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  • Visual Studio 2010 compile error with std::string?

    - by AJG85
    So this is possibly the strangest thing I've seen recently and was curious how this could happen. The compiler gave me an error saying that std::string is undefined when used as a return type but not when used as a parameter in methods of a class! #pragma once #include <string> #include <vector> // forward declarations class CLocalReference; class CResultSetHandle; class MyClass { public: MyClass() {} ~MyClass {} void Retrieve(const CLocalReference& id, CResultSetHandle& rsh, std::string& item); // this is fine const std::string Retrieve(const CLocalReference& id, CResultSetHandle& rsh); // this fails with std::string is undefined?!?! }; Doing a Rebuild All it still happened I had to choose clean solution and then Rebuild All again after for the universe to realign. While it's resolved for the moment I'd still like to know what could have caused this because I'm at a loss as to why when there should be no conflicts especially when I always use fully qualified names for STL.

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  • DCI: How to implement Context with Dependency Injection?

    - by ciscoheat
    Most examples of a DCI Context are implemented as a Command pattern. When using Dependency Injection though, it's useful to have the dependencies injected in the constructor and send the parameters into the executing method. Compare the Command pattern class: public class SomeContext { private readonly SomeRole _someRole; private readonly IRepository<User> _userRepository; // Everything goes into the constructor for a true encapsuled command. public SomeContext(SomeRole someRole, IRepository<User> userRepository) { _someRole = someRole; _userRepository = userRepository; } public void Execute() { _someRole.DoStuff(_userRepository); } } With the Dependency injected class: public class SomeContext { private readonly IRepository<User> _userRepository; // Only what can be injected using the DI provider. public SomeContext(IRepository<User> userRepository) { _userRepository = userRepository; } // Parameters from the executing method public void Execute(SomeRole someRole) { someRole.DoStuff(_userRepository); } } The last one seems a bit nicer, but I've never seen it implemented like this so I'm curious if there are any things to consider.

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  • Java Generics Issue (w/ Spring)

    - by drewzilla
    I think I may be a victim of type erasure but thought I'd check with others here first. I have the requirement to do something like this: public interface FooFactory { public <T extends Bar> Foo<T> createFoo( Class<T> clazz ); } It is perfectly valid to write this code. However, I'm trying to implement this functionality using a Spring BeanFactory and I can't do it. What I'd like to do is this... public class FooFactoryImpl implements BeanFactoryAware { private BeanFactory beanFactory; public <T extends Bar> Foo<T> createFoo( Class<T> clazz ) { return beanFactory.getBean( ????????? ); } public void setBeanFactory( BeanFactory beanFactory ) { this.beanFactory = beanFactory; } } As you can see, I've put in ???????? where I'd like to retrieve a bean of type Foo<T>, where T extends Bar. However, it is not possible to derive a Class object of type Foo<T> and so I assume what I'm trying to do is impossible? Anyone else see a way round this or an alternative way of implementing what I'm trying to do? Thanks, Andrew

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  • Ordering the results of a Hibernate Criteria query by using information of the child entities of the

    - by pkainulainen
    I have got two entities Person and Book. Only one instance of a specific book is stored to the system (When a book is added, application checks if that book is already found before adding a new row to the database). Relevant source code of the entities is can be found below: @Entity @Table(name="persons") @SequenceGenerator(name="id_sequence", sequenceName="hibernate_sequence") public class Person extends BaseModel { @Id @Column(name = "id") @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_sequence") private Long id = null; @ManyToMany(targetEntity=Book.class) @JoinTable(name="persons_books", joinColumns = @JoinColumn( name="person_id"), inverseJoinColumns = @JoinColumn( name="book_id")) private List<Book> ownedBooks = new ArrayList<Book>(); } @Entity @Table(name="books") @SequenceGenerator(name="id_sequence", sequenceName="hibernate_sequence") public class Book extends BaseModel { @Id @Column(name = "id") @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_sequence") private Long id = null; @Column(name="name") private String name = null; } My problem is that I want to find persons, which are owning some of the books owned by a specific persons. The returned list of persons should be ordered by using following logic: The person owning most of the same books should be at the first of the list, second person of the the list does not own as many books as the first person, but more than the third person. The code of the method performing this query is added below: @Override public List<Person> searchPersonsWithSimilarBooks(Long[] bookIds) { Criteria similarPersonCriteria = this.getSession().createCriteria(Person.class); similarPersonCriteria.add(Restrictions.in("ownedBooks.id", bookIds)); //How to set the ordering? similarPersonCriteria.addOrder(null); return similarPersonCriteria.list(); } My question is that can this be done by using Hibernate? And if so, how it can be done? I know I could implement a Comparator, but I would prefer using Hibernate to solve this problem.

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  • Implementing IEnumeralbe on Non-Listed Items

    - by Stacey
    I have a class that contains a static number of objects. This class needs to be frequently 'compared' to other classes that will be simple List objects. public partial class Sheet { public Item X{ get; set; } public Item Y{ get; set; } public Item Z{ get; set; } } the items are obviously not going to be "X" "Y" "Z", those are just generic names for example. The problem is that due to the nature of what needs to be done, a List won't work; even though everything in here is going to be of type Item. It is like a checklist of very specific things that has to be tested against in both code and runtime. This works all fine and well; it isn't my issue. My issue is iterating it. For instance I want to do the following... List<Item> UncheckedItems = // Repository Logic Here. UncheckedItems contains all available items; and the CheckedItems is the Sheet class instance. CheckedItems will contain items that were moved from Unchecked to Checked; however due to the nature of the storage system, items moved to Checked CANNOT be REMOVED from Unchecked. I simply want to iterate through "Checked" and remove anything from the list in Unchecked that is already in "Checked". So naturally, that would go like this with a normal list. foreach(Item item in Unchecked) { if( Checked.Contains(item) ) Unchecked.Remove( item ); } But since "Sheet" is not a 'List', I cannot do that. So I wanted to implement IEnumerable so that I could. Any suggestions? I've never implemented IEnumerable directly before and I'm pretty confused as to where to begin.

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  • C++ Design Question on template types

    - by user231536
    I have a templated class template <typename T> class MyContainerClass For types to be substituted for T, it has to satisfy many requirements: for example, get_id(), int data(), etc. Obviously none of the fundamental types (PODs) are substitutable. One way I can provide this is via wrappers for the PODs that provide these functions. Is this an acceptable way? Another way would be to change the template to: template < typename T, typename C=traits<T> > class MyContainerClass and inside MyContainerClass, call traits::data() instead of data() on T objects. I will specialize traits<int>, traits<const char *> etc. Is this good design ? How do I design such a traits class (completely static methods or allow for inheritance) ? Or are the wrapper classes a good solution? What other alternatives are there?

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  • jQuery Drill down selector ?

    - by Etienne
    Hi, I have made this piece of code that makes a roll hover effect on any image you add the class 'simplehover' to it : //rollover effect on links $(".simplehover").mouseover(function () { $(this).attr("src", $(this).attr("src").replace("-off.", "-on.")); }).mouseout(function () { $(this).attr("src", $(this).attr("src").replace("-on.", "-off.")); }); <img src="slogan.gif" class="simplehover" /> Im trying to get it work if you add the class 'simplehover' to the surrounding element : . (especially usefull for ASP.net asp:HyperLink tag which automatically generate the IMG tag inside the hyperlink. <a href="#" class="simplehover"> <img src="slogan.gif" /> </a> If I change my selector for : $(".simplehover img") , it will work, however it no longer works in senario #1. I tried this with no luck: $(".simplehover").mouseover(function () { if ($(this).has('img')) { $(this) = $(this).children(); } ... Anyone can figure this out?

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  • MySQL subquery and bracketing

    - by text
    Here are my tables respondents: field sample value respondentid : 1 age : 2 gender : male survey_questions: id : 1 question : Q1 answer : sample answer answers: respondentid : 1 question : Q1 answer : 1 --id of survey question I want to display all respondents who answered the certain survey, display all answers and total all the answer and group them according to the age bracket. I tried using this query: SELECT res.Age, res.Gender, answer.id, answer.respondentid, SUM(CASE WHEN res.Gender='Male' THEN 1 else 0 END) AS males, SUM(CASE WHEN res.Gender='Female' THEN 1 else 0 END) AS females, CASE WHEN res.Age < 1 THEN 'age1' WHEN res.Age BETWEEN 1 AND 4 THEN 'age2' WHEN res.Age BETWEEN 4 AND 9 THEN 'age3' WHEN res.Age BETWEEN 10 AND 14 THEN 'age4' WHEN res.Age BETWEEN 15 AND 19 THEN 'age5' WHEN res.Age BETWEEN 20 AND 29 THEN 'age6' WHEN res.Age BETWEEN 30 AND 39 THEN 'age7' WHEN res.Age BETWEEN 40 AND 49 THEN 'age8' ELSE 'age9' END AS ageband FROM Respondents AS res INNER JOIN Answers as answer ON answer.respondentid=res.respondentid INNER JOIN Questions as question ON answer.Answer=question.id WHERE answer.Question='Q1' GROUP BY ageband ORDER BY res.Age ASC I was able to get the data but the listing of all answers are not present. Do I have to subquery SELECT into my current SELECT statement to show the answers? I want to produce something like this: ex: # of Respondents is 3 ages: 2,3 and 6 Question: what are your favorite subjects? Ages 1-4: subject 1: 1 subject 2: 2 subject 3: 2 total respondents for ages 1-4 : 2 Ages 5-10: subject 1: 1 subject 2: 1 subject 3: 0 total respondents for ages 5-10 : 1

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  • How do I run an array through an IF statement in rails?

    - by codyvbrown
    I am creating an application that highlights user messages from a stream based on whether or not the user has been 'vouched'. It works fine if it's setup for a single author. For example controller: @vouch = Vouch.last.vouched_user_nickname view: <% Twitter::Search.new(params[:id]).each do |tweet| %> <li> <%= image_tag tweet.profile_image_url %> <% if @vouch.include? tweet.from_user %> <div class="flit_message_containerh"> <u> <a href="http://twitter.com/<%= tweet.from_user %>"> <%= tweet.from_user %></a></u> <%= linkup_mentions(auto_link(h tweet.text)) %> <div class="time_ago"> <%= link_to distance_of_time_in_words_to_now(tweet.created_at) , tweet %> <% else %> <div class="flit_message_container"> <u> <a href="http://twitter.com/<%= tweet.from_user %>"> <%= tweet.from_user %></a></u> <%= linkup_mentions(auto_link(h tweet.text)) %> <div class="time_ago"> <%= link_to distance_of_time_in_words_to_now(tweet.created_at) , tweet %> <% end %> But I'm having trouble doing it for multiple user nicknames. @vouch = Vouch.find(:all, :select => "vouched_user_nickname", :group => 'vouched_user_nickname' ) Any ideas would be greatly appreciated. I'm a rails noob.

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  • Faster Javascript text replace

    - by Stacey
    Given the following javascript (jquery) $("#username").keyup(function () { selected.username = $("#username").val(); var url = selected.protocol + (selected.prepend == true ? selected.username : selected.url) + "/" + (selected.prepend == true ? selected.url : selected.username); $("#identifier").val(url); }); This code basically reads a textbox (username), and when it is typed into, it reconstructs the url that is being displayed in another textbox (identifier). This works fine - there are no problems with its functionality. However it feels 'slow' and 'sluggish'. Is there a cleaner/faster way to accomplish this task? Here is the HTML as requested. <fieldset class="identifier delta"> <form action="/authenticate/openid" method="post" target="_top" > <input type="text" class="openid" id="identifier" name="identifier" readonly="readonly" /> <input type='text' id='username' name='username' class="left" style='display: none;'/> <input type="submit" value="Login" style="height: 32px; padding-top: 1px; margin-right: 0px;" class="login right" /> </form> </fieldset> The identifier textbox just has a value set based on the hyperlink anchor of a button.

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  • simplemodal click events stopped working in IE7

    - by prettynerd
    Here's my code: $('#alertInfo').modal({ close :false, overlayId :'confirmModalOverlay', containerId :'confirmModalContainer', onShow : function(dialog) { dialog.data.find('.message').append(message); dialog.data.find('.yes').click(function(){ if ($.isFunction(callback)) callback.apply(); $.modal.close(); }); dialog.data.find('.close').click(function(){ $.modal.close(); }); } }); Basically, this is a dialogue box which I call to show a warning message that has a "X" button (with class 'close') and an "OK" button (with class 'yes'). The problem occurs in IE7. When I call this dialogue box and use my "X" button to close it everytime, my "X" button does not work anymore on the third time I call it (YES ON THE THIRD TIME!). However, if I use my "OK" button to close the dialogue box, it works fine no matter how many times I call it. I thought I found a workaround by unbinding and binding my click event of the '.close' class, as below: dialog.data.find('.close').unbind('click'); dialog.data.find('.close').bind('click',function(){$.modal.close();}); and it worked!!! unfortunately, however, the problem now occurs in my "OK" button. so, i did the same unbinding and binding the click event of the '.yes' class, as below: dialog.data.find('.yes').unbind('click'); dialog.data.find('.yes').bind('click', function() { if ($.isFunction(callback)) callback.apply(); $.modal.close(); }); BUT NOPE, IT DOES NOT WORK.. please help me.. @ericmmartin, i hope you're online now.. huhu..

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  • How to override part of an overload function in JavaScript

    - by Guan Yuxin
    I create a class with a function like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return -1; } basically it is just an overload function composed of index() and index(child). Then I create a sub class,SubObj or whatever, inherits from Obj SubObj.prototype.prototype=Obj; Now, it's time to override the index(child) function,however, index() is also in the function an I don't want to overwrite it too. One solution is to write like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return this._index(this); } Obj.prototype._index=function(this){ return -1; } SubObj.prototype._index=function(this){/* overwriteing */} But this will easily mislead other coders as _index(child) should be both private(should not be used except index() function) and public(is an overload function of index(),which is public) you guys have better idea?

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  • object references an unsaved transient instance

    - by developer
    Hi, I have 2 tables, user and userprofile, both with almost identical fields. user table references userprofile table by primary key ID. My requirement is that on click of a button I need to dump user table record to userprofile table. Now for a particular user table, if there is a corresponding userprofile entry, I am successfully able to dump the data, but if there is no record in userprofile table then I need to create a new record by dumping all the data. My problem is that I am able to update the data when the record is present in userprofile table, but in the case wherein I have to create a new record I get the below error "object references an unsaved transient instance - save the transient instance before flushing". `<class name="User"> <id name="ID" type="Int32"> <generator class="native" /> </id> <many-to-one name="Pid" class="UserProfile" /> </class>` UserProfile is another table and Pid above references the Primary key ID of UserProfile table.

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  • PHP classes, parse syntax errors when using 'var' to declare variables

    - by jon
    I am a C# guy trying to translate some of my OOP understanding over to php. I'm trying to make my first class object, and are hitting a few hitches. Here is the beginning of the class: <?php require("Database/UserDB.php"); class User { private var $uid; private var $username; private var $password; private var $realname; private var $email; private var $address; private var $phone; private var $projectArray; public function _construct($username) { $userArray = UserDB::GetUserArray($username); $uid = $userArray['uid']; $username = $userArray['username']; $realname = $userArray['realname']; $email = $userArray['email']; $phone = $userArray['phone']; $i = 1; $projectArray = UserDB::GetUserProjects($this->GetID()); while($projectArray[$i] != null) { $projectArray[$i] = new Project($projectArray[$i]); } UserDB.php is where I have all my static functions interacting with the Database for this User Class. I am getting errors using when I use var, and I'm getting confused. I know I don't HAVE to use var, or declare the variables at all, but I feel it is a better practice to do so. the error is "unexpected T_VAR, expecting T_VARIABLE" When I simply remove var from the declarations it works. Why is this?

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  • Creating an adjacency List for DFS

    - by user200081
    I'm having trouble creating a Depth First Search for my program. So far I have a class of edges and a class of regions. I want to store all the connected edges inside one node of my region. I can tell if something is connected by the getKey() function I have already implemented. If two edges have the same key, then they are connected. For the next region, I want to store another set of connected edges inside that region, etc etc. However, I am not fully understanding DFS and I'm having some trouble implementing it. I'm not sure when/where to call DFS again. Any help would be appreciated! class edge { private: int source, destination, length; int key; edge *next; public: getKey(){ return key; } } class region { edge *data; edge *next; region() { data = new edge(); next = NULL; } }; void runDFS(int i, edge **edge, int a) { region *head = new region(); aa[i]->visited == true;//mark the first vertex as true for(int v = 0; v < a; v++) { if(tem->edge[i].getKey() == tem->edge[v].getKey()) //if the edges of the vertex have the same root { if(head->data == NULL) { head->data = aa[i]; head->data->next == NULL; } //create an edge if(head->data) { head->data->next = aa[i]; head->data->next->next == NULL; }//if there is already a node connected to ti } if(aa[v]->visited == false) runDFS(v, edge, a); //call the DFS again } //for loop }

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  • IE8 and below <input type="image"> value work around

    - by kielie
    Hi guys, I have a slight problem, I am trying to capture the input of two buttons, one yes, one no, into a database but for some reason the database doesn't always show the value of the button clicked, it just shows up blank. <form action="refer.php" method="post" id="formID" > <div class="prompt_container" style="float: left;"> <span class="prompt_item"><input type="image" src="images/yes.jpg" alt="submit" value="yes" onclick="this.disabled=true,this.form.submit();" /></span> <input type="hidden" name="refer" value="yes"> </div> </form> <form action="thank_you.php" method="post" id="formID" > <div class="prompt_container" style="float: right;"> <span class="prompt_item"><input type="image" src="images/no.jpg" alt="submit" value="no" onclick="this.disabled=true,this.form.submit();" /></span> <input type="hidden" name="refer" value="no" > </div> </form> Apparently anything lower than IE8 will ignore the value attribute of all form inputs. How could I get this to work properly in all browsers? jQuery or Javascript maybe?

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  • Java Variable Initialization

    - by Samuel Brainard
    Here's a piece of code I wrote. public class cube { private int length; private int breadth; private int height; private int volume; private int density; private int weight; public cube(int l,int b,int h, int d) { length=l; breadth=b; height=h; density=d; } public void volmeShow(){ volume=length*breadth*height; System.out.println("The Volume of the cube is "+this.volume); So if I implement the above cube class like this, public class cubeApp { public static void main(String[] args){ cube mycube = new cube(5,6,9,2); mycube.volumeShow(); I get an output that tells me Volume is 270. But I get an output that says Volume is 0 if I define the volume variable like this: public class cube { private int length; private int breadth; private int height; private int volume=length*breadth*height; private int density; private int weight; public cube(int l,int b,int h, int d) { length=l; breadth=b; height=h; density=d; } public void volmeShow(){ System.out.println("The Volume of the cube is "+this.volume); Can somebody please explain why this is happening? Thanks, Samuel.

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  • Sorting the output from XmlSerializer in C#

    - by prosseek
    In this post, I could get an XML file generated based on C# class. Can I reorder the XML elements based on its element? My code uses var ser = new XmlSerializer(typeof(Module)); ser.Serialize(WriteFileStream, report, ns); WriteFileStream.Close(); to get the XML file, but I need to have the XML file sorted based on a BlocksCovered variable. public class ClassInfo { public string ClassName; public int BlocksCovered; public int BlocksNotCovered; public double CoverageRate; public ClassInfo() {} public ClassInfo(string ClassName, int BlocksCovered, int BlocksNotCovered, double CoverageRate) { this.ClassName = ClassName; this.BlocksCovered = BlocksCovered; this.BlocksNotCovered = BlocksNotCovered; this.CoverageRate = CoverageRate; } } [XmlRoot("Module")] public class Module { [XmlElement("Class")] public List<ClassInfo> ClassInfoList; public int BlocksCovered; public int BlocksNotCovered; public string moduleName; public Module() { ClassInfoList = new List<ClassInfo>(); BlocksCovered = 0; BlocksNotCovered = 0; moduleName = ""; } } Module report = new Module(); ... TextWriter WriteFileStream = new StreamWriter(xmlFileName); XmlSerializerNamespaces ns = new XmlSerializerNamespaces(); ns.Add("", ""); var ser = new XmlSerializer(typeof(Module)); ser.Serialize(WriteFileStream, report, ns); WriteFileStream.Close();

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  • Adding variably named fields to Python classes

    - by Carson Myers
    I have a python class, and I need to add an arbitrary number of arbitrarily long lists to it. The names of the lists I need to add are also arbitrary. For example, in PHP, I would do this: class MyClass { } $c = new MyClass(); $n = "hello" $c.$n = array(1, 2, 3); How do I do this in Python? I'm also wondering if this is a reasonable thing to do. The alternative would be to create a dict of lists in the class, but since the number and size of the lists is arbitrary, I was worried there might be a performance hit from this. If you are wondering what I'm trying to accomplish, I'm writing a super-lightweight script interpreter. The interpreter walks through a human-written list and creates some kind of byte-code. The byte-code of each function will be stored as a list named after the function in an "app" class. I'm curious to hear any other suggestions on how to do this as well.

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  • how are association, aggregation and composition written?

    - by ajsie
    i have read some posts about the differences between these 3 relationships and i think i get the point. i just wonder, are all these written the same when coding? question 1: all 3 are just a value of the object type in a instance variable? class A { public $b = '' public function __construct($object) { $this->b = $object // <-- could be a association, aggregation or a composition relation? } } question 2: does it have to be an instance variable or can it be a static one? class A { public static $b = '' // <-- nothing changed? public function __construct($object) { $this->b = $object } } question 3: is there a difference in where the object is created? i tend to think that composition object is created inside the object: class A { public $b = '' public function __construct() { $this->b = new Object // is created inside the object } } and aggregation/association is passed through a constructor or another method: class A { public $b = '' public function __construct($object) { // passed through a method $this->b = $object } } question 4: why/when is this important to know. do i have to comment an object inside another what relation its about or do you do it in an UML diagram? could someone shed a light on these questions. thanks!

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  • XML Serialization : Has property of type Class1 : Class1 has another property : How to write the property of Class1 into XML?

    - by Wonderlander
    I want to serialize a class. In this class there's a property, type of Class1, while there are other properties in Class1. public abstract class ComponentBase { [ToSerialize]//An attribute defined my me, indicating whether or not to serialize this property. public ComponentArgs Parameters { get; set; } } public class ComponentArgs { public string WorkingPath { get; set; } public IList<Language> Languages { get; set; } public string ComponentOutputPath { get; set; } } The information serialized must be put into a Dictionary, such as ComponentSettings[str_Name]=str_Value. The method used in reading this value is Reflection. pinfo: Property Info got via Type.GetProperties(); componentSettings.Add(pinfo.Name, pinfo.GetValue((object)this, null).ToString()); The information after serialization is: <Parameters>MS.STBIntl.Pippin.Framework.ComponentArgs</Parameters> instead of the value of ComponentArgs.WorkingPath. The solution I thought of is to append to the following line an if judgement: componentSettings.Add(pinfo.Name, pinfo.GetValue((object)this, null).ToString()); if(pinfo is ComponentArgs) componentSettings.Add(pinfo.Name, pinfo.GetValue( (ComponentArgs)this, null).WorkingPath+"\n"+ LanguageList+"\n"+ //Language list is a concatinated string of all elements in the list. (ComponentArgs)this, null).ComponentOutputPath+"\n"+ ); When deserializing, add a judgement of whether the value contains more than 2 "\n", if so, extract each value from the string. But this way seems clumsy and much more like an workaround. I wonder if there's any more professional way of doing it? My reviewer is very particular and he won't accept such a solution. If you know a way, could you please share it with me? Thanks a lot.

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  • Generics in a bidirectional association

    - by Verhoevenv
    Let's say I have two classes A and B, with B a subtype of A. This is only part of a richer type hierarchy, obviously, but I don't think that's relevant. Assume A is the root of the hierarchy. There is a collection class C that keeps track of a list of A's. However, I want to make C generic, so that it is possible to make an instance that only keeps B's and won't accept A's. class A(val c: C[A]) { c.addEntry(this) } class B(c: C[A]) extends A(c) class C[T <: A]{ val entries = new ArrayBuffer[T]() def addEntry(e: T) { entries += e } } object Generic { def main(args : Array[String]) { val c = new C[B]() new B(c) } } The code above obviously give the error 'type mismatch: found C[B], required C[A]' on the new B(c) line. I'm not sure how this can be fixed. It's not possible to make C covariant in T (like C[+T <: A]) because the ArrayBuffer is non-variantly typed in T. It's not possible to make the constructor of B require a C[B] because C can't be covariant. Am I barking up the wrong tree here? I'm a complete Scala newbie, so any ideas and tips might be helpful. Thank you! EDIT: Basically, what I'd like to have is that the compiler accepts both val c = new C[B]() new B(c) and val c = new C[A]() new B(c) but would reject val c = new C[B]() new A(c) It's probably possible to relax the typing of the ArrayBuffer in C to be A instead of T, and thus in the addEntry method as well, if that helps.

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  • Any workarounds for non-static member array initialization?

    - by TomiJ
    In C++, it's not possible to initialize array members in the initialization list, thus member objects should have default constructors and they should be properly initialized in the constructor. Is there any (reasonable) workaround for this apart from not using arrays? [Anything that can be initialized using only the initialization list is in our application far preferable to using the constructor, as that data can be allocated and initialized by the compiler and linker, and every CPU clock cycle counts, even before main. However, it is not always possible to have a default constructor for every class, and besides, reinitializing the data again in the constructor rather defeats the purpose anyway.] E.g. I'd like to have something like this (but this one doesn't work): class OtherClass { private: int data; public: OtherClass(int i) : data(i) {}; // No default constructor! }; class Foo { private: OtherClass inst[3]; // Array size fixed and known ahead of time. public: Foo(...) : inst[0](0), inst[1](1), inst[2](2) {}; }; The only workaround I'm aware of is the non-array one: class Foo { private: OtherClass inst0; OtherClass inst1; OtherClass inst2; OtherClass *inst[3]; public: Foo(...) : inst0(0), inst1(1), inst2(2) { inst[0]=&inst0; inst[1]=&inst1; inst[2]=&inst2; }; }; Edit: It should be stressed that OtherClass has no default constructor, and that it is very desirable to have the linker be able to allocate any memory needed (one or more static instances of Foo will be created), using the heap is essentially verboten. I've updated the examples above to highlight the first point.

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  • Nested bind expressions

    - by user328543
    This is a followup question to my previous question. #include <functional> int foo(void) {return 2;} class bar { public: int operator() (void) {return 3;}; int something(int a) {return a;}; }; template <class C> auto func(C&& c) -> decltype(c()) { return c(); } template <class C> int doit(C&& c) { return c();} template <class C> void func_wrapper(C&& c) { func( std::bind(doit<C>, std::forward<C>(c)) ); } int main(int argc, char* argv[]) { // call with a function pointer func(foo); func_wrapper(foo); // error // call with a member function bar b; func(b); func_wrapper(b); // call with a bind expression func(std::bind(&bar::something, b, 42)); func_wrapper(std::bind(&bar::something, b, 42)); // error // call with a lambda expression func( [](void)->int {return 42;} ); func_wrapper( [](void)->int {return 42;} ); return 0; } I'm getting a compile errors deep in the C++ headers: functional:1137: error: invalid initialization of reference of type ‘int (&)()’ from expression of type ‘int (*)()’ functional:1137: error: conversion from ‘int’ to non-scalar type ‘std::_Bind(bar, int)’ requested func_wrapper(foo) is supposed to execute func(doit(foo)). In the real code it packages the function for a thread to execute. func would the function executed by the other thread, doit sits in between to check for unhandled exceptions and to clean up. But the additional bind in func_wrapper messes things up...

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  • How to make a transition in flex 4 on a fill that contains a linear gradient?

    - by Totty
    <?xml version="1.0" encoding="utf-8"?> <s:Rect id="background" top="0" right="0" bottom="0" left="0" height="30"> <s:fill> <s:SolidColor color="#000000"/> </s:fill> <s:fill.over> <s:LinearGradient rotation="90"> <s:GradientEntry color="#FF5800" alpha="1.0" ratio="0"/> <s:GradientEntry color="#EE0202" alpha="1.0" ratio="1"/> </s:LinearGradient> </s:fill.over> <s:fill.down> <s:LinearGradient rotation="90"> <s:GradientEntry color="#EE0202" alpha="1.0" ratio="0"/> <s:GradientEntry color="#AF0000" alpha="1.0" ratio="1"/> </s:LinearGradient> </s:fill.down> </s:Rect> <s:RichText id="labelDisplay" paddingLeft="10" paddingRight="10" textAlign="center" fontFamily="Myriad Pro" fontSize="16" tabStops="S0 S50 S100 S150" color="#FFFFFF" y="8" color.over="#000000" tabStops.over="S0 S50 S100 S150" color.down="#000000" tabStops.down="S0 S50 S100 S150" color.disabled="#EE0202" tabStops.disabled="S0 S50 S100 S150" color.up="#EE0202" tabStops.up="S0 S50 S100 S150"> <s:filters> <s:DropShadowFilter includeIn="over" blurX="0" blurY="0" distance="1" hideObject="false" inner="false" color="#FFFFFF" strength="1" alpha="1" quality="2" knockout="false" angle="45.0"/> <s:DropShadowFilter includeIn="down" blurX="0" blurY="0" distance="1" hideObject="false" inner="false" color="#CCCCCC" strength="1" alpha="1" quality="2" knockout="false" angle="45.0"/> <s:BlurFilter includeIn="disabled" blurX="4.0" blurY="4.0" quality="2"/> </s:filters> </s:RichText> here is the code, I would like to make a smooth transition when enters the "over" state. any help?

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