeRepository { Add<T>(T employee) where T : Employee } Be the best approach, or do I need to abstract a different repository for each type?

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  • VB.NET take each letter of a word and display in ListBox

    - by Kaleet
    Private Sub btnWord_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnWord.Click Dim Inputter As String Dim Words As String = "" Do Inputter = InputBox("Enter word", "Enter Word") If Inputter <> String.Empty Then lstDisplay.Items.Add(Inputter) Word += Inputter.Substring(0, 1) End If Loop Until Inputter <> String.Empty ' SOMETHING GOES HERE!!!!!' lstDisplay.Items.Add("---") lstDisplay.Items.Add(Word) End Sub Here is how it works, when you click the button it displays an input box so for example type in "CAT". But I can't figure out how to get it to do C (newline) A (newline) T (newline) within the listbox. Please help! C A T - CAT

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  • c++ inheritance

    - by Meloun
    Hi, i am trouble with this.. Is there some solution or i have to keep exactly class types? //header file Class Car { public: Car(); virtual ~Car(); }; class Bmw:Car { public: Bmw(); virtual ~Bmw(); }; void Start(Car& mycar) {}; //cpp file Car::Car(){} Car::~Car() {} Bmw::Bmw() :Car::Car(){} Bmw::~Bmw() {} int main() { Car myCar; Bmw myBmw; Start(myCar); //works Start(myBmw); //!! doesnt work return 0; }

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  • Neo4j+Gremlin : Trouble with T.gte and floating point node attributes

    - by letronje
    For a type of nodes in my graph, attribute values for an attribute(named 'some_count') is either missing or an integer or a float. I'm trying to write gremlin to filter these nodes based on minimum value for this attribute. I first verified that the values are indeed present by firing the following gremlin g.v(XXX)._().in('category').hasNot('some_count', T.eq, null).back(1).some_count Next, I tried filtering by exact value and that works and show me the matching nodes or gives an empty array if there is no match g.v(XXX)._().in('category').hasNot('some_count', T.eq, null).back(1).has('some_count', T.eq, 120000.0d) But the following query that uses the 'greater than or equal to' comparator doesn't work. g.v(XXX)._().in('category').hasNot('some_count', T.eq, null).back(1).has('some_count', T.gte, 1.0d) this returns nil (I'm querying via ruby/rails using Neo4j AR Adapter ) Instead of returning an empty array for no match, it returns a nil, which tells me something could be wrong with the query itself. I'm running neo4j community server 1.8. Is there a way I can ask Neo4j to log errors/queries, to see what could be going wrong ?

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  • Inconsistent Behavior From Declared DLL Function

    - by Steven
    Why might my GetRawData declared function return a correct value when called from my VB.NET application, but return zero when called from my ASP.NET page? The code is exactly the same except for class type difference (Form / Page) and calling event handler (Form1_Load, Page_Load). Note: In the actual code, #DLL# and #RAWDATAFILE# are both absolute filenames to my DLL and raw data file respectively. Note: The DLL file was not created by Visual Studio. Form1.vb Public Class Form1 Declare Auto Function GetRawData Lib "#DLL#" (ByVal filename() As Byte, _ ByVal byteArray() As Byte, _ ByVal length As Int32) As Int32 Private Sub Form1_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load Dim buffer(10485760) As Byte Dim msg As String, length As Integer = 10485760 Dim filename As String = "#RAWDATAFILE#" length = GetRawData(Encoding.Default.GetBytes(filename), buffer, length) Default.aspx.vb Partial Public Class _Default Inherits System.Web.UI.Page Declare Auto Function GetRawData Lib "#DLL#" (ByVal filename() As Byte, _ ByVal byteArray() As Byte, _ ByVal length As Int32) As Int32 Protected Sub Page_Load(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles Me.Load Dim buffer(10485760) As Byte Dim msg As String, length As Integer = 10485760 Dim filename As String = "#RAWDATAFILE#" length = GetRawData(Encoding.Default.GetBytes(filename), buffer, length)

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  • PHP OOP: Unique method per argument type?

    - by sunwukung
    I'm writing a little homebrew ORM (academic interest). I'm trying to adhere to the TDD concept as a training exercise, and as part of that exercise I'm writing documentation for the API as I develop the class. Case in point - I'm working on a classic "getCollection" type mapper class. I want it to be able to retrieve collections of asset X (let's say blog posts) for a specific user, and also collections based on an arbitrary array of numeric values. So - you might have a method like any one of these $User = $UserMapper->load(1); $ArticleCollection = $ArticleMapper->getCollection(range(10,20)); $ArticleCollection = $ArticleMapper->getCollection($User); $ArticleCollection = $ArticleMapper->getCollection($User->getId()); So, in writing the documentation for the getCollection method - I want to declare the @param variable in the Docblock. Is it better to have a unique method for each argument type, or is it acceptable to have a method that delegates to the correct internal method/class based on argument type?

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  • Hibernate - join un related objects

    - by CuriousMind
    I have a requirement, wherein I have to join two unrelated objects using Hibernate HQL. Here is the sample POJO class class Product{ int product_id; String name; String description; } and Class Item{ int item_id; String name; String description; int quantity; int product_id; //Note that there is no composed product object. } Now I want to perform a query like select * from Product p left outer join Item i on p.product_id = i.item_id I want a multidimensional array as an output of this query so that I can have separate instances of Product and Item, instead of one composed in another. Is there any way to do this in Hibernate?

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  • How/When/Where to Extend Gem Classes (via class_eval and Modules) in Rails 3?

    - by viatropos
    What is the recommended way to extend class behavior, via class_eval and modules (not by inheritance) if I want to extend a class buried in a Gem from a Rails 3 app? An example is this: I want to add the ability to create permalinks for tags and categories (through the ActsAsTaggableOn and ActsAsCategory gems). They have defined Tag and Category models. I want to basically do this: Category.class_eval do has_friendly_id :title end Tag.class_eval do has_friendly_id :title end Even if there are other ways of adding this functionality that might be specific to the gem, what is the recommended way to add behavior to classes in a Rails 3 application like this? I have a few other gems I've created that I want to do this to, such as a Configuration model and an Asset model. I would like to be able to add create an app/models/configuration.rb model class to my app, and it would act as if I just did class_eval. Anyways, how is this supposed to work? I can't find anything that covers this from any of the current Rails 3 blogs/docs/gists.

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  • How is inheritance implemented at the memory level?

    - by cambr
    Suppose I have class A { public: void print(){cout<<"A"; }}; class B: public A { public: void print(){cout<<"B"; }}; class C: public C { }; How is inheritance implemented at the memory level? Does C copy print() code to itself or does it have a pointer to the it that points somewhere in A part of the code? How does the same thing happen when we override the previous definition, for example in B (at the memory level)?

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  • Sort collection within collection using Linq

    - by user327066
    Hi, I have a one-to-many Linq query and I would like to sort on a property within the "many" collection. For example in the pseudo-code below, I am returned a List from the Linq query but I would like to sort / order the Products property based on the SequenceNumber property of the Product class. How can I do this? Any information is appreciated. Thanks. class Order { int OrderId; List<Product> Products; } class Product { string name; int SequenceNumber; }

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  • How do I reference the other object in django models

    - by UserZero
    Hi, first post here.In Django, I want to have many files be associated with a particular model, so I'm doing a seperate model called files and have model 'A' 'have many' files. But I want my files to be saved in director named by model 'A'. So For example I want something like this: class Show(models.Model): name = models.CharField() showfolder = models.FilePathField() class Episode(models.Model): show = models.ForeignKey(Show) name = models.CharField() files = models.ManyToManyField(mp3) class Mp3(models.Model): file = FileField(upload_to=Episode.show.showfolder) So hopefully that last line expresses what I WANT it to do(get the folder name from Show object associated with the episode). The question is how would I really write that?(besides jumping through hoops in the controller.) Thanks.

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  • .replace method in jquery

    - by amit
    i want to replace class me to old when user clicks on a tag, i want to do that only with .replace function. My purpose to learn how replace method work. But the function which i have made not working. <head> <script type="text/javascript" src="jquery-1.7.2.js"></script> <script type="text/javascript"> $(function(){ $('a').click(function(){ $(this).attr('class').replace('me','old') }) }) </script> </head> <body> <a href="#" class="me">click</a> </body>

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