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• What are the best workarounds for known problems with Hibernate's schema validation of floating poin

  - by Jason Novak

  I have several Java classes with double fields that I am persisting via Hibernate. For example, I have @Entity public class Node ... private double value; When Hibernate's org.hibernate.dialect.Oracle10gDialect creates the DDL for the Node table, it maps the value field to a "double precision" type. create table MDB.Node (... value double precision not null, ... It would appear that in Oracle, "double precision" is an alias for "float". So, when I try to verify the database schema using the org.hibernate.cfg.AnnotationConfiguration.validateSchema() method, Oracle appears to describe the value column as a "float". This causes Hibernate to throw the following Exception org.hibernate.HibernateException: Wrong column type in DBO.ACL_RULE for column value. Found: float, expected: double precision A very similar problem is listed in Hibernate's JIRA database as HHH-1961 (http://opensource.atlassian.com/projects/hibernate/browse/HHH-1961). I'd like to avoid doing anything that will break MySql, Postgres, and Sql Server support so extending the Oracle10gDialect appears to be the most promising of the workarounds mentioned in HHH-1961. But extending a Dialect is something I've never done before and I'm afraid there may be some nasty gotchas. What is the best workaround for this problem that won't break our compatibility with MySql, Postgres, and Sql Server? Thanks for taking the time to look at this!

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• Get notified when objective-c dom updates are ready initiated from webview

  - by Josh

  I am programmatically updating the DOM on a WebKit webview via DOMElement objects - for complex UI, there is usually a javascript component to any element that I add. This begs the need to be notified when the updates complete -- is there any such event? I know regular divs dont fire an onload or onready event, correct? The other assumption I had, which may be totally wrong, is that DOMElement updates aren't synchronous, so I can't do something like this and be confident it will meet with the label actually in the DOM: DOMElement *displayNameLabel = [document createElement:@"div"]; [displayNameLabel setAttribute:@"class" value:@"user-display-name"]; [displayNameLabel setTextContent:currentAvatar.avatarData.displayName]; [[document getElementById:@"user-card-content"] appendChild:displayNameLabel]; id win = [webView windowScriptObject]; [win evaluateWebScript:@"javascriptInstantiateLabel()"]; Is this true? I am using jquery within the body of the html already, so I don't mind subscribing to a particular classes set of events via "live." I thought I might be able to do something like: $(".some-class-to-be-added-later").live( "ready", function(){ // Instantiate some fantastic javascript here for .some-class }); but have experienced no joy so far. Is there any way on either side (objective-c since I don't programmatically firing javascript post load, or javascript) to be notified when the element is in the DOM? Thanks, Josh

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• PHP syntax for referencing self with late static binding

  - by Chris

  When I learned PHP it was pretty much in procedural form, more recently I've been trying to adapt to the OOP way of doing things. Hoever the tutorials I've been following were produced before PHP 5.3 when late static binding was introduced. What I want to know is how do I reference self when calling a function from a parent class. For example these two methods were written for a User class which is a child of DatabaseObject. Right now they're sitting inside the User class, but, as they're used in other child classes of DatabaseObject I'd like to promote them to be included inside DatabaseObject. public static function find_all() { global $database; $result_set = self::find_by_sql("select * from ".self::$table_name); return $result_set; } and: protected function cleaned_attributes() { global $database; $clean_attributes = array(); foreach($this->attributes() as $key => $value) { $clean_attributes[$key] = $database->escape_value($value); } return $clean_attributes; } So I have three questions: 1) How do I change the self:: reference when I move it to the parent. Is it static:: or something similar? 2) When calling the function from my code do I call it in the same way, as a function of the child class eg User::find_all() or is there a change there also? 3) Is there anything else I need to know before I start chopping bits up?

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• Missing Intellisense While Describing Custom Control Properties Declaratively

  - by Albert Bori

  So, I've been working on this project for a few days now, and have been unable to resolve the issue of getting intellisense support for my custom-defined inner properties for a user control (ascx, mind you). I have seen the solution to this (using server controls, .cs mind you) many times. Spelled out in this article very well. Everything works for me while using ascx controls except intellisense. Here's the outline of my code: [PersistChildren(true)] [ParseChildren(typeof(BreadCrumbItem))] [ControlBuilder(typeof(BreadCrumbItem))] public partial class styledcontrols_buttons_BreadCrumb : System.Web.UI.UserControl { ... [PersistenceMode(PersistenceMode.InnerDefaultProperty)] public List<BreadCrumbItem> BreadCrumbItems { get { return _breadCrumbItems; } set { _breadCrumbItems = value; } } ... protected override void AddParsedSubObject(object obj) { base.AddParsedSubObject(obj); if (obj is BreadCrumbItem) BreadCrumbItems.Add(obj as BreadCrumbItem); } ... public class BreadCrumbItem : ControlBuilder { public string Text { get; set; } public string NavigateURL { get; set; } public override Type GetChildControlType(string tagName, System.Collections.IDictionary attribs) { if (String.Compare(tagName, "BreadCrumbItem", true) == 0) { return typeof(BreadCrumbItem); } return null; } } } Here's my mark up (which works fine, just no intellisense on the child object declarations): <%@ Register src="../styledcontrols/buttons/BreadCrumb.ascx" tagname="BreadCrumb" tagprefix="uc1" %> ... <uc1:BreadCrumb ID="BreadCrumb1" runat="server" BreadCrumbTitleText="Current Page"> <BreadCrumbItem Text="Home Page" NavigateURL="~/test/breadcrumbtest.aspx?iwentsomewhere=1" /> <BreadCrumbItem Text="Secondary Page" NavigateURL="~/test/breadcrumbtest.aspx?iwentsomewhere=1" /> </uc1:BreadCrumb> I think the issue lies with how the intellisense engine traverses supporting classes. All the working examples I see of this are not ascx, but Web Server Controls (cs, in a compiled assembly). If anyone could shed some light on how to accomplish this with ascx controls, I'd appreciate it.

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• Web API Getting Http 500 error : Issue Solved See Below

  - by Joe Grasso

  Here is my MVC Controller and everything is fine: private UnitOfWork UOW; public InventoryController() { UOW = new UnitOfWork(); } // GET: /Inventory/ public ActionResult Index() { var products = UOW.ProductRepository.GetAll().ToList(); return View(products); } Same method call in API Controller gives me an Http 500 Error: private UnitOfWork _unitOfWork; public TestController() { _unitOfWork = new UnitOfWork(); } public IEnumerable<Product> Get() { var products = _unitOfWork.ProductRepository.GetAll().ToList(); return products; } Debugging shows that indeed there is data being returned in both controllers' UOW calls. I then added a customer configuration in Global: public static void CustomizeConfig(HttpConfiguration config) { config.Formatters.Remove(config.Formatters.XmlFormatter); var json = config.Formatters.JsonFormatter; json.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver(); } I am still receiving an Http 500 in API Controller ONLY and at a loss as to why. Any ideas? UPDATE: It appears using lazy loading caused the problem. When I set the associated properties to NON-VIRTUAL the Test API provided the necessary JSON string. However, whereas before I had the Vendor class included, I only have VendorId. I really wanted to included the associated classes. Any ideas? I know there are alot of smart people out there. Anyone?

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• Rails named_scope across multiple tables

  - by wakiki

  I'm trying to tidy up my code by using named_scopes in Rails 2.3.x but where I'm struggling with the has_many :through associations. I'm wondering if I'm putting the scopes in the wrong place... Here's some pseudo code below. The problem is that the :accepted named scope is replicated twice... I could of course call :accepted something different but these are the statuses on the table and it seems wrong to call them something different. Can anyone shed light on whether I'm doing the following correctly or not? I know Rails 3 is out but it's still in beta and it's a big project I'm doing so I can't use it in production yet. class Person < ActiveRecord::Base has_many :connections has_many :contacts, :through => :connections named_scope :accepted, :conditions => ["connections.status = ?", Connection::ACCEPTED] # the :accepted named_scope is duplicated named_scope :accepted, :conditions => ["memberships.status = ?", Membership::ACCEPTED] end class Group < ActiveRecord::Base has_many :memberships has_many :members, :through => :memberships end class Connection < ActiveRecord::Base belongs_to :person belongs_to :contact, :class_name => "Person", :foreign_key => "contact_id" end class Membership < ActiveRecord::Base belongs_to :person belongs_to :group end I'm trying to run something like person.contacts.accepted and group.members.accepted which are two different things. Shouldn't the named_scopes be in the Membership and Connection classes? One solution is to just call the two different named scope something different in the Person class or even to create separate associations (ie. has_many :accepted_members and has_many :accepted_contacts) but it seems hackish and in reality I have many more than just accepted (ie. banned members, ignored connections, pending, requested etc etc)

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• What is the correct way to handle object which is instance of class in apache.xerces?

  - by Roman

  Preface: I'm working on docx parser for java. docx format is based on xml. When I read document its parts are being unmarshalled (with JAXB). And I get a tree of certain elements based on xml markup. Almost problem: But some elements (which are at very deep xml level) returned not as certain class from docx spec (i.e. CTStyle, CTDrawing, CTInline etc) but as Object. Those objects are indeed instances of xerces classes, e.g. ElementNSImpl. Problem: How should I handle these objects. The simplest approach is: CTGraphicData gData = getGraphicData (); Object obj = gData.getAny().get(0); ElementNSImpl element = (ElementNSImpl)obj; But it doesn't seem to be a good solution. I've never worked with xerces directly. What is the better way to do this casting? (If anyone also give me a tip about right way to iterate through nodes it would be great).

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• Replace textfields with dropdown select fields

  - by 47

  I have three model classes that look as below: class Model(models.Model): model = models.CharField(max_length=20, blank=False) manufacturer = models.ForeignKey(Manufacturer) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = ''+str(self.manufacturer)+" "+str(self.model) return name class Series(models.Model): series = models.CharField(max_length=20, blank=True, null=True) model = models.ForeignKey(Model) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = str(self.model)+" "+str(self.series) return name class Manufacturer(models.Model): MANUFACTURER_POPULARITY_CHOICES = ( ('1', 'Primary'), ('2', 'Secondary'), ('3', 'Tertiary'), ) manufacturer = models.CharField(max_length=15, blank=False) date_added = models.DateField(default=datetime.today) manufacturer_popularity = models.CharField(max_length=1, choices=MANUFACTURER_POPULARITY_CHOICES) def __unicode__(self): return self.manufacturer I want to have the fields for model series and manufacturer represented as dropdowns instead of text fields. I have customized the model forms as below: class SeriesForm(ModelForm): series = forms.ModelChoiceField(queryset=Series.objects.all()) class Meta: model = Series exclude = ('model', 'date_added',) class ModelForm(ModelForm): model = forms.ModelChoiceField(queryset=Model.objects.all()) class Meta: model = Model exclude = ('manufacturer', 'date_added',) class ManufacturerForm(ModelForm): manufacturer = forms.ModelChoiceField(queryset=Manufacturer.objects.all()) class Meta: model = Manufacturer exclude = ('date_added',) However, the dropdowns are populated with the unicode in the respective class...how can I further customize this to get the end result I want? Also, how can I populate the forms with the correct data for editing? Currently only SeriesForm is populated. The starting point of all this is from another class whose declaration is as below: class CommonVehicle(models.Model): year = models.ForeignKey(Year) series = models.ForeignKey(Series) .... def __unicode__(self): name = ''+str(self.year)+" "+str(self.series) return name

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• RIA Services for transmitting non DB object-graph

  - by Mike Gates

  I have been getting into RIA services because I thought it would simplify dealing with the services layer of web applications I wish to build. I see lots of examples out there showing how to create DomainService classes which expose and consume entities that have some kind of relational database backing, and therefore have foreign-key relationships. However, I would like to know how to expose and consume normal object graphs...objects that contain references to eachother but don't have foreign keys. For example, say I want a service operation called "GetFolderInformation(string pathToFolder)". I want this to return a custom object called "FolderInformation" structured with: - string Name - IEnumerable<FileInformation> Files I cannot get this to work because it seems that RIA wants to deal with entities that have foreign key relationships. Why? Why can't the serializer just see my object references and recreate that in the proxy on the other side? Data exists behind service layers that doesn't necessarily have foreign key relationships...like folder/file for example. EDIT: I realized I hadn't asked my question! My question is, is there a way to do what I am trying to do?

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• Maven jaxb generate plugin to read xsd files from multiple directories

  - by ziggy

  If i have xsd file in the following directories src/main/resources/xsd src/main/resources/schema/common src/main/resources/schema/soap How can i instruct the maven jaxb plugin to generate jaxb classes using all schema files in the above directory? I can get it to generate the class files if i specify one of the folders but i cant get i dont know how to include all three folders. Here is how i generate the files for one folder: <plugin> <groupId>org.jvnet.jaxb2.maven2</groupId> <artifactId>maven-jaxb2-plugin</artifactId> <executions> <execution> <goals> <goal>generate</goal> </goals> </execution> </executions> <configuration> <schemaDirectory>src/main/resources/xsd</schemaDirectory> </configuration> </plugin> I tried adding multiple entries in the element but it just ignores all of them if i do that. Thanks

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• SubSonic 3 screws up selecteditem?

  - by SteveCav

  If you have a moment, please try this: -Download Subsonic 3. -Start a new proj and add SS's ActiveRecord templates. -Point it to any SQL Server DB and generate the classes. -Add a WPF project. -Create a window and add a combobox or listbox. -Set the ItemsSource from the SS DAL, and format it how you wish. -Add a button that will show you some value from the SelectedItem (using messagebox, console, whatever). -Run the project. -Click on the third item in the list. -Click on the second item in the list. -Click on the button. When I do that, the button gives me the value of the THIRD item, not the second. In other words, once the SelectedItem is set the first time it STAYS, no matter which item is subsequently highlighted on the screen. This is happening to me whatever control I use (combobox, listbox, even datagrid) and it ONLY happens with Subsonic Activerecord objects. If I write my own POCOs with identical properties and bind a list of them instead, the controls behave as expected. Does this happen to you? Any ideas?

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• Writing language converter in ANTLR

  - by Stefan

  I'm writing a converter between some dialects of the same programming language. I've found a grammar on the net - it's complex and handles all the cases. Now I'm trying to write the appropriate actions. Most of the input is just going to be rewritten to output. What I need to do is parse function calls, do my magic (rename function, reorder arguments, etc) and write it. I'm using AST as output. When I come across a function call, I build a custom object structure (from classes defined in my target language), call the appropriate function and I have a string that represents the transformed function that I want to get. The problem is, what I'm supposed to do with that string? I'd like to replace the .text attribute of the enclosing rule, but setText() is only available on lexer rules and the rule's .text attribute is read-only. How to solve this problem? program : statement_list { output = $statement_list.text; } ; //... statement : expression_statement // ... ; expression_statement : function_call // ... ; function_call : ID '(' { /* build the object, assign name */ Function function = new Function(); //... } ( arg1 = expression { /* add first parameter */ } ( ',' arg2 = expression { /* add the rest of parameters */ } )* )? ')' { /* convert the function call */ string converted = Tools.Convert(function); // $setText(converted); // doesn't work // $functionCall.text = converted; // doesn't work } ;

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• How to minify JS in PHP easily...Or something else

  - by RickyAYoder

  I've done some looking around, but I'm still confused a bit. I tried Crockford's JSMin, but Win XP can't unzip the executable file for some reason. What I really want though is a simple and easy-to-use JS minifier that uses PHP to minify JS code--and return the result. The reason why is because: I have 2 files (for example) that I'm working between: scripts.js and scripts_template.js scripts_template is normal code that I write out--then I have to minify it and paste the minified script into scripts.js--the one that I actually USE on my website. I want to eradicate the middle man by simply doing something like this on my page: <script type="text/javascript" src="scripts.php"></script> And then for the contents of scripts.php: <?php include("include.inc"); header("Content-type:text/javascript"); echo(minify_js(file_get_contents("scripts_template.js"))); This way, whenever I update my JS, I don't have to constantly go to a website to minify it and re-paste it into scripts.js--everything is automatically updated. Yes, I have also tried Crockford's PHP Minifier and I've taken a look at PHP Speedy, but I don't understand PHP classes just yet...Is there anything out there that a monkey could understand, maybe something with RegExp? How about we make this even simpler? I just want to remove tab spaces--I still want my code to be readable. It's not like the script makes my site lag epically, it's just anything is better than nothing. Tab removal, anyone? And if possible, how about removing completely BLANK lines?

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• .Net xsd.exe tool doesn't generate all types

  - by Mrchief

  For some reason, MS .Net (v3.5) tool - xsd.exe doesn't generate types when they are not used inside any element. e.g. XSD File (I threw in the complex element to avoid this warning - "Warning: cannot generate classes because no top-level elements with complex type were found."): <?xml version="1.0" encoding="utf-8"?> <xs:schema targetNamespace="http://tempuri.org/XMLSchema.xsd" elementFormDefault="qualified" xmlns="http://tempuri.org/XMLSchema.xsd" xmlns:mstns="http://tempuri.org/XMLSchema.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema" > <xs:simpleType name="EnumTest"> <xs:restriction base="xs:string"> <xs:enumeration value="item1" /> <xs:enumeration value="item2" /> <xs:enumeration value="item3" /> </xs:restriction> </xs:simpleType> <xs:complexType name="myComplexType"> <xs:attribute name="Name" use="required" type="xs:string"/> </xs:complexType> <xs:element name="myElem" type="myComplexType"></xs:element> </xs:schema> When i run this thru xsd.exe using xsd /c xsdfile.xsd I don't see EnumTest in the generated cs file. Note; Even though I don't use the enum here, but in my actual project, I have cases like this where we send enum's string value as output. How can I force the xsd tool to include these? Or should I switch to some other tool? I work in Visual Studio 2008.

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• [C#] How to use delegate to perform callback between caller and web service helper class?

  - by codemonkie

  I have 2 classes A and B, where they belongs to the same namespace but resides in seperate files namely a.cs and b.cs, where class B essentially is a helper wrapping a web service call as follow: public class A { public A() // constructor { protected static B b = new B(); } private void processResult1(string result) { // come here when result is successful } private void processResult2(string result) { // come here when result is failed } static void main() { b.DoJobHelper(...); } } public class B { private com.nowhere.somewebservice ws; public B() { this.ws = new com.nowhere.somewebservice(); ws.JobCompleted += new JobCompletedEventHandler(OnCompleted); } void OnCompleted(object sender, JobCompletedEventArgs e) { string s; Guid taskID = (Guid)e.UserState; switch (s) { case "Success": // Call processResult1(); break; case "Failed": // Call processResult2(); break; default: break; } } public void DoJobHelper() { Object userState = Guid.NewGuid(); ws.DoJob(..., userState); } } (1) I have seen texts on the net on using delegates for callbacks but failed to apply that to my case. All I want to do is to call the appropriate processResult() method upon OnCompleted() event, but dunno how to and where to declare the delegate: public delegate void CallBack(string s); (2) There is a sender object passed in to OnCompleted() but never used, did I miss anything there? Or how can I make good use of sender? Any helps appreciated.

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• Entity Framework 4 / POCO - Where to start?

  - by Basiclife

  Hi, I've been programming for a while and have used LINQ-To-SQL and LINQ-To-Entities before (although when using entities it has been on a Entity/Table 1-1 relationship - ie not much different than L2SQL) I've been doing a lot of reading about Inversion of Control, Unit of Work, POCO and repository patterns and would like to use this methodology in my new applications. Where I'm struggling is finding a clear, concise beginners guide for EF4 which doesn't assume knowledge of EF1. The specific questions I need answered are: Code first / model first? Pros/cons in regards to EF4 (ie what happens if I do code first, change the code at a later date and need to regenerate my DB model - Does the data get preserved and transformed or dropped?) Assuming I'm going code-first (I'd like to see how EF4 converts that to a DB schema) how do I actually get started? Quite often I've seen articles with entity diagrams stating "So this is my entity model, now I'm going to ..." - Unfortunately, I'm unclear if they're created the model in the designer, saved it to generate code then stopped any further auto-code generation -or- They've coded (POCO)? classes and the somehow imported them into the deisgner view? I suppose what I really need is an understanding of where the "magic" comes from and how to add it myself if I'm not just generating an EF model directly from a DB. I'm aware the question is a little vague but I don't know what I don't know - So any input / correction / clarification appreciated. Needless to say, I don't expect anyone to sit here and teach me EF - I'd just like some good tutorials/forums/blogs/etc. for complete entity newbies Many thanks in advance

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• Is this an example of LINQ-to-SQL?

  - by Edward Tanguay

  I made a little WPF application with a SQL CE database. I built the following code with LINQ to get data out of the database, which was surprisingly easy. So I thought "this must be LINQ-to-SQL". Then I did "add item" and added a "LINQ-to-SQL classes" .dbml file, dragged my table onto the Object Relational Designer but it said, "The selected object uses an unsupported data provider." So then I questioned whether or not the following code actually is LINQ-to-SQL, since it indeed allows me to access data from my SQL CE database file, yet officially "LINQ-to-SQL" seems to be unsupported for SQL CE. So is the following "LINQ-to-SQL" or not? using System.Linq; using System.Data.Linq; using System.Data.Linq.Mapping; using System.Windows; namespace TestLinq22 { public partial class Window1 : Window { public Window1() { InitializeComponent(); MainDB db = new MainDB(@"Data Source=App_Data\Main.sdf"); var customers = from c in db.Customers select new {c.FirstName, c.LastName}; TheListBox.ItemsSource = customers; } } [Database(Name = "MainDB")] public class MainDB : DataContext { public MainDB(string connection) : base(connection) { } public Table<Customers> Customers; } [Table(Name = "Customers")] public class Customers { [Column(DbType = "varchar(100)")] public string FirstName; [Column(DbType = "varchar(100)")] public string LastName; } }

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• C# visually subclass datagridview control VS2005

  - by DRapp

  Maybe its something stupid, but I'm having a problem with a subclass of a DataGridView Control in VS2005 C#. I know I can subclass from almost anything by doing public class MyDataGridView : DataGridView {} no problem, and I put in some things / elements I want applicable globally. Now, I take this gridview and put into a custom user control that will contain other controls too. So I have something like created by the visual designer. I grab some buttons, label, and my derived "MyDataGridView" on it. public partial class MyCompoundDGVPlus : UserControl So, now, I can visually draw, move, change all sorts of settings as needed, no problem. Now, I want this "MyCompoundDGVPlus" class as the basis for other classes, of which I will manipulate settings specific, but want all to have the same look / feel, and otherwise similar flow, hence the derivations. I've even set the "modifiers" setting to public, so I SHOULD be able to modify any of the properties of the controls at any derived level. So, now, I create a new subclass of "MyFirstDetailedDGVPlus" derived from "MyCompoundDGVPlus". Ok visually, all the label, button, datagridview appear. However, now I want to specifically define the columns of the datagridview here in this class visually, but its locked. However, the LABEL on the form, I CAN get all the property settings.... What am I missing.

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• Avoiding Service Locator with AutoFac 2

  - by Page Brooks

  I'm building an application which uses AutoFac 2 for DI. I've been reading that using a static IoCHelper (Service Locator) should be avoided. IoCHelper.cs public static class IoCHelper { private static AutofacDependencyResolver _resolver; public static void InitializeWith(AutofacDependencyResolver resolver) { _resolver = resolver; } public static T Resolve<T>() { return _resolver.Resolve<T>(); } } From answers to a previous question, I found a way to help reduce the need for using my IoCHelper in my UnitOfWork through the use of Auto-generated Factories. Continuing down this path, I'm curious if I can completely eliminate my IoCHelper. Here is the scenario: I have a static Settings class that serves as a wrapper around my configuration implementation. Since the Settings class is a dependency to a majority of my other classes, the wrapper keeps me from having to inject the settings class all over my application. Settings.cs public static class Settings { public static IAppSettings AppSettings { get { return IoCHelper.Resolve<IAppSettings>(); } } } public interface IAppSettings { string Setting1 { get; } string Setting2 { get; } } public class AppSettings : IAppSettings { public string Setting1 { get { return GetSettings().AppSettings["setting1"]; } } public string Setting2 { get { return GetSettings().AppSettings["setting2"]; } } protected static IConfigurationSettings GetSettings() { return IoCHelper.Resolve<IConfigurationSettings>(); } } Is there a way to handle this without using a service locator and without having to resort to injecting AppSettings into each and every class? Listed below are the 3 areas in which I keep leaning on ServiceLocator instead of constructor injection: AppSettings Logging Caching

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• Who architected / designed C++'s IOStreams, and would it still be considered well-designed by today'

  - by stakx

  First off, it may seem that I'm asking for subjective opinions, but that's not what I'm after. I'd love to hear some well-grounded arguments on this topic. In the hope of getting some insight into how a modern streams / serialization framework ought to be designed, I recently got myself a copy of the book Standard C++ IOStreams and Locales by Angelika Langer and Klaus Kreft. I figured that if IOStreams wasn't well-designed, it wouldn't have made it into the C++ standard library in the first place. After having read various parts of this book, I am starting to have doubts if IOStreams can compare to e.g. the STL from an overall architectural point-of-view. Read e.g. this interview with Alexander Stepanov (the STL's "inventor") to learn about some design decisions that went into the STL. What surprises me in particular: It seems to be unknown who was responsible for IOStreams' overall design (I'd love to read some background information about this — does anyone know good resources?); Once you delve beneath the immediate surface of IOStreams, e.g. if you want to extend IOStreams with your own classes, you get to an interface with fairly cryptic and confusing member function names, e.g. getloc/imbue, uflow/underflow, snextc/sbumpc/sgetc/sgetn, pbase/pptr/epptr (and there's probably even worse examples). This makes it so much harder to understand the overall design and how the single parts co-operate. Even the book I mentioned above doesn't help that much (IMHO). Thus my question: If you had to judge by today's software engineering standards (if there actually is any general agreement on these), would C++'s IOStreams still be considered well-designed? (I wouldn't want to improve my software design skills from something that's generally considered outdated.)

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• How to tell axis2 to use an existing object as a service?

  - by Christian Hausknecht

  I am trying to expose some methods of a running application as a webservice. The core idea is to use an embedded web-server and send the soap messages to the apache axis2 framework in order to invoke the services. The problem is, that axis2's createService methods only accept Classes as parameter, not existing objects. So I believe that axis2 itself creates an object of the service class and then uses it to call methods when an external service call arrives. But I need to pass an existing object for being used as a service, because I need to call methods of other objects of the running application within the service methods. So the "standard" way that axis2 creates a new instance of the service class and calls then its methods is obviously no sulution for me. So is there a way to realize this? Or is there another solution? Perhaps you can pass objects later on to the allready created service object by axis2? If there is another solution without axis2 I might consider that one. Basically I am only interested in exposing some functionality of a runnning application as a webservice.

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• Java: Initializing a public static field in superclass that needs a different value in every subclas

  - by BinaryMuse

  Good evening, I am developing a set of Java classes so that a container class Box contains a List of a contained class Widget. A Widget needs to be able to specify relationships with other Widgets. I figured a good way to do this would be to do something like this: public abstract class Widget { public static class WidgetID { // implementation stolen from Google's GWT private static int nextHashCode; private final int index; public WidgetID() { index = ++nextHashCode; } public final int hashCode() { return index; } } public abstract WidgetID getWidgetID(); } so sublcasses of Widget could: public class BlueWidget extends Widget { public static final WidgetID WIDGETID = new WidgetID(); @Override public WidgetID getWidgetID() { return WIDGETID; } } Now, BlueWidget can do getBox().addWidgetRelationship(RelationshipTypes.SomeType, RedWidget.WIDGETID, and Box can iterate through it's list comparing the second parameter to iter.next().getWidgetID(). Now, all this works great so far. What I'm trying to do is keep from having to declare the public static final WidgetID WIDGETID in all the subclasses and implement it instead in the parent Widget class. The problem is, if I move that line of code into Widget, then every instance of a subclass of Widget appears to get the same static final WidgetID for their Subclassname.WIDGETID. However, making it non-static means I can no longer even call Subclassname.WIDGETID. So: how do I create a static WidgetID in the parent Widget class while ensuring it is different for every instance of Widget and subclasses of Widget? Or am I using the wrong tool for the job here? Thanks!

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• Multiple, Simultaneous Factories and Protocols in Twisted: Same Service, Different Ports

  - by RichardCroasher

  Greetings, Forum. I'm working on a program in Python that uses Twisted to manage networking. The basis of this program is a TCP service that is to listen for connections on multiple ports. However, instead of using one Twisted factory to handle a protocol object for each port, I am trying to use a separate factory for each port. The reason for this is to force a separation among the groups of clients connecting to the different ports. Unfortunately, it appears that this architecture isn't quite working: clients that connect to one port appear to be available among all the factories (e.g., the protocol class used by each factory includes a 'self.factory.clients.append (self)' statement...instead of adding a given client to just the factory for a particular port, the client is added to all factories), and whenever I shutdown service on one port the listeners on all ports also stop. I've been working with Twisted for a short while, and fear I simply don't fully understand how its factory classes are managed. My question is: is it simply not possible to have multiple, simultaneous instances of the same factory and same protocol in use across different ports (without these instances stepping on each other's toes)?

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• Data Flow Object Graph and An Execution Engine for it

  - by M Dotnet

  I would like to build a custom workflow engine from scratch. The input to this workflow is a data flow diagram which is composed of a series of activities connected together through lines where each each represent the data flow. Each activity can export multiple outputs. Activities are complex math functions but the logic is hidden from the user. My workflow engine job is to execute the given data flow diagram. Each activity within the data flow diagram is a custom activity and each activity can output different outputs. How do you suggest to model the data flow diagram object? I need to be able to construct the data flow diagram problematically (no need for drag and drop) but I need to display the final result graphically (for display and debugging purposes). Are there any libraries out there that I could use? Should I keep the workflow presentable as an xml? I know that there are many projects out there trying to essentially doing similar thing by building such workflow engines but I need something light weight and open source. I do not need any state machine execution engine and mine is primarily sequential workflow with fork and join capabilities. My activities are wrappable as basic C# classes and I do NOT want to use anything as heavy as .NET workflow foundation.

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• Two objects with dependencies for each other. Is that bad?

  - by Kasper Grubbe

  Hi SO. I am learning a lot about design patterns these days. And I want to ask you about a design question that I can't find an answer to. Currently I am building a little Chat-server using sockets, with multiple Clients. Currently I have three classes. Person-class which holds information like nick, age and a Room-object. Room-class which holds information like room-name, topic and a list of Persons currently in that room. Hotel-class which have a list of Persons and a list of Rooms on the server. I have made a diagram to illustrate it (Sorry for the big size!): http://i.imgur.com/Kpq6V.png I have a list of players on the server in the Hotel-class because it would be nice to keep track of how many there are online right now (Without having to iterate through all of the rooms). The persons live in the Hotel-class because I would like to be able to search for a specific Person without searching the rooms. Is this bad design? Is there another way of achieve it? Thanks.

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