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• Using boost asio for pub/sub style tcp in a game loop

  - by unohoo

  I have been reading through the boost asio documentation for a couple of hours now, and while I think the documentation is really great, I am still left a bit confused on how to implement the system that I need. I have to stream info, from a game engine, to a list of computers over tcp. One snag is that, unlike traditional pub/sub, the computer that does the distribution of info is actually the computer that has to connect to the subscribers as well (instead of the subscribers registering with the publisher). This is done via a config file - a list of ip's/ports along with the data that they each require. The subscribers listen, but do not know the ip of the publisher. (As a side note, I'm quite new to network programming, so maybe I'm missing something .. but it's strange that I do not find much information regarding this style of "inverted" client-server model..) I am looking for suggestions for the implementation of such a system using boost asio. Of course I have to integrate the networking into an already existing engine, so with regards to that: What would be a good way to handle messages being sent to multiple computers every frame? Use async_write, call io_service.run and then reset every frame? Would having io_service.run have its own thread be better? Or should I just use threads and use blocking writes?

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• nullable bool is being passed to the controller null all the time regardless of the value

  - by user1807954

  I'm trying to pass a nullable bool to my controller. But when I pass the bool value from my view to the controller, it's being passed null all the time regardless of the value it has in my view. Here is my view: @model Cars.Models.Car @using (Html.BeginForm("Index", "Home", FormMethod.Post, new { id = "CategoryFormID"})) { <label>Convertible:</label> <input type="checkbox" id="ConvertibleID" name="convertible"/> <button type="submit" name="submit" value="search" id="SubmitID">Search</button> } And my controller: [HttpPost] public ActionResult Index(bool? convertible){ var cars = from d in db.Car select d; if (convertible.HasValue) { cars = cars.Where(x => x.Convertible == convertible); } return View("SearchResult", cars); } I also have other fields such as drop down lists and text fields, but they're being passed flawless. Any help would be really appreciated. Update: Thank you for your fast responds. However, I did try giving it a value="True" as you guys suggested. There is only 2 options now: null and true. But my intention is to use nullable bool to have three options: null (when user doesn't touch the checkbox), true(checked) and false(unchecked). I know it sounds not smart and silly, but I'm just trying to figure out how nullable bool is working, and what is the intention of having such a thing in C# (I'm new with C#). I was wondering if it is possible to do so with just checkbox and without the use of dropdownlist or radio buttons.

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• Checking for nil in view in Ruby on Rails

  - by seaneshbaugh

  I've been working with Rails for a while now and one thing I find myself constantly doing is checking to see if some attribute or object is nil in my view code before I display it. I'm starting to wonder if this is always the best idea. My rationale so far has been that since my application(s) rely on user input unexpected things can occur. If I've learned one thing from programming in general it's that users inputting things the programmer didn't think of is one of the biggest sources of run-time errors. By checking for nil values I'm hoping to sidestep that and have my views gracefully handle the problem. The thing is though I typically for various reasons have similar nil or invalid value checks in either my model or controller code. I wouldn't call it code duplication in the strictest sense, but it just doesn't seem very DRY. If I've already checked for nil objects in my controller is it okay if my view just assumes the object truly isn't nil? For attributes that can be nil that are displayed it makes sense to me to check every time, but for the objects themselves I'm not sure what is the best practice. Here's a simplified, but typical example of what I'm talking about: controller code def show @item = Item.find_by_id(params[:id]) @folders = Folder.find(:all, :order => 'display_order') if @item == nil or @item.folder == nil redirect_to(root_url) and return end end view code <% if @item != nil %> display the item's attributes here <% if @item.folder != nil %> <%= link_to @item.folder.name, folder_path(@item.folder) %> <% end %> <% else %> Oops! Looks like something went horribly wrong! <% end %> Is this a good idea or is it just silly?

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• Google app engine: Poor Performance with JDO + Datastore

  - by Bosh

  I have a simple data model that includes USERS: store basic information (key, name, phone # etc) RELATIONS: describe, e.g. a friendship between two users (supplying a relationship_type + two user keys) I'm getting very poor performance, for instance, if I try to print the first names of all of a user's friends. Say the user has 500 friends: I can fetch the list of friend user_ids very easily in a single query. But then, to pull out first names, I have to do 500 back-and-forth trips to the Datastore, each of which seems to take on the order of 30 ms. If this were SQL, I'd just do a JOIN and get the answer out fast. I understand there are rudimentary facilities for performing joins across un-owned relations in a relaxed implementation of JDO (as described at http://gae-java-persistence.blogspot.com) but they sound experimental and non-standard (e.g. my code won't work in any other JDO implementation). Is this really my best bet? Otherwise, how do people extract satisfactory performance from JDO/Datastore in this kind of (very common) situation? -Bosh

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• How to reference using Entity Framework and Asp.Net Mvc 2

  - by Picflight

  Tables CREATE TABLE [dbo].[Users]( [UserId] [int] IDENTITY(1,1) NOT NULL, [UserName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL, [Email] [varchar](255) COLLATE SQL_Latin1_General_CP1_CI_AS NULL, [BirthDate] [smalldatetime] NULL, [CountryId] [int] NULL, CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED ([UserId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[TeamMember]( [UserId] [int] NOT NULL, [TeamMemberUserId] [int] NOT NULL, [CreateDate] [smalldatetime] NOT NULL CONSTRAINT [DF_TeamMember_CreateDate] DEFAULT (getdate()), CONSTRAINT [PK_TeamMember] PRIMARY KEY CLUSTERED ([UserId] ASC, [TeamMemberUserId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] dbo.TeamMember has both UserId and TeamMemberUserId as the index key. My goal is to show a list of Users on my View. In the list I want to flag, or highlight the Users that are Team Members of the LoggedIn user. My ViewModel public class UserViewModel { public int UserId { get; private set; } public string UserName { get; private set; } public bool HighLight { get; private set; } public UserViewModel(Users users, bool highlight) { this.UserId = users.UserId; this.UserName = users.UserName; this.HighLight = highlight; } } View <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MvcPaging.IPagedList<MyProject.Mvc.Models.UserViewModel>>" %> <% foreach (var item in Model) { %> <%= item.UserId %> <%= item.UserName %> <%if (item.HighLight) { %> Team Member <% } else { %> Not Team Member <% } %> How do I toggle the TeamMember or Not If I add dbo.TeamMember to the EDM, there are no relationships on this table, how will I wire it to Users object? So I am comparing the LoggedIn UserId with this list(SELECT TeamMemberUserId FROM TeamMember WHERE UserId = @LoggedInUserId)

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• Store the cache data locally

  - by Lu Lu

  Hello, I develops a C# Winform application, it is a client and connect to web service to get data. The data returned by webservice is a DataTable. Client will display it on a DataGridView. My problem is that: Client will take more time to get all data from server (web service is not local with client). So I must to use a thread to get data. This is my model: Client create a thread to get data - thread complete and send event to client - client display data on datagridview on a form. However, when user closes the form, user can open this form in another time, and client must get data again. This solution will cause the client slowly. So, I think about a cached data: Client <---get/add/edit/delete--- Cached Data ---get/add/edit/delete---Server (web service) Please give me some suggestions. Example: cached data should be developed in another application which is same host with client? Or cached data is running in client. Please give me some techniques to implement this solution. If having any examples, please give me. Thanks.

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• Setting up relations/mappings for a SQLAlchemy many-to-many database

  - by Brent Ramerth

  I'm new to SQLAlchemy and relational databases, and I'm trying to set up a model for an annotated lexicon. I want to support an arbitrary number of key-value annotations for the words which can be added or removed at runtime. Since there will be a lot of repetition in the names of the keys, I don't want to use this solution directly, although the code is similar. My design has word objects and property objects. The words and properties are stored in separate tables with a property_values table that links the two. Here's the code: from sqlalchemy import Column, Integer, String, Table, create_engine from sqlalchemy import MetaData, ForeignKey from sqlalchemy.orm import relation, mapper, sessionmaker from sqlalchemy.ext.declarative import declarative_base engine = create_engine('sqlite:///test.db', echo=True) meta = MetaData(bind=engine) property_values = Table('property_values', meta, Column('word_id', Integer, ForeignKey('words.id')), Column('property_id', Integer, ForeignKey('properties.id')), Column('value', String(20)) ) words = Table('words', meta, Column('id', Integer, primary_key=True), Column('name', String(20)), Column('freq', Integer) ) properties = Table('properties', meta, Column('id', Integer, primary_key=True), Column('name', String(20), nullable=False, unique=True) ) meta.create_all() class Word(object): def __init__(self, name, freq=1): self.name = name self.freq = freq class Property(object): def __init__(self, name): self.name = name mapper(Property, properties) Now I'd like to be able to do the following: Session = sessionmaker(bind=engine) s = Session() word = Word('foo', 42) word['bar'] = 'yes' # or word.bar = 'yes' ? s.add(word) s.commit() Ideally this should add 1|foo|42 to the words table, add 1|bar to the properties table, and add 1|1|yes to the property_values table. However, I don't have the right mappings and relations in place to make this happen. I get the sense from reading the documentation at http://www.sqlalchemy.org/docs/05/mappers.html#association-pattern that I want to use an association proxy or something of that sort here, but the syntax is unclear to me. I experimented with this: mapper(Word, words, properties={ 'properties': relation(Property, secondary=property_values) }) but this mapper only fills in the foreign key values, and I need to fill in the other value as well. Any assistance would be greatly appreciated.

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• LinqToSQL not updating database

  - by codegarten

  Hi. I created a database and dbml in visual studio 2010 using its wizards. Everything was working fine until i checked the tables data (also in visual studio server explorer) and none of my updates were there. using (var context = new CenasDataContext()) { context.Log = Console.Out; context.Cenas.InsertOnSubmit(new Cena() { id = 1}); context.SubmitChanges(); } This is the code i am using to update my database. At this point my database has one table with one field (PK) named ID. *INSERT INTO [dbo].Cenas VALUES (@p0) -- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [1] -- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1* This is LOG from the execution (printed the context log into the console). The problem i'm having is that these updates are not persistent in the database. I mean that when i query my database (visual studio server explorer - new query) i see the table is empty, every time. I am using a SQL Server database file (.mdf).

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• Is WordPress MVC compliant?

  - by kovshenin

  Some people consider WordPress a blogging platform, some think of it as a CMS, some refer to WordPress as a development framework. Whichever it is, the question still remains. Is WordPress MVC compliant? I've read the forums and somebody asked about MVC about three years ago. There were some positive answers, and some negative ones. While nobody knows exactly what MVC is and everybody thinks of it in their own way, there's still a general concept that's present in all the discussions. I have little experience with MVC frameworks and there doesn't seem to be anything about the framework itself. Most of the MVC is done by the programmer, am I right? Now, going back to WordPress, could we consider the core rewrite engine (WP_Rewrite) the controller? Queries & plugin logic as the model? And themes as the view? Or am I getting it all wrong? Thanks ;)

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• How can I implement CRUD operations in a base class for an entity framework app?

  - by hminaya

  I'm working a simple EF/MVC app and I'm trying to implement some Repositories to handle my entities. I've set up a BaseObject Class and a IBaseRepository Interface to handle the most basic operations so I don't have to repeat myself each time: public abstract class BaseObject<T> { public XA.Model.Entities.XAEntities db; public BaseObject() { db = new Entities.XAEntities(); } public BaseObject(Entities.XAEntities cont) { db = cont; } public void Delete(T entity) { db.DeleteObject(entity); db.SaveChanges(); } public void Update(T entity) { db.AcceptAllChanges(); db.SaveChanges(); } } public interface IBaseRepository<T> { void Add(T entity); T GetById(int id); IQueryable<T> GetAll(); } But then I find myself having to implement 3 basic methods in every Repository ( Add, GetById & GetAll): public class AgencyRepository : Framework.BaseObject<Agency>, Framework.IBaseRepository<Agency> { public void Add(Agency entity) { db.Companies.AddObject(entity); db.SaveChanges(); } public Agency GetById(int id) { return db.Companies.OfType<Agency>().FirstOrDefault(x => x.Id == id); } public IQueryable<Agency> GetAll() { var agn = from a in db.Companies.OfType<Agency>() select a; return agn; } } How can I get these into my BaseObject Class so I won't run in conflict with DRY.

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• Asp MVC - "The Id field is required" validation message on Create; Id not set to [Required]

  - by burnt_hand

  This is happening when I try to create the entity using a Create style action in Asp.Net MVC 2. The POCO has the following properties: public int Id {get;set;} [Required] public string Message {get; set} On the creation of the entity, the Id is set automatically, so there is no need for it on the Create action. The ModelState says that "The Id field is required", but I haven't set that to be so. Is there something automatic going on here? EDIT - Reason Revealed The reason for the issue is answered by Brad Wilson via Paul Speranza in one of the comments below where he says (cheers Paul): You're providing a value for ID, you just didn't know you were. It's in the route data of the default route ("{controller}/{action}/{id}"), and its default value is the empty string, which isn't valid for an int. Use the [Bind] attribute on your action parameter to exclude ID. My default route was: new { controller = "Customer", action = "Edit", id = " " } // Parameter defaults EDIT - Update Model technique I actually changed the way I did this again by using TryUpdateModel and the exclude parameter array asscoiated with that. [HttpPost] public ActionResult Add(Venue collection) { Venue venue = new Venue(); if (TryUpdateModel(venue, null, null, new[] { "Id" })) { _service.Add(venue); return RedirectToAction("Index", "Manage"); } return View(collection); }

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• how to check null value of Integer type field in ASP.NET MVC view?

  - by Vikas

  Hi, I have integer type field in database which is having property "Not Null". when i create a view & do a validation, if i left that field blank, it will consider it as 0 so i can not compare it with 0 because if someone insert a value 0 then it will be considered as error! one another problem is that i am using Model error as described in the book "ASP.NET MVC 1.0" @ Scott Gu blog. And I am checking the value in partial class of object (created by LINQ-To-SQL). i.e public partial class Person { public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } public IEnumerable<RuleViolation> GetRuleViolations() { if (String.IsNullOrEmpty(Name)) yield return new RuleViolation("Name is Required", "Name"); if (Age == 0) yield return new RuleViolation("Age is Required", "Age"); yield break; } partial void OnValidate(ChangeAction action) { if (!IsValid) throw new ApplicationException("Rule violations prevent saving"); } } There is also problem with range. Like in database if i declared as smallint i.e. short in c#, now if i exceed that range then it gives error as "A Value is reguired". so finally is there any best way for validation in ASP.NET MVC?

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• Linq to SQL code generator features

  - by Anders Abel

  I'm very fond of Linq to SQL and the programming model it encourages. I think that in many cases when you are in control of both the database schema and the code it is not worth the effort to have different relational and object models for the data. Working with Linq to SQL makes it simple to have type safe data access from .NET, using the partial extension methods to implement business rules. Unfortunately I do not like the dbml designer due to the lack of a schema refresh function. So far I have used SqlMetal, but that lacks the customization options of the dbml designer. Because of that I've started working on a tool which regenerates the whole code file like SqlMetal, but has the ability to do the customizations that are available in the dbml designer (and maybe more in the future). The customizations will be described in an xml file which only contains those parts that shouldn't have default values. This should keep the xml file size down as well as the maintenance burden of it. To help me focus on the right features, I would like to know: What would be your favourite feature in a linq to sql code generator?

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• Testing ActionFilterAttributes with MSpec

  - by Tomas Lycken

  I'm currently trying to grasp MSpec, mainly to learn new ways of (T/B)DD to be able to make an educated decision on which technology to use. Previously, I've mostly (read: only) used the built-in MSTest framework with Moq, so BDD is quite new for me. I'm writing an ASP.NET MVC app, and I want to implement PRG. Last time I did this, I used action filters to export and import ModelState via TempData, so that I could return a RedirectResult and the validation errors would still be there when the user got the view. I tested that scenario by verifying two things: a) That the ExportModelStateAttribute I had written was applied (among tests for my controller) b) That the attribute worked (among tests for action filter attributes) However, in BDD I've understood I should be even more concerned with behavior, and even less with implementation. This means I should probably just verify that the model state is in tempdata when the action has finished executing - not necessarily that it's done via an attribute. To further complicate things, attributes are not run when calling the action directly in the test, so I can't just call the action and see if the job's been done. How should I spec/test this in MSpec?

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• Organizing Eager Queries in an ObjectContext

  - by Nix

  I am messing around with Entity Framework 3.5 SP1 and I am trying to find a cleaner way to do the below. I have an EF model and I am adding some Eager Loaded entities and i want them all to reside in the "Eager" property in the context. We originally were just changing the entity set name, but it seems a lot cleaner to just use a property, and keep the entity set name in tact. Example: Context - EntityType - AnotherType - Eager (all of these would have .Includes to pull in all assoc. tables) - EntityType - AnotherType Currently I am using composition but I feel like there is an easier way to do what I want. namespace Entities{ public partial class TestObjectContext { EagerExtensions Eager { get;set;} public TestObjectContext(){ Eager = new EagerExtensions (this); } } public partial class EagerExtensions { TestObjectContext context; public EagerExtensions(TestObjectContext _context){ context = _context; } public IQueryable<TestEntity> TestEntity { get { return context.TestEntity .Include("TestEntityType") .Include("Test.Attached.AttachedType") .AsQueryable(); } } } } public class Tester{ public void ShowHowIWantIt(){ TestObjectContext context= new TestObjectContext(); var query = from a in context.Eager.TestEntity select a; } }

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• Is it possible to replace values ina queryset before sending it to your template?

  - by Issy

  Hi Guys, Wondering if it's possible to change a value returned from a queryset before sending it off to the template. Say for example you have a bunch of records Date | Time | Description 10/05/2010 | 13:30 | Testing... etc... However, based on the day of the week the time may change. However this is static. For example on a monday the time is ALWAYS 15:00. Now you could add another table to configure special cases but to me it seems overkill, as this is a rule. How would you replace that value before sending it to the template? I thought about using the new if tags (if day=1), but this is more of business logic rather then presentation. Tested this in a custom template tag def render(self, context): result = self.model._default_manager.filter(from_date__lte=self.now).filter(to_date__gte=self.now) if self.day == 4: result = result.exclude(type__exact=2).order_by('time') else: result = result.order_by('type') result[0].time = '23:23:23' context[self.varname] = result return '' However it still displays the results from the DB, is this some how related to 'lazy' evaluation of templates? Thanks! Update Responding to comments below: It's not stored wrong in the DB, its stored Correctly However there is a small side case where the value needs to change. So for example I have a From Date & To date, my query checks if todays date is between those. Now with this they could setup a from date - to date for an entire year, and the special cases (like mondays as an example) is taken care off. However if you want to store in the DB you would have to capture several more records to cater for the side case. I.e you would be capturing the same information just to cater for that 1 day when the time changes. (And the time always changes on the same day, and is always the same)

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• Applying fine-grained security to an existing application

  - by Mark

  I've inherited a reasonably large and complex ASP.NET MVC3 web application using EF Code First on SQL Server. It uses ASP.NET Membership roles with database authentication. The controller actions are secured with attributes derived from AuthorizeAttribute that map roles to actions. There are extension methods for the finer points, such as showing a particular widget to particular roles. This is works great and I have a good understanding of the current security model. I've been asked to provide finer grained security at the data level. For example a 'Customer' user can only see data (throughout the database) associated with themselves and not other Customers. The problem is that 'Customer' is only 1 of 5 different types with their own specific restrictions (each of the 9 roles is one of these 5 types). The best thing I can think of is to go through all the data repositories and extend each and every LINQ statements/query with a filter for every user type. Even if I had time for that it doesn't seem like the most elegant way. Any suggestions? I really don't know where to start with this so anything could be helpful. Many thanks.

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• How should I secure my webapp written using Wicket, Spring, and JPA?

  - by Martin

  So, I have an web-based application that is using the Wicket 1.4 framework, and it uses Spring beans, the Java Persistence API (JPA), and the OpenSessionInView pattern. I'm hoping to find a security model that is declarative, but doesn't require gobs of XML configuration -- I'd prefer annotations. Here are the options so far: Spring Security (guide) - looks complete, but every guide I find that combines it with Wicket still calls it Acegi Security, which makes me think it must be old. Wicket-Auth-Roles (guide 1 and guide 2) - Most guides recommend mixing this with Spring Security, and I love the declarative style of @Authorize("ROLE1","ROLE2",etc). I'm concerned about having to extend AuthenticatedWebApplication, since I'm already extending org.apache.wicket.protocol.http.WebApplication, and Spring is already proxying that behind org.apache.wicket.spring.SpringWebApplicationFactory. SWARM / WASP (guide) - This looks the newest (though the main contributor passed away years ago), but I hate all of the JAAS-styled text files that declare permissions for principals. I also don't like the idea of making an Action class for every single thing a user might want to do. Secure models also aren't immediately obvious to me. Plus, there isn't an Authn example. Additionally, it looks like lots of folks recommend mixing the first and second options. I can't tell what the best practice is at all, though.

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• Why would ASP.NET MVC use session state?

  - by ray247

  Recommended by the ASP.NET team to use cache instead of session, we stopped using session from working with the WebForm model the last few years. So we normally have the session turned off in the web.config <sessionState mode="Off" /> But, now when I'm testing out a ASP.NET MVC application with this setting it throw an error in class SessionStateTempDataProvider inside the mvc framework, it asked me to turn on session state, I did and it worked. Looking at the source it uses session Dictionary<string, object> tempDataDictionary = httpContext.Session[TempDataSessionStateKey] as Dictionary<string, object>; // line 20 in SessionStateTempDataProvider.cs So, why would they use session here? What am I missing? Thanks, Ray. ======================================================== Edit Sorry didn't mean for this post to debate on session vs. cache, but rather in the context of the ASP.NET MVC, I was just wondering why session is used here. In this Scott Watermasysk blog post he mentioned on turning off session too as a good practice, so I'm just wondering do I have to turn it on to use MVC from here on?

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• What changes in Core Data after a save?

  - by Splash6

  I have a Core Data based mac application that is working perfectly well until I save a file. When I save a file it seems like something changes in core data because my original fetch request no longer fetches anything. This is the fetch request that works before saving but returns an empty array after saving. NSEntityDescription *outputCellEntityDescription = [NSEntityDescription entityForName:@"OutputCell" inManagedObjectContext:[[self document] managedObjectContext]]; NSFetchRequest *outputCellRequest = [[[NSFetchRequest alloc] init] autorelease]; [outputCellRequest setEntity:outputCellEntityDescription]; NSPredicate *outputCellPredicate = [NSPredicate predicateWithFormat:@"(cellTitle = %@)", outputCellTitle]; [outputCellRequest setPredicate:outputCellPredicate]; NSError *outputCellError = nil; NSArray *outputCellArray = [[[self document] managedObjectContext] executeFetchRequest:outputCellRequest error:&outputCellError]; I have checked with [[[self document] managedObjectContext] registeredObjects] to see that the object still exists after the save and nothing seems to have changed and the object still exists. It is probably something fairly basic but does anyone know what I might be doing wrong? If not can anyone give me any pointers to what might be different in the Core Data model after a save so I might have some clues why the fetch request stops working after saving?

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• Where do I put javaassist code?

  - by DutrowLLC

  I have an application running on google app engine. I'm using restlets and I have a couple of layers set up including the restlet layer, the model layer, the business layer, and the data layer. I'm attempting to use javaassist to modify some classes, but I'm unsure where to actually put the code. I tried to put the code in the static initialization block: public class Person { String firstName; String getFirstName(){return null;} static{ ClassPool pool = ClassPool.getDefault(); try { CtClass CtPerson = pool.get("Person"); CtMethod CtGetFirstName = CtPerson.getDeclaredMethod("GetFirstName"); CtGetFirstName.setBody("return firstName;"); CtPerson.toClass(); } catch (Exception e) { e.printStackTrace(); } } } ...but that resulted in this error: javassist.CannotCompileException:.....attempted duplicate class definition...". I guess it makes sense that I can't edit the class file in the middle of its generation. I know the code works because I was able to run it correctly by simply putting it in a location that would run when I sent the program a command. (accessed a Restlet resource). The code ran fine if an instance of the class had not already been instantiated, however once I instantiated an instance of the affected class, the javaassist code failed. I assume I need to put this code somewhere that it will only run either: once after the program starts, directly before a class is instantiated for the first time, or even better, during compile time.

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• Difference in BackgroundWorker thread access in VS2010 / .NET 4.0?

  - by Jonners

  Here's an interesting one - in VS2005 / VS2008 running against .NET 2.0 / .NET 3.0 / .NET 3.5, a BackgroundWorker thread may not directly update controls on a WinForms form that initiated that thread - you'll get a System.InvalidOperationException out of the BackgroundWorker stating "Cross-thread operation not valid: Control 'thecontrol' accessed from a thread other than the thread it was created on". I remember hitting this back in 2004 or so when I first started writing .NET WinForms apps with background threads. There are several ways around the problem - this is not a question asking for that answer. I've been told recently that this kind of operation is now allowed when written in VS2010 / .NET 4.0. This seems unlikely to me, since this kind of object access restriction has always been a fairly fundamental part of thread-safe programming. Allowing a BackgroundWorker thread direct access to objects owned not by itself but by its parent UI form seems contrary to that principle. A trawl through the .NET 4.0 docs hasn't revealed any obvious changes that could account for this behaviour. I don't have VS2010 / .NET 4.0 to test this out - does anyone who has access to that toolset know for sure whether the model has changed to allow that kind of thread interaction? I'd like to either take advantage of it in future, or deploy the cluestick. ;)

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• 3D Animation Rotating and Translating simultaneously in WPF

  - by sklitzz

  Hi, I have ModelVisual3D of a cube. I want to translate and rotate it at the same time. I wish the center of rotation to be in the middle of the cube(the cube rotates around its own axis). But when I try to do this applying both transformations the effect is not what you would expect. Since the object is translating the center of rotation is different thus making it move and rotate in a strange way. How do I get the desired effect? Transform3DGroup transGroup = new Transform3DGroup(); DoubleAnimation cardAnimation = new DoubleAnimation(); cardAnimation.From = 0; cardAnimation.To = 3; cardAnimation.Duration = new Duration(TimeSpan.FromSeconds(2)); Transform3D transform = new TranslateTransform3D(0,0,0); transGroup.Children.Add(transform); RotateTransform3D rotateTransform = new RotateTransform3D(); AxisAngleRotation3D rotateAxis = new AxisAngleRotation3D(new Vector3D(0, 1, 0), 180); Rotation3DAnimation rotateAnimation = new Rotation3DAnimation(rotateAxis, TimeSpan.FromSeconds(2)); rotateAnimation.DecelerationRatio = 0.8; transGroup.Children.Add(rotateTransform); Model.Transform = transGroup; transform.BeginAnimation(TranslateTransform3D.OffsetXProperty, cardAnimation); rotateTransform.BeginAnimation(RotateTransform3D.RotationProperty, rotateAnimation);

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• How to efficiently compare the sign of two floating-point values while handling negative zeros

  - by François Beaune

  Given two floating-point numbers, I'm looking for an efficient way to check if they have the same sign, given that if any of the two values is zero (+0.0 or -0.0), they should be considered to have the same sign. For instance, SameSign(1.0, 2.0) should return true SameSign(-1.0, -2.0) should return true SameSign(-1.0, 2.0) should return false SameSign(0.0, 1.0) should return true SameSign(0.0, -1.0) should return true SameSign(-0.0, 1.0) should return true SameSign(-0.0, -1.0) should return true A naive but correct implementation of SameSign in C++ would be: bool SameSign(float a, float b) { if (fabs(a) == 0.0f || fabs(b) == 0.0f) return true; return (a >= 0.0f) == (b >= 0.0f); } Assuming the IEEE floating-point model, here's a variant of SameSign that compiles to branchless code (at least with with Visual C++ 2008): bool SameSign(float a, float b) { int ia = binary_cast<int>(a); int ib = binary_cast<int>(b); int az = (ia & 0x7FFFFFFF) == 0; int bz = (ib & 0x7FFFFFFF) == 0; int ab = (ia ^ ib) >= 0; return (az | bz | ab) != 0; } with binary_cast defined as follow: template <typename Target, typename Source> inline Target binary_cast(Source s) { union { Source m_source; Target m_target; } u; u.m_source = s; return u.m_target; } I'm looking for two things: A faster, more efficient implementation of SameSign, using bit tricks, FPU tricks or even SSE intrinsics. An efficient extension of SameSign to three values.

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• What VC++ compiler/linker does when building a C++ project with Managed Extension

  - by ???

  The initial problem is that I tried to rebuild a C++ project with debug symbols and copied it to test machine, The output of the project is external COM server(.exe file). When calling the COM interface function, there's a RPC call failre: COMException(0x800706BE): The remote procedure call failed. According to the COM HRESULT design, if the FACILITY code is 7, it's actually a WIN32 error, and the win32 error code is 0x6BE, which is the above mentioned "remote procedure call failed". All I do is replace the COM server .exe file, the origin file works well. When I checked into the project, I found it's a C++ project with Managed Extension. When I checking the DLL with reflector, it shows there's 2 additional .NET assembly reference. Then I checked the project setting and found nothing about the extra 2 assembly reference. I turned on the show includes option of compiler and verbose library of linker, and try to analyze whether the assembly is indirectly referenced via .h file. I've collect all the .h file and grep all the files with '#using' '#import' and the assembly file itself. There really is a '#using ' in one of the .h file but not-relevant to the referenced assembly. And about the linked .lib library files, only one of the .lib file is a side-product of another managed-extension-enabled C++ project, all others are produced by a pure, traditional C++ project. For the managed-extension-enabled C++ project, I checked the output DLL assembly, it did NOT reference to the 2 assembly. I even try to capture the access of the additional assembly file via sysinternal's filemon and procmon, but the rebuild process does NOT access these file. I'm very confused about the compile and linking process model of a VC++/CLI project, where the additional assembly reference slipped into the final assembly? Thanks in advance for any of your help.

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