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  • Doubt in abstract classes

    - by mohit
    public abstract class Person { private String name; public Person(String name) { this.name = name; System.out.println("Person"); } public String getName() { return name; } abstract public String getDescription(); } public class Student extends Person { private String major; public Student(String name, String major) { super(name); this.major = major; } public String getMajor() { return major; } @Override public String getDescription() { return "student" + super.getName() + " having" + major; } } public class PersonTest { public static void main(String[] args) { Person person = new Student("XYZ", "ABC"); System.out.println(person.getDescription()); } } Ques: We cannot create objects of abstract classes, then why Person Constructor has been invoked, even its an abstract class?

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  • Java: using generic wildcards with subclassing

    - by gibberish
    Say I have a class Foo, a class A and some subclass B of A. Foo accepts A and its sublclasses as the generic type. A and B both require a Foo instance in their constructor. I want A's Foo to be of type A , and B's Foo to be of type B or a superclass of B. So in effect, So I only want this: Foo<X> bar = new Foo<X>; new B(bar); to be possible if X is either A, B, or a both subclass of A and superclass of B. So far this is what I have: class Foo<? extends A>{ //construct } class A(Foo<A> bar){ //construct } class B(Foo<? super B> bar){ super(bar); //construct } The call to super(...) doesn't work, because <A> is stricter than <? super B>. Is it somehow possible to use the constructor (or avoid code duplication by another means) while enforcing these types? Edit: Foo keeps a collection of elements of the generic parameter type, and these elements and Foo have a bidirectional link. It should therefore not be possible to link an A to a Foo.

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  • Why is C# statically typed?

    - by terrani
    I am a PHP web programmer who is trying to learn C#. I would like to know why C# requires me to specify the data type when creating a variable. Class classInstance = new Class(); Why do we need to know the data type before a class instance?

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  • Wierdness debugging Visual Studio C++ 2008

    - by Jeff Dege
    I have a legacy C++ app, that in its most incarnation we've been building with makefiles and VS2003's command-line tool. I'm trying to get it to build using VS2008 and MsBuild. The build is working OK, but I'm getting errors where I'd never seen errors, before, and stepping through in VS2008's debugger only confuses me. The app links a number of static libraries, which fall into two categories: those that are part of the same application suite, and those that are shared between a number of application suites. Originally, I had a .csproj file for each static library, and two .sln files, one for the application suite (including the suite-specific libraries) and one for the non-suite-specific shared libraries. The shared libraries were included in the link, their projects were not included in the application suite .sln. The application instantiates an object from a class that is defined in one of the shared libraries. The class has a member object of a class that wraps a linked list. The constructor of the linked list class sets its "head" pointer to null. When I run the app, and try to add an element to the linked list, I get an error - the head pointer contains the value 0xCCCCCCCC. So I step through with the debugger. And see weirdness. When the current line in the debugger is in a source file belonging to the static library, the head pointer contains 0x00000000. When I step into the constructor, I can see the pointer being set to that value, and when I'm stepped into any other method of the class, I can see that the head pointer still contains 0x00000000. But when I step out into methods that are defined in the application suite .sln, it contains 0xCCCCCCCC. It's not like it's being overwritten. It changes back and forth depending upon which source file I am currently debugging. So I included the shared library's project in the application suite .sln, and now I see the head pointer containing 0xCCCCCCCC all the time. It looks like the constructor of the linked list class is not being called. So now, I'm entirely confused. Anyone have any ideas?

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  • NHibernate: How is identity Id updated when saving a transient instance?

    - by bretddog
    If I use session-per-transaction and call: session.SaveOrUpdate(entity) corrected: session.SaveOrUpdateCopy(entity) ..and entity is a transient instance with identity-Id=0. Shall the above line automatically update the Id of the entity, and make the instance persistent? Or should it do so on transaction.Commit? Or do I have to somehow code that explicitly? Obviously the Id of the database row (new, since transient) is autogenerated and saved as some number, but I'm talking about the actual parameter instance here. Which is the business logic instance. EDIT Mappings: public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Name); HasMany(x => x.Staff) // 1:m .Cascade.All(); HasManyToMany(x => x.Products) // m:m .Cascade.All() .Table("StoreProduct"); } } public class EmployeeMap : ClassMap<Employee> { public EmployeeMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.FirstName); Map(x => x.LastName); References(x => x.Store); // m:1 } } public class ProductMap : ClassMap<Product> { public ProductMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Name).Length(20); Map(x => x.Price).CustomSqlType("decimal").Precision(9).Scale(2); HasManyToMany(x => x.StoresStockedIn) .Cascade.All() .Inverse() .Table("StoreProduct"); } } EDIT2 Class definitions: public class Store { public int Id { get; private set; } public string Name { get; set; } public IList<Product> Products { get; set; } public IList<Employee> Staff { get; set; } public Store() { Products = new List<Product>(); Staff = new List<Employee>(); } // AddProduct & AddEmployee is required. "NH needs you to set both sides before // it will save correctly" public void AddProduct(Product product) { product.StoresStockedIn.Add(this); Products.Add(product); } public void AddEmployee(Employee employee) { employee.Store = this; Staff.Add(employee); } } public class Employee { public int Id { get; private set; } public string FirstName { get; set; } public string LastName { get; set; } public Store Store { get; set; } } public class Product { public int Id { get; private set; } public string Name { get; set; } public decimal Price { get; set; } public IList<Store> StoresStockedIn { get; private set; } }

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  • Single website multiple connection strings using asp mvc 2 and nhibernate

    - by jjjjj
    Hi In my website i use ASP MVC 2 + Fluent NHibernate as orm, StructureMap for IoC container. There are several databases with identical metadata(and so entities and mappings are the same). On LogOn page user fiils in login, password, rememberme and chooses his server from dropdownlist (in fact he chooses database). Web.config contains all connstrings and we can assume that they won't be changed in run-time. I suppose that it is required to have one session factory per database. Before using multiple databases, i loaded classes to my StructureMap ObjectFactory in Application_Start ObjectFactory.Initialize(init => init.AddRegistry<ObjectRegistry>()); ObjectFactory.Configure(conf => conf.AddRegistry<NhibernateRegistry>()); NhibernateRegistry class: public class NhibernateRegistry : Registry { public NhibernateRegistry() { var sessionFactory = NhibernateConfiguration.Configuration.BuildSessionFactory(); For<Configuration>().Singleton().Use( NhibernateConfiguration.Configuration); For<ISessionFactory>().Singleton().Use(sessionFactory); For<ISession>().HybridHttpOrThreadLocalScoped().Use( ctx => ctx.GetInstance<ISessionFactory>().GetCurrentSession()); } } In Application_BeginRequest i bind opened nhibernate session to asp session(nhibernate session per request) and in EndRequest i unbind them: protected void Application_BeginRequest( object sender, EventArgs e) { CurrentSessionContext.Bind(ObjectFactory.GetInstance<ISessionFactory>().OpenSession()); } Q1: How can i realize what SessionFactory should i use according to authenticated user? is it something like UserData filled with database name (i use simple FormsAuthentication) For logging i use log4net, namely AdoNetAppender which contains connectionString(in xml, of course). Q2: How can i manage multiple connection strings for this database appender, so logs would be written to current database? I have no idea how to do that except changing xml all the time and reseting xml configuration, but its really bad solution.

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  • Java/Hibernate using interfaces over the entities.

    - by Dennetik
    I am using annoted Hibernate, and I'm wondering whether the following is possible. I have to set up a series of interfaces representing the objects that can be persisted, and an interface for the main database class containing several operations for persisting these objects (... an API for the database). Below that, I have to implement these interfaces, and persist them with Hibernate. So I'll have, for example: public interface Data { public String getSomeString(); public void setSomeString(String someString); } @Entity public class HbnData implements Data, Serializable { @Column(name = "some_string") private String someString; public String getSomeString() { return this.someString; } public void setSomeString(String someString) { this.someString = someString; } } Now, this works fine, sort of. The trouble comes when I want nested entities. The interface of what I'd want is easy enough: public interface HasData { public Data getSomeData(); public void setSomeData(Data someData); } But when I implement the class, I can follow the interface, as below, and get an error from Hibernate saying it doesn't know the class "Data". @Entity public class HbnHasData implements HasData, Serializable { @OneToOne(cascade = CascadeType.ALL) private Data someData; public Data getSomeData() { return this.someData; } public void setSomeData(Data someData) { this.someData = someData; } } The simple change would be to change the type from "Data" to "HbnData", but that would obviously break the interface implementation, and thus make the abstraction impossible. Can anyone explain to me how to implement this in a way that it will work with Hibernate?

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  • How to implement "select sum()" in Grails

    - by xain
    I have a relationship like this: class E { string name hasMany = [me:ME] } class M { float price } class ME { E e M m int quantity } And I'd hate to iterate to achieve this: "obtain the sum of the quantity in ME times the price of the corresponding M for a given E". Any hints on how to implement it using GORM/HQL ? Thanks in advance

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  • How can I "override" deepcopy in Python?

    - by Az
    Hi there, I'd like to override __deepcopy__ for a given SQLAlchemy-mapped class such that it ignores any SQLA attributes but deepcopies everything else that's part of the class. I'm not particularly familiar with overriding any of Python's built-in objects in particular but I've got some idea as to what I want. Let's just make a very simple class User that's mapped using SQLA. class User(object): def __init__(self, user_id, name): self.user_id = user_id self.name = name I've used dir() to see, before and after mapping, what SQLAlchemy-specific attributes there are and I've found _sa_class_manager and _sa_instance_state. Provided those are the only ones how would I ignore that when defining __deepcopy__? Also, are there any attributes the SQLA injects into the mapped object? (I asked this in a previous question (as an edit a few days after I selected an answer to the main question, though) but I think I missed the train there. Apologies for that.)

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  • How could I implement a fuzzy time date replacer using Knockout?

    - by rball
    I'd like to implement what this plugin does using jQuery: https://github.com/rmm5t/jquery-timeago A short description of that plugin: This will turn all abbr elements with a class of timeago and an ISO 8601 timestamp in the title (conforming to the datetime design pattern microformat): <abbr class="timeago" title="2011-12-17T09:24:17Z">December 17, 2011</abbr> Into something like this: <abbr class="timeago" title="December 17, 2011">about 1 day ago</abbr> Except using knockout my markup looks like this: <abbr data-bind="attr: { title: Posted }" class="timeago"></abbr> I think something isn't synced up because nothing is happening even if I put the call to timeago within the viewmodel itself. I'm guessing I need a subscriber that's attached to the observable "Posted" but I'm not sure how to set that up.

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  • django model relation definition

    - by Laurent Luce
    Hello, Let say I have 3 models: A, B and C with the following relations. A can have many B and many C. B can have many C Is the following correct: class A(models.Model): ... class B(models.Model): ... a = ForeignKey(A) class C(models.Model): ... a = ForeignKey(A) b = ForeignKey(B)

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  • How to treat Base* pointer as Derived<T>* pointer?

    - by dehmann
    I would like to store pointers to a Base class in a vector, but then use them as function arguments where they act as a specific class, see here: #include <iostream> #include <vector> class Base {}; template<class T> class Derived : public Base {}; void Foo(Derived<int>* d) { std::cerr << "Processing int" << std::endl; } void Foo(Derived<double>* d) { std::cerr << "Processing double" << std::endl; } int main() { std::vector<Base*> vec; vec.push_back(new Derived<int>()); vec.push_back(new Derived<double>()); Foo(vec[0]); Foo(vec[1]); delete vec[0]; delete vec[1]; return 0; } This doesn't compile: error: call of overloaded 'Foo(Base*&)' is ambiguous Is it possible to make it work? I need to process the elements of the vector differently, according to their int, double, etc. types.

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  • Ads in whole app iPhone problem

    - by lars
    I am using mobclix together with admob. The code is to big to add it in all classes. So i created a new class: Ads Everytime i want an ad in a view, i have to send the view to the ad class: - (void)initAd:(UIView *) pView { NSLog(@"ads init"); self.loadedView = pView; ..... To create an ad in a class: Ad* ad = [Ads new]; [ad initAd:self.view]; I dont know if thats the right way. I have to create a new Ads object everytime i change a view (or class). Is there a way to always have an Ads instance running, or is there another better way? Thanks alot!!

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  • How to call Java code from Javascript and assign a value to a JSP page?

    - by Frank
    I have the following "form.jsp" program, it generates a drop down list, below the list is a textarea to show the display_name of a selected item, now when user selected a item, it shows the selected item id in the textarea, how to call the DB from my code and get the display_name in the javascript so the result display_name will be shown in the textarea ? <%@ taglib prefix="s" uri="/struts-tags"%> <script type="text/javascript"> function callme(Display_Name) { alert('callme : Display_Name = '+Display_Name); var v=document.getElementById('hiddenValue').value; alert('hiddenValue : v = '+v); document.getElementById('defaultDisplayName').value=Display_Name; } </script> <s:hidden id="pricelist.id" name="pricelist.id" value="%{pricelist.id}"/> <div class="dialog"> <table> <tbody> <s:if test="%{enableProductList}"> <tr class="prop"> <td valign="top" class="name required"><label for="description">Product:</label></td> <td valign="top"> <s:select id="productPrice.product" name="productPrice.product" headerKey="0" headerValue="-- Select Product --" list="products" listKey="id" listValue="name" value="productPrice.product.id" theme="simple" displayName1='value' onchange="callme(value)" /> <s:hidden id="hiddenValue" name="hiddenValue" value="123"/> </td> </tr> </s:if> <tr class="prop"> <td valign="top" class="name"><label for="description">Default Display Name:</label></td> <td valign="top"><s:textarea id="defaultDisplayName" name="defaultDisplayName" theme="simple" readonly="true"/></td> </tr> See attached image for details, in the DB, a product table has the product Id and display_name, I know the Id, how to use Java to get the display_name and plug it into the jsp ?

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  • preload image with jquery

    - by robertdd
    ok, I spent 2 days trying to preloaded images but no succes! i have this function: jQuery.getlastimage = function(id) { $.getjs(); $.post('operations.php', {'operation':'getli', 'id':id,}, function(lastimg){ $("#upimages" + id).html('<a href="uploads/'+ lastimg +'?'+ (new Date()).getTime() +'"><img class="thumbs" id="' + id + '" alt="' + lastimg + '" src="uploads/' + lastimg +'?'+ (new Date()).getTime() + '" /></a>'); }); }; while the image loading i want to appear a gif or a text "Loading...". the function will get something like this: <div class="upimage"> <ul class="thumbs" id="upimagesQueue"> **<li id="#upimagesRIFDIB"> <a href="uploads/0001.jpg?1271800088379"> <img src="uploads/0001.jpg?1271800088379" alt="0001.jpg" id="RIFDIB" class="thumbs"> </a> </li>** <li> .... </li> </ul> </div> i tryed like this: ... $.post('operations.php', {'operation':'getli', 'id':id,}, function(lastimg){ $("#upimages" + id) .html('<a href="uploads/'+ lastimg +'?'+ (new Date()).getTime() +'"><img class="thumbs" id="' + id + '" alt="' + lastimg + '" src="uploads/' + lastimg +'?'+ (new Date()).getTime() + '" /></a>') .hide() .load(function() { $(this).show(); }); ... but all the <li> will hide and after is loading the image appear, i want the <li> to apear with a gif or a text in it and after the image is loaded the link and the image to apear! How to do this? Anyone have an idea? Thanks!

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  • Sharing a database connection with included classes in a Sinatra application

    - by imightbeinatree
    I'm converting a part of a rails application to its own sinatra application. It has some beefy work to do and rather than have a million helps in app.rb, I've separated some of it out into classes. Without access to rails I'm rewriting finder several methods and needing access to the database inside of my class. What's the best way to share a database connection between your application and a class? Or would you recommend pushing all database work into its own class and only having the connection established there? Here is what I have in in app.rb require 'lib/myclass' configure :production do MysqlDB = Sequel.connect('mysql://user:password@host:port/db_name') end I want to access it in lib/myclass.rb class Myclass def self.find_by_domain_and_stub(domain, stub) # want to do a query here end end I've tried several things but nothing that seems to work well enough to even include as an example.

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  • PHP Value Object auto create

    - by JonoB
    Assume that I have a class value object defined in php, where each variable in the class is defined. Something like: class UserVO { public $id; public $name; } I now have a function in another class, which is expecting an array ($data). function save_user($data) { //run code to save the user } How do I tell php that the $data parameter should be typed as a UserVO? I could then have code completion to do something like: $something = $data->id; //typed as UserVO.id $else = $data->name; //typed as UserVO.name I'm guessing something like the following, but this obviously doesnt work $my_var = $data as new userVO();

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  • How to align floated elements such that their bottoms match

    - by AJM
    I'm writing a web page where I show a title and a date over some text. My HTML: <div class="post"> <h2>Post 1</h2> <span class="date">February 28, 2011</span> <div class="post-content"> ... </div> </div> My css: .post h2 { float: left; } .date { float: right; } .post-content { clear: both; } What I want to do is vertically align the title and date such that their bottoms match. Right now they don't: I tried wrapping the two text elements in a div, setting the div's position to relative, and using absolute positioning on the two text elements (and taking out the float declarations). That didn't work because the top margin is not preserved due to the wrapper div collapsing, even though I gave it a clearfix class.

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  • Extending existing data structure in Scala.

    - by Lukasz Lew
    I have a normal tree defined in Scala. sealed abstract class Tree case class Node (...) extends Tree case class Leaf (...) extends Tree Now I want to add a member variable to all nodes and leaves in the tree. Is it possible with extend keyword or do I have to modify the tree classes by adding [T]?

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  • ASP.NET MVC4: How do I keep from having multiple identical results in my lookup tables

    - by sehummel
    I'm new to ASP.NET so this may be an easy question. I'm seeding my database with several rows of dummy data. Here is one of my rows: new Software { Title = "Microsoft Office", Version = "2012", SerialNumber = "12346231434543", Platform = "PC", Notes = "Macs really rock!", PurchaseDate = "2011-12-04", Suite = true, SubscriptionEndDate = null, SeatCount = 0, SoftwareTypes = new List<SoftwareType> { new SoftwareType { Type="Suite" }}, Locations = new List<Location> { new Location { LocationName = "Paradise" }}, Publishers = new List<SoftwarePublisher> { new SoftwarePublisher { Publisher = "Microsoft" }}} But when I do this, a new row is created for each location, with the LocationName being set in each row like this. We only have two locations. How do I get it to create a LocationID property for the Software class and in my Locations class. Here is my Location class: public class Location { public int Id { get; set; } [Required] [StringLength(20)] public string LocationName { get; set; } public virtual Software Software { get; set; } } I have this line in my Software class to reference this table: public virtual List<Location> Locations { get; set; } Again, what I want when I am done is a Locations table with two entries, and a LocationID field in my Software table. How do I do this?

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  • Load iframe in html, only with jquery

    - by phpExe
    In this jquery code: $(document).ready(function(){ $list = $(".channeList li"); $list.click(function(){ var $this = $(this); var $mainDesc = $(".ply"); var iframe = $("a", $this).attr("rel"); $("iframe", $mainDesc).attr("src", iframe); } ); } ); There is a list o channels in left that iframe loads from a rel's. I want to load first iframe in <div class="ply"></div> In html, I dont want insert the first item. Can we do this without load first item in html and do this only with jquery? The php function channel() { if (is_numeric($_GET['kanalID'])) { $kanalID = $_GET['kanalID']; } if ($_GET['kanalID'] == "") { $kanalID = 1;} $channel = '<ul class="channeList">'; foreach ($tv as $id => $kanal) { $class = $kanalID == $id ? $class = "currentt": ''; $channel .= '<li> <a href="#" rel="http://mysite.com/index.php?id='.$id.'&w=500&h=320" >'.$kanal.'</a></li>'; } $channel .= '</ul>'; $channel .= '<div class="ply"><iframe frameborder=0 width="500" height="320"></iframe></div>'; return $channel; } Thanks in advance

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  • Django left join m2m field.

    - by duder
    Here's my Model: class User(models.Model): pass class Item(models.Model): pass class ItemVote(models.Model): user = models.ForeignKey(User) item = models.ForeignKey(Item) vote = models.BooleanField() I want to retrieve a list of Items, and I want to know if the current user has voted for each Item. How do I alter my query object so that it will generate sql similar to: SELECT ... FROM items LEFT OUTER JOIN item_votes ON (item_votes.user_id = ? AND item_votes.item_id = items.id)

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  • Access to field in extended flatpage in django

    - by Stanislav Feldman
    How to access field in extended flatpage in django? I wrote this: class ExtendedFlatPage(FlatPage): teaser = CharField(max_length=150) class ExtendedFlatPageForm(FlatpageForm): teaser = CharField(max_length=150) class Meta: model = ExtendedFlatPage class ExtendedFlatPageAdmin(FlatPageAdmin): form = ExtendedFlatPageForm fieldsets = ( (None, {'fields': ('url', 'title', 'teaser', 'content', 'sites',)}), ) admin.site.unregister(FlatPage) admin.site.register(ExtendedFlatPage, ExtendedFlatPageAdmin) And creation in admin is ok. But then in flatpages/default.html I tried this: <html> <body> <h1>{{ flatpage.title }}</h1> <strong>{{ flatpage.teaser }}</strong> <p>{{ flatpage.content }}</p> </body> </html> And there was no flatpage.teaser! What is wrong?

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  • Compare Properties automatically

    - by juergen d
    I want to get the names of all properties that changed for matching objects. I have these (simplified) classes: public enum PersonType { Student, Professor, Employee } class Person { public string Name { get; set; } public PersonType Type { get; set; } } class Student : Person { public string MatriculationNumber { get; set; } } class Subject { public string Name { get; set; } public int WeeklyHours { get; set; } } class Professor : Person { public List<Subject> Subjects { get; set; } } Now I want to get the objects where the Property values differ: List<Person> oldPersonList = ... List<Person> newPersonList = ... List<Difference> = GetDifferences(oldPersonList, newPersonList); public List<Difference> GetDifferences(List<Person> oldP, List<Person> newP) { //how to check the properties without casting and checking //for each type and individual property?? //can this be done with Reflection even in Lists?? } In the end I would like to have a list of Differences like this: class Difference { public List<string> ChangedProperties { get; set; } public Person NewPerson { get; set; } public Person OldPerson { get; set; } } The ChangedProperties should contain the name of the changed properties.

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