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• C# array of objects - conditional validation

  - by fishdump

  Sorry about the vague title! I have an class with a number of member variables (system, zone, site, ...) public sealed class Cello { public String Company; public String Zone; public String System; public String Site; public String Facility; public String Process; //... } I have an array of objects of this class. private Cello[] m_cellos = null; // ... I need to know whether the array contains objects with the same site but different systems, zones or companies since such a situation would be illegal. I have various other checks to make but they are all along similar lines. The Array class has a number of functions that look promising but I am not very up on defining 'key selector' functions and things like that. Any suggestions or pointers would be greatly appreciated. --- Alistair.

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• hibernate annotation bi-directional mapping

  - by smithystar

  I'm building a web application using Spring framework and Hibernate with annotation and get stuck with a simple mapping between two entities. I'm trying to create a many-to-many relationship between User and Course. I followed one of the Hibernate tutorials and my implementation is as follows: User class: @Entity @Table(name="USER") public class User { private Long id; private String email; private String password; private Set<Course> courses = new HashSet<Course>(0); @Id @GeneratedValue @Column(name="USER_ID") public Long getId() { return id; } public void setId(Long id) { this.id = id; } @Column(name="USER_EMAIL") public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } @Column(name="USER_PASSWORD") public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @ManyToMany(cascade = CascadeType.ALL) @JoinTable(name = "USER_COURSE", joinColumns = { @JoinColumn(name = "USER_ID") }, inverseJoinColumns = { @JoinColumn(name = "COURSE_ID") }) public Set<Course> getCourses() { return courses; } public void setCourses(Set<Course> courses) { this.courses = courses; } } Course class: @Entity @Table(name="COURSE") public class Course { private Long id; private String name; @Id @GeneratedValue @Column(name="COURSE_ID") public Long getId() { return id; } public void setId(Long id) { this.id = id; } @Column(name="NAME") public String getName() { return name; } public void setName(String name) { this.name = name; } } The problem is that this implementation only allows me to go one way user.getCourses() What do I need to change, so I can go in both directions? user.getCourses() course.getUsers() Any help would be appreciated.

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• Query distinct list of choices for Django form with App Engine Datastore

  - by Brian

  I've been trying to figure this out for hours across a couple of days, and can not get it to work. I've been everywhere. I'll continue trying to figure it out, but was hoping for a quicker solution. I'm using App Engine datastore + Django. Using a query in a view and custom forms, I was able to get a list to the form but then I was not able to post. I have been trying to figure out how to dynamically add the choices as part of the Django form... I've tried various ways with no success. Help! Below are the two models. I'd like to get a distinct list of address_id to show in the location field in InfoForm. This fields could (and maybe should) be named the same, but I thought it'd be easier if they were named different. class Info(db.Model): user = db.UserProperty() location = db.StringProperty() info = db.StringProperty() created = db.DateTimeProperty(auto_now_add=True) modified = db.DateTimeProperty(auto_now=True) class Locations(db.Model): user = db.UserProperty() address_id = db.StringProperty() address = db.StringProperty() class InfoForm(djangoforms.ModelForm): info = forms.ChoiceField(choices=INFO_CHOICES) location = forms.ChoiceField() class Meta: model = Info exclude = ['user','created','modified']

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• Make a <div> disappear inside a javascript script

  - by KeenClock

  First of all, I have this line of code on a random page : <script type="text/javascript" src="script.php"></script> On the page named "script.php", I have a <div class="something">random text</div> and the random text is displayed and everything is working fine. Now, I would like to know if it's possible to make that specific <div> to disappear without having to modify the code inside the "script.php" page. Thank you ! Edit: Thank you to all of you, you helped me found a solution, here is an example : <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="fr" lang="fr"><head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Random page</title> <style type="text/css"> div.something { font-family: Tahoma; font-size: 12px; font-weight: bold; text-decoration: underline; } </style> <script type="text/javascript"> function hideSomething() { document.getElementsByClassName("something")[2].style.display = "none"; } </script> </head> <body> <div class="something">random text 1</div> <div class="something">random text 2</div> <div class="something">random text 3</div> <br /><input type="submit" value="Disappear" onclick="hideSomething()" /> </body> </html>

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• Why do I get null objects in a many-to-many bag?

  - by Jim Geurts

  I have a bag defined for a many-to-many list: <class name="Author" table="Authors"> <id name="Id" column="AuthorId"> <generator class="identity" /> </id> <property name="Name" /> <bag name="Books" table="Author_Book_Map" where="IsDeleted=0" fetch="join"> <key column="AuthorId" /> <many-to-many class="Book" column="BookId" where="IsDeleted=0" /> </bag> </class> If I return all author objects using something like the following, I will get what initially appeared to be duplicate Author records: Session.Query<Author>().List<Author>() The extra author objects are created when an author is mapped to Book objects that have IsDeleted = 1 and IsDeleted = 0. Rather than creating one Author object with an enumerable that contains only the books with IsDeleted = 0, it will create two author objects. The first author object has a Books enumerable that contains books with IsDeleted = 0. The second author object will contain an enumerable of null book objects. Similarly, if an object only has one book map, and that map points to a book with IsDeleted = 1, then an author object is returned with a Books collection having one null object. I'm thinking part of the problem stems from the map table objects linking to rows that satisfy the where condition on the bag object but do not meet the many-to-many where condition. This is happening with NHibernate version 3.0.0.4980. Is this a configuration issue or something else?

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• incorrect height in Chrome when "-webkit-appearance: none" and value="" on <input> tag

  - by Avi Steiner

  In Chrome v17.0.963.79 on Windows 7, I seem to be having an inexplicable problem when applying the -webkit-appearance: none style to an <input> tag. The problem is as follows: I have a stylesheet, let's call it potatofoot.css, which consists of the code .tbl { display: table; } .tblRow { display: table-row; } .tblCell { display: table-cell; } input { -webkit-appearance: none; }? and I have an html file, let's call it blech.html, which contains the code <div class="tbl"> <div class="tblRow"> <label class="tblCell">Name</label> <input type="text" class="tblCell" value="I'M NOT EMPTY! OH, YEAH!"> </div><!--end tblRow--> </div><!--end tbl--> This displays fine (see this jsfiddle). But when I empty the value attribute, as in this jsfiddle, the entire table grows from a height of 26px to a height of 31px, the label moves to the bottom, and the input stays at the top. However, if I remove -webkit-appearance: none;, everything shows up the same with and without out the value attribute being filled. What's going on?

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• Selecting an option with given value

  - by Maven

  I am trying to select a particular option from a select list depending on the value, I have following markup: <select name="class" id="class"> <option value="1">679460ED-0B15-4ED9-B3C8-A8C276DF1C82</option> <option value="2">B99BF873-7DF0-4E7F-95FF-3F1FD1A26139</option> <option value="3">1DCD5AD7-F57C-414</option> <option value="4">6B0170AA-F044-4F9C-8BB8-31A51E452CE4</option> <option value="5">C6A8B</option> <option value="6">1BBD6FA4-335A-4D8F-8681-DFED317B8052</option> <option value="7">727D71AB-F7D1-4B83-9D6D-6BEEAAB</option> <option value="8">BC4DE8A2-C864-4C7C-B83C-EE2450AF11B1</option> <option value="9">AIR CONDITIONING SYSTEM</option> <option value="10">POWER GENERATION SYSTEM</option> </select> <script> selectThisValue('#class',3); </script> in .js function selectThisValue(element,value) { console.log(value); var elem = $(element + ' option[value=' + value + ']'); console.log(elem); elem.attr("selected", "selected"); } Results for console.log are as follows: 3 [prevObject: i.fn.i.init[1], context: document, selector: "#class option[value=3]", jquery: "1.10.2", constructor: function…] But this is not working, no errors are given but nothing happens also. Please help identifying the where am I wrong.

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• C++ MFC server app with sockets crashes and I cannot find the fault, help!

  - by usermeister

  My program has one dialog and two sockets. Both sockets are derived from CAsyncSocket, one is for listening, other is for receiving data from client. My program crashes when client tries to connect to server application and server needs to initialize receiving socket. This is my MFC dialog class. class CFileTransferServerDlg : public CDialog { ... ListeningSocket ListenSock; ReceivingSocket* RecvSock; void OnAccept(); // called when ListenSock gets connection attempt ... }; This is my derived socket class for receiving data that calls parent dialogs method when event is signaled. class ReceivingSocket : public CAsyncSocket { CFileTransferServerDlg* m_pDlg; // for accessing parent dialogs controls virtual void OnReceive(int nErrorCode); } ReceivingSocket::ReceivingSocket() { } This is dialogs function that handles incoming connection attempt when listening socket gets event notification. This is where the crash happens. void CFileTransferServerDlg::OnAccept() { RecvSock = new ReceivingSocket; /* CRASH */ } OR void CFileTransferServerDlg::OnAccept() { ReceivingSocket* tmpSock = new ReceivingSocket; tmpSock->SetParentDlg(this); CString message; if( ListenSock.Accept(*tmpSock) ) /* CRASH */ { message.LoadStringW(IDS_CLIENT_CONNECTED); m_txtStatus.SetWindowTextW(message); RecvSock = tmpSock; } } My program crashes when I try to create a socket for receiving file sent from client application. OnAccept starts when Listening socket signals incoming connection attempt, but my application then crashes. I've tried running it on another computer and connection attempt was succesful. What could be wrong? Error in debug mode: Unhandled exception at 0x009c30e1 in FileTransferServer.exe: 0xC0000005: Access violation reading location 0xccccce58.

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• Compressing a database to a single file?

  - by Assimilater

  Hi all. In my contact manager program I have been storing information by reading and writing comma delimited files for each individual contact, and storing notes in a file for each note, and I'm wondering how I could go about shrinking them all into one file effectively. I have attempted using data entry tools in the visual studio toolbox and template class, though I have never quite figured out how to use them. What would be especially convenient is if I could store data as data type IOwner (a class I created) as opposed to strings. I'd also need to figure out how to tell the program what to do when a file is opened (I've noticed in the properties how to associate a file type with the program though am not sure how to tell it what to do when it's opened). Edit: How about rephrasing the question: I have a class IContact with various properties some of them being lists of other class objects. I have a public list of IContact. Can I write Contacts as List(Of IContact) to a file as opposed to a bunch of strings? Second part of the question: I have associated .cms files with my program. But if a user opens the file, what code should the program run through in an attempt to deal with the file? This file is going to contain data that the program needs to read, how do I tell it to read a file when the program is opened vicariously because the file was opened? Does this make the question clearer?

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• Problem with derived ControlTemplates in WPF

  - by Frank Fella

  The following xaml code works: <Window x:Class="DerivedTemplateBug.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:DerivedTemplateBug" Title="Window1" Height="300" Width="300"> <Button> <Button.Template> <ControlTemplate> <Border BorderBrush="Black" BorderThickness="2"> <TextBlock>Testing!</TextBlock> </Border> </ControlTemplate> </Button.Template> </Button> </Window> Now, if you define the following data template: using System.Windows.Controls; namespace DerivedTemplateBug { public class DerivedTemplate : ControlTemplate { } } And then swap the ControlTemplate for the derived class: <Window x:Class="DerivedTemplateBug.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:DerivedTemplateBug" Title="Window1" Height="300" Width="300"> <Button> <Button.Template> <local:DerivedTemplate> <Border BorderBrush="Black" BorderThickness="2"> <TextBlock>Testing!</TextBlock> </Border> </local:DerivedTemplate> </Button.Template> </Button> </Window> You get the following error: Invalid ContentPropertyAttribute on type 'DerivedTemplateBug.DerivedTemplate', property 'Content' not found. Can anyone tell me why this is the case?

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• Empty UL inside LI element

  - by zorglub76

  Can anyone explain me why the hell UL element cannot be empty? And why this HTML: <ul> <li class="header"> <a href="#">Work</a> <ul/> </li> <li class="header"> <a href="#">New</a> <ul/> </li> <li class="header"> <a href="#">Ungrouped</a> <ul/> </li> <li class="header"> <a href="#">Offline</a> <ul/> </li> </ul> is rendered like this: Work --New ----Ungrouped ------Offline

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• Rails nested attributes with a join model, where one of the models being joined is a new record

  - by gzuki

  I'm trying to build a grid, in rails, for entering data. It has rows and columns, and rows and columns are joined by cells. In my view, I need for the grid to be able to handle having 'new' rows and columns on the edge, so that if you type in them and then submit, they are automatically generated, and their shared cells are connected to them correctly. I want to be able to do this without JS. Rails nested attributes fail to handle being mapped to both a new record and a new column, they can only do one or the other. The reason is that they are a nested specifically in one of the two models, and whichever one they aren't nested in will have no id (since it doesn't exist yet), and when pushed through accepts_nested_attributes_for on the top level Grid model, they will only be bound to the new object created for whatever they were nested in. How can I handle this? Do I have to override rails handling of nested attributes? My models look like this, btw: class Grid < ActiveRecord::Base has_many :rows has_many :columns has_many :cells, :through => :rows accepts_nested_attributes_for :rows, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } accepts_nested_attributes_for :columns, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } end class Column < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :rows, :through => :grid end class Row < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :columns, :through => :grid accepts_nested_attributes_for :cells end class Cell < ActiveRecord::Base belongs_to :row belongs_to :column has_one :grid, :through => :row end

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• jQuery draggable removing without changing position of other elements

  - by Yurish

  Hi! I am building a page layout configuration system on jQuery. So everyone, who is using my website can make it personal by moving elements on webpage. But, I have a problem. Every element on my page is a draggable div with option to be removed from page if necessary. When user wants to remove an element, he clicks on inner div and the following function is called: <script language="javascript"> $(function() { $('.close').click(function(){ $(this).parent().hide(); }); }); </script> <div class="main"><div class="close"></div></div> When user wants to add an element on page, he clicks on link and followinf function is called: function addNewWidget(page_name, size){ var page = $('#'+page_name); var closeDiv = $(document.createElement("div")).attr("class", "close").html('X'); closeDiv.click(function(){ $(this).parent().hide(); }); var div = $(document.createElement("div")) div.attr("class", "drag"); div.appendTo(page); closeDiv.appendTo(div); div.draggable({ containment: "#page", scroll: false, grid: [200, 200] }); div.css("top:0; left:0"); div.addClass(size); div.addClass('widget'); } Everything works fine, but when element is removed, other elements, which were on page are moving up. It is because of element positioning in the code. These divs in the code are before div, which was removed, and their absolute top is changed by -heghtOfRemovedElement Is there any way to prevent other elements from moving up?

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• Using groovy ws with enum types?

  - by Jared

  I'm trying to use groovy ws to call a webservice. One of the properties of the generated class is it's self a class with an enum type. Although the debug messages show that the com.test.FinalActionType is created at runtime when the WSDL is read I can't create an instance of it using code like proxy.create("com.test.FinalActionType") When I try and assign a string to my class uin place of an instance of FinalActionType groovy is not able to do the conversion. How can I get an instance of this class to use in a webservice call? I've pasted the important part of the WSDL below. <xsd:simpleType name="FinalActionType"> <xsd:restriction base="xsd:string"> <xsd:enumeration value="stop"/> <xsd:enumeration value="quit"/> <xsd:enumeration value="continue"/> <xsd:whiteSpace value="collapse"/> </xsd:restriction> </xsd:simpleType>

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• How to use StructureMap to inject repository classes to the controller?

  - by Lorenzo

  In the current application I am working on I have a custom ControllerFactory class that create a controller and automatically sets the Elmah ErrorHandler. public class BaseControllerFactory : DefaultControllerFactory { public override IController CreateController( RequestContext requestContext, string controllerName ) { var controller = base.CreateController( requestContext, controllerName ); var c = controller as Controller; if ( c != null ) { c.ActionInvoker = new ErrorHandlingActionInvoker( new HandleErrorWithElmahAttribute() ); } return controller; } protected override IController GetControllerInstance( RequestContext requestContext, Type controllerType ) { try { if ( ( requestContext == null ) || ( controllerType == null ) ) return base.GetControllerInstance( requestContext, controllerType ); return (Controller)ObjectFactory.GetInstance( controllerType ); } catch ( StructureMapException ) { System.Diagnostics.Debug.WriteLine( ObjectFactory.WhatDoIHave() ); throw new Exception( ObjectFactory.WhatDoIHave() ); } } } I would like to use StructureMap to inject some code in my controllers. For example I would like to automatically inject repository classes in them. I have already created my repository classes and also I have added a constructor to the controller that receive the repository class public FirmController( IContactRepository contactRepository ) { _contactRepository = contactRepository; } I have then registered the type within StructureMap ObjectFactory.Initialize( x => { x.For<IContactRepository>().Use<MyContactRepository>(); }); How should I change the code in the CreateController method to have the IContactRepository concrete class injected in the FirmController? EDIT: I have changed the BaseControllerFactory to use Structuremap. But I get an exception on the line return (Controller)ObjectFactory.GetInstance( controllerType ); Any hint?

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• Regular Expression doesn't match

  - by dododedodonl

  Hi All, I've got a regular expression in my cocoa-touch app (using RegexKitLite). NSString *week = [[NSString alloc] initWithFormat:@"%@", [pageContent stringByReplacingOccurrencesOfRegex:@"<select name=\"week\" class=\"selectbox\" style='width:134' onChange=\"doDisplayTimetable(NavBar, topDir);\">(.+?)<option value=\"(.+?)\">(.+?)</option>" withString:@"$2"]]; I expect it to match with the section of this (what is in NSString pageContent): <span class="selection"> <nobr> Periode<br> <span class="absatz"> &nbsp;<br> </span> <select name="week" class="selectbox" style='width:134' onChange="doDisplayTimetable(NavBar, topDir);"> <option value="14">17-5 - 16-7</option> </select> </nobr> </span> But it doesn't... I need the value of the option, it is possible that there is more than one (in that case I need them both separated by a ,. Can someone help me out? Regards, Dodo

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• jQuery code works for console but not in-page.

  - by justSteve

  I have a form element defined as: <div class="field"> <div class="name"> <label for="User_LastName"> Last name: <span class="asterisk">*</span></label> </div> <div class="value"> <%= Html.TextBox("User.LastName", Model.LastName)%> <%= Html.ValidationMessage("User.LastName")%> </div> </div> and a jQuery selector that is supposed to detect when the input gets focus and highlight the parent: $("input").focus(function() { //watching for an event where an input form comes into focus $(this) .parent() .addClass("curFocus") .children("div") .toggle(); }); If i paste this code into firebug's console - things work as planned. However, i'm running this from a 'RenderPartial' .net mvc page. Other jQuery code sitting within the same $(document).ready(function() { block work correctly. The form uses html helpers to generate the inputs which might complicate the process somewhat - but even so... i'm seeing correct behavior when that code's in console but not in a 'real-time' page. How do i troubleshoot this?

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• Strange befaviour of spring transaction support for JPA + Hibernate +@Transactional annotation

  - by abovesun

  I found out really strange behavior on relatively simple use case, probably I can't understand it because of not deep knowledges of spring @Transactional nature, but this is quite interesting. I have simple User dao that extends spring JpaDaoSupport class and contains standard save method: @Transactional public User save(User user) { getJpaTemplate().persist(user); return user; } If was working fine until I've add new method to same class: User getSuperUser(), this method should return user with isAdmin == true, and if there is no super user in db, method should create one. Thats how it was looking like: public User createSuperUser() { User admin = null; try { admin = (User) getJpaTemplate().execute(new JpaCallback() { public Object doInJpa(EntityManager em) throws PersistenceException { return em.createQuery("select u from UserImpl u where u.admin = true").getSingleResult(); } }); } catch (EmptyResultDataAccessException ex) { User admin = new User('login', 'password'); admin.setAdmin(true); save(admin); // THIS IS THE POINT WHERE STRANGE THING COMING OUT } return admin; } As you see code is strange forward and I was very confused when found out that no transaction was created and committed on invocation of save(admin) method and no new user wasn't actually created despite @Transactional annotation. In result we have situation: when save() method invokes from outside of UserDAO class - @Transactional annotation counted and user successfully created, but if save() invokes from inside of other method of the same dao class - @Transactional annotation ignored. Here how I was change save() method to force it always create transaction. public User save(User user) { getJpaTemplate().execute(new JpaCallback() { public Object doInJpa(EntityManager em) throws PersistenceException { em.getTransaction().begin(); em.persist(user); em.getTransaction().commit(); return null; } }); return user; } As you see I manually invoke begin and commit. Any ideas?

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• how to fetch more than 1000 entities NON keybased?

  - by user291071

  If I should be approaching this problem through a different method, please suggest so. I am creating an item based collaborative filter. I populate the db with the LinkRating2 class and for each link there are more than a 1000 users that I need to call and collect their ratings to perform calculations which I then use to create another table. So I need to call more than 1000 entities for a given link. For instance lets say there are over a 1000 users rated 'link1' there will be over a 1000 instances of this class for the given link property that I need to call. How would I complete this example? class LinkRating2(db.Model): user = db.StringProperty() link = db.StringProperty() rating2 = db.FloatProperty() query =LinkRating2.all() link1 = 'link string name' a = query.filter('link = ', link1) aa = a.fetch(1000)##how would i get more than 1000 for a given link1 as shown? ##keybased over 1000 in other post example i need method for a subset though not key class MyModel(db.Expando): @classmethod def count_all(cls): """ Count *all* of the rows (without maxing out at 1000) """ count = 0 query = cls.all().order('__key__') while count % 1000 == 0: current_count = query.count() if current_count == 0: break count += current_count if current_count == 1000: last_key = query.fetch(1, 999)[0].key() query = query.filter('__key__ > ', last_key) return count

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• GWT + JDO + ArrayList

  - by dvieira

  Hi, I'm getting a Null ArrayList in a program i'm developing. For testing purposes I created this really small example that still has the same problem. I already tried diferent Primary Keys, but the problem persists. Any ideas or suggestions? 1-Employee class @PersistenceCapable(identityType = IdentityType.APPLICATION) public class Employee { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String key; @Persistent private ArrayList<String> nicks; public Employee(ArrayList<String> nicks) { this.setNicks(nicks); } public String getKey() { return key; } public void setNicks(ArrayList<String> nicks) { this.nicks = nicks; } public ArrayList<String> getNicks() { return nicks; } } 2-EmployeeService public class BookServiceImpl extends RemoteServiceServlet implements EmployeeService { public void addEmployee(){ ArrayList<String> nicks = new ArrayList<String>(); nicks.add("name1"); nicks.add("name2"); Employee employee = new Employee(nicks); PersistenceManager pm = PMF.get().getPersistenceManager(); try { pm.makePersistent(employee); } finally { pm.close(); } } /** * @return * @throws NotLoggedInException * @gwt.typeArgs <Employee> */ public Collection<Employee> getEmployees() { PersistenceManager pm = getPersistenceManager(); try { Query q = pm.newQuery("SELECT FROM " + Employee.class.getName()); Collection<Employee> list = pm.detachCopyAll((Collection<Employee>)q.execute()); return list; } finally { pm.close(); } } }

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• which is better: a lying copy constructor or a non-standard one?

  - by PaulH

  I have a C++ class that contains a non-copyable handle. The class, however, must have a copy constructor. So, I've implemented one that transfers ownership of the handle to the new object (as below) class Foo { public: Foo() : h_( INVALID_HANDLE_VALUE ) { }; // transfer the handle to the new instance Foo( const Foo& other ) : h_( other.Detach() ) { }; ~Foo() { if( INVALID_HANDLE_VALUE != h_ ) CloseHandle( h_ ); }; // other interesting functions... private: /// disallow assignment const Foo& operator=( const Foo& ); HANDLE Detach() const { HANDLE h = h_; h_ = INVALID_HANDLE_VALUE; return h; }; /// a non-copyable handle mutable HANDLE h_; }; // class Foo My problem is that the standard copy constructor takes a const-reference and I'm modifying that reference. So, I'd like to know which is better (and why): a non-standard copy constructor: Foo( Foo& other ); a copy-constructor that 'lies': Foo( const Foo& other ); Thanks, PaulH

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• How to deal with a Java serialized object whose package changed?

  - by Alex

  I have a Java class that is stored in an HttpSession object that's serialized and transfered between servers in a cluster environment. For the purpose of this explanation, lets call this class "Person". While in the process of improving the code, this class was moved from "com.acme.Person" to "com.acme.entity.Person". Internally, the class remains exactly the same (same fields, same methods, same everything). The problem is that we have two sets of servers running the old code and the new code at the same time. The servers with the old code have serialized HttpSession object and when the new code unserializes it, it throws a ClassNotFoundException because it can't find the old reference to com.acme.Person. At this point, it's easy to deal with this because we can just recreate the object using the new package. The problem then becomes that the HttpSession in the new servers, will serialize the object with the new reference to com.acme.entity.Person, and when this is unserialized in the servers running the old code, another exception will be thrown. At this point, we can't deal with this exception anymore. What's the best strategy to follow for this kind of cases? Is there a way to tell the new servers to serialize the object with the reference to the old package and unserialize references to the old package to the new one? How would we transition to using the new package and forgetting about the old one once all servers run the new code?

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• How do I alias the scala setter method 'myvar_$eq(myval)' to something more pleasing when in java?

  - by feydr

  I've been converting some code from java to scala lately trying to teach myself the language. Suppose we have this scala class: class Person() { var name:String = "joebob" } Now I want to access it from java so I can't use dot-notation like I would if I was in scala. So I can get my var's contents by issuing: person = Person.new(); System.out.println(person.name()); and set it via: person = Person.new(); person.name_$eq("sallysue"); System.out.println(person.name()); This holds true cause our Person Class looks like this in javap: Compiled from "Person.scala" public class Person extends java.lang.Object implements scala.ScalaObject{ public Person(); public void name_$eq(java.lang.String); public java.lang.String name(); public int $tag() throws java.rmi.RemoteException; } Yes, I could write my own getters/setters but I hate filling classes up with that and it doesn't make a ton of sense considering I already have them -- I just want to alias the _$eq method better. (This actually gets worse when you are dealing with stuff like antlr because then you have to escape it and it ends up looking like person.name_\$eq("newname"); Note: I'd much rather have to put up with this rather than fill my classes with more setter methods. So what would you do in this situation?

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• Member function overloading/template specialization issue

  - by Ferruccio

  I've been trying to call the overloaded table::scan_index(std::string, ...) member function without success. For the sake of clarity, I have stripped out all non-relevant code. I have a class called table which has an overloaded/templated member function named scan_index() in order to handle strings as a special case. class table : boost::noncopyable { public: template <typename T> void scan_index(T val, std::function<bool (uint recno, T val)> callback) { // code } void scan_index(std::string val, std::function<bool (uint recno, std::string val)> callback) { // code } }; Then there is a hitlist class which has a number of templated member functions which call table::scan_index(T, ...) class hitlist { public: template <typename T> void eq(uint fieldno, T value) { table* index_table = db.get_index_table(fieldno); // code index_table->scan_index<T>(value, [&](uint recno, T n)->bool { // code }); } }; And, finally, the code which kicks it all off: hitlist hl; // code hl.eq<std::string>(*fieldno, p1.to_string()); The problem is that instead of calling table::scan_index(std::string, ...), it calls the templated version. I have tried using both overloading (as shown above) and a specialized function template (below), but nothing seems to work. After staring at this code for a few hours, I feel like I'm missing something obvious. Any ideas? template <> void scan_index<std::string>(std::string val, std::function<bool (uint recno, std::string val)> callback) { // code }

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• What are the best practices for writing maintainable CSS?

  - by Art

  I am just starting to explore this area and wonder what are the best practices when it comes to production of clean, well-structured and maintainable CSSes. There seems to be few different approaches to structuring CSS rules. One of the most commonly encountered ones I saw was throwing everything together in one rule, i.e. margins, borders, typefaces, backgrounds, something like this: .my-class { border-top:1px solid #c9d7f1; font-size:1px; font-weight:normal; height:0; position:absolute; top:24px; width:100%; } Another approach I noticed employed grouping of properties, say text-related properties like font-size, typeface, emphasis etc goes into one rule, backgrounds go into other, borders/margins go into yet another one: .my-class { border-top:1px solid #c9d7f1; } .my-class { font-size:1px; font-weight:normal; } .my-class { height:0; top:24px; width:100%; position:absolute; } I guess I am looking for a silver bullet here which I know I am not going to get, bet nevertheless - what are the best practices in this space?

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