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• Entity Framework and multi-tenancy database design

  - by Junto

  I am looking at multi-tenancy database schema design for an SaaS concept. It will be ASP.NET MVC - EF, but that isn't so important. Below you can see an example database schema (the Tenant being the Company). The CompanyId is replicated throughout the schema and the primary key has been placed on both the natural key, plus the tenant Id. Plugging this schema into the Entity Framework gives the following errors when I add the tables into the Entity Model file (Model1.edmx): The relationship 'FK_Order_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderId, CompanyId}' of the table 'Order'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Order' uses the set of foreign keys '{OrderId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_Order_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderId, CompanyId}' of the table 'Order'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Customer' uses the set of foreign keys '{CustomerId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Order' uses the set of foreign keys '{OrderId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The relationship 'FK_OrderLine_Product' uses the set of foreign keys '{ProductId, CompanyId}' that are partially contained in the set of primary keys '{OrderLineId, CompanyId}' of the table 'OrderLine'. The set of foreign keys must be fully contained in the set of primary keys, or fully not contained in the set of primary keys to be mapped to a model. The question is in two parts: Is my database design incorrect? Should I refrain from these compound primary keys? I'm questioning my sanity regarding the fundamental schema design (frazzled brain syndrome). Please feel free to suggest the 'idealized' schema. Alternatively, if the database design is correct, then is EF unable to match the keys because it perceives these foreign keys as a potential mis-configured 1:1 relationships (incorrectly)? In which case, is this an EF bug and how can I work around it?

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• WCF Data Service BeginSaveChanges not saving changes in Silverlight app

  - by Enigmativity

  I'm having a hell of a time getting WCF Data Services to work within Silverlight. I'm using the VS2010 RC. I've struggled with the cross domain issue requiring the use of clientaccesspolicy.xml & crossdomain.xml files in the web server root folder, but I just couldn't get this to work. I've resorted to putting both the Silverlight Web App & the WCF Data Service in the same project to get past this issue, but any advice here would be good. But now that I can actually see my data coming from the database and being displayed in a data grid within Silverlight I thought my troubles were over - but no. I can edit the data and the in-memory entity is changing, but when I call BeginSaveChanges (with the appropriate async EndSaveChangescall) I get no errors, but no data updates in the database. Here's my WCF Data Services code: public class MyDataService : DataService<MyEntities> { public static void InitializeService(DataServiceConfiguration config) { config.SetEntitySetAccessRule("*", EntitySetRights.All); config.SetServiceOperationAccessRule("*", ServiceOperationRights.All); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } protected override void OnStartProcessingRequest(ProcessRequestArgs args) { base.OnStartProcessingRequest(args); HttpContext context = HttpContext.Current; HttpCachePolicy c = HttpContext.Current.Response.Cache; c.SetCacheability(HttpCacheability.ServerAndPrivate); c.SetExpires(HttpContext.Current.Timestamp.AddSeconds(60)); c.VaryByHeaders["Accept"] = true; c.VaryByHeaders["Accept-Charset"] = true; c.VaryByHeaders["Accept-Encoding"] = true; c.VaryByParams["*"] = true; } } I've pinched the OnStartProcessingRequest code from Scott Hanselman's article Creating an OData API for StackOverflow including XML and JSON in 30 minutes. Here's my code from my Silverlight app: private MyEntities _wcfDataServicesEntities; private CollectionViewSource _customersViewSource; private ObservableCollection<Customer> _customers; private void UserControl_Loaded(object sender, RoutedEventArgs e) { if (!System.ComponentModel.DesignerProperties.GetIsInDesignMode(this)) { _wcfDataServicesEntities = new MyEntities(new Uri("http://localhost:7156/MyDataService.svc/")); _customersViewSource = this.Resources["customersViewSource"] as CollectionViewSource; DataServiceQuery<Customer> query = _wcfDataServicesEntities.Customer; query.BeginExecute(result => { _customers = new ObservableCollection<Customer>(); Array.ForEach(query.EndExecute(result).ToArray(), _customers.Add); Dispatcher.BeginInvoke(() => { _customersViewSource.Source = _customers; }); }, null); } } private void button1_Click(object sender, RoutedEventArgs e) { _wcfDataServicesEntities.BeginSaveChanges(r => { var response = _wcfDataServicesEntities.EndSaveChanges(r); string[] results = new[] { response.BatchStatusCode.ToString(), response.IsBatchResponse.ToString() }; _customers[0].FinAssistCompanyName = String.Join("|", results); }, null); } The response string I get back data binds to my grid OK and shows "-1|False". My intent is to get a proof-of-concept working here and then do the appropriate separation of concerns to turn this into a simple line-of-business app. I've spent hours and hours on this. I'm being driven insane. Any ideas how to get this working?

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• Best practices for using the Entity Framework with WPF DataBinding

  - by Ken Smith

  I'm in the process of building my first real WPF application (i.e., the first intended to be used by someone besides me), and I'm still wrapping my head around the best way to do things in WPF. It's a fairly simple data access application using the still-fairly-new Entity Framework, but I haven't been able to find a lot of guidance online for the best way to use these two technologies (WPF and EF) together. So I thought I'd toss out how I'm approaching it, and see if anyone has any better suggestions. I'm using the Entity Framework with SQL Server 2008. The EF strikes me as both much more complicated than it needs to be, and not yet mature, but Linq-to-SQL is apparently dead, so I might as well use the technology that MS seems to be focusing on. This is a simple application, so I haven't (yet) seen fit to build a separate data layer around it. When I want to get at data, I use fairly simple Linq-to-Entity queries, usually straight from my code-behind, e.g.: var families = from family in entities.Family.Include("Person") orderby family.PrimaryLastName, family.Tag select family; Linq-to-Entity queries return an IOrderedQueryable result, which doesn't automatically reflect changes in the underlying data, e.g., if I add a new record via code to the entity data model, the existence of this new record is not automatically reflected in the various controls referencing the Linq query. Consequently, I'm throwing the results of these queries into an ObservableCollection, to capture underlying data changes: familyOC = new ObservableCollection<Family>(families.ToList()); I then map the ObservableCollection to a CollectionViewSource, so that I can get filtering, sorting, etc., without having to return to the database. familyCVS.Source = familyOC; familyCVS.View.Filter = new Predicate<object>(ApplyFamilyFilter); familyCVS.View.SortDescriptions.Add(new System.ComponentModel.SortDescription("PrimaryLastName", System.ComponentModel.ListSortDirection.Ascending)); familyCVS.View.SortDescriptions.Add(new System.ComponentModel.SortDescription("Tag", System.ComponentModel.ListSortDirection.Ascending)); I then bind the various controls and what-not to that CollectionViewSource: <ListBox DockPanel.Dock="Bottom" Margin="5,5,5,5" Name="familyList" ItemsSource="{Binding Source={StaticResource familyCVS}, Path=., Mode=TwoWay}" IsSynchronizedWithCurrentItem="True" ItemTemplate="{StaticResource familyTemplate}" SelectionChanged="familyList_SelectionChanged" /> When I need to add or delete records/objects, I manually do so from both the entity data model, and the ObservableCollection: private void DeletePerson(Person person) { entities.DeleteObject(person); entities.SaveChanges(); personOC.Remove(person); } I'm generally using StackPanel and DockPanel controls to position elements. Sometimes I'll use a Grid, but it seems hard to maintain: if you want to add a new row to the top of your grid, you have to touch every control directly hosted by the grid to tell it to use a new line. Uggh. (Microsoft has never really seemed to get the DRY concept.) I almost never use the VS WPF designer to add, modify or position controls. The WPF designer that comes with VS is sort of vaguely helpful to see what your form is going to look like, but even then, well, not really, especially if you're using data templates that aren't binding to data that's available at design time. If I need to edit my XAML, I take it like a man and do it manually. Most of my real code is in C# rather than XAML. As I've mentioned elsewhere, entirely aside from the fact that I'm not yet used to "thinking" in it, XAML strikes me as a clunky, ugly language, that also happens to come with poor designer and intellisense support, and that can't be debugged. Uggh. Consequently, whenever I can see clearly how to do something in C# code-behind that I can't easily see how to do in XAML, I do it in C#, with no apologies. There's been plenty written about how it's a good practice to almost never use code-behind in WPF page (say, for event-handling), but so far at least, that makes no sense to me whatsoever. Why should I do something in an ugly, clunky language with god-awful syntax, an astonishingly bad editor, and virtually no type safety, when I can use a nice, clean language like C# that has a world-class editor, near-perfect intellisense, and unparalleled type safety? So that's where I'm at. Any suggestions? Am I missing any big parts of this? Anything that I should really think about doing differently?

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• NHibernate which cache to use for WinForms application

  - by chiccodoro

  I have a C# WinForms application with a database backend (oracle) and use NHibernate for O/R mapping. I would like to reduce communication to the database as much as possible since the network in here is quite slow, so I read about second level caching. I found this quite good introduction, which lists the following available cache implementations. I'm wondering which implementation I should use for my application. The caching should be simple, it should not significantly slow down the first occurrence of a query, and it should not take much memory to load the implementing assemblies. (With NHibernate and Castle, the application already takes up to 80 MB of RAM!) Velocity: uses Microsoft Velocity which is a highly scalable in-memory application cache for all kinds of data. Prevalence: uses Bamboo.Prevalence as the cache provider. Bamboo.Prevalence is a .NET implementation of the object prevalence concept brought to life by Klaus Wuestefeld in Prevayler. Bamboo.Prevalence provides transparent object persistence to deterministic systems targeting the CLR. It offers persistent caching for smart client applications. SysCache: Uses System.Web.Caching.Cache as the cache provider. This means that you can rely on ASP.NET caching feature to understand how it works. SysCache2: Similar to NHibernate.Caches.SysCache, uses ASP.NET cache. This provider also supports SQL dependency-based expiration, meaning that it is possible to configure certain cache regions to automatically expire when the relevant data in the database changes. MemCache: uses memcached; memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load. Basically a distributed hash table. SharedCache: high-performance, distributed and replicated memory object caching system. See here and here for more info My considerations so far were: Velocity seems quite heavyweight and overkill (the files totally take 467 KB of disk space, haven't measured the RAM it takes so far because I didn't manage to make it run, see below) Prevalence, at least in my first attempt, slowed down my query from ~0.5 secs to ~5 secs, and caching didn't work (see below) SysCache seems to be for ASP.NET, not for winforms. MemCache and SharedCache seem to be for distributed scenarios. Which one would you suggest me to use? There would also be a built-in implementation, which of course is very lightweight, but the referenced article tells me that I "(...) should never use this cache provider for production code but only for testing." Besides the question which fits best into my situation I also faced problems with applying them: Velocity complained that "dcacheClient" tag not specified in the application configuration file. Specify valid tag in configuration file," although I created an app.config file for the assembly and pasted the example from this article. Prevalence, as mentioned above, heavily slowed down my first query, and the next time the exact same query was executed, another select was sent to the database. Maybe I should "externalize" this topic into another post. I will do that if someone tells me it is absolutely unusual that a query is slowed down so much and he needs further details to help me.

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• Exposing model object using bindings in custom NSCell of NSTableView

  - by Hooligancat

  I am struggling trying to perform what I would think would be a relatively common task. I have an NSTableView that is bound to it's array via an NSArrayController. The array controller has it's content set to an NSMutableArray that contains one or more NSObject instances of a model class. What I don't know how to do is expose the model inside the NSCell subclass in a way that is bindings friendly. For the purpose of illustration, we'll say that the object model is a person consisting of a first name, last name, age and gender. Thus the model would appear something like this: @interface PersonModel : NSObject { NSString * firstName; NSString * lastName; NSString * gender; int * age; } Obviously the appropriate setters, getters init etc for the class. In my controller class I define an NSTableView, NSMutableArray and an NSArrayController: @interface ControllerClass : NSObject { IBOutlet NSTableView * myTableView; NSMutableArray * myPersonArray; IBOutlet NSArrayController * myPersonArrayController; } Using Interface Builder I can easily bind the model to the appropriate columns: myPersonArray --> myPersonArrayController --> table column binding This works fine. So I remove the extra columns, leaving one column hidden that is bound to the NSArrayController (this creates and keeps the association between each row and the NSArrayController) so that I am down to one visible column in my NSTableView and one hidden column. I create an NSCell subclass and put the appropriate drawing method to create the cell. In my awakeFromNib I establish the custom NSCell subclass: PersonModel * aCustomCell = [[[PersonModel alloc] init] autorelease]; [[myTableView tableColumnWithIdentifier:@"customCellColumn"] setDataCell:aCustomCell]; This, too, works fine from a drawing perspective. I get my custom cell showing up in the column and it repeats for every managed object in my array controller. If I add an object or remove an object from the array controller the table updates accordingly. However... I was under the impression that my PersonModel object would be available from within my NSCell subclass. But I don't know how to get to it. I don't want to set each NSCell using setters and getters because then I'm breaking the whole model concept by storing data in the NSCell instead of referencing it from the array controller. And yes I do need to have a custom NSCell, so having multiple columns is not an option. Where to from here? In addition to the Google and StackOverflow search, I've done the obligatory walk through on Apple's docs and don't seem to have found the answer. I have found a lot of references that beat around the bush but nothing involving an NSArrayController. The controller makes life very easy when binding to other elements of the model entity (such as a master/detail scenario). I have also found a lot of references (although no answers) when using Core Data, but Im not using Core Data. As per the norm, I'm very grateful for any assistance that can be offered!

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• Flushing a queue using AMQP, Rabbit, and Ruby

  - by jeffshantz

  I'm developing a system in Ruby that is going to make use of RabbitMQ to send messages to a queue as it does some work. I am using: Ruby 1.9.1 Stable RabbitMQ 1.7.2 AMQP gem v0.6.7 (http://github.com/tmm1/amqp) Most of the examples I have seen on this gem have their publish calls in an EM.add_periodic_timer block. This doesn't work for what I suspect is a vast majority of use cases, and certainly not for mine. I need to publish a message as I complete some work, so putting a publish statement in an add_periodic_timer block doesn't suffice. So, I'm trying to figure out how to publish a few messages to a queue, and then "flush" it, so that any messages I've published are then delivered to my subscribers. To give you an idea of what I mean, consider the following publisher code: #!/usr/bin/ruby require 'rubygems' require 'mq' MESSAGES = ["hello","goodbye","test"] AMQP.start do queue = MQ.queue('testq') messages_published = 0 while (messages_published < 50) if (rand() < 0.4) message = MESSAGES[rand(MESSAGES.size)] puts "#{Time.now.to_s}: Publishing: #{message}" queue.publish(message) messages_published += 1 end sleep(0.1) end AMQP.stop do EM.stop end end So, this code simply loops, publishing a message with 40% probability on each iteration of the loop, and then sleeps for 0.1 seconds. It does this until 50 messages have been published, and then stops AMQP. Of course, this is just a proof of concept. Now, my subscriber code: #!/usr/bin/ruby require 'rubygems' require 'mq' AMQP.start do queue = MQ.queue('testq') queue.subscribe do |header, msg| puts "#{Time.now.to_s}: Received #{msg}" end end So, we just subscribe to the queue, and for each message received, we print it out. Great, except that the subscriber only receives all 50 messages when the publisher calls AMQP.stop. Here's the output from my publisher. It has been truncated in the middle for brevity: $ ruby publisher.rb 2010-04-14 21:45:42 -0400: Publishing: test 2010-04-14 21:45:42 -0400: Publishing: hello 2010-04-14 21:45:42 -0400: Publishing: test 2010-04-14 21:45:43 -0400: Publishing: test 2010-04-14 21:45:44 -0400: Publishing: test 2010-04-14 21:45:44 -0400: Publishing: goodbye 2010-04-14 21:45:45 -0400: Publishing: goodbye 2010-04-14 21:45:45 -0400: Publishing: test 2010-04-14 21:45:45 -0400: Publishing: test . . . 2010-04-14 21:45:55 -0400: Publishing: test 2010-04-14 21:45:55 -0400: Publishing: test 2010-04-14 21:45:55 -0400: Publishing: test 2010-04-14 21:45:55 -0400: Publishing: goodbye Next, the output from my subscriber: $ ruby consumer.rb 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received hello 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received goodbye 2010-04-14 21:45:56 -0400: Received goodbye 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received test . . . 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received test 2010-04-14 21:45:56 -0400: Received goodbye If you note the timestamps in the output, the subscriber only receives all of the messages once the publisher has stopped AMQP and exited. So, being an AMQP newb, how can I get my messages to deliver immediately? I tried putting AMQP.start and AMQP.stop in the body of the while loop of the publisher, but then only the first message gets delivered -- though strangely, if I turn on logging, there are no error messages reported by the server and the messages do get sent to the queue, but never get received by the subscriber. Suggestions would be much appreciated. Thanks for reading.

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• Google App Engine - Secure Cookies

  - by tponthieux

  I'd been searching for a way to do cookie based authentication/sessions in Google App Engine because I don't like the idea of memcache based sessions, and I also don't like the idea of forcing users to create google accounts just to use a website. I stumbled across someone's posting that mentioned some signed cookie functions from the Tornado framework and it looks like what I need. What I have in mind is storing a user's id in a tamper proof cookie, and maybe using a decorator for the request handlers to test the authentication status of the user, and as a side benefit the user id will be available to the request handler for datastore work and such. The concept would be similar to forms authentication in ASP.NET. This code comes from the web.py module of the Tornado framework. According to the docstrings, it "Signs and timestamps a cookie so it cannot be forged" and "Returns the given signed cookie if it validates, or None." I've tried to use it in an App Engine Project, but I don't understand the nuances of trying to get these methods to work in the context of the request handler. Can someone show me the right way to do this without losing the functionality that the FriendFeed developers put into it? The set_secure_cookie, and get_secure_cookie portions are the most important, but it would be nice to be able to use the other methods as well. #!/usr/bin/env python import Cookie import base64 import time import hashlib import hmac import datetime import re import calendar import email.utils import logging def _utf8(s): if isinstance(s, unicode): return s.encode("utf-8") assert isinstance(s, str) return s def _unicode(s): if isinstance(s, str): try: return s.decode("utf-8") except UnicodeDecodeError: raise HTTPError(400, "Non-utf8 argument") assert isinstance(s, unicode) return s def _time_independent_equals(a, b): if len(a) != len(b): return False result = 0 for x, y in zip(a, b): result |= ord(x) ^ ord(y) return result == 0 def cookies(self): """A dictionary of Cookie.Morsel objects.""" if not hasattr(self,"_cookies"): self._cookies = Cookie.BaseCookie() if "Cookie" in self.request.headers: try: self._cookies.load(self.request.headers["Cookie"]) except: self.clear_all_cookies() return self._cookies def _cookie_signature(self,*parts): self.require_setting("cookie_secret","secure cookies") hash = hmac.new(self.application.settings["cookie_secret"], digestmod=hashlib.sha1) for part in parts:hash.update(part) return hash.hexdigest() def get_cookie(self,name,default=None): """Gets the value of the cookie with the given name,else default.""" if name in self.cookies: return self.cookies[name].value return default def set_cookie(self,name,value,domain=None,expires=None,path="/", expires_days=None): """Sets the given cookie name/value with the given options.""" name = _utf8(name) value = _utf8(value) if re.search(r"[\x00-\x20]",name + value): # Don't let us accidentally inject bad stuff raise ValueError("Invalid cookie %r:%r" % (name,value)) if not hasattr(self,"_new_cookies"): self._new_cookies = [] new_cookie = Cookie.BaseCookie() self._new_cookies.append(new_cookie) new_cookie[name] = value if domain: new_cookie[name]["domain"] = domain if expires_days is not None and not expires: expires = datetime.datetime.utcnow() + datetime.timedelta( days=expires_days) if expires: timestamp = calendar.timegm(expires.utctimetuple()) new_cookie[name]["expires"] = email.utils.formatdate( timestamp,localtime=False,usegmt=True) if path: new_cookie[name]["path"] = path def clear_cookie(self,name,path="/",domain=None): """Deletes the cookie with the given name.""" expires = datetime.datetime.utcnow() - datetime.timedelta(days=365) self.set_cookie(name,value="",path=path,expires=expires, domain=domain) def clear_all_cookies(self): """Deletes all the cookies the user sent with this request.""" for name in self.cookies.iterkeys(): self.clear_cookie(name) def set_secure_cookie(self,name,value,expires_days=30,**kwargs): """Signs and timestamps a cookie so it cannot be forged""" timestamp = str(int(time.time())) value = base64.b64encode(value) signature = self._cookie_signature(name,value,timestamp) value = "|".join([value,timestamp,signature]) self.set_cookie(name,value,expires_days=expires_days,**kwargs) def get_secure_cookie(self,name,include_name=True,value=None): """Returns the given signed cookie if it validates,or None""" if value is None:value = self.get_cookie(name) if not value:return None parts = value.split("|") if len(parts) != 3:return None if include_name: signature = self._cookie_signature(name,parts[0],parts[1]) else: signature = self._cookie_signature(parts[0],parts[1]) if not _time_independent_equals(parts[2],signature): logging.warning("Invalid cookie signature %r",value) return None timestamp = int(parts[1]) if timestamp < time.time() - 31 * 86400: logging.warning("Expired cookie %r",value) return None try: return base64.b64decode(parts[0]) except: return None uid=1234|1234567890|d32b9e9c67274fa062e2599fd659cc14 Parts: 1. uid is the name of the key 2. 1234 is your value in clear 3. 1234567890 is the timestamp 4. d32b9e9c67274fa062e2599fd659cc14 is the signature made from the value and the timestamp

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• Is it bad practice to apply class-based design to JavaScript programs?

  - by helixed

  JavaScript is a prototyped-based language, and yet it has the ability to mimic some of the features of class-based object-oriented languages. For example, JavaScript does not have a concept of public and private members, but through the magic of closures, it's still possible to provide the same functionality. Similarly, method overloading, interfaces, namespaces and abstract classes can all be added in one way or another. Lately, as I've been programming in JavaScript, I've felt like I'm trying to turn it into a class-based language instead of using it in the way it's meant to be used. It seems like I'm trying to force the language to conform to what I'm used to. The following is some JavaScript code I've written recently. It's purpose is to abstract away some of the effort involved in drawing to the HTML5 canvas element. /* Defines the Drawing namespace. */ var Drawing = {}; /* Abstract base which represents an element to be drawn on the screen. @param The graphical context in which this Node is drawn. @param position The position of the center of this Node. */ Drawing.Node = function(context, position) { return { /* The method which performs the actual drawing code for this Node. This method must be overridden in any subclasses of Node. */ draw: function() { throw Exception.MethodNotOverridden; }, /* Returns the graphical context for this Node. @return The graphical context for this Node. */ getContext: function() { return context; }, /* Returns the position of this Node. @return The position of this Node. */ getPosition: function() { return position; }, /* Sets the position of this Node. @param thePosition The position of this Node. */ setPosition: function(thePosition) { position = thePosition; } }; } /* Define the shape namespace. */ var Shape = {}; /* A circle shape implementation of Drawing.Node. @param context The graphical context in which this Circle is drawn. @param position The center of this Circle. @param radius The radius of this circle. @praram color The color of this circle. */ Shape.Circle = function(context, position, radius, color) { //check the parameters if (radius < 0) throw Exception.InvalidArgument; var node = Drawing.Node(context, position); //overload the node drawing method node.draw = function() { var context = this.getContext(); var position = this.getPosition(); context.fillStyle = color; context.beginPath(); context.arc(position.x, position.y, radius, 0, Math.PI*2, true); context.closePath(); context.fill(); } /* Returns the radius of this Circle. @return The radius of this Circle. */ node.getRadius = function() { return radius; }; /* Sets the radius of this Circle. @param theRadius The new radius of this circle. */ node.setRadius = function(theRadius) { radius = theRadius; }; /* Returns the color of this Circle. @return The color of this Circle. */ node.getColor = function() { return color; }; /* Sets the color of this Circle. @param theColor The new color of this Circle. */ node.setColor = function(theColor) { color = theColor; }; //return the node return node; }; The code works exactly like it should for a user of Shape.Circle, but it feels like it's held together with Duct Tape. Can somebody provide some insight on this?

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• Temporary "Backup" of SharePoint Content During Feature and Solution Deployment

  - by ccomet

  I need to decide on a method for storing a subset of the content in a SharePoint site, so that when I delete and recreate certain lists as part of a feature activation, I can re-insert all of this content back where it should belong. I have an idea myself, but I don't know if it's the only method and more importantly, the right method. My client has me creating a SharePoint system for them to communicate with their clients. The business process has maybe 5 stages in it (maybe it's more, I don't even know because they don't tell me everything), and the current system I've written over the past months is maybe 2 stages through. This meets our deadline of completing those systems by Monday next week... but at that point my client is planning on making the site live from that point. In effect, their work with their clients will be running parallel with my work for them. As I complete my own work on a separate test server, I'll push each following stage of the process onto the live server. Scheduled downtimes during non-business times (like a weekend) will be available for me to perform these pushes. Keeping pace so that my development is faster than the actual business process is my own problem and off-topic... so let's get back to the problem I stated at the start of this post. In this system, we have sets of features which will create lists for their associated content types and field types when activated, and delete these lists when the feature is deactivated. Most updates don't need to deactivate and reactivate these features, such as workflow changes, custom actions, custom forms, and similar ilk. But there are some parts which do require this. On my test server, it's okay for me to obliterate lists, but once the site is live and there's real correspondence data, it's absolutely unacceptable to do this. So when I need to implement a new change in functionality, I need to be able to store the currently present data in several lists, deactivate the feature, reactivate the feature, and restore all of this data. Perhaps I have hoist myself by my own petard with the feature system I implemented. Unfortunately, the necessity to later on make several of these "project sites" meant I had to do a lot of my code with the concept of "Can be deployed repeatedly" in mind. My current plan is to run through lists and libraries which will be affected by the particular feature that is to be reset. Files and all of their versions will be saved in a directory on the server. Then, a set of text files will be used to store all of the important field values for the items. This includes a lot of cross-list reference lookups that will need to be maintained, but that's simple enough. Then, I deactivate the feature, deploy the new solution, and reactivate the feature. We upload all of the files in the order specified by their versions and update them with the stored fields for those versions, so that we retain the version structure. As each one is first uploaded, the new ID is picked out, and all relevant lookups in the rest of the files are updated (in some manner that I make sure I don't re-update it later with an incorrect value, of course). After that, we run through all the rest of the items in the order most conducive to keeping the relational data correct. This roughly summarizes what my current plan is. To my advantage, there are no long running workflows in the system that will be affected by this, so there's nothing I will have to worry about making sure nothing is "still running" when I do this stuff. I don't really know all the cons of this approach... I can imagine they're quite hefty. But I'm unsure what other choices I even have, and my searches haven't turned up anything. Is there anyone who can think of a better idea? Or will anyone just tell me that I really have no other choice? Thanks in advance!

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• What is "elegant" code?

  - by Breton

  I see a lot of lip service and talk about the most "elegant" way to do this or that. I think if you spend enough time programming you begin to obtain a sort of intuitive feel for what it is we call "elegance". But I'm curious. Even if we can look at a bit of code, and say instinctively "That's elegant", or "That's messy", I wonder if any of us really understands what that means. Is there a precise definition for this "elegance" we keep referring to? If there is, what is it? Now, what I mean by a precise definition, is a series of statements which can be used to derive questions about a peice of code, or a program as a whole, and determine objectively, or as objectively as possible, whether that code is "elegant" or not. May I assert, that perhaps no such definition exists, and it's all just personal preference. In this case, I ask you a slightly different question: Is there a better word for "elegance", or a better set of attributes to use for judging code quality that is perhaps more objective than merely appealing to individual intuition and taste? Perhaps code quality is a matter of taste, and the answer to both of my questions is "no". But I can't help but feel that we could be doing better than just expressing wishy washy feelings about our code quality. For example, user interface design is something that to a broad range of people looks for all the world like a field of study that oughtta be 100% subjective matter of taste. But this is shockingly and brutally not the case, and there are in fact many objective measures that can be applied to a user interface to determine its quality. A series of tests could be written to give a definitive and repeatable score to user interface quality. (See GOMS, for instance). Now, okay. is Elegance simply "code quality" or is it something more? Is it something that can be measured? Or is it a matter of taste? Does our profession have room for taste? Maybe I'm asking the wrong questions altogether. Help me out here. Bonus Round If there is such a thing as elegance in code, and that concept is useful, do you think that justifies classifying the field of programming as an "Art" capital A, or merely a "craft". Or is it just an engineering field populated by a bunch of wishful thinking humans? Consider this question in the light of your thoughts about the elegance question. Please note that there is a distinction between code which is considered "art" in itself, and code that was written merely in the service of creating an artful program. When I ask this question, I ask if the code itself justifies calling programming an art. Bounty Note I liked the answers to this question so much, I think I'd like to make a photographic essay book from it. Released as a free PDF, and published on some kind of on demand printing service of course, such as "zazz" or "tiggle" or "printley" or something . I'd like some more answers, please!

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• Getting an invalidoperationexception when deserialising XML

  - by Paul Johnson

  Hi, I'm writing a simple proof of concept application to load up an XML file and depending on the very simple code, create a window and put something into it (it's for a much larger project). Due to limitations in Mono, I'm having to run in this way. The code I currently have looks like this using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Windows.Forms; using System.IO; using System.Collections; using System.Xml; using System.Xml.Serialization; namespace form_from_xml { public class xmlhandler : Form { public void loaddesign() { FormData f; f = null; try { string path_env = Path.GetDirectoryName(Application.ExecutablePath) + Path.DirectorySeparatorChar; // code dies on the line below XmlSerializer s = new XmlSerializer(typeof(FormData)); TextReader r = new StreamReader(path_env + "designer-test.xml"); f = (FormData)s.Deserialize(r); r.Close(); } catch (System.IO.FileNotFoundException) { MessageBox.Show("Unable to find the form file", "File not found", MessageBoxButtons.OK); } } } [XmlRoot("Forms")] public class FormData { private ArrayList formData; public FormData() { formData = new ArrayList(); } [XmlElement("Element")] public Elements[] elements { get { Elements[] elements = new Elements[formData.Count]; formData.CopyTo(elements); return elements; } set { if (value == null) return; Elements[] elements = (Elements[])value; formData.Clear(); foreach (Elements element in elements) formData.Add(element); } } public int AddItem(Elements element) { return formData.Add(element); } } public class Elements { [XmlAttribute("formname")] public string name; [XmlAttribute("winxsize")] public int winxs; [XmlAttribute("winysize")] public int winys; [XmlAttribute("type")] public object type; [XmlAttribute("xpos")] public int xpos; [XmlAttribute("ypos")] public int ypos; [XmlAttribute("externaldata")] public bool external; [XmlAttribute("externalplace")] public string externalplace; [XmlAttribute("text")] public string text; [XmlAttribute("questions")] public bool questions; [XmlAttribute("questiontype")] public object qtype; [XmlAttribute("numberqs")] public int numberqs; [XmlAttribute("answerfile")] public string ansfile; [XmlAttribute("backlink")] public int backlink; [XmlAttribute("forwardlink")] public int forwardlink; public Elements() { } public Elements(string fn, int wx, int wy, object t, int x, int y, bool ext, string extpl, string te, bool q, object qt, int num, string ans, int back, int end) { name = fn; winxs = wx; winys = wy; type = t; xpos = x; ypos = y; external = ext; externalplace = extpl; text = te; questions = q; qtype = qt; numberqs = num; ansfile = ans; backlink = back; forwardlink = end; } } } With a very simple xmlhandler xml = new xmlhander(); xml.loaddesign(); attached to a winform button. Everything is in the same namespace and the xml file actually exists. This is annoying me now - can anyone spot the error of my ways? Paul

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• Java: how to do fast copy of a BufferedImage's pixels? (include unit test)

  - by WizardOfOdds

  I want to do a copy (of a rectangle area) of the ARGB values from a source BufferedImage into a destination BufferedImage. No compositing should be done: if I copy a pixel with an ARGB value of 0x8000BE50 (alpha value at 128), then the destination pixel must be exactly 0x8000BE50, totally overriding the destination pixel. I've got a very precise question and I made a unit test to show what I need. The unit test is fully functional and self-contained and is passing fine and is doing precisely what I want. However, I want a faster and more memory efficient method to replace copySrcIntoDstAt(...). That's the whole point of my question: I'm not after how to "fill" the image in a faster way (what I did is just an example to have a unit test). All I want is to know what would be a fast and memory efficient way to do it (ie fast and not creating needless objects). The proof-of-concept implementation I've made is obviously very memory efficient, but it is slow (doing one getRGB and one setRGB for every pixel). Schematically, I've got this: (where A indicates corresponding pixels from the destination image before the copy) AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA And I want to have this: AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAABBBBAAA AAAAAAAAAAAAABBBBAAA AAAAAAAAAAAAAAAAAAAA where 'B' represents the pixels from the src image. I'm looking for an exact replacement of the method, not for an API link/quote. import org.junit.Test; import java.awt.image.BufferedImage; import static org.junit.Assert.*; public class TestCopy { private static final int COL1 = 0x8000BE50; // alpha at 128 private static final int COL2 = 0x1732FE87; // alpha at 23 @Test public void testPixelsCopy() { final BufferedImage src = new BufferedImage( 5, 5, BufferedImage.TYPE_INT_ARGB ); final BufferedImage dst = new BufferedImage( 20, 20, BufferedImage.TYPE_INT_ARGB ); convenienceFill( src, COL1 ); convenienceFill( dst, COL2 ); copySrcIntoDstAt( src, dst, 3, 4 ); for (int x = 0; x < dst.getWidth(); x++) { for (int y = 0; y < dst.getHeight(); y++) { if ( x >= 3 && x <= 7 && y >= 4 && y <= 8 ) { assertEquals( COL1, dst.getRGB(x,y) ); } else { assertEquals( COL2, dst.getRGB(x,y) ); } } } } // clipping is unnecessary private static void copySrcIntoDstAt( final BufferedImage src, final BufferedImage dst, final int dx, final int dy ) { // TODO: replace this by a much more efficient method for (int x = 0; x < src.getWidth(); x++) { for (int y = 0; y < src.getHeight(); y++) { dst.setRGB( dx + x, dy + y, src.getRGB(x,y) ); } } } // This method is just a convenience method, there's // no point in optimizing this method, this is not what // this question is about private static void convenienceFill( final BufferedImage bi, final int color ) { for (int x = 0; x < bi.getWidth(); x++) { for (int y = 0; y < bi.getHeight(); y++) { bi.setRGB( x, y, color ); } } } }

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• news feed using .Net Dataservices / OData / Atom ?

  - by Stephan

  Let's say I have an web CMS type application, and an EDM model with an entity called 'article', and I need to offer the ability for client applications, to a read/query the articles (and other resources stored in our database) a straightforward syndication feed of these articles to end users (along the lines of a simple RSS feed) It seems to me that for the first task, and .net 4's dataservice would be perfect for the job. For the second case, I'm wondering (a) whether atom the right format to choose - I think it is - and (b) whether it's possible to achieve such a feed using the same ado.net OData service. I took a look at some of the examples out there and briefly set up a proof of concept: http://localhost/projectname/DataService.svc/Articles <?xml version="1.0" encoding="utf-8" standalone="yes"?> <feed xml:base="http://localhost/projectname/DataService.svc/" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom"> <title type="text">Articles</title> <id>http://localhost/projectname/DataService.svc/Articles</id> <updated>2010-05-21T09:41:22Z</updated> <link rel="self" title="Articles" href="Articles" /> <entry> <id>http://---------DataService.svc/Articles(1)</id> <title type="text"></title> <updated>2010-05-21T09:41:22Z</updated> <author> <name /> </author> <link rel="edit" title="Article" href="Articles(1)" /> <category term="Model1.Article" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> <content type="application/xml"> <m:properties> <d:int_ContentID m:type="Edm.Int32">1</d:int_ContentID> <d:Titel>hello world</d:Titel> <d:Source>http://www.google.com</d:Source> </m:properties> </content> </entry> </feed> and noticed that, though the feed works and items are showing up, the title tag on the entry level is left blank. (as a result, when you check this feed in a feed reader, you will see no title). I searched msdn but haven't found a way to do that, but it should be possible. Stackoverflow itself uses an atom feed in that fashion, so it should be possible. Right? So I suppose my question is; Is there a way to make the ado.net dataservice Atom feed look like something suitable for your average news feed reader? - OR, am I using the wrong tool for the wrong purposes, and should I be looking elsewhere (.net syndication API's perhaps)?

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• Is it a missing implementation with JPA implementation of hibernate??

  - by Jegan

  Hi all, On my way in understanding the transaction-type attribute of persistence.xml, i came across an issue / discrepency between hibernate-core and JPA-hibernate which looks weird. I am not pretty sure whether it is a missing implementation with JPA of hibernate. Let me post the comparison between the outcome of JPA implementation and the hibernate implementation of the same concept. Environment Eclipse 3.5.1 JSE v1.6.0_05 Hibernate v3.2.3 [for hibernate core] Hibernate-EntityManger v3.4.0 [for JPA] MySQL DB v5.0 Issue 1.Hibernate core package com.expt.hibernate.core; import java.io.Serializable; public final class Student implements Serializable { private int studId; private String studName; private String studEmailId; public Student(final String studName, final String studEmailId) { this.studName = studName; this.studEmailId = studEmailId; } public int getStudId() { return this.studId; } public String getStudName() { return this.studName; } public String getStudEmailId() { return this.studEmailId; } private void setStudId(int studId) { this.studId = studId; } private void setStudName(String studName) { this.studName = stuName; } private void setStudEmailId(int studEmailId) { this.studEmailId = studEmailId; } } 2. JPA implementaion of Hibernate package com.expt.hibernate.jpa; import java.io.Serializable; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name = "Student_Info") public final class Student implements Serializable { @Id @GeneratedValue @Column(name = "STUD_ID", length = 5) private int studId; @Column(name = "STUD_NAME", nullable = false, length = 25) private String studName; @Column(name = "STUD_EMAIL", nullable = true, length = 30) private String studEmailId; public Student(final String studName, final String studEmailId) { this.studName = studName; this.studEmailId = studEmailId; } public int getStudId() { return this.studId; } public String getStudName() { return this.studName; } public String getStudEmailId() { return this.studEmailId; } } Also, I have provided the DB configuration properties in the associated hibernate-cfg.xml [in case of hibernate core] and persistence.xml [in case of JPA (hibernate entity manager)]. create a driver and perform add a student and query for the list of students and print their details. Then the issue comes when you run the driver program. Hibernate core - output Exception in thread "main" org.hibernate.InstantiationException: No default constructor for entity: com.expt.hibernate.core.Student at org.hibernate.tuple.PojoInstantiator.instantiate(PojoInstantiator.java:84) at org.hibernate.tuple.PojoInstantiator.instantiate(PojoInstantiator.java:100) at org.hibernate.tuple.entity.AbstractEntityTuplizer.instantiate(AbstractEntityTuplizer.java:351) at org.hibernate.persister.entity.AbstractEntityPersister.instantiate(AbstractEntityPersister.java:3604) .... .... This exception is flashed when the driver is executed for the first time itself. JPA Hibernate - output First execution of the driver on a fresh DB provided the following output. DEBUG SQL:111 - insert into student.Student_Info (STUD_EMAIL, STUD_NAME) values (?, ?) 17:38:24,229 DEBUG SQL:111 - select student0_.STUD_ID as STUD1_0_, student0_.STUD_EMAIL as STUD2_0_, student0_.STUD_NAME as STUD3_0_ from student.Student_Info student0_ student list size == 1 1 || Jegan || [email protected] second execution of the driver provided the following output. DEBUG SQL:111 - insert into student.Student_Info (STUD_EMAIL, STUD_NAME) values (?, ?) 17:40:25,254 DEBUG SQL:111 - select student0_.STUD_ID as STUD1_0_, student0_.STUD_EMAIL as STUD2_0_, student0_.STUD_NAME as STUD3_0_ from student.Student_Info student0_ Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.InstantiationException: No default constructor for entity: com.expt.hibernate.jpa.Student at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:614) at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:76) at driver.StudentDriver.main(StudentDriver.java:43) Caused by: org.hibernate.InstantiationException: No default constructor for entity: com.expt.hibernate.jpa.Student .... .... Could anyone please let me know if you have encountered this sort of inconsistency? Also, could anyone please let me know if the issue is a missing implementation with JPA-Hibernate? ~ Jegan

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• Why can't my program display this dialog box, while another program can?

  - by nonoitall

  I'm trying to write a wrapper for Winamp input plugins and have hit a bit of a snag. I'd like my wrapper to be able to display a plugin's configuration dialog, which is (or should be) achieved by calling the plugin's Config(HWND hwndParent) function. For most plugins, this works fine and my program is able to display the plugin's configuration dialog. However, 64th Note (a plugin for playing USF files) is giving me problems. Winamp can display its configuration dialog just fine, but whenever I try to display it from my wrapper, the dialog gets destroyed before it ever shows itself. Thankfully, 64th Note is open source, so I took a look at its innards to try and get an idea of what's going wrong. I've trimmed off the irrelevant bits and am left with this: Config function in the plugin (should show configuration dialog): void Config(HWND hwndParent) { DialogBox(slave, (const char *) IDD_CONFIG_WINDOW, NULL, configDlgProc); } (Slave is the plugin DLL's HINSTANCE handle.) The proc for the dialog is as follows (I have stripped out all the functionality, since it doesn't appear to have an influence on this problem): BOOL CALLBACK configDlgProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam) { return 0; } The template for IDD_CONFIG_WINDOW is as follows: IDD_CONFIG_WINDOW DIALOGEX 0, 0, 269, 149 STYLE DS_SETFONT | DS_MODALFRAME | WS_POPUP | WS_CAPTION | WS_SYSMENU CAPTION "64th Note configuration" FONT 8, "MS Sans Serif", 0, 0, 0x0 BEGIN DEFPUSHBUTTON "OK",IDOK,212,38,50,14 CONTROL "Play Forever",IDC_NOLENGTH,"Button",BS_AUTORADIOBUTTON,7,7,55,8 CONTROL "Always Use Default Length",IDC_SETLEN,"Button",BS_AUTORADIOBUTTON,7,17,101,8 CONTROL "Default Length",IDC_DEFLEN,"Button",BS_AUTORADIOBUTTON,7,29,63,8 EDITTEXT IDC_DEFLENVAL,71,28,38,12,ES_AUTOHSCROLL EDITTEXT IDC_DEFFADEVAL,71,42,38,12,ES_AUTOHSCROLL CONTROL "Detect Silence",IDC_DETSIL,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,7,56,63,8 EDITTEXT IDC_DETSILVAL,71,56,38,12,ES_AUTOHSCROLL CONTROL "Slider2",IDC_PRISLIDER,"msctls_trackbar32",TBS_AUTOTICKS | WS_TABSTOP,74,90,108,11 EDITTEXT IDC_TITLEFMT,7,127,255,15,ES_AUTOHSCROLL CONTROL "Default to file name on missing field",IDC_FNONMISSINGTAG, "Button",BS_AUTOCHECKBOX | WS_TABSTOP,50,114,124,8 CONTROL "Use Recompiler CPU",IDC_RECOMPILER,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,7,83,8 CONTROL "Round Frequency",IDC_ROUNDFREQ,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,16,73,8 CONTROL "Seek Backwards",IDC_BACKWARDS,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,26,70,8 CONTROL "Fast Seek",IDC_FASTSEEK,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,35,48,8 CONTROL "RSP Sections",IDC_SECTIONS,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,45,60,8 CONTROL "Soft Amplify",IDC_SOFTAMP,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,54,53,8 CONTROL "Audio HLE",IDC_AUDIOHLE,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,63,50,8 CONTROL "Auto Audio HLE",IDC_AUTOAUDIOHLE,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,72,64,8 CONTROL "Display Errors",IDC_DISPERROR,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,81,58,8 EDITTEXT IDC_RELVOL,211,104,28,12,ES_AUTOHSCROLL PUSHBUTTON "Cancel",IDCANCEL,212,54,50,14 PUSHBUTTON "Help",IDHELPBUTTON,212,71,50,14 LTEXT "Title format:",IDC_STATIC,7,113,38,8 LTEXT "seconds",IDC_STATIC,112,29,28,8 LTEXT "Default Fade",IDC_STATIC,19,43,42,8 LTEXT "seconds",IDC_STATIC,112,43,28,8 LTEXT "seconds",IDC_STATIC,112,57,28,8 CTEXT "CPU Thread Priority",IDC_STATIC,7,91,63,8 CTEXT "Look ma, I'm data!",IDC_CPUPRI,75,104,108,8 LTEXT "Relative Volume",IDC_STATIC,199,94,52,8 LTEXT "Fade Type",IDC_STATIC,7,75,35,8 COMBOBOX IDC_FADETYPE,45,72,87,74,CBS_DROPDOWNLIST | WS_TABSTOP END Naturally, without any substance in the proc function, the dialog doesn't have any functionality, but it still displays in Winamp when the Config function is invoked. However, it does not appear when I invoke it from my wrapper program. When I monitored the messages sent to the dialog in its proc function, I saw that WM_DESTROY and WM_NCDESTROY were sent within the first few messages, though I have no clue as to why. If I change the Config function so that it displays the plugin's About dialog instead of its configuration dialog, both Winamp and my wrapper will display the About dialog, which suggests that there is something unique to the configuration dialog template that's causing the problem. The modified Config function reads like so: void Config(HWND hwndParent) { DialogBox(slave, (const char *) IDD_ABOUTBOX, NULL, configDlgProc); } The template for the About dialog is as follows: IDD_ABOUTBOX DIALOGEX 0, 0, 152, 151 STYLE DS_SETFONT | DS_MODALFRAME | WS_POPUP | WS_CAPTION | WS_SYSMENU CAPTION "About 64th Note" FONT 8, "MS Sans Serif", 0, 0, 0x1 BEGIN LTEXT "64th Note v1.2 beta 3\nBased on Project 64 1.6 by Zilmar and Jabo\nAudio HLE by Azimer\nPSF concept and tagging by Neill Corlett\nPlayer by hcs, Josh W, dr0\nhttp://hcs64.com/usf",IDC_STATIC,7,94,138,50 CONTROL 110,IDC_STATIC,"Static",SS_BITMAP,26,7,95,86,WS_EX_DLGMODALFRAME END Like I said, my wrapper displays the About dialog just fine, as does Winamp. Why can Winamp display the Config dialog, while my wrapper cannot?

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• Appropriate programming design questions.

  - by Edward

  I have a few questions on good programming design. I'm going to first describe the project I'm building so you are better equipped to help me out. I am coding a Remote Assistance Tool similar to TeamViewer, Microsoft Remote Desktop, CrossLoop. It will incorporate concepts like UDP networking (using Lidgren networking library), NAT traversal (since many computers are invisible behind routers nowadays), Mirror Drivers (using DFMirage's Mirror Driver (http://www.demoforge.com/dfmirage.htm) for realtime screen grabbing on the remote computer). That being said, this program has a concept of being a client-server architecture, but I made only one program with both the functionality of client and server. That way, when the user runs my program, they can switch between giving assistance and receiving assistance without having to download a separate client or server module. I have a Windows Form that allows the user to choose between giving assistance and receiving assistance. I have another Windows Form for a file explorer module. I have another Windows Form for a chat module. I have another Windows Form form for a registry editor module. I have another Windows Form for the live control module. So I've got a Form for each module, which raises the first question: 1. Should I process module-specific commands inside the code of the respective Windows Form? Meaning, let's say I get a command with some data that enumerates the remote user's files for a specific directory. Obviously, I would have to update this on the File Explorer Windows Form and add the entries to the ListView. Should I be processing this code inside the Windows Form though? Or should I be handling this in another class (although I have to eventually pass the data to the Form to draw, of course). Or is it like a hybrid in which I process most of the data in another class and pass the final result to the Form to draw? So I've got like 5-6 forms, one for each module. The user starts up my program, enters the remote machine's ID (not IP, ID, because we are registering with an intermediary server to enable NAT traversal), their password, and connects. Now let's suppose the connection is successful. Then the user is presented with a form with all the different modules. So he can open up a File Explorer, or he can mess with the Registry Editor, or he can choose to Chat with his buddy. So now the program is sort of idle, just waiting for the user to do something. If the user opens up Live Control, then the program will be spending most of it's time receiving packets from the remote machine and drawing them to the form to provide a 'live' view. 2. Second design question. A spin off question #1. How would I pass module-specific commands to their respective Windows Forms? What I mean is, I have a class like "NetworkHandler.cs" that checks for messages from the remote machine. NetworkHandler.cs is a static class globally accessible. So let's say I get a command that enumerates the remote user's files for a specific directory. How would I "give" that command to the File Explorer Form. I was thinking of making an OnCommandReceivedEvent inside NetworkHandler, and having each form register to that event. When the NetworkHandler received a command, it would raise the event, all forms would check it to see if it was relevant, and the appropriate form would take action. Is this an appropriate/the best solution available? 3. The networking library I'm using, Lidgren, provides two options for checking networking messages. One can either poll ReadMessage() to return null or a message, or one can use an AutoResetEvent OnMessageReceived (I'm guessing this is like an event). Which one is more appropriate?

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• [C#][Design] Appropriate programming design questions.

  - by Edward

  I have a few questions on good programming design. I'm going to first describe the project I'm building so you are better equipped to help me out. I am coding a Remote Assistance Tool similar to TeamViewer, Microsoft Remote Desktop, CrossLoop. It will incorporate concepts like UDP networking (using Lidgren networking library), NAT traversal (since many computers are invisible behind routers nowadays), Mirror Drivers (using DFMirage's Mirror Driver (http://www.demoforge.com/dfmirage.htm) for realtime screen grabbing on the remote computer). That being said, this program has a concept of being a client-server architecture, but I made only one program with both the functionality of client and server. That way, when the user runs my program, they can switch between giving assistance and receiving assistance without having to download a separate client or server module. I have a Windows Form that allows the user to choose between giving assistance and receiving assistance. I have another Windows Form for a file explorer module. I have another Windows Form for a chat module. I have another Windows Form form for a registry editor module. I have another Windows Form for the live control module. So I've got a Form for each module, which raises the first question: 1. Should I process module-specific commands inside the code of the respective Windows Form? Meaning, let's say I get a command with some data that enumerates the remote user's files for a specific directory. Obviously, I would have to update this on the File Explorer Windows Form and add the entries to the ListView. Should I be processing this code inside the Windows Form though? Or should I be handling this in another class (although I have to eventually pass the data to the Form to draw, of course). Or is it like a hybrid in which I process most of the data in another class and pass the final result to the Form to draw? So I've got like 5-6 forms, one for each module. The user starts up my program, enters the remote machine's ID (not IP, ID, because we are registering with an intermediary server to enable NAT traversal), their password, and connects. Now let's suppose the connection is successful. Then the user is presented with a form with all the different modules. So he can open up a File Explorer, or he can mess with the Registry Editor, or he can choose to Chat with his buddy. So now the program is sort of idle, just waiting for the user to do something. If the user opens up Live Control, then the program will be spending most of it's time receiving packets from the remote machine and drawing them to the form to provide a 'live' view. 2. Second design question. A spin off question #1. How would I pass module-specific commands to their respective Windows Forms? What I mean is, I have a class like "NetworkHandler.cs" that checks for messages from the remote machine. NetworkHandler.cs is a static class globally accessible. So let's say I get a command that enumerates the remote user's files for a specific directory. How would I "give" that command to the File Explorer Form. I was thinking of making an OnCommandReceivedEvent inside NetworkHandler, and having each form register to that event. When the NetworkHandler received a command, it would raise the event, all forms would check it to see if it was relevant, and the appropriate form would take action. Is this an appropriate/the best solution available? 3. The networking library I'm using, Lidgren, provides two options for checking networking messages. One can either poll ReadMessage() to return null or a message, or one can use an AutoResetEvent OnMessageReceived (I'm guessing this is like an event). Which one is more appropriate?

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• Android sqlight problem always null

  - by yoav.str

  every time i am using the db its null and i just dont get it i use this code for the SQL when I have quarry : public class GameSQLHelper { static final String[] COUNTRIES = new String[] { "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra" }; private static final String DB_PATH = "/countryCityGame/databases/"; private static final String DATABASE_NAME = "events.db"; private static final int DATABASE_VERSION = 1; private final Context mCtx; // Table name public static final String TABLE = "myDataBase"; // Columns public static final String LETTER = "letter"; public static final String TYPE = "type"; public static final String VALUE = "value"; //my database SQLiteDatabase myDataBase; private static class DatabaseHelper extends SQLiteOpenHelper { private static final String TAG = null; DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { String sql = "create table " + TABLE + "( " + BaseColumns._ID + " integer primary key autoincrement, " + LETTER + " text not null, " + TYPE + " text not null," + VALUE + " text not null );"; Log.d("EventsData", "onCreate: " + sql); db.execSQL(sql); insertValuesToDB(db); } private void insertValuesToDB(SQLiteDatabase db) { if (db == null){ } else{ db.execSQL("INSERT INTO " + TABLE + " ("+LETTER+","+ TYPE +"," + VALUE +")" + " VALUES ('A', 'country', 'Angola');"); ContentValues initialValues = new ContentValues(); for (int i = 0 ; i < COUNTRIES.length ; i++){ Character tmp = (Character)COUNTRIES[i].charAt(0); initialValues.put(VALUE, COUNTRIES[i]); initialValues.put(TYPE, "country"); initialValues.put(LETTER,tmp.toString(tmp)); db.insert(TABLE, null, initialValues); } } } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); db.execSQL("DROP TABLE IF EXISTS notes"); onCreate(db); } } /** * Constructor - takes the context to allow the database to be * opened/created * * @param ctx the Context within which to work */ public GameSQLHelper(Context ctx) { this.mCtx = ctx; } public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { if (oldVersion >= newVersion) return; String sql = null; if (oldVersion == 1) sql = "alter table " + TABLE + " add note text;"; if (oldVersion == 2) sql = ""; Log.d("EventsData", "onUpgrade : " + sql); if (sql != null) db.execSQL(sql); } public void openDataBase() throws SQLException{ //Open the database String myPath = DB_PATH + DATABASE_NAME; myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); } public boolean existInDataBase(String serchStr ){ Cursor c = null ; try{ openDataBase(); c = myDataBase.query(true, TABLE, new String[] {TYPE }, VALUE + "=" + serchStr, null, null, null, null, null); } catch(Exception e){ Log.d("sqlExacption", e.getMessage()); } if (c == null) return false; return true; } } whenever i call this class (i hold an instace of him initialized : mDbHelper = new GameSQLHelper(this); where this is an activity ) i always get my mDbHelper as null how can i change it , its my first time working with sql outside of mysql platform so i am kind of having problmes understanding tje concept , and the android notepad example didnt help me .

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• Session state provider and global.asax not interacting properly?

  - by yodaj007

  I'm experimenting with creating a crude, proof-of-concept session state store provider in ASP.Net. But I've got a problem and I'm not sure what to do about it. The website works properly when using the InProc provider. The Session_Start in global.asax is called on session creation as it should. But not if I implement my own provider. The Session_Start method from global.asax isn't being called at all if a new session is being created (that is, I delete the session state file). Am I missing something important here? public class TestSessionProvider : SessionStateStoreProviderBase { private const string ROOT = "c:\\projects\\sessions\\"; private const int TIMEOUT_MINUTES = 30; public string ApplicationName { get { return HostingEnvironment.ApplicationVirtualPath; } } private string GetFilename(string id) { string filename = String.Format("{0}_{1}.session", ApplicationName, id); char[] invalids = Path.GetInvalidPathChars(); for (int i = 0; i < invalids.Length; i++) { filename = filename.Replace(invalids[i], '_'); } return Path.Combine(ROOT, Path.GetFileName(filename)); } public override void Initialize(string name, NameValueCollection config) { if (config == null) throw new ArgumentNullException("config"); if (String.IsNullOrEmpty(name)) name = "Sporkalicious"; base.Initialize(name, config); } public override SessionStateStoreData CreateNewStoreData(HttpContext context, int timeout) { SessionStateItemCollection items = new SessionStateItemCollection(); HttpStaticObjectsCollection objects = SessionStateUtility.GetSessionStaticObjects(context); return new SessionStateStoreData(items, objects, TIMEOUT_MINUTES); } /// <summary> /// The CreateUninitializedItem method is used with cookieless sessions when the regenerateExpiredSessionId /// attribute is set to true, which causes SessionStateModule to generate a new SessionID value when an /// expired session ID is encountered. /// </summary> /// <param name="context"></param> /// <param name="id"></param> /// <param name="timeout"></param> public override void CreateUninitializedItem(HttpContext context, string id, int timeout) { FileStream fs = File.Open(GetFilename(id), FileMode.CreateNew, FileAccess.Write, FileShare.None); BinaryWriter writer = new BinaryWriter(fs); SessionStateItemCollection coll = new SessionStateItemCollection(); coll.Serialize(writer); fs.Flush(); fs.Close(); } public override SessionStateStoreData GetItem(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions) { return GetItemExclusive(context, id, out locked, out lockAge, out lockId, out actions); } public override SessionStateStoreData GetItemExclusive(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions) { locked = false; lockAge = TimeSpan.FromDays(1); lockId = 0; actions = SessionStateActions.None; if (!File.Exists(GetFilename(id))) { return null; } FileStream fs = File.Open(GetFilename(id), FileMode.Open, FileAccess.ReadWrite, FileShare.Read); BinaryReader reader = new BinaryReader(fs); SessionStateItemCollection coll = SessionStateItemCollection.Deserialize(reader); fs.Close(); return new SessionStateStoreData(coll, new HttpStaticObjectsCollection(), TIMEOUT_MINUTES); } public override void ReleaseItemExclusive(HttpContext context, string id, object lockId) { } public override void RemoveItem(HttpContext context, string id, object lockId, SessionStateStoreData item) { File.Delete(GetFilename(id)); } public override void ResetItemTimeout(HttpContext context, string id) { } public override void SetAndReleaseItemExclusive(HttpContext context, string id, SessionStateStoreData item, object lockId, bool newItem) { if (!File.Exists(GetFilename(id))) { CreateUninitializedItem(context, id, 10); } FileStream fs = File.Open(GetFilename(id), FileMode.Truncate, FileAccess.Write, FileShare.None); BinaryWriter writer = new BinaryWriter(fs); SessionStateItemCollection coll = (SessionStateItemCollection)item.Items; coll.Serialize(writer); fs.Flush(); fs.Close(); } public override bool SetItemExpireCallback(SessionStateItemExpireCallback expireCallback) { return false; } public override void InitializeRequest(HttpContext context){} public override void EndRequest(HttpContext context){} public override void Dispose(){} }

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• Test whether pixel is inside the blobs for ofxOpenCV

  - by mia

  I am doing an application of the concept of the dodgeball and need to test of the pixel of the ball is in the blobs capture(which is the image of the player) I am stucked and ran out of idea of how to implement it. I manage to do a little progress which have the blobs but I not sure how to test it. Please help. I am a newbie who in a desperate condition. Thank you. This is some of my code. void testApp::setup(){ #ifdef _USE_LIVE_VIDEO vidGrabber.setVerbose(true); vidGrabber.initGrabber(widthS,heightS); #else vidPlayer.loadMovie("fingers.mov"); vidPlayer.play(); #endif widthS = 320; heightS = 240; colorImg.allocate(widthS,heightS); grayImage.allocate(widthS,heightS); grayBg.allocate(widthS,heightS); grayDiff.allocate(widthS,heightS); ////<---what I want bLearnBakground = true; threshold = 80; //////////circle////////////// counter = 0; radius = 0; circlePosX = 100; circlePosY=200; } void testApp::update(){ ofBackground(100,100,100); bool bNewFrame = false; #ifdef _USE_LIVE_VIDEO vidGrabber.grabFrame(); bNewFrame = vidGrabber.isFrameNew(); #else vidPlayer.idleMovie(); bNewFrame = vidPlayer.isFrameNew(); #endif if (bNewFrame){ if (bLearnBakground == true){ grayBg = grayImage; // the = sign copys the pixels from grayImage into grayBg (operator overloading) bLearnBakground = false; } #ifdef _USE_LIVE_VIDEO colorImg.setFromPixels(vidGrabber.getPixels(),widthS,heightS); #else colorImg.setFromPixels(vidPlayer.getPixels(),widthS,heightS); #endif grayImage = colorImg; grayDiff.absDiff(grayBg, grayImage); grayDiff.threshold(threshold); contourFinder.findContours(grayDiff, 20, (340*240)/3, 10, true); // find holes } ////////////circle//////////////////// counter = counter + 0.05f; if(radius>=50){ circlePosX = ofRandom(10,300); circlePosY = ofRandom(10,230); } radius = 5 + 3*(counter); } void testApp::draw(){ // draw the incoming, the grayscale, the bg and the thresholded difference ofSetColor(0xffffff); //white colour grayDiff.draw(10,10);// draw start from point (0,0); // we could draw the whole contour finder // or, instead we can draw each blob individually, // this is how to get access to them: for (int i = 0; i < contourFinder.nBlobs; i++){ contourFinder.blobs[i].draw(10,10); } ///////////////circle////////////////////////// //let's draw a circle: ofSetColor(0,0,255); char buffer[255]; float a = radius; sprintf(buffer,"radius = %i",a); ofDrawBitmapString(buffer, 120, 300); if(radius>=50) { ofSetColor(255,255,255); counter = 0; } else{ ofSetColor(255,0,0); } ofFill(); ofCircle(circlePosX,circlePosY,radius); }

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• Where are the function address literals in c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). <UPDATE> After some reading with help from answer by Chris Dodd, what I'm looking for is literal function addresses as template parameters. Chris' answer indicates how to do this for standard functions, but how can the addresses of member functions be used as template parameters? Since the standard prohibits non-static member function addresses as template parameters (c++03 14.3.2.3), I suspect the work around is quite complicated. Any ideas for a workaround? Below the original form of the question is left as is for context. </UPDATE> The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one. Edit The intent of this question is not to implement delegates, rather to identify a pattern that will embed a conventional function call, (in immediate mode) directly into third party code, possibly a template.

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• What's a clean way to have the server return a JavaScript function which would then be invoked?

  - by Khnle

  My application is architected as a host of plug-ins that have not yet been written. There's a long reason for this, but with each new year, the business logic will be different and we don't know what it will be like (Think of TurboTax if that helps). The plug-ins consist of both server and client components. The server components deals with business logic and persisting the data into database tables which will be created at a later time as well. The JavaScript manipulates the DOM for the browsers to render afterward. Each plugin lives in a separate assembly, so that they won't disturb the main application, i.e., we don't want to recompile the main application. Long story short, I am looking for a way to return JavaScript functions to the client from an Ajax get request, and execute these JavaScript functions (which are just returned). Invoking a function in Javascript is easy. The hard part is how to organize or structure so that I won't have to deal with maintenance problem. So concat using StringBuilder to end up with JavaScript code as a result of calling toString() from the string builder object is out of the question. I want to have no difference between writing JavaScript codes normally and writing Javascript codes for this dynamic purpose. An alternative is to manipulate the DOM on the server side, but I doubt that it would be as elegantly as using jQuery on the client side. I am open for a C# library that supports chainable calls like jQuery that also manipulates the DOM too. Do you have any idea or is it too much to ask or are you too confused? Edit1: The point is to avoid recompiling, hence the plug-ins architecture. In some other parts of the program, I already use the concept of dynamically loading Javascript files. That works fine. What I am looking here is somewhere in the middle of the program when an Ajax request is sent to the server. Edit 2: To illustrate my question: Normally, you would see the following code. An Ajax request is sent to the server, a JSON result is returned to the client which then uses jQuery to manipulate the DOM (creating tag and adding to the container in this case). $.ajax({ type: 'get', url: someUrl, data: {'': ''}, success: function(data) { var ul = $('<ul>').appendTo(container); var decoded = $.parseJSON(data); $.each(decoded, function(i, e) { var li = $('<li>').text(e.FIELD1 + ',' + e.FIELD2 + ',' + e.FIELD3); ul.append(li); }); } }); The above is extremely simple. But next year, what the server returns is totally different and how the data to be rendered would also be different. In a way, this is what I want: var container = $('#some-existing-element-on-the-page'); $.ajax({ type: 'get', url: someUrl, data: {'': ''}, success: function(data) { var decoded = $.parseJSON(data); var fx = decoded.fx; var data = decode.data; //fx is the dynamic function that create the DOM from the data and append to the existing container fx(container, data); } }); I don't need to know, at this time what data would be like, but in the future I will, and I can then write fx accordingly.

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• Inheriting XML files and modifying values

  - by Veehmot

  This is a question about concept. I have an XML file, let's call it base: <base id="default"> <tags> <tag>tag_one</tag> <tag>tag_two</tag> <tag>tag_three</tag> </tags> <data> <data_a>blue</data_a> <data_b>3</data_b> </data> </base> What I want to do is to be able to extend this XML in another file, modifying individual properties. For example, I want to inherit that file and make a new one with a different data/data_a node: <base id="green" import="default"> <data> <data_a>green</data_a> </data> </base> So far it's pretty simple, it replaces the old data/data_a with the new one. I even can add a new node: <base id="ext" import="default"> <moredata> <data>extended version</data> </moredata> </base> And still it's pretty simple. The problem comes when I want to delete a node or deal with XML Lists (like the tags node). How should I reference a particular index on a list? I was thinking doing something like: <base id="diffList" import="default"> <tags> <tag index="1">this is not anymore tag_two</tag> </tags> </base> And for deleting a node / array index: <base id="deleting" import="default"> <tags> <tag index="2"/> </tags> <data/> </base> <!-- This will result in an XML containing these values: --> <base> <tag>tag_one</tag> <tag>tag_two</tag> </base> But I'm not happy with my solutions. I don't know anything about XSLT or other XML transformation tools, but I think someone must have done this before. The key goal I'm looking for is ease to write the XML by hand (both the base and the "extended"). I'm open to new solutions besides XML, if they are easy to write manually. Thanks for reading.

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• CSS optimization - extra classes in dom or preprocessor-repetitive styling in css file?

  - by anna.mi

  I'm starting on a fairly large project and I'm considering the option of using LESS for pre-processing my css. the useful thing about LESS is that you can define a mixin that contains for example: .border-radius(@radius) { -webkit-border-radius: @radius; -moz-border-radius: @radius; -o-border-radius: @radius; -ms-border-radius: @radius; border-radius: @radius; } and then use it in a class declaration as .rounded-div { .border-radius(10px); } to get the outputted css as: .rounded-div { -webkit-border-radius: 10px; -moz-border-radius: 10px; -o-border-radius: 10px; -ms-border-radius: 10px; border-radius: 10px; } this is extremely useful in the case of browser prefixes. However this same concept could be used to encapsulate commonly-used css, for example: .column-container { overflow: hidden; display: block; width: 100%; } .column(@width) { float: left; width: @width; } and then use this mixin whenever i need columns in my design: .my-column-outer { .column-container(); background: red; } .my-column-inner { .column(50%); font-color: yellow; } (of course, using the preprocessor we could easily expand this to be much more useful, eg. pass the number of columns and the container width as variables and have LESS determine the width of each column depending on the number of columns and container width!) the problem with this is that when compliled, my final css file would have 100 such declarations, copy&pasted, making the file huge and bloated and repetitive. The alternative to this would be to use a grid system which has predefined classes for each column-layout option, eg .c-50 ( with a "float: left; width:50%;" definition ), .c-33, .c-25 to accomodate for a 2-column, 3-column and 4-column layout and then use these classes to my dom. i really mislike the idea of the extra classes, from experience it results to bloated dom (creating extra divs just to attach the grid classes to). Also the most basic tutorial for html/css would tell you that the dom should be separated from the styling - grid classes are styling related! to me, its the same as attaching a "border-radius-10" class to the .rounded-div example above! on the other hand, the large css file that would result from the repetitive code is also a disadvantage so i guess my question is, which one would you recommend? and which do you use? and, which solution is best for optimization? apart from the larger file size, has there even been any research on whether browser renders multiple classes faster than a large css file, or the other way round? tnx! i'd love to hear your opinion!

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• Please clarify how create/update happens against child entities of an aggregate root

  - by christian

  After much reading and thinking as I begin to get my head wrapped around DDD, I am a bit confused about the best practices for dealing with complex hierarchies under an aggregate root. I think this is a FAQ but after reading countless examples and discussions, no one is quite talking about the issue I'm seeing. If I am aligned with the DDD thinking, entities below the aggregate root should be immutable. This is the crux of my trouble, so if that isn't correct, that is why I'm lost. Here is a fabricated example...hope it holds enough water to discuss. Consider an automobile insurance policy (I'm not in insurance, but this matches the language I hear when on the phone w/ my insurance company). Policy is clearly an entity. Within the policy, let's say we have Auto. Auto, for the sake of this example, only exists within a policy (maybe you could transfer an Auto to another policy, so this is potential for an aggregate as well, which changes Policy...but assume it simpler than that for now). Since an Auto cannot exist without a Policy, I think it should be an Entity but not a root. So Policy in this case is an aggregate root. Now, to create a Policy, let's assume it has to have at least one auto. This is where I get frustrated. Assume Auto is fairly complex, including many fields and maybe a child for where it is garaged (a Location). If I understand correctly, a "create Policy" constructor/factory would have to take as input an Auto or be restricted via a builder to not be created without this Auto. And the Auto's creation, since it is an entity, can't be done beforehand (because it is immutable? maybe this is just an incorrect interpretation). So you don't get to say new Auto and then setX, setY, add(Z). If Auto is more than somewhat trivial, you end up having to build a huge hierarchy of builders and such to try to manage creating an Auto within the context of the Policy. One more twist to this is later, after the Policy is created and one wishes to add another Auto...or update an existing Auto. Clearly, the Policy controls this...fine...but Policy.addAuto() won't quite fly because one can't just pass in a new Auto (right!?). Examples say things like Policy.addAuto(VIN, make, model, etc.) but are all so simple that that looks reasonable. But if this factory method approach falls apart with too many parameters (the entire Auto interface, conceivably) I need a solution. From that point in my thinking, I'm realizing that having a transient reference to an entity is OK. So, maybe it is fine to have a entity created outside of its parent within the aggregate in a transient environment, so maybe it is OK to say something like: auto = AutoFactory.createAuto(); auto.setX auto.setY or if sticking to immutability, AutoBuilder.new().setX().setY().build() and then have it get sorted out when you say Policy.addAuto(auto) This insurance example gets more interesting if you add Events, such as an Accident with its PolicyReports or RepairEstimates...some value objects but most entities that are all really meaningless outside the policy...at least for my simple example. The lifecycle of Policy with its growing hierarchy over time seems the fundamental picture I must draw before really starting to dig in...and it is more the factory concept or how the child entities get built/attached to an aggregate root that I haven't seen a solid example of. I think I'm close. Hope this is clear and not just a repeat FAQ that has answers all over the place.

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