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• Upgrade to Delphi 2010, or stick with Delphi 7 "forever"?

  - by tim11g

  I am an individual user of Delphi, starting back in the early Turbo Pascal days. I have quite a bit of code developed over the years, but I have never sold software commercially or used it for business. Historically, Borland supported the non-professional users with lower cost versions, but Embarcadero does not. As I consider upgrading to Delphi 2010, I am put off by the high price. Embarcadero is also trying to "encourage" upgrading by threatening to charge "new user" prices for upgrades after Dec 31st. I have several questions for the community to help me decide whether to upgrade. 1) I have read about difficulties updating existing code to support the unicode string types. I have no need for unicode strings, and I am happy with the string support in D7. Will I have to modify existing code and components just to re-compile under D2010? Or are there compiler options to allow backward compatibility if new string types are not required? 2) The main reason I'm considering upgrading is for IDE improvements, and to get access to new APIs added to Windows since 2002. Are there any Windows 7 APIs or capabilities that would be impossible to support from my programs compiled using using Delphi 7 (assuming appropriate JEDI API libraries, for example)? 3) Is there anything else about Delphi 2010 that is really compelling for someone who is primarily interested in Win32 apps, and not working with databases? I have read that D2010 is slow to load, and other versions between D7 and D2010 have had stability issues, and the help system was "broken". What is the biggest benefit to D2010?

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• WPF/Silverlight AutoCompleteBox with ability to add new values to list.

  - by WillH

  Hi, I would like to use autocompletebox with a list of values, but also add new values to the list if a user enters one that isn't present. I currently have a string property in my view model called 'Comment'. Currently this is bound to a textbox in the view - user types a comment and the view model is updated. Simple. To save time, my customer would like it to autocomplete from previous values, so the way I thought to do this is something like: ViewModel public string Comment; public ObservableCollection<string> CommentsList { ... } (populate the CommentsList when the viewmodel is created) View <AutoCompleteComboBox ItemsSource="{Binding CommentsList}" SelectedItem="{Binding Comment, Mode=TwoWay/> So when the user selects a value, it saves the value in the Comment property. This works fine if the user selects an item in the list, but if the user types in a new value, the comment property is not updated (it is null because the selected item was not in the list). Is this possible with autocompletebox? Thanks in advance, Will

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• resolving overloads in boost.python

  - by swarfrat

  I have a C++ class like this: class ConnectionBase { public: ConnectionBase(); template <class T> Publish(const T&); private: virtual void OnEvent(const Overload_a&) {} virtual void OnEvent(const Overload_b&) {} }; My templates & overloads are a known fixed set of types at compile time. The application code derives from ConnectionBase and overrides OnEvent for the events it cares about. I can do this because the set of types is known. OnEvent is private because the user never calls it, the class creates a thread that calls it as a callback. The C++ code works. I have wrapped this in boost.python, I can import it and publish from python. I want do create the equivalent of the following in python : class ConnectionDerived { public: ConnectionDerived(); private: virtual void OnEvent(const Overload_b&) { // application code } }; But ... since python isn't typed, and all the boost.python examples I've seen dealing with internals are on the C++ side, I'm a little puzzled as to how to do this. How do I override specific overloads?

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• Delphi dbExpress and Interbase: Unicode migration steps and risks?

  - by mjustin

  Currently, our database uses Win1252 as the only character encoding. We will have to support Unicode in the database tables soon, which means we have to perform this migration for four databases and around 80 Delphi applications which run in-house in a 24/7 environment. Are there recommendations for database migrations to UTF-8 (or UNICODE_FSS) for Delphi applications? Some questions listed below. Many thanks in advance for your answers! are there tools which help with the migration of the existing databases (sizes between 250 MB and 2 GB, no Blob fields), by dumping the data, recreating the database with UNICODE_FSS or UTF-8, and loading the data back? are there known problems with Delphi 2009, dbExpress and Interbase 7.5 related to Unicode character sets? would you recommend to upgrade the databases to Interbase 2009 first? (This upgrade is planned but does not have a high priority) can we simply migrate the database and Delphi will handle the Unicode character sets automatically, or will we have to change all character field types in every Datamodule (dfm and source code) too? which strategy would you recommend to work on the migration in parallel with the normal development and maintenance of the existing application? The application runs in-house so development and database administration is done internally. Update: one problem I found now is that there are two different persistent field types for Unicode and non Unicode character fields. For the existing database, dbExpress creates TStringField objects. For the Unicode database fields, dbExpress creates (or expects!) TWideStringField objects. So we can not just change the database and the connection code page to Unicode. We also have to modify all datamodules to use the new field type. The modified datamodule however will not be backwards compatible.

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• doublechecking: no db-wide 'unicode switch' for sql server in the foreseeable future, i.e. like Orac

  - by user72150

  Hi all, I believe I know the answer to this question, but wanted to confirm: Question Does Sql server (or will it in the foreseeable future), offer a database-wide "unicode switch" which says "store all characters in unicode (UTF-16, UCS-2, etc)", i.e. like Oracle. The Context Our application has provided "CJK" (Chinese-Japanese-Korean) support for years--using Oracle as the db store. Recently folks have been asking for the same support in sql server. We store our db schema definition in xml and generate the vendor-specific definitions (oracle, sql server) using vendor-specific xsl. We can make the change easily. The problem is for upgrades. Generated scripts would need to change the column types for 100+ columns from varchar to nvarchar, varchar(max) to nvarchar(max), etc. These changes require dropping and recreating indexes and foreign keys if the any indexes/fk's exist on the column. Non-trivial. Risky. DB-wide character encodings for us would eliminate programming changes. (I.e. we would not to change the column types from varchar to nvarchar; sql server would correctly store unicode data in varchar columns). I had thought that eventually sql server would "see the light" and allow storing unicode in varchar/clob columns. Evidently not yet. Recap So just to triple check: does mssql offer a database-wide switch for character encoding? Will it in SQL2008R3? or 2010? thanks, bill

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• Detecting browser capabilities and selective events for mouse and touch

  - by skidding

  I started using touch events for a while now, but I just stumbled upon quite a problem. Until now, I checked if touch capabilities are supported, and applied selective events based on that. Like this: if(document.ontouchmove === undefined){ //apply mouse events }else{ //apply touch events } However, my scripts stopped working in Chrome5 (which is currently beta) on my computer. I researched it a bit, and as I expected, in Chrome5 (as opposed to older Chrome, Firefox, IE, etc.) document.ontouchmove is no longer undefined but null. At first I wanted to submit a bug report, but then I realized: There are devices that have both mouse and touch capabilities, so that might be natural, maybe Chrome now defines it because my OS might support both types of events. So the solutions seems easy: Apply BOTH event types. Right? Well the problem now take place on mobile. In order to be backward compatible and support scripts that only use mouse events, mobile browsers might try to fire them as well (on touch). So then with both mouse and touch events set, a certain handler might be called twice every time. What is the way to approach this? Is there a better way to check and apply selective events, or must I ignore the problems that might occur if browsers fire both touch and mouse events at times?

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• WPF/SL EventAggregator implementation with durable subscribers behavior?

  - by sha1dy

  Hi. Currently I'm building an application using latest Prism for Silverlight 4. I've a module and in that module I've two views with view models. Also I've a module view with two regions for each view. In module initialization I'm registering my views and view models in Unity container and also register views with corresponding regions. The problem is that views should display something similar to table-detail information - first view shows available entities ans the second view shows detail of selected entity. I need a way how to pass them initial selected entity. Newly created first view doesn't have any selected entity and newly created second view doesn't show any details. Currently I'm doing that this way: In module I create two view models and register them as instances in Unity container and then I register views as types for corresponding regions. Each view subscribes to EntitySelectedEvent from EventAggregator. Module initializer publish this event after initialization and this way two views are selecting the same entity. I know this looks ugly - I tried publishing this event from one of view models but the problems is that EventAggregator in Prism doesn't support durable subscribers - this means that if the second view model didn't subscribe to event before the first view model fired it, it won't receive and event. I know this is a normal behavior of EventAggregator, but I'm looking for a solution when view models can fire events without depending on initialization order of them - that is the first model can fire event before the second model was created and the second model will receive this 'queued' event after subscribing to it. Are there any other messaging implementations for WPF/SL which do support such behavior or using a mediator (in my example it's a module itself) isn't such a bad idea after all? One big problem with mediator is that models must be created right away in initialize and they can't be registered as types in container because this leads again to missing subscribers.

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• ASP.NET MVC Using Castle Windsor IoC

  - by Mad Halfling

  I have an app, modelled on the one from Apress Pro ASP.NET MVC that uses castle windsor's IoC to instantiate the controllers with their respective repositories, and this is working fine e.g. public class ItemController : Controller { private IItemsRepository itemsRepository; public ItemController(IItemsRepository windsorItemsRepository) { this.itemsRepository = windsorItemsRepository; } with using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using Castle.Windsor; using Castle.Windsor.Configuration.Interpreters; using Castle.Core.Resource; using System.Reflection; using Castle.Core; namespace WebUI { public class WindsorControllerFactory : DefaultControllerFactory { WindsorContainer container; // The constructor: // 1. Sets up a new IoC container // 2. Registers all components specified in web.config // 3. Registers all controller types as components public WindsorControllerFactory() { // Instantiate a container, taking configuration from web.config container = new WindsorContainer(new XmlInterpreter(new ConfigResource("castle"))); // Also register all the controller types as transient var controllerTypes = from t in Assembly.GetExecutingAssembly().GetTypes() where typeof(IController).IsAssignableFrom(t) select t; foreach (Type t in controllerTypes) container.AddComponentWithLifestyle(t.FullName, t, LifestyleType.Transient); } // Constructs the controller instance needed to service each request protected override IController GetControllerInstance(Type controllerType) { return (IController)container.Resolve(controllerType); } } } controlling the controller creation. I sometimes need to create other repository instances within controllers, to pick up data from other places, can I do this using the CW IoC, if so then how? I have been playing around with the creation of new controller classes, as they should auto-register with my existing code (if I can get this working, I can register them properly later) but when I try to instantiate them there is an obvious objection as I can't supply a repos class for the constructor (I was pretty sure that was the wrong way to go about it anyway). Any help (especially examples) would be much appreciated. Cheers MH

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• Storing class constants (for use as bitmask) in a database?

  - by fireeyedboy

  Let's say I have a class called Medium which can represent different types of media. For instance: uploaded video embedded video uploaded image embedded image I represent these types with contants, like this: class MediumAbstract { const UPLOAD = 0x0001; const EMBED = 0x0010; const VIDEO = 0x0100; const IMAGE = 0x1000; const VIDEO_UPLOAD = 0x0101; // for convenience const VIDEO_EMBED = 0x0110; // for convenience const IMAGE_UPLOAD = 0x1001; // for convenience const IMAGE_EMBED = 0x1010; // for convenience const ALL = 0x1111; // for convenience } Thus, it is easy for me to do a combined search on them on an (abstract) repository, with something like: { public function findAllByType( $type ) { ... } } $media = $repo->findAllByType( MediumAbstract::VIDEO | MediumAbstract::IMAGE_UPLOAD ); // or $media = $repo->findAllByType( MediumAbstract::ALL ); // etc.. How do you feel about using these constant values in a concrete repository like a database? Is it ok? Or should I substitute them with meaningful data in the database. Table medium: | id | type | location | etc.. ------------------------------------------------- | 1 | use constants here? | /some/path | etc.. (Of course I'll only be using the meaningful constants: VIDEO_UPLOAD, VIDEO_EMBED, IMAGE_UPLOAD and IMAGE_EMBED)

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• Model relationships in ASP.NET MVC

  - by Fabiano

  Hi I recently started evaluating ASP.NET MVC. While it is really easy and quick to create Controllers and Views for Models with only primitive properties (like shown in the starter videos from the official page) I didn't find any good way to work with references to complex types. Let's say, I have these Models: public class Customer { public int Id { get; set; } public string Name { get; set; } public Address Address { get; set; } public IList<Order> Orders { get; set; } } public class Address { public int Id { get; set; } public string ..... ..... } public class Order { public int Id { get; set; } public Customer Customer { get; set; } public string OrderName { get; set; } ..... } Note that I don't have foreign keys in the models (like it's typical for LINQ to SQL, which is also used in the sample video) but an object reference. How can I handle such references in asp.net mvc? Does someone has some good tips or links to tutorials about this problem? maybe including autobinding with complex types.

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• Oracle Data Provider and casting

  - by mrjoltcola

  I use Oracle's specific data provider, not the Microsoft provider that is being discontinued. The thing I've found about ODP.NET is how picky it is with data types. Where JDBC and other ADO providers just convert and make things work, ODP.NET will throw an invalid cast exception unless you get it exactly right. Consider this code: String strSQL = "SELECT DOCUMENT_SEQ.NEXTVAL FROM DUAL"; OracleCommand cmd = new OracleCommand(strSQL, conn); reader = cmd.ExecuteReader(); if (reader != null && reader.Read()) { Int64 id = reader.GetInt64(0); return id; } Due to ODP.NET's pickiness on conversion, this doesn't work. My usual options are: 1) Retrieve into a Decimal and return it with a cast to an Int64 (I don't like this because Decimal is just overkill, and at least once I remember reading it was deprecated...) Decimal id = reader.GetDecimal(0); return (Int64)id; 2) Or cast in the SQL statement to make sure it fits into Int64, like NUMBER(18) String strSQL = "SELECT CAST(DOCUMENT_SEQ.NEXTVAL AS NUMBER(18)) FROM DUAL"; I do (2), because I feel its just not clean pulling a number into a .NET Decimal when my domain types are Int32 or Int64. Other providers I've used are nice (smart) enough to do the conversion on the fly. Any suggestions from the ODP.NET gurus?

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• What algorithms are suitable for this simple machine learning problem?

  - by user213060

  I have a what I think is a simple machine learning question. Here is the basic problem: I am repeatedly given a new object and a list of descriptions about the object. For example: new_object: 'bob' new_object_descriptions: ['tall','old','funny']. I then have to use some kind of machine learning to find previously handled objects that had similar descriptions, for example, past_similar_objects: ['frank','steve','joe']. Next, I have an algorithm that can directly measure whether these objects are indeed similar to bob, for example, correct_objects: ['steve','joe']. The classifier is then given this feedback training of successful matches. Then this loop repeats with a new object. a Here's the pseudo-code: Classifier=new_classifier() while True: new_object,new_object_descriptions = get_new_object_and_descriptions() past_similar_objects = Classifier.classify(new_object,new_object_descriptions) correct_objects = calc_successful_matches(new_object,past_similar_objects) Classifier.train_successful_matches(object,correct_objects) But, there are some stipulations that may limit what classifier can be used: There will be millions of objects put into this classifier so classification and training needs to scale well to millions of object types and still be fast. I believe this disqualifies something like a spam classifier that is optimal for just two types: spam or not spam. (Update: I could probably narrow this to thousands of objects instead of millions, if that is a problem.) Again, I prefer speed when millions of objects are being classified, over accuracy. What are decent, fast machine learning algorithms for this purpose?

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• Synchronizing a collection of wrapped objects with a collection of unwrapped objects

  - by Kenneth Cochran

  I have two classes: Employee and EmployeeGridViewAdapter. Employee is composed of several complex types. EmployeeGridViewAdapter wraps a single Employee and exposes its members as a flattened set of system types so a DataGridView can handle displaying, editing, etc. I'm using VS's builtin support for turning a POCO into a data source, which I then attach to a BindingSource object. When I attach the DataGridView to the BindingSource it creates the expected columns and at runtime I can perform the expected CRUD operations. All is good so far. The problem is the collection of adapters and the collection of employees aren't being synchronized. So all the employees I create an runtime never get persisted. Here's a snippet of the code that generates the collection of EmployeeGridViewAdapter's: var employeeCollection = new List<EmployeeGridViewAdapter>(); foreach (var employee in this.employees) { employeeCollection.Add(new EmployeeGridViewAdapter(employee)); } this.view.Employees = employeeCollection; Pretty straight forward but I can't figure out how to synchronize changes back to the original collection. I imagine edits are already handled because both collections reference the same objects but creating new employees and deleting employees aren't happening so I can't be sure.

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• Delphi 2009 dbExpress and Interbase: Unicode migration steps and risks?

  - by mjustin

  Currently, our database uses Win1252 as the only character encoding. We will have to support Unicode in the database tables soon, which means we have to perform this migration for four databases and around 80 Delphi applications which run in-house in a 24/7 environment. Are there recommendations for database migrations to UTF-8 (or UNICODE_FSS) for Delphi applications? Some questions listed below. Many thanks in advance for your answers! are there tools which help with the migration of the existing databases (sizes between 250 MB and 2 GB, no Blob fields), by dumping the data, recreating the database with UNICODE_FSS or UTF-8, and loading the data back? are there known problems with Delphi 2009, dbExpress and Interbase 7.5 related to Unicode character sets? would you recommend to upgrade the databases to Interbase 2009 first? (This upgrade is planned but does not have a high priority) can we simply migrate the database and Delphi will handle the Unicode character sets automatically, or will we have to change all character field types in every Datamodule (dfm and source code) too? which strategy would you recommend to work on the migration in parallel with the normal development and maintenance of the existing application? The application runs in-house so development and database administration is done internally. Update: one problem I found now is that there are two different persistent field types for Unicode and non Unicode character fields. For the existing database, dbExpress creates TStringField objects. For the Unicode database fields, dbExpress creates (or expects!) TWideStringField objects. This looks like a lot of work lies ahead. While we could try to avoid persistent fields (and add calculated fields at run time), Of course we would prefer a solution which does not require so many changes in existing units and DFM files.

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• How to Write to a User.Config file through ConfigurationManager?

  - by Josh G

  I'm trying to persist user settings to a configuration file using ConfigurationManager. I want to scope these settings to the user only, because application changes can't be saved on Vista/Win 7 without admin privileges. This seems to get me the user's configuration, which appears to be saved here in Win 7 ([Drive]:\Users\[Username]\AppData\Local\[ApplicationName]\[AssemblyName][hash]\[Version\) Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.PerUserRoamingAndLocal); Whenever I try to save any changes at all to this config I get this exception: InnerException: System.InvalidOperationException Message="ConfigurationSection properties cannot be edited when locked." Source="System.Configuration" StackTrace: at System.Configuration.SectionInformation.VerifyIsEditable() at System.Configuration.MgmtConfigurationRecord.GetConfigDefinitionUpdates(Boolean requireUpdates, ConfigurationSaveMode saveMode, Boolean forceSaveAll, ConfigDefinitionUpdates& definitionUpdates, ArrayList& configSourceUpdates) I have tried adding a custom ConfigurationSection to this config. I have tried adding to the AppSettingsSection. Whenever I call config.Save() it throws the exception above. Any ideas? I tried using the ApplicationSettingsBase class through the Project-Settings designer, but it doesn't appear that you can save custom types with this. I want similar functionality with the ability to save custom types. Thanks.

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• Multiple user roles in Ruby on Rails

  - by aguynamedloren

  I am building an inventory management application with four different user types: admin, employee, manufacturer, transporter. I haven't started coding yet, but this is what I'm thinking.. Manufacturers and transporters are related with has_many :through many-to-many association with products as follows: class Manufacturer < ActiveRecord::Base has_many :products has_many :transporters, :through => :products end class Product < ActiveRecord::Base belongs_to :manufacturer belongs_to :transporter end class Transporter < ActiveRecord::Base has_many :products has_many :manufacturers, :through => :products end All four user types will be able to login, but they will have different permissions and views, etc. I don't think I can put them in the same table (Users), however, because they will have different requirements, ie: vendors and manufacturers must have a billing address and contact info (through validations), but admins and employees should not have these fields. If possible, I would like to have a single login screen as opposed to 4 different screens. I'm not asking for the exact code to build this, but I'm having trouble determining the best way to make it happen. Any ideas would be greatly appreciated - thanks!

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• Testing a wide variety of computers with a small company

  - by Tom the Junglist

  Hello everyone, I work for a small dotcom which will soon be launching a reasonably-complicated Windows program. We have uncovered a number of "WTF?" type scenarios that have turned up as the program has been passed around to the various not-technical-types that we've been unable to replicate. One of the biggest problems we're facing is that of testing: there are a total of three programmers -- only one working on this particular project, me -- no testers, and a handful of assorted other staff (sales, etc). We are also geographically isolated. The "testing lab" consists of a handful of VMWare and VPC images running sort-of fresh installs of Windows XP and Vista, which runs on my personal computer. The non-technical types try to be helpful when problems arise, we have trained them on how to most effectively report problems, and the software itself sports a wide array of diagnostic features, but since they aren't computer nerds like us their reporting is only so useful, and arranging remote control sessions to dig into the guts of their computers is time-consuming. I am looking for resources that allow us to amplify our testing abilities without having to put together an actual lab and hire beta testers. My boss mentioned rental VPS services and asked me to look in to them, however they are still largely very much self-service and I was wondering if there were any better ways. How have you, or any other companies in a similar situation handled this sort of thing? EDIT: According to the lingo, our goal here is to expand our systems testing capacity via an elastic computing platform such as Amazon EC2. At this point I am not sure suggestions of beefing up our unit/integration testing are going to help very much as we are consistently hitting walls at the systems testing phase. Has anyone attempted to do this kind of software testing on a cloud-type service like EC2? Tom

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• Deserializing a FileStream on Client using WCF

  - by Grandpappy

  I'm very new to WCF, so I apologize in advance if I misstate something. This is using .NET 4.0 RC1. Using WCF, I am trying to deserialize a response from the server. The base response has a Stream as its only MessageBodyMember. public abstract class StreamedResponse { [MessageBodyMember] public Stream Stream { get; set; } public StreamedResponse() { this.Stream = Stream.Null; } } The derived versions of this class are actually what's serialized, but they don't have a MessageBodyMember attribute (they have other base types such as int, string, etc listed as MessageHeader values). [MessageContract] public class ChildResponse : StreamedResponse { [DataMember] [MessageHeader] public Guid ID { get; set; } [DataMember] [MessageHeader] public string FileName { get; set; } [DataMember] [MessageHeader] public long FileSize { get; set; } public ChildResponse() : base() { } } The Stream is always a FileStream, in my specific case (but may not always be). At first, WCF said FileStream was not a known type, so I added it to the list of known types and now it serializes. It also appears, at first glance, to deserialize it on the client's side (it's the FileStream type). The problem is that it doesn't seem to be usable. All the CanRead, CanWrite, etc are false, and the Length, Position, etc properties throw exceptions when being used. Same with ReadByte(). What am I missing that would keep me from getting a valid FileStream?

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• how to 'scale' these three tables?

  - by iddqd

  I have the following Tables: Players id playerName Weapons id type otherData Weapons2Player id playersID_reference weaponsID_reference That was nice and simple. Now I need to SELECT items from the Weapons table, according to some of their characteristics that i previously just packed into the otherData column (since it was only needed on the client side). The problem is, that the types have varying characteristics - but also a lot of similar data. So I'm trying to decide on the following possibilities, all of which have their pros and cons. Solution A Kill the Weapons table, and create a new table for each Weapon-Type: Weapons_Swords id bladeType damage otherData Weapons_Guns id accuracy damage ammoType otherData But how will i Link these to the Players ? create Weapons_Swords2Players, Weapons_Guns2Players for each weapon-type? (Will result in a lot more JOINS when loading the player with all his weapons...and it's also more complicated to insert a new player) or add another column to Weapons2Players called WeaponsTypeTable, then do sub-selects to the correct Weapons sub-table (seems easier, but not really right, slightly easier insert i guess) Solution B Keep the Weapons table, and add all the fields i need to it. The Problem is that then there will be NULL fields, since not all Weapon-Types use all fields (can't be right) Weapons id type accuracy damage ammoType bladeType otherData This seems to be pretty basic stuff, but i just can't decide what's best. Or is there a correct Solution C? many thanks.

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• Why is Collection<String>.class Illegal?

  - by Peter

  I am puzzled by generics. You can declare a field like: Class<Collection<String>> clazz = ... It seems logical that you could assign this field with: Class<Collection<String>> clazz = Collection<String>.class; However, this generates an error: Syntax error on token ">", void expected after this token So it looks like the .class operator does not work with generics. So I tried: class A<S> {} class B extends A<String> {} Class<A<String>> c = B.class; Also does not work, generates: Type mismatch: cannot convert from Class<Test.StringCollection> to Class<Collection<String>> Now, I really fail to see why this should not work. I know generic types are not reified but in both cases it seems to be fully type safe without having access to runtime generic types. Anybody an idea? Peter Kriens

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• Multiple Table Inheritance vs. Single Table Inheritance in Ruby on Rails

  - by Tony

  I have been struggling for the past few hours thinking about which route I should go. I have a Notification model. Up until now I have used a notification_type column to manage the types but I think it will be better to create separate classes for the types of notifications as they behave differently. Right now, there are 3 ways notifications can get sent out: SMS, Twitter, Email Each notification would have: id subject message valediction sent_people_count deliver_by geotarget event_id list_id processed_at deleted_at created_at updated_at Seems like STI is a good candidate right? Of course Twitter/SMS won't have a subject and Twitter won't have a sent_people_count, valediction. I would say in this case they share most of their fields. However what if I add a "reply_to" field for twitter and a boolean for DM? My point here is that right now STI makes sense but is this a case where I may be kicking myself in the future for not just starting with MTI? To further complicate things, I want a Newsletter model which is sort of a notification but the difference is that it won't use event_id or deliver_by. I could see all subclasses of notification using about 2/3 of the notification base class fields. Is STI a no-brainer, or should I use MTI? Thanks!

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• C# style Action<T>, Func<T,T>, etc in C++0x

  - by Austin Hyde

  C# has generic function types such as Action<T> or Func<T,U,V,...> With the advent of C++0x and the ability to have template typedef's and variadic template parameters, it seems this should be possible. The obvious solution to me would be this: template <typename T> using Action<T> = void (*)(T); however, this does not accommodate for functors or C++0x lambdas, and beyond that, does not compile with the error "expected unqualified-id before 'using'" My next attempt was to perhaps use boost::function: template <typename T> using Action<T> = boost::function<void (T)>; This doesn't compile either, for the same reason. My only other idea would be STL style template arguments: template <typename T, typename Action> void foo(T value, Action f) { f(value); } But this doesn't provide a strongly typed solution, and is only relevant inside the templated function. Now, I will be the first to admit that I am not the C++ wiz I prefer to think I am, so it's very possible there is an obvious solution I'm not seeing. Is it possible to have C# style generic function types in C++?

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• question/problem regarding assigning an array of char *

  - by Fantastic Fourier

  Hi I'm working with C and I have a question about assigning pointers. struct foo { int _bar; char * _car[MAXINT]; // this is meant to be an array of char * so that it can hold pointers to names of cars } int foofunc (void * arg) { int bar; char * car[MAXINT]; struct foo thing = (struct foo *) arg; bar = arg->_bar; // this works fine car = arg->_car; // this gives compiler errors of incompatible types in assignment } car and _car have same declaration so why am I getting an error about incompatible types? My guess is that it has something to do with them being pointers (because they are pointers to arrays of char *, right?) but I don't see why that is a problem. when i declared char * car; instead of char * car[MAXINT]; it compiles fine. but I don't see how that would be useful to me later when I need to access certain info using index, it would be very annoying to access that info later. in fact, I'm not even sure if I am going about the right way, maybe there is a better way to store a bunch of strings instead of using array of char *?

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• strict aliasing and alignment

  - by cooky451

  I need a safe way to alias between arbitrary POD types, conforming to ISO-C++11 explicitly considering 3.10/10 and 3.11 of n3242 or later. There are a lot of questions about strict aliasing here, most of them regarding C and not C++. I found a "solution" for C which uses unions, probably using this section union type that includes one of the aforementioned types among its elements or nonstatic data members From that I built this. #include <iostream> template <typename T, typename U> T& access_as(U* p) { union dummy_union { U dummy; T destination; }; dummy_union* u = (dummy_union*)p; return u->destination; } struct test { short s; int i; }; int main() { int buf[2]; static_assert(sizeof(buf) >= sizeof(double), ""); static_assert(sizeof(buf) >= sizeof(test), ""); access_as<double>(buf) = 42.1337; std::cout << access_as<double>(buf) << '\n'; access_as<test>(buf).s = 42; access_as<test>(buf).i = 1234; std::cout << access_as<test>(buf).s << '\n'; std::cout << access_as<test>(buf).i << '\n'; } My question is, just to be sure, is this program legal according to the standard?* It doesn't give any warnings whatsoever and works fine when compiling with MinGW/GCC 4.6.2 using: g++ -std=c++0x -Wall -Wextra -O3 -fstrict-aliasing -o alias.exe alias.cpp * Edit: And if not, how could one modify this to be legal?

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• Possible to have multiple Profiles in ASP.NET for different users?

  - by asple

  My application has a few different user types with their own members. For example, I have the student user as well as the teacher user. I authenticate my users through active directory in my custom MembershipProvider's ValidateUser method. While querying AD, I pull out all their relevant information. I'd like to put that information into a Profile, but from what I've read and the examples I've sen, you can only define a single Profile (like so): <profile defaultProvider="CustomProfileProvider" enabled="true"> <properties> <add name="YearLevel" type="String" /> <add name="Name" type="String" /> <add name="Age" type="String" /> </properties> </profile> The above profile would work for a student, but not for a teacher, who does not have a value for "YearLevel" in AD. Is it possible to have multiple profiles to accomplish this? Or is it easier to add all properties from AD spanning all user types, then in my code, just check what user type they are and then access their specific properties?

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