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  • EnvDTE Retrieving the data type from a CodeElement

    - by chrischu
    I am using EnvDTE to generate some code in my latest project. I have a reference to a CodeClass-Object for a given C#-Class but now I wanted to loop through all of its members (in codeClass.Members) and check their types. However I can't manage to retrieve the type of the given member from the CodeElement-Object that I get when looping through codeClass.Members. How can I retrieve the type (int, string etc.)? PS: Reflection is not an option for my usecase.

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  • 32 bit dllimport generating incorrect format error (0x8007000b) on win7 x64 platform

    - by DFP
    Hello, I'm trying to install and run a 32 bit application on a Win7 x64 machine. The application is built as a Win32 app. It runs fine on 32 bit platforms. On the x64 machine it installs correctly in the Programs(x86) directory and runs fine until I make a call into a 32 bit dll. At that time I get the incorrect format error (0x8007000b) indicating it is trying to load the dll of the wrong bitness. Indeed it is trying to load the 64 bit dll from the System32 directory rather than the 32 bit version in the SystemWOW64 directory. Another 32 bit application provided by the dll vendor runs correctly and it does load the 32 bit dll from the SystemWOW64 directory. I do not have source to their application to see how they are accessing the DLL. I'm using the DllImport function as shown below to access the dll. Is there a way to decorate the DllImport calls to force it to load the 32 bit version? Any thoughts appreciated. Thanks, DP public static class Micronas { [DllImport(@"UAC2.DLL")] public static extern short UacBuildDeviceList(uint uFlags); [DllImport(@"UAC2.DLL")] public static extern short UacGetNumberOfDevices(); [DllImport(@"UAC2.DLL")] public static extern uint UacGetFirstDevice(); [DllImport(@"UAC2.DLL")] public static extern uint UacGetNextDevice(uint handle); [DllImport(@"UAC2.DLL")] public static extern uint UacSetXDFP(uint handle, short adr, uint data); [DllImport(@"UAC2.DLL")] public unsafe static extern uint UacGetXDFP(uint handle, short adr, IntPtr data); }

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  • Are there white lists for Yahoo, Gmail, Hotmail and AOL?

    - by Waleed Eissa
    In my website (under development), the members can send messages to each other which are sent directly to their email, now I'm worried that some members can send spam to other members (I have a spam filter but it doesn't give 100% protection as you know), I'm worried that my domain might get blacklisted on Yahoo, Gmail, Hotmail or AOL which will cause any messages sent from my domain to end up in the spam folder, this is why I want to add the domain of my website to their whitelists (if they exist). P.S. I don't want to use private messages that members check on the site and I have my reason for this. Thanks

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  • ADO.NET Commands and SQL query plans

    - by ingredient_15939
    I've been reading up on query plans and how to minimise duplicate plans being created by SQL Server for the same basic query. For example, if I understand correctly, sending both these query strings will result in 2 different query plans: "SELECT FirstName FROM Members WHERE LastName = 'Lee'" "SELECT FirstName FROM Members WHERE LastName = 'MacGhilleseatheanaich'" Using a stored procedure avoids this, as the query plan is the same, and "LastName" is passed as a variable, eg: CREATE PROCEDURE sp_myStoredProcedure @LastName varchar(100) AS SELECT FirstName FROM Members WHERE LastName = @LastName Go Now, my question is whether the same applies to the Command object (eg. SQLClient.SQLCommand in ADO.NET). The reason I ask is that string parameters don't have a defined max length, as in the code above. Take the following code: MyCmd.CommandText = "SELECT FirstName FROM Members WHERE LastName = @LastName" MyCmd.Parameters.AddWithValue("@LastName", "Lee") Then later: MyCmd.Parameters.Clear() MyCmd.Parameters.AddWithValue("@LastName", "MacGhilleseatheanaich") Since @LastName hasn't been declared to SQL Server as having a defined maximum length, will SQL Server create a new query plan for every different value when I execute the command this way?

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  • Why overload true and false instead of defining bool operator?

    - by Joe Enos
    I've been reading about overloading true and false in C#, and I think I understand the basic difference between this and defining a bool operator. The example I see around is something like: public static bool operator true(Foo foo) { return (foo.PropA > 0); } public static bool operator false(Foo foo) { return (foo.PropA <= 0); } To me, this is the same as saying: public static implicit operator bool(Foo foo) { return (foo.PropA > 0); } The difference, as far as I can tell, is that by defining true and false separately, you can have an object that is both true and false, or neither true nor false: public static bool operator true(Foo foo) { return true; } public static bool operator false(Foo foo) { return true; } //or public static bool operator true(Foo foo) { return false; } public static bool operator false(Foo foo) { return false; } I'm sure there's a reason this is allowed, but I just can't think of what it is. To me, if you want an object to be able to be converted to true or false, a single bool operator makes the most sense. Can anyone give me a scenario where it makes sense to do it the other way? Thanks

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  • Get All Users in an Active Directory Group

    - by Matt Hanson
    I'm using the following code sample to get a list of all users in a specified AD group (in this case, all users in the "Domain Users" group). My listed code works great, with one exception: it won't return users who have their primary group set to "Domain Users". How can I get a list of all users in the group, including those who have it set as their primary group? Private Sub GetUsers() Dim groupSearcher As New DirectorySearcher Dim groupSearchRoot As New DirectoryEntry("LDAP://OU=Users,DC=domain,DC=com") With groupSearcher .SearchRoot = groupSearchRoot .Filter = "(&(ObjectClass=Group)(CN=Domain Users))" End With Dim members As Object members = groupSearcher.FindOne.GetDirectoryEntry.Invoke("Members", Nothing) For Each member As Object In CType(members, IEnumerable) Console.WriteLine(New DirectoryEntry(member).Name.Remove(0, 3)) Next End Sub

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  • Best way to get a single value from a DataTable?

    - by PiersMyers
    I have a number of static classes that contain tables like this: using System; using System.Data; using System.Globalization; public static class TableFoo { private static readonly DataTable ItemTable; static TableFoo() { ItemTable = new DataTable("TableFoo") { Locale = CultureInfo.InvariantCulture }; ItemTable.Columns.Add("Id", typeof(int)); ItemTable.Columns["Id"].Unique = true; ItemTable.Columns.Add("Description", typeof(string)); ItemTable.Columns.Add("Data1", typeof(int)); ItemTable.Columns.Add("Data2", typeof(double)); ItemTable.Rows.Add(0, "Item 1", 1, 1.0); ItemTable.Rows.Add(1, "Item 2", 1, 1.0); ItemTable.Rows.Add(2, "Item 3", 2, 0.75); ItemTable.Rows.Add(3, "Item 4", 4, 0.25); ItemTable.Rows.Add(4, "Item 5", 1, 1.0); } public static DataTable GetItemTable() { return ItemTable; } public static int Data1(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (int)dr[0]["Data1"]; } public static double Data2(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (double)dr[0]["Data2"]; } } Is there a better way of writing the Data1 or Data2 methods that return a single value from a single row that matches the given id?

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  • how to make an import library

    - by user295030
    a requirement was sent to me below: API should be in the form of static library. company xxx will link the library into a third party application to prevent any possible exposure of the code(dll) could they mean an import library? An import library is a library that automates the process of loading and using a dynamic library. On Windows, this is typically done via a small static library (.lib) of the same name as the dynamic library (.dll). The static library is linked into the program at compile time, and then the functionality of the dynamic library can effectively be used as if it were a static library. this might be what they might be eluding to.....I am not sure how to make this in vs2008 . Additional facts: I have a static lib that i use in my current application. Now, I have to convert my app that uses that static lib into an import lib so that they can use a third party prog to access the API's they providede me which in turn will use that static lib i am using. I hope I am clearly explaining this. I am just not sure how to go about it in vs2008. I am looking for specific steps to do this. I already have the coding done. Just need to convert it into the form they are asking and I have to provide the API they want. Other than that then I need to create a test prog which will act as that third party prog so I can make sure my import library works.

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  • Why MSMQ won't send a space character?

    - by cyclotis04
    I'm exploring MSMQ services, and I wrote a simple console client-server application that sends each of the client's keystrokes to the server. Whenever hit a control character (DEL, ESC, INS, etc) the server understandably throws an error. However, whenever I type a space character, the server receives the packet but doesn't throw an error and doesn't display the space. Server: namespace QIM { class Program { const string QUEUE = @".\Private$\qim"; static MessageQueue _mq; static readonly object _mqLock = new object(); static XmlSerializer xs; static void Main(string[] args) { lock (_mqLock) { if (!MessageQueue.Exists(QUEUE)) _mq = MessageQueue.Create(QUEUE); else _mq = new MessageQueue(QUEUE); } xs = new XmlSerializer(typeof(string)); _mq.BeginReceive(new TimeSpan(0, 1, 0), new object(), OnReceive); while (Console.ReadKey().Key != ConsoleKey.Escape) { } } static void OnReceive(IAsyncResult result) { Message msg; lock (_mqLock) { try { msg = _mq.EndReceive(result); Console.Write("."); Console.Write(xs.Deserialize(msg.BodyStream)); } catch (Exception ex) { Console.Write(ex); } } _mq.BeginReceive(new TimeSpan(0, 1, 0), new object(), OnReceive); } } } Client: namespace QIM_Client { class Program { const string QUEUE = @".\Private$\qim"; static MessageQueue _mq; static void Main(string[] args) { if (!MessageQueue.Exists(QUEUE)) _mq = MessageQueue.Create(QUEUE); else _mq = new MessageQueue(QUEUE); ConsoleKeyInfo key = new ConsoleKeyInfo(); while (key.Key != ConsoleKey.Escape) { key = Console.ReadKey(); _mq.Send(key.KeyChar.ToString()); } } } } Client Input: Testing, Testing... Server Output: .T.e.s.t.i.n.g.,..T.e.s.t.i.n.g...... You'll notice that the space character sends a message, but the character isn't displayed.

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  • memcache is not storing data accross requests

    - by morpheous
    I am new to using memcache, so I may be doing something wrong. I have written a wrapper class around memcache. The wrapper class has only static methods, so is a quasi singleton. The class looks something like this: class myCache { private static $memcache = null; private static $initialized = false; public static function init() { if (self::$initialized) return; self::$memcache = new Memcache(); if (self::configure()) //connects to daemon { self::store('foo', 'bar'); } else throw ConnectionError('I barfed'); } public static function store($key, $data, $flag=MEMCACHE_COMPRESSED, $timeout=86400) { if (self::$memcache->get($key)!== false) return self::$memcache->replace($key, $data, $flag, $timeout); return self::$memcache->set($key, $data, $flag, $timeout); } public static function fetch($key) { return self::$memcache->get($key); } } //in my index.php file, I use the class like this require_once('myCache.php'); myCache::init(); echo 'Stored value is: '. myCache::fetch('foo'); The problem is that the myCache::init() method is being executed in full everytime a page is requested. I then remembered that static variables do not maintain state accross page requests. So I decided instead, to store the flag that indicates whether the server contains the start up data (for our purposes, the variable 'foo', with value 'bar') in memcache itself. Once the status flag is stored in memcache itself, It solves the problem of the initialisation data being loaded for every page request (which quite frankly, defeats the purpose of memcache). However, having solved that problem, when I come to fetch the data in memcache, it is empty. I dont understand whats going on. Can anyone clarify how I can store my data once and retrieve it accross page requests? BTW, (just to clarify), the get/set is working correctly, and if I allow memcache to load the initialisation data for each page request, (which is silly), then the data is available in memcache.

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  • A Question on Encapsulation.

    - by Bragaadeesh
    Hi, I know that encapsulation is binding the members and its behavior in one single entity. And it has made me think that the members have to be private. Does this mean if a class having public members is not following 100% Encapsulation rule? Thanks

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  • java singleton instantiation

    - by jurchiks
    I've found three ways of instantiating a Singleton, but I have doubts as to whether any of them is the best there is. I'm using them in a multi-threaded environment and prefer lazy instantiation. Sample 1: private static final ClassName INSTANCE = new ClassName(); public static ClassName getInstance() { return INSTANCE; } Sample 2: private static class SingletonHolder { public static final ClassName INSTANCE = new ClassName(); } public static ClassName getInstance() { return SingletonHolder.INSTANCE; } Sample 3: private static ClassName INSTANCE; public static synchronized ClassName getInstance() { if (INSTANCE == null) INSTANCE = new ClassName(); return INSTANCE; } The project I'm using ATM uses Sample 2 everywhere, but I kind of like Sample 3 more. There is also the Enum version, but I just don't get it. The question here is - in which cases I should/shouldn't use any of these variations? I'm not looking for lengthy explanations though (there's plenty of other topics about that, but they all eventually turn into arguing IMO), I'd like it to be understandable with few words.

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  • Can I get rid of this read lock?

    - by Pieter
    I have the following helper class (simplified): public static class Cache { private static readonly object _syncRoot = new object(); private static Dictionary<Type, string> _lookup = new Dictionary<Type, string>(); public static void Add(Type type, string value) { lock (_syncRoot) { _lookup.Add(type, value); } } public static string Lookup(Type type) { string result; lock (_syncRoot) { _lookup.TryGetValue(type, out result); } return result; } } Add will be called roughly 10/100 times in the application and Lookup will be called by many threads, many of thousands of times. What I would like is to get rid of the read lock. How do you normally get rid of the read lock in this situation? I have the following ideas: Require that _lookup is stable before the application starts operation. The could be build up from an Attribute. This is done automatically through the static constructor the attribute is assigned to. Requiring the above would require me to go through all types that could have the attribute and calling RuntimeHelpers.RunClassConstructor which is an expensive operation; Move to COW semantics. public static void Add(Type type, string value) { lock (_syncRoot) { var lookup = new Dictionary<Type, string>(_lookup); lookup.Add(type, value); _lookup = lookup; } } (With the lock (_syncRoot) removed in the Lookup method.) The problem with this is that this uses an unnecessary amount of memory (which might not be a problem) and I would probably make _lookup volatile, but I'm not sure how this should be applied. (John Skeets' comment here gives me pause.) Using ReaderWriterLock. I believe this would make things worse since the region being locked is small. Suggestions are very welcome.

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  • DBTransactions between stateless calls using GUIDs

    - by Marty Trenouth
    I'm looking to add transactional support to my DB engine and providing to Abstract Transaction Handling down to passing in Guids with the DB Action Command. The DB engine would run similar to: private static Database DB; public static Dictionary<Guid,DBTransaction> Transactions = new ...() public static void DoDBAction(string cmdstring,List<Parameter> parameters,Guid TransactionGuid) { DBCommand cmd = BuildCommand(cmdstring,parameters); if(Transactions.ContainsKey(TransactionGuid)) cmd.Transaction = Transactions[TransactionGuid]; DB.ExecuteScalar(cmd); } public static BuildCommand(string cmd, List<Parameter> parameters) { // Create DB command from EntLib Database and assign parameters } public static Guid BeginTransaction() { // creates new Transaction adding it to "Transactions" and opens a new connection } public static Guid Commit(Guid g) { // Commits Transaction and removes it from "Transactions" and closes connection } public static Guid Rollback(Guid g) { // Rolls back Transaction and removes it from "Transactions" and closes connection } The Calling system would run similar to: Guid g try { g = DBEngine.BeginTransaction() DBEngine.DoDBAction(cmdstring1, parameters,g) // do some other stuff DBEngine.DoDBAction(cmdstring2, parameters2,g) // sit here and wait for a response from other item DBEngine.DoDBAction(cmdstring3, parameters3,g) DBEngine.Commit(g) } catch(Exception){ DBEngine.Rollback(g);} Does this interfere with .NET connection pooling (other than a connection be accidently left open)? Will EntLib keep the connection open until the commit or rollback?

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  • Mysql two table query

    - by Sergio
    I'm using two tables. First (friendlist), which contains users who are on the list of friends and the other table (members) that contains the basic data of the users. Friendlist looks like: id | myid | date | user ----------------------------------------- 001 | 50624 | 2010-01-01 | 32009 002 | 41009 | 2010-05-05 | 50624 003 | 50624 | 2010-03-02 | 23007 The column "myid" contains members who added other users (those from column "user") to their frindlist. I want to get the list of all users that I have added to list and those who add me to their friendlist. In this example, if my id is 50624, the list would look like: | allfriends | --------------- 32009 41009 23007 Then I need to check all users from "allfriend" list with data from the table "members". I want to get only the users with status 1. The members table looks like: id | status | photo -------------------------------- 32009 | 0 | 1.jpg 41009 | 1 | 2.jpg 23007 | 1 | 3.jpg How this mysql query should look like? Thanks for any help.

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  • C++, function pointer to the template function pointer

    - by Ian
    I am having a pointer to the common static method class MyClass { private: static double ( *pfunction ) ( const Object *, const Object *); ... }; pointing to the static method class SomeClass { public: static double getA ( const Object *o1, const Object *o2); ... }; Initialization: double ( *MyClass::pfunction ) ( const Object *o1, const Object *o2 ) = &SomeClass::getA; I would like to convert this pointer to the static template function pointer: template <class T> static T ( *pfunction ) ( const Object <T> *, const Object <T> *); //Compile error where: class SomeClass { public: template <class T> static double getA ( const Object <T> *o1, const Object <T> *o2); ... }; But there is some error... Thanks for your help...

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  • How to access the private variables of a class in its subclass?

    - by giri
    This is a question I was asked in an interview: I have class A with private members and Class B extends A. I know private members of a class cannot be accessed, but the question is: I need to access private members of class A from class B, rather than create variables with the same value in class B. I hope I am clear with this question. Thanks.

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  • Is there any workaround for making a structure member somehow 'private' in C ?

    - by nomemory
    I am developing a simple library in C, for my own + some friends personal use. I am currently having a C structure with some members that should be somehow hidden from the rest of the application, as their use is only internal. Modifying by accident one of this members will probably make the library 'go wild'. Is there any 'workaround' to hide those members so that they can't be accessible ?

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  • Object Design catalog and resources

    - by Tauren
    I'm looking for web sites, books, or other resources that provide a catalog of object designs used in common scenarios. I'm not looking for generic design patterns, but for samples of actual object designs that were used to solve real problems. For instance, I'm about to build an internal messaging system for a web application, similar to Facebook's messaging system. This system will allow administrators to send messages to all members, to selected groups of members, or to individuals. Members can send messages to other members or groups of members. Fairly common stuff and a feature that I'm sure thousands of web applications require. I know each situation is different and there are a million ways to design this solution. Although this scenario isn't really all that complex, I'm sure the basic design of the necessary objects and relationships for a system like this has already been done many times. It would be nice to review other similar designs before building my own. Is there a place where people can share their designs and others can browse/search through the catalog to review and provide feedback on them? StackOverflow could be used to a degree for this, but doesn't really provide a catalog of designs. Any other resources that would relate?

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  • Not all symbols of an DLL-exported class is exported (VS9)

    - by mandrake
    I'm building a DLL from a group of static libraries and I'm having a problem where only parts of classes are exported. What I'm doing is declaring all symbols I want to export with a preprocessor definition like: #if defined(MYPROJ_BUILD_DLL) //Build as a DLL # define MY_API __declspec(dllexport) #elif defined(MYPROJ_USE_DLL) //Use as a DLL # define MY_API __declspec(dllimport) #else //Build or use as a static lib # define MY_API #endif For example: class MY_API Foo{ ... } I then build static library with MYPROJ_BUILD_DLL & MYPROJ_USE_DLL undefined causing a static library to be built. In another build I create a DLL from these static libraries. So I define MYPROJ_BUILD_DLL causing all symbols I want to export to be attributed with __declspec(dllexport) (this is done by including all static library headers in the DLL-project source file). Ok, so now to the problem. When I use this new DLL I get unresolved externals because not all symbols of a class is exported. For example in a class like this: class MY_API Foo{ public: Foo(char const* ); int bar(); private: Foo( char const*, char const* ); }; Only Foo::Foo( char const*, char const*); and int Foo::bar(); is exported. How can that be? I can understand if the entire class was missing, due to e.g. I forgot to include the header in the DLL-build. But it's only partial missing. Also, say if Foo::Foo( char const*) was not implemented; then the DLL build would have unresolved external errors. But the build is fine (I also double checked for declarations without implementation). Note: The combined size of the static libraries I'm combining is in the region of 30MB, and the resulting DLL is 1.2MB. I'm using Visual Studio 9.0 (2008) to build everything. And Depends to check for exported symbols.

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  • Implementing a bitfield using java enums

    - by soappatrol
    Hello, I maintain a large document archive and I often use bit fields to record the status of my documents during processing or when validating them. My legacy code simply uses static int constants such as: static int DOCUMENT_STATUS_NO_STATE = 0 static int DOCUMENT_STATUS_OK = 1 static int DOCUMENT_STATUS_NO_TIF_FILE = 2 static int DOCUMENT_STATUS_NO_PDF_FILE = 4 This makes it pretty easy to indicate the state a document is in, by setting the appropriate flags. For example: status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE; Since the approach of using static constants is bad practice and because I would like to improve the code, I was looking to use Enums to achieve the same. There are a few requirements, one of them being the need to save the status into a database as a numeric type. So there is a need to transform the enumeration constants to a numeric value. Below is my first approach and I wonder if this is the correct way to go about this? class DocumentStatus{ public enum StatusFlag { DOCUMENT_STATUS_NOT_DEFINED(1<<0), DOCUMENT_STATUS_OK(1<<1), DOCUMENT_STATUS_MISSING_TID_DIR(1<<2), DOCUMENT_STATUS_MISSING_TIF_FILE(1<<3), DOCUMENT_STATUS_MISSING_PDF_FILE(1<<4), DOCUMENT_STATUS_MISSING_OCR_FILE(1<<5), DOCUMENT_STATUS_PAGE_COUNT_TIF(1<<6), DOCUMENT_STATUS_PAGE_COUNT_PDF(1<<7), DOCUMENT_STATUS_UNAVAILABLE(1<<8), private final long statusFlagValue; StatusFlag(long statusFlagValue) { this.statusFlagValue = statusFlagValue } public long getStatusFlagValue(){ return statusFlagValue } } /** * Translates a numeric status code into a Set of StatusFlag enums * @param numeric statusValue * @return EnumSet representing a documents status */ public EnumSet<StatusFlag> getStatusFlags(long statusValue) { EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class) StatusFlag.each { statusFlag -> long flagValue = statusFlag.statusFlagValue if ( (flagValue&statusValue ) == flagValue ) { statusFlags.add(statusFlag) } } return statusFlags } /** * Translates a set of StatusFlag enums into a numeric status code * @param Set if statusFlags * @return numeric representation of the document status */ public long getStatusValue(Set<StatusFlag> flags) { long value=0 flags.each { statusFlag -> value|=statusFlag.getStatusFlagValue() } return value } public static void main(String[] args) { DocumentStatus ds = new DocumentStatus(); Set statusFlags = EnumSet.of( StatusFlag.DOCUMENT_STATUS_OK, StatusFlag.DOCUMENT_STATUS_UNAVAILABLE) assert ds.getStatusValue( statusFlags )==258 // 0000.0001|0000.0010 long numericStatusCode = 56 statusFlags = ds.getStatusFlags(numericStatusCode) assert !statusFlags.contains(StatusFlag.DOCUMENT_STATUS_OK) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_TIF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_PDF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_OCR_FILE) } }

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  • Questions on Juval Lowy's IDesign C# Coding Standard

    - by Jan
    We are trying to use the IDesign C# Coding standard. Unfortunately, I found no comprehensive document to explain all the rules that it gives, and also his book does not always help. Here are the open questions that remain for me (from chapter 2, Coding Practices): No. 26: Avoid providing explicit values for enums unless they are integer powers of 2 No. 34: Always explicitly initialize an array of reference types using a for loop No. 50: Avoid events as interface members No. 52: Expose interfaces on class hierarchies No. 73: Do not define method-specific constraints in interfaces No. 74: Do not define constraints in delegates Here's what I think about those: I thought that providing explicit values would be especially useful when adding new enum members at a later point in time. If these members are added between other already existing members, I would provide explicit values to make sure the integer representation of existing members does not change. No idea why I would want to do this. I'd say this totally depends on the logic of my program. I see that there is alternative option of providing "Sink interfaces" (simply providing already all "OnXxxHappened" methods), but what is the reason to prefer one over the other? Unsure what he means here: Could this mean "When implementing an interface explicitly in a non-sealed class, consider providing the implementation in a protected virtual method that can be overridden"? (see Programming .NET Components 2nd Edition, end of chapter “Interfaces and Class Hierarchies”). I suppose this is about providing a "where" clause when using generics, but why is this bad on an interface? I suppose this is about providing a "where" clause when using generics, but why is this bad on a delegate?

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  • Some questions about special operators i've never seen in C++ code.

    - by toto
    I have downloaded the Phoenix SDK June 2008 (Tools for compilers) and when I'm reading the code of the Hello sample, I really feel lost. public ref class Hello { //-------------------------------------------------------------------------- // // Description: // // Class Variables. // // Remarks: // // A normal compiler would have more flexible means for holding // on to all this information, but in our case it's simplest (if // somewhat inelegant) if we just keep references to all the // structures we'll need to access as classstatic variables. // //-------------------------------------------------------------------------- static Phx::ModuleUnit ^ module; static Phx::Targets::Runtimes::Runtime ^ runtime; static Phx::Targets::Architectures::Architecture ^ architecture; static Phx::Lifetime ^ lifetime; static Phx::Types::Table ^ typeTable; static Phx::Symbols::Table ^ symbolTable; static Phx::Phases::PhaseConfiguration ^ phaseConfiguration; 2 Questions : What's that ref keyword? What is that sign ^ ? What is it doing protected: virtual void Execute ( Phx::Unit ^ unit ) override; }; override is a C++ keyword too? It's colored as such in my Visual Studio. I really want to play with this framework, but this advanced C++ is really an obstacle right now. Thank you.

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  • Dynamic Dispatch without Virtual Functions

    - by Kristopher Johnson
    I've got some legacy code that, instead of virtual functions, uses a kind field to do dynamic dispatch. It looks something like this: // Base struct shared by all subtypes // Plain-old data; can't use virtual functions struct POD { int kind; int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); }; enum Kind { Kind_Derived1, Kind_Derived2, Kind_Derived3 }; struct Derived1: POD { Derived1(): kind(Kind_Derived1) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; struct Derived2: POD { Derived2(): kind(Kind_Derived2) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; struct Derived3: POD { Derived3(): kind(Kind_Derived3) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; and then the POD class's function members are implemented like this: int POD::GetFoo() { // Call kind-specific function switch (kind) { case Kind_Derived1: { Derived1 *pDerived1 = static_cast<Derived1*>(this); return pDerived1->GetFoo(); } case Kind_Derived2: { Derived2 *pDerived2 = static_cast<Derived2*>(this); return pDerived2->GetFoo(); } case Kind_Derived3: { Derived3 *pDerived3 = static_cast<Derived3*>(this); return pDerived3->GetFoo(); } default: throw UnknownKindException(kind, "GetFoo"); } } POD::GetBar(), POD::GetBaz(), POD::GetXyzzy(), and other members are implemented similarly. This example is simplified. The actual code has about a dozen different subtypes of POD, and a couple dozen methods. New subtypes of POD and new methods are added pretty frequently, and so every time we do that, we have to update all these switch statements. The typical way to handle this would be to declare the function members virtual in the POD class, but we can't do that because the objects reside in shared memory. There is a lot of code that depends on these structs being plain-old-data, so even if I could figure out some way to have virtual functions in shared-memory objects, I wouldn't want to do that. So, I'm looking for suggestions as to the best way to clean this up so that all the knowledge of how to call the subtype methods is centralized in one place, rather than scattered among a couple dozen switch statements in a couple dozen functions. What occurs to me is that I can create some sort of adapter class that wraps a POD and uses templates to minimize the redundancy. But before I start down that path, I'd like to know how others have dealt with this.

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  • C# Debug.Assert-s use the same error message. Should I promote it to a static variable?

    - by Hamish Grubijan
    I love Asserts but not code duplication, and in several places I use a Debug.Assert which checks for the same condition like so: Debug.Assert(kosherBaconList.SelectedIndex != -1, "An error message along the lines - you should not ever be able to click on edit button without selecting a kosher bacon first."); This is in response to an actual bug, although the actual list does not contain kosher bacon. Anyhow, I can think of two approaches: private static readonly mustSelectKosherBaconBeforeEditAssertMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; ... Debug.Assert( kosherBaconList.SelectedIndex != -1, mustSelectKosherBaconBeforeEditAssertMessage) or: if (kosherBaconList.SelectedIndex == -1) { AssertMustSelectKosherBaconBeforeEdit(); } ... [Conditional("DEBUG")] private void AssertMustSelectKosherBaconBeforeEdit() { // Compiler will optimize away this variable. string errorMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; Debug.Assert(false, errorMessage); } or is there a third way which sucks less than either one above? Please share. General helpful relevant tips are also welcome.

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