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  • Several different project types in solution use same class. Where can I place this class?

    - by user3605366
    I have one solution with 3 related projects: 1) a Windows console app that reads data and stores it to a mssql DB, 2) WCF service that will retrieve from mssql data, 3) website that will read from the WCF. There could be other projects in the future. The first two projects (and any related future projects) use a Sqlhelper class. Should I create a separate project for it? The most ideal one would be a class library, but I don't know if a WCF invoking a DLL is correct. Any help is appreciated. Thanks.

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  • Declaring two classes that contain instance variables of each others' types.

    - by Benji XVI
    Let’s say you wish to have two classes like so, each declaring an instance variable that is of the other’s class. @interface A : NSObject { B *something; } @end @interface B : NSObject { A *something; } @end It seems to be impossible to declare these classes with these instance variables. In order for A to include an IV of class B, B must already be compiled, and so its @interface must come before A’s. But A’s must be put before B’s for the same reason. Putting the two class declarations in separate files, and #import-ing each other’s .h doesn’t work either, for obvious reasons. So, what is the solution? Or is this either (1) impossible or (2) indicative of a bad design anyway?

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  • How to identify each parameter type in a C# method?

    - by user465876
    I have a C# method say: MyMethod(int num, string name, Color color, MyComplexType complex) Using reflection, how can I distinctly identify each of the parameter types of any method? I want to perform some task by parameter type. If the type is simple int, string or boolean then I do something, if it is Color, XMLDocument, etc I do something else and if it is user defined type like MyComplexType or MyCalci etc then I want to do certain task. I am able to retrieve all the parameters of a method using ParameterInfo and can loop through each parameter and get their types. But how can I identify each data type? foreach (var parameter in parameters) { //identify primitive types?? //identify value types //identify reference types } Edit: this is apart of my code to create a propert grid sort of page where I want to show the parameter list with data types for the selected method. If the parameter has any userdefined type/reference type then I want to expand it further to show all the elements under it with datatypes.

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  • Password Security: Short and Complex versus ‘Short or Lengthy’ and Less Complex

    - by Akemi Iwaya
    Creating secure passwords for our online accounts is a necessary evil due to the huge increase in database and account hacking that occurs these days. The problem though is that no two companies have a similar policy for complex and secure password creation, then factor in the continued creation of insecure passwords or multi-site use of the same password and trouble is just waiting to happen. Ars Technica decided to take a look at multiple password types, how users fared with them, and how well those password types held up to cracking attempts in their latest study. The password types that Ars Technica looked at were comprehensive8, basic8, and basic16. The comprehensive type required a variety of upper-case, lower-case, digits, and symbols with no dictionary words allowed. The only restriction on the two basic types was the number of characters used. Which type do you think was easier for users to adopt and did better in the two password cracking tests? You can learn more about how well users did with the three password types and the results of the tests by visiting the article linked below. What are your thoughts on the matter? Are shorter, more complex passwords better or worse than using short or long, but less complex passwords? What methods do you feel work best since most passwords are limited to approximately 16 characters in length? Perhaps you use a service like LastPass or keep a dedicated list/notebook to manage your passwords. Let us know in the comments!    

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  • Thread Synchronization and Synchronization Primitives

    When considering synchronization in an application, the decision truly depends on what the application and its worker threads are going to do. I would use synchronization if two or more threads could possibly manipulate the same instance of an object at the same time. An example of this in C# can be demonstrated through the use of storing data in a static object. A static object is initialized once per application and the data within the object can be accessed by all threads. I would use the synchronization primitives to prevent any data from being manipulated by multiple threads simultaneously. This would reduce any data corruption from occurring within the object. On the other hand if all the threads used non static objects and were independent of the other tasks there would be no need to use synchronization. Synchronization Primitives in C#: Basic Blocking Locking Signaling Non-Blocking Synchronization Constructs The Basic Blocking methods include Sleep, Join, and Task.Wait.  These methods force threads to wait until other threads have completed. In addition, these methods can also force a thread to wait a set amount of time before continuing to work.   The Locking primitive prevents a thread from entering a critical section of code while another thread is in the same critical section.  If another thread attempts to enter a locked code, it will wait, until the code block is released. The Signaling primitive allows a thread to temporarily pause work until receiving a notification from another thread that it is ok to continue working. The Signaling primitive removes the need for polling.The Non-Blocking Synchronization Constructs protect access to a common field by calling upon processor primitives.

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  • Date and Time Support in SQL Server 2008

    - by Aamir Hasan
      Using the New Date and Time Data Types Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} 1.       The new date and time data types in SQL Server 2008 offer increased range and precision and are ANSI SQL compatible. 2.       Separate date and time data types minimize storage space requirements for applications that need only date or time information. Moreover, the variable precision of the new time data type increases storage savings in exchange for reduced accuracy. 3.       The new data types are mostly compatible with the original date and time data types and use the same Transact-SQL functions. 4.       The datetimeoffset data type allows you to handle date and time information in global applications that use data that originates from different time zones. SELECT c.name, p.* FROM politics pJOIN country cON p.country = c.codeWHERE YEAR(Independence) < 1753ORDER BY IndependenceGO8.    Highlight the SELECT statement and click Execute ( ) to show the use of some of the date functions.T-SQLSELECT c.name AS [Country Name],        CONVERT(VARCHAR(12), p.Independence, 107) AS [Independence Date],       DATEDIFF(YEAR, p.Independence, GETDATE()) AS [Years Independent (appox)],       p.GovernmentFROM politics pJOIN country cON p.country = c.codeWHERE YEAR(Independence) < 1753ORDER BY IndependenceGO10.    Select the SET DATEFORMAT statement and click Execute ( ) to change the DATEFORMAT to day-month-year.T-SQLSET DATEFORMAT dmyGO11.    Select the DECLARE and SELECT statements and click Execute ( ) to show how the datetime and datetime2 data types interpret a date literal.T-SQLSET DATEFORMAT dmyDECLARE @dt datetime = '2008-12-05'DECLARE @dt2 datetime2 = '2008-12-05'SELECT MONTH(@dt) AS [Month-Datetime], DAY(@dt)     AS [Day-Datetime]SELECT MONTH(@dt2) AS [Month-Datetime2], DAY(@dt2)     AS [Day-Datetime2]GO12.    Highlight the DECLARE and SELECT statements and click Execute ( ) to use integer arithmetic on a datetime variable.T-SQLDECLARE @dt datetime = '2008-12-05'SELECT @dt + 1GO13.    Highlight the DECLARE and SELECT statements and click Execute ( ) to show how integer arithmetic is not allowed for datetime2 variables.T-SQLDECLARE @dt2 datetime = '2008-12-05'SELECT @dt2 + 1GO14.    Highlight the DECLARE and SELECT statements and click Execute ( ) to show how to use DATE functions to do simple arithmetic on datetime2 variables.T-SQLDECLARE @dt2 datetime2(7) = '2008-12-05'SELECT DATEADD(d, 1, @dt2)GO15.    Highlight the DECLARE and SELECT statements and click Execute ( ) to show how the GETDATE function can be used with both datetime and datetime2 data types.T-SQLDECLARE @dt datetime = GETDATE();DECLARE @dt2 datetime2(7) = GETDATE();SELECT @dt AS [GetDate-DateTime], @dt2 AS [GetDate-DateTime2]GO16.    Draw attention to the values returned for both columns and how they are equal.17.    Highlight the DECLARE and SELECT statements and click Execute ( ) to show how the SYSDATETIME function can be used with both datetime and datetime2 data types.T-SQLDECLARE @dt datetime = SYSDATETIME();DECLARE @dt2 datetime2(7) = SYSDATETIME();SELECT @dt AS [Sysdatetime-DateTime], @dt2     AS [Sysdatetime-DateTime2]GO18.    Draw attention to the values returned for both columns and how they are different.Programming Global Applications with DateTimeOffset 2.    If you have not previously created the SQLTrainingKitDB database while completing another demo in this training kit, highlight the CREATE DATABASE statement and click Execute ( ) to do so now.T-SQLCREATE DATABASE SQLTrainingKitDBGO3.    Select the USE and CREATE TABLE statements and click Execute ( ) to create table datetest in the SQLTrainingKitDB database.T-SQLUSE SQLTrainingKitDBGOCREATE TABLE datetest (  id integer IDENTITY PRIMARY KEY,  datetimecol datetimeoffset,  EnteredTZ varchar(40)); Reference:http://www.microsoft.com/downloads/details.aspx?FamilyID=E9C68E1B-1E0E-4299-B498-6AB3CA72A6D7&displaylang=en   

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  • Plan your SharePoint 2010 Content Type Hub carefully

    - by Wayne
    Currently setting up a new environment on SharePoint 2010 (which was made available for download yesterday if anyone missed that :-). One of the new features of SharePoint 2010 is to set up a Content Type Hub (which is a part of the Metadata Service Application), which is a hub for all Content Types that other Site Collections can subscribe to. That is you only need to manage your content types in one location. Setting up the Content Type Hub is not that difficult but you must make it very careful to avoid a lot of work and troubleshooting. Here is a short tutorial with a few tips and tricks to make it easy for you to get started. Determine location of Content Type Hub First of all you need to decide in which Site Collection to place your Content Type Hub; in the root site collection or a specific one. I think using a specific Site Collection that only acts as a Content Type Hub is the best way, there are no best practice as of now. So I create a new Site Collection, at for instance http://server/sites/CTH/. The top-level site of this site collection should be for instance a Team Site. You cannot use Blank Site by default, which would have been the best option IMHO, since that site does not have the Taxonomy feature stapled upon it (check the TaxonomyFeatureStapler feature for which site templates that can be used). Configure Managed Metadata Service Application Next you need to create your Managed Metadata Service Application or configure the existing one, Central Administration > Application Management > Manage Service Applications. Select the Managed Metadata service application and click Properties if you already have created it. In the bottom of the dialog window when you are creating the service application or when you are editing the properties is a section to fill in the Content Type Hub. In this text box fill in the URL of the Content Type Hub. It is essential that you have decided where your Content Type Hub will reside, since once this is set you cannot change it. The only way to change it is to rebuild the whole managed metadata service application! Also make sure that you enter the URL correctly. I did copy and paste the URL once and got the /default.aspx in the URL which funked the whole service up. Make sure that you only use the URL to the Site Collection of the hub. Now you have to set up so that other Site Collections can consume the content types from the hub. This is done by selecting the connection for the managed metadata service application and clicking properties. A new dialog window opens and there you need to click the Consumes content types from the Content Type Gallery at nnnn. Now you are free to syndicate your Content Types from the Hub. Publish Content Types To publish a Content Type from the hub you need to go to Site Settings > Content Types and select the content type that you would like to publish. Then select Manage publishing for this content type. This takes you to a page from where you can Publish, Unpublish or Republish the content type. Once the content type is published it can take up to an hour for the subscribing Site Collections to get it. This is controlled by the Content Type Subscriber job that is scheduled to run once an hour. To speed up your publishing just go to Central Administration > Monitoring > Review Job Definitions > Content Type Subscriber and click Run now and you content type is very soon available for use. Published Content Type status You can check the status of the content type publishing in your destination site collections by selecting Site Settings > Content Type Publishing. From here you can force a refresh of all subscribed content types, see which ones that are subscribed and finally check the publishing error log. This error log is very useful for detecting errors during the publishing. For instance if you use any features such as ratings, metadata, document ids in your content type hub and your destination site collection does not have those features available this will be reported here.

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  • C#/.NET Little Wonders: Fun With Enum Methods

    - by James Michael Hare
    Once again lets dive into the Little Wonders of .NET, those small things in the .NET languages and BCL classes that make development easier by increasing readability, maintainability, and/or performance. So probably every one of us has used an enumerated type at one time or another in a C# program.  The enumerated types we create are a great way to represent that a value can be one of a set of discrete values (or a combination of those values in the case of bit flags). But the power of enum types go far beyond simple assignment and comparison, there are many methods in the Enum class (that all enum types “inherit” from) that can give you even more power when dealing with them. IsDefined() – check if a given value exists in the enum Are you reading a value for an enum from a data source, but are unsure if it is actually a valid value or not?  Casting won’t tell you this, and Parse() isn’t guaranteed to balk either if you give it an int or a combination of flags.  So what can we do? Let’s assume we have a small enum like this for result codes we want to return back from our business logic layer: 1: public enum ResultCode 2: { 3: Success, 4: Warning, 5: Error 6: } In this enum, Success will be zero (unless given another value explicitly), Warning will be one, and Error will be two. So what happens if we have code like this where perhaps we’re getting the result code from another data source (could be database, could be web service, etc)? 1: public ResultCode PerformAction() 2: { 3: // set up and call some method that returns an int. 4: int result = ResultCodeFromDataSource(); 5:  6: // this will suceed even if result is < 0 or > 2. 7: return (ResultCode) result; 8: } So what happens if result is –1 or 4?  Well, the cast does not fail, so what we end up with would be an instance of a ResultCode that would have a value that’s outside of the bounds of the enum constants we defined. This means if you had a block of code like: 1: switch (result) 2: { 3: case ResultType.Success: 4: // do success stuff 5: break; 6:  7: case ResultType.Warning: 8: // do warning stuff 9: break; 10:  11: case ResultType.Error: 12: // do error stuff 13: break; 14: } That you would hit none of these blocks (which is a good argument for always having a default in a switch by the way). So what can you do?  Well, there is a handy static method called IsDefined() on the Enum class which will tell you if an enum value is defined.  1: public ResultCode PerformAction() 2: { 3: int result = ResultCodeFromDataSource(); 4:  5: if (!Enum.IsDefined(typeof(ResultCode), result)) 6: { 7: throw new InvalidOperationException("Enum out of range."); 8: } 9:  10: return (ResultCode) result; 11: } In fact, this is often recommended after you Parse() or cast a value to an enum as there are ways for values to get past these methods that may not be defined. If you don’t like the syntax of passing in the type of the enum, you could clean it up a bit by creating an extension method instead that would allow you to call IsDefined() off any isntance of the enum: 1: public static class EnumExtensions 2: { 3: // helper method that tells you if an enum value is defined for it's enumeration 4: public static bool IsDefined(this Enum value) 5: { 6: return Enum.IsDefined(value.GetType(), value); 7: } 8: }   HasFlag() – an easier way to see if a bit (or bits) are set Most of us who came from the land of C programming have had to deal extensively with bit flags many times in our lives.  As such, using bit flags may be almost second nature (for a quick refresher on bit flags in enum types see one of my old posts here). However, in higher-level languages like C#, the need to manipulate individual bit flags is somewhat diminished, and the code to check for bit flag enum values may be obvious to an advanced developer but cryptic to a novice developer. For example, let’s say you have an enum for a messaging platform that contains bit flags: 1: // usually, we pluralize flags enum type names 2: [Flags] 3: public enum MessagingOptions 4: { 5: None = 0, 6: Buffered = 0x01, 7: Persistent = 0x02, 8: Durable = 0x04, 9: Broadcast = 0x08 10: } We can combine these bit flags using the bitwise OR operator (the ‘|’ pipe character): 1: // combine bit flags using 2: var myMessenger = new Messenger(MessagingOptions.Buffered | MessagingOptions.Broadcast); Now, if we wanted to check the flags, we’d have to test then using the bit-wise AND operator (the ‘&’ character): 1: if ((options & MessagingOptions.Buffered) == MessagingOptions.Buffered) 2: { 3: // do code to set up buffering... 4: // ... 5: } While the ‘|’ for combining flags is easy enough to read for advanced developers, the ‘&’ test tends to be easy for novice developers to get wrong.  First of all you have to AND the flag combination with the value, and then typically you should test against the flag combination itself (and not just for a non-zero)!  This is because the flag combination you are testing with may combine multiple bits, in which case if only one bit is set, the result will be non-zero but not necessarily all desired bits! Thanks goodness in .NET 4.0 they gave us the HasFlag() method.  This method can be called from an enum instance to test to see if a flag is set, and best of all you can avoid writing the bit wise logic yourself.  Not to mention it will be more readable to a novice developer as well: 1: if (options.HasFlag(MessagingOptions.Buffered)) 2: { 3: // do code to set up buffering... 4: // ... 5: } It is much more concise and unambiguous, thus increasing your maintainability and readability. It would be nice to have a corresponding SetFlag() method, but unfortunately generic types don’t allow you to specialize on Enum, which makes it a bit more difficult.  It can be done but you have to do some conversions to numeric and then back to the enum which makes it less of a payoff than having the HasFlag() method.  But if you want to create it for symmetry, it would look something like this: 1: public static T SetFlag<T>(this Enum value, T flags) 2: { 3: if (!value.GetType().IsEquivalentTo(typeof(T))) 4: { 5: throw new ArgumentException("Enum value and flags types don't match."); 6: } 7:  8: // yes this is ugly, but unfortunately we need to use an intermediate boxing cast 9: return (T)Enum.ToObject(typeof (T), Convert.ToUInt64(value) | Convert.ToUInt64(flags)); 10: } Note that since the enum types are value types, we need to assign the result to something (much like string.Trim()).  Also, you could chain several SetFlag() operations together or create one that takes a variable arg list if desired. Parse() and ToString() – transitioning from string to enum and back Sometimes, you may want to be able to parse an enum from a string or convert it to a string - Enum has methods built in to let you do this.  Now, many may already know this, but may not appreciate how much power are in these two methods. For example, if you want to parse a string as an enum, it’s easy and works just like you’d expect from the numeric types: 1: string optionsString = "Persistent"; 2:  3: // can use Enum.Parse, which throws if finds something it doesn't like... 4: var result = (MessagingOptions)Enum.Parse(typeof (MessagingOptions), optionsString); 5:  6: if (result == MessagingOptions.Persistent) 7: { 8: Console.WriteLine("It worked!"); 9: } Note that Enum.Parse() will throw if it finds a value it doesn’t like.  But the values it likes are fairly flexible!  You can pass in a single value, or a comma separated list of values for flags and it will parse them all and set all bits: 1: // for string values, can have one, or comma separated. 2: string optionsString = "Persistent, Buffered"; 3:  4: var result = (MessagingOptions)Enum.Parse(typeof (MessagingOptions), optionsString); 5:  6: if (result.HasFlag(MessagingOptions.Persistent) && result.HasFlag(MessagingOptions.Buffered)) 7: { 8: Console.WriteLine("It worked!"); 9: } Or you can parse in a string containing a number that represents a single value or combination of values to set: 1: // 3 is the combination of Buffered (0x01) and Persistent (0x02) 2: var optionsString = "3"; 3:  4: var result = (MessagingOptions) Enum.Parse(typeof (MessagingOptions), optionsString); 5:  6: if (result.HasFlag(MessagingOptions.Persistent) && result.HasFlag(MessagingOptions.Buffered)) 7: { 8: Console.WriteLine("It worked again!"); 9: } And, if you really aren’t sure if the parse will work, and don’t want to handle an exception, you can use TryParse() instead: 1: string optionsString = "Persistent, Buffered"; 2: MessagingOptions result; 3:  4: // try parse returns true if successful, and takes an out parm for the result 5: if (Enum.TryParse(optionsString, out result)) 6: { 7: if (result.HasFlag(MessagingOptions.Persistent) && result.HasFlag(MessagingOptions.Buffered)) 8: { 9: Console.WriteLine("It worked!"); 10: } 11: } So we covered parsing a string to an enum, what about reversing that and converting an enum to a string?  The ToString() method is the obvious and most basic choice for most of us, but did you know you can pass a format string for enum types that dictate how they are written as a string?: 1: MessagingOptions value = MessagingOptions.Buffered | MessagingOptions.Persistent; 2:  3: // general format, which is the default, 4: Console.WriteLine("Default : " + value); 5: Console.WriteLine("G (default): " + value.ToString("G")); 6:  7: // Flags format, even if type does not have Flags attribute. 8: Console.WriteLine("F (flags) : " + value.ToString("F")); 9:  10: // integer format, value as number. 11: Console.WriteLine("D (num) : " + value.ToString("D")); 12:  13: // hex format, value as hex 14: Console.WriteLine("X (hex) : " + value.ToString("X")); Which displays: 1: Default : Buffered, Persistent 2: G (default): Buffered, Persistent 3: F (flags) : Buffered, Persistent 4: D (num) : 3 5: X (hex) : 00000003 Now, you may not really see a difference here between G and F because I used a [Flags] enum, the difference is that the “F” option treats the enum as if it were flags even if the [Flags] attribute is not present.  Let’s take a non-flags enum like the ResultCode used earlier: 1: // yes, we can do this even if it is not [Flags] enum. 2: ResultCode value = ResultCode.Warning | ResultCode.Error; And if we run that through the same formats again we get: 1: Default : 3 2: G (default): 3 3: F (flags) : Warning, Error 4: D (num) : 3 5: X (hex) : 00000003 Notice that since we had multiple values combined, but it was not a [Flags] marked enum, the G and default format gave us a number instead of a value name.  This is because the value was not a valid single-value constant of the enum.  However, using the F flags format string, it broke out the value into its component flags even though it wasn’t marked [Flags]. So, if you want to get an enum to display appropriately for whether or not it has the [Flags] attribute, use G which is the default.  If you always want it to attempt to break down the flags, use F.  For numeric output, obviously D or  X are the best choice depending on whether you want decimal or hex. Summary Hopefully, you learned a couple of new tricks with using the Enum class today!  I’ll add more little wonders as I think of them and thanks for all the invaluable input!   Technorati Tags: C#,.NET,Little Wonders,Enum,BlackRabbitCoder

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  • CLR via C# 3rd Edition is out

    - by Abhijeet Patel
    Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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  • Using Umbraco&rsquo;s Dropdown Datatype

    - by MightyZot
    In Umbraco, you could consider document types like models and data types as property types for those modes. For example, you may create a document type called “Prices” to represent a page that displays a list of prices. And, then, you might create a document type called “Price Item” to represent the price list items. A property called “Price” could then represent the price of an item. When you create the Price property, you specify the data type, which in this case might be “Number”, indicating that this particular field accepts only numerical values. Consequently, you could also create a drop down list property called “Category”, allowing you to categorize the items in your price list. To add items to the drop down list, you modify the data type definition in the Developer module of the Umbraco administrative utility. Instead of modifying the drop down data type itself, you should first make a copy by right-clicking on the Data Types node and choosing Create. Give your new data type a name in the Create dialog and click the Create button. In the Edit datatype dialog, change “Render control” to “Dropdown list”.  To add your list items, simply enter that value into the textbox next to “Add prevalue” and click Save or press the Enter key. Now that you have a new drop down list data type created, along with assigned list items, you can use it in your document type definitions just like you would the other data types.

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  • MVC: Why put the business logic in the model? What happens when I've multiple types of storage?

    - by Steffen Winkler
    I always thought that the business logic has to be in the controller and that the controller, since it is the 'middle' part, stays static and that the model/view have to be capsuled via interfaces, that way you could change the business logic without affecting anything else, program multiple Models (one for each database/type of storage) and a dozens of views (for different platforms for example). Now I read in this question that you should always put the business logic into the model and that the controller is deeply connected with the view. To me, that doesn't really make sense and implies that each time I want to have the means of supporting another database/type of storage I've to rewrite my whole model including the business logic. And if I want another view, I've to rewrite both the view and the controller. May someone explain why that is or if I went wrong somewhere? Currently, that whole thing doesn't really make sense to me.

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  • First languages with generic programming support

    - by oluies
    Which was the first language with generic programming support, and what was the first major staticly typed language (widely used) with generics support. Generics implement the concept of parameterized types to allow for multiple types. The term generic means "pertaining to or appropriate to large groups of classes." I have seen the following mentions of "first": First-order parametric polymorphism is now a standard element of statically typed programming languages. Starting with System F [20,42] and functional programming lan- guages, the constructs have found their way into mainstream languages such as Java and C#. In these languages, first-order parametric polymorphism is usually called generics. From "Generics of a Higher Kind", Adriaan Moors, Frank Piessens, and Martin Odersky Generic programming is a style of computer programming in which algorithms are written in terms of to-be-specified-later types that are then instantiated when needed for specific types provided as parameters. This approach, pioneered by Ada in 1983 From Wikipedia Generic Programming

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  • First languages with generic programming support

    - by oluies
    Which was the first language with generic programming support, and what was the first major staticly typed language (widely used) with generics support. Generics implement the concept of parameterized types to allow for multiple types. The term generic means "pertaining to or appropriate to large groups of classes." I have seen the following mentions of "first": First-order parametric polymorphism is now a standard element of statically typed programming languages. Starting with System F [20,42] and functional programming lan- guages, the constructs have found their way into mainstream languages such as Java and C#. In these languages, first-order parametric polymorphism is usually called generics. From "Generics of a Higher Kind", Adriaan Moors, Frank Piessens, and Martin Odersky Generic programming is a style of computer programming in which algorithms are written in terms of to-be-specified-later types that are then instantiated when needed for specific types provided as parameters. This approach, pioneered by Ada in 1983 From Wikipedia Generic Programming

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  • Best Practices Generating WebService Proxies for Oracle Sales Cloud (Fusion CRM)

    - by asantaga
    I've recently been building a REST Service wrapper for Oracle Sales Cloud and initially all was going well, however as soon as I added all of my Web Service proxies I started to get weird errors..  My project structure looks like this What I found out was if I only had the InteractionsService & OpportunityService WebService Proxies then all worked ok, but as soon as I added the LocationsService Proxy, I would start to see strange JAXB errors. Example of the error message Exception in thread "main" javax.xml.ws.WebServiceException: Unable to create JAXBContextat com.sun.xml.ws.model.AbstractSEIModelImpl.createJAXBContext(AbstractSEIModelImpl.java:164)at com.sun.xml.ws.model.AbstractSEIModelImpl.postProcess(AbstractSEIModelImpl.java:94)at com.sun.xml.ws.model.RuntimeModeler.buildRuntimeModel(RuntimeModeler.java:281)at com.sun.xml.ws.client.WSServiceDelegate.buildRuntimeModel(WSServiceDelegate.java:762)at weblogic.wsee.jaxws.spi.WLSProvider$ServiceDelegate.buildRuntimeModel(WLSProvider.java:982)at com.sun.xml.ws.client.WSServiceDelegate.createSEIPortInfo(WSServiceDelegate.java:746)at com.sun.xml.ws.client.WSServiceDelegate.addSEI(WSServiceDelegate.java:737)at com.sun.xml.ws.client.WSServiceDelegate.getPort(WSServiceDelegate.java:361)at weblogic.wsee.jaxws.spi.WLSProvider$ServiceDelegate.internalGetPort(WLSProvider.java:934)at weblogic.wsee.jaxws.spi.WLSProvider$ServiceDelegate$PortClientInstanceFactory.createClientInstance(WLSProvider.java:1039)...... Looking further down I see the error message is related to JAXB not being able to find an objectFactory for one of its types Caused by: java.security.PrivilegedActionException: com.sun.xml.bind.v2.runtime.IllegalAnnotationsException: 6 counts of IllegalAnnotationExceptionsThere's no ObjectFactory with an @XmlElementDecl for the element {http://xmlns.oracle.com/apps/crmCommon/activities/activitiesService/}AssigneeRsrcOrgIdthis problem is related to the following location:at protected javax.xml.bind.JAXBElement com.oracle.xmlns.apps.crmcommon.activities.activitiesservice.ActivityAssignee.assigneeRsrcOrgId at com.oracle.xmlns.apps.crmcommon.activities.activitiesservice.ActivityAssignee This is very strange... My first thoughts are that when I generated the WebService Proxy I entered the package name as "oracle.demo.pts.fusionproxy.servicename" and left the generated types as blank. This way all the generated types get put into the same package hierarchy and when deployed they get merged... Sounds resaonable and appears to work but not in this case..  To resolve this I regenerate the proxy but this time setting : Package name : To the name of my package eg. oracle.demo.pts.fusionproxy.interactionsRoot Package for Generated Types :  Package where the types will be generated to, e.g. oracle.demo.pts.fusionproxy.SalesParty.types When I ran the application now, it all works , awesome eh???? Alas no, there is a serious side effect. The problem now is that to help coding I've created a collection of helper classes , these helper classes take parameters which use some of the "generic" datatypes, like FindCriteria. e.g. This wont work any more public static FindCriteria createCustomFindCriteria(FindCriteria pFc,String pAttributes) Here lies a gremlin of a problem.. I cant use this method anymore, this is because the FindCriteria datatype is now being defined two, or more times, in the generated code for my project. If you leave the Root Package for types blank it will get generated to com.oracle.xmlns, and if you populate it then it gets generated to your custom package.. The two datatypes look the same, sound the same (and if this were a duck would sound the same), but THEY ARE NOT THE SAME... Speaking to development, they recommend you should not be entering anything in the Root Packages section, so the mystery thickens why does it work.. Well after spending sometime with some colleagues of mine in development we've identified the issue.. Alas different parts of Oracle Fusion Development have multiple schemas with the same namespace, when the WebService generator generates its classes its not seeing the other schemas properly and not generating the Object Factories correctly...  Thankfully I've found a workaround Solution Overview When generating the proxies leave the Root Package for Generated Types BLANK When you have finished generating your proxies, use the JAXB tool XJC and generate Java classes for all datatypes  Create a project within your JDeveloper11g workspace and import the java classes into this project Final bit.. within the project dependencies ensure that the JAXB/XJC generated classes are "FIRST" in the classpath Solution Details Generate the WebServices SOAP proxies When generating the proxies your generation dialog should look like this Ensure the "unwrap" parameters is selected, if it isn't then that's ok, it simply means when issuing a "get" you need to extract out the Element Generate the JAXB Classes using XJC XJC provides a command line switch called -wsdl, this (although is experimental/beta) , accepts a HTTP WSDL and will generate the relevant classes. You can put these into a single batch/shell script xjc -wsdl https://fusionservername:443/appCmmnCompInteractions/InteractionService?wsdlxjc -wsdl https://fusionservername443/opptyMgmtOpportunities/OpportunityService?wsdl Create Project in JDeveloper to store the XJC "generated" JAXB classes Within the project folder create a filesystem folder called "src" and copy the generated files into this folder. JDeveloper11g should then see the classes and display them, if it doesnt try clicking the "refresh" button In your main project ensure that the JDeveloper XJC project is selected as a dependancy and IMPORTANT make sure it is at the top of the list. This ensures that the classes are at the front of the classpath And voilà.. Hopefully you wont see any JAXB generation errors and you can use common datatypes interchangeably in your project, (e.g. FindCriteria etc)

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  • New Development Snapshot

    More bug fixing and rounding out IKVM.Reflection. Changes: Fixed resolution of generic type instance names with "fake" type as type argument. Fixed bug in Finalize/finalize special casing for .NET types that caused exception when reflecting on them. Fixed Finalize/finalize special casing for .NET types to also work for java.lang.Throwable derived types. Removed fake core class library types from ikvmstub and added a -bootstrap...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Artificial Neural Networks

    - by user1724140
    I have an Artificial Networks which needs to recognize 130 different types of moves encoded in terms of 1s and 0s. Therefore the number of outputs I used is 8 so that all my patterns could be distinguished. However, by using 8 outputs, the different types of patterns possible is 256, leaving me with 126 different types of patterns useless. Do these extra 126 different patterns ruin my ANN's ability? Is there a better way not to have these unused holes?

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  • Unable to import Eclipse project to Android studio

    - by Binoy Babu
    Whenever I try to import my Eclipse project to Android Studio I get the following error : You are using an old, unsupported version of Gradle. Please use version 1.8 or greater. Please point to a supported Gradle version in the project's Gradle settings or in the project's Gradle wrapper (if applicable.) Consult IDE log for more details (Help | Show Log) Im using Android Studio 0.3 and Ubuntu, I also tried it on a Windows 8 box with fresh install but getting the same error. I'm using default gradle wrapper and I tried checking and unchecking auto import option. Is this a bug? How can I get around it. How do I update gradle to 1.8 or check the current gradle version? My build.gradle is given below. buildscript { repositories { mavenCentral() } dependencies { classpath 'com.android.tools.build:gradle:0.6.3' // I also tried using 0.6.1 and 0.5.+ } } apply plugin: 'android' dependencies { compile fileTree(dir: 'libs', include: '*.jar') } android { compileSdkVersion 18 buildToolsVersion "18.0.1" sourceSets { main { manifest.srcFile 'AndroidManifest.xml' java.srcDirs = ['src'] resources.srcDirs = ['src'] aidl.srcDirs = ['src'] renderscript.srcDirs = ['src'] res.srcDirs = ['res'] assets.srcDirs = ['assets'] } // Move the tests to tests/java, tests/res, etc... instrumentTest.setRoot('tests') // Move the build types to build-types/<type> // For instance, build-types/debug/java, build-types/debug/AndroidManifest.xml, ... // This moves them out of them default location under src/<type>/... which would // conflict with src/ being used by the main source set. // Adding new build types or product flavors should be accompanied // by a similar customization. debug.setRoot('build-types/debug') release.setRoot('build-types/release') } }

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  • PHP SOAP error: Method element needs to belong to the namespace

    - by kdm
    I'm unable to retrieve data from an XML document, any help is greatly appreciated. I'm using PHP 5.2.10 and the WSDL url is an internal link within my company. The following code produces an error. $url = "http://dta-info/IVR/IVRINFO?WSDL"; $params = array("zANI" => "12345"); try{ $client = new SoapClient($url, array( 'trace' => 1, 'connection_timeout' => 2, 'location' => $url ) ); }catch(SoapFault $fault){ echo "faultstring: {$fault->faultstring})\n"; } try{ $result = $client->GetIVRinfo($params); }catch(SoapFault $fault){ echo "(faultcode: {$fault->faultcode}, faultstring: {$fault->faultstring} )\n"; } (faultcode: SOAP-ENV:Client, faultstring: There should be no path or parameters after a SOAP vname. ) So i tried to use a non-wsdl mode but i receive a different error no matter how i try to format the params. $url = "http://dta-info/IVR/IVRINFO"; $params = array("zANI" => "12345"); try{ $client = new SoapClient(null, array( 'trace' => 1, 'connection_timeout' => 2, 'location' => $url, 'uri' => $uri, 'style' => SOAP_DOCUMENT, 'use' => SOAP_LITERAL, 'soap_version' => SOAP_2 ) ); }catch(SoapFault $fault){ echo "faultstring: {$fault->faultstring})\n"; } try{ $result = $client->GetIVRinfo($params); }catch(SoapFault $fault){ echo "(faultcode: {$fault->faultcode}, faultstring: {$fault->faultstring} )\n"; } (faultcode: SOAP-ENV:Client, faultstring: The method element needs to belong to the namespace 'http://GETIVRINFO/IVR/IVRINFO'. ) I have tested this WSDL with a tool called SoapUI and it returns the results with no errors. So it leads me to believe I'm not formatting the vars or headers correctly with PHP. I also tried passing in a xml fragment as the param but that returns the same error. What am i doing wrong?????? $params = '<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ivr="http://GETIVRINFO/IVR/IVRINFO"> <soapenv:Header/> <soapenv:Body> <ivr:GetIVRinfo> <!--Optional:--> <ivr:zANI>12345</ivr:zANI> </ivr:GetIVRinfo> </soapenv:Body> </soapenv:Envelope>'; Here is the WSDL document: <?xml version="1.0"?><wsdl:definitions name="IVR" targetNamespace="http://GETIVRINFO/IVR/IVRINFO" xmlns:tns="http://GETIVRINFO/IVR/IVRINFO" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:sql="http://schemas.microsoft.com/SQLServer/2001/12/SOAP" xmlns:sqltypes="http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types" xmlns:sqlmessage="http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types/SqlMessage" xmlns:sqlresultstream="http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types/SqlResultStream"> <wsdl:types><xsd:schema targetNamespace='http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types' elementFormDefault='qualified' attributeFormDefault='qualified'> <xsd:import namespace='http://www.w3.org/2001/XMLSchema'/> <xsd:simpleType name='nonNegativeInteger'> <xsd:restriction base='xsd:int'> <xsd:minInclusive value='0'/> </xsd:restriction> </xsd:simpleType> <xsd:attribute name='IsNested' type='xsd:boolean'/> <xsd:complexType name='SqlRowSet'> <xsd:sequence> <xsd:element ref='xsd:schema'/> <xsd:any/> </xsd:sequence> <xsd:attribute ref='sqltypes:IsNested'/> </xsd:complexType> <xsd:complexType name='SqlXml' mixed='true'> <xsd:sequence> <xsd:any/> </xsd:sequence> </xsd:complexType> <xsd:simpleType name='SqlResultCode'> <xsd:restriction base='xsd:int'> <xsd:minInclusive value='0'/> </xsd:restriction> </xsd:simpleType> </xsd:schema> <xsd:schema targetNamespace='http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types/SqlMessage' elementFormDefault='qualified' attributeFormDefault='qualified'> <xsd:import namespace='http://www.w3.org/2001/XMLSchema'/> <xsd:import namespace='http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types'/> <xsd:complexType name='SqlMessage'> <xsd:sequence minOccurs='1' maxOccurs='1'> <xsd:element name='Class' type='sqltypes:nonNegativeInteger'/> <xsd:element name='LineNumber' type='sqltypes:nonNegativeInteger'/> <xsd:element name='Message' type='xsd:string'/> <xsd:element name='Number' type='sqltypes:nonNegativeInteger'/> <xsd:element name='Procedure' type='xsd:string'/> <xsd:element name='Server' type='xsd:string'/> <xsd:element name='Source' type='xsd:string'/> <xsd:element name='State' type='sqltypes:nonNegativeInteger'/> </xsd:sequence> <xsd:attribute ref='sqltypes:IsNested'/> </xsd:complexType> </xsd:schema> <xsd:schema targetNamespace='http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types/SqlResultStream' elementFormDefault='qualified' attributeFormDefault='qualified'> <xsd:import namespace='http://www.w3.org/2001/XMLSchema'/> <xsd:import namespace='http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types'/> <xsd:import namespace='http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types/SqlMessage'/> <xsd:complexType name='SqlResultStream'> <xsd:choice minOccurs='1' maxOccurs='unbounded'> <xsd:element name='SqlRowSet' type='sqltypes:SqlRowSet'/> <xsd:element name='SqlXml' type='sqltypes:SqlXml'/> <xsd:element name='SqlMessage' type='sqlmessage:SqlMessage'/> <xsd:element name='SqlResultCode' type='sqltypes:SqlResultCode'/> </xsd:choice> </xsd:complexType> </xsd:schema> <xsd:schema targetNamespace="http://GETIVRINFO/IVR/IVRINFO" elementFormDefault="qualified" attributeFormDefault="qualified"> <xsd:import namespace="http://www.w3.org/2001/XMLSchema"/> <xsd:import namespace="http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types"/> <xsd:import namespace="http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types/SqlMessage"/> <xsd:import namespace="http://schemas.microsoft.com/SQLServer/2001/12/SOAP/types/SqlResultStream"/> <xsd:element name="GetIVRinfo"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="1" name="zANI" type="xsd:string" nillable="true"/> </xsd:sequence> </xsd:complexType> </xsd:element> <xsd:element name="GetIVRinfoResponse"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="1" maxOccurs="1" name="GetIVRinfoResult" type="sqlresultstream:SqlResultStream"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:schema> </wsdl:types> <wsdl:message name="GetIVRinfoIn"> <wsdl:part name="parameters" element="tns:GetIVRinfo"/> </wsdl:message> <wsdl:message name="GetIVRinfoOut"> <wsdl:part name="parameters" element="tns:GetIVRinfoResponse"/> </wsdl:message> <wsdl:portType name="SXSPort"> <wsdl:operation name="GetIVRinfo"> <wsdl:input message="tns:GetIVRinfoIn"/> <wsdl:output message="tns:GetIVRinfoOut"/> </wsdl:operation> </wsdl:portType> <wsdl:binding name="SXSBinding" type="tns:SXSPort"> <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/> <wsdl:operation name="GetIVRinfo"> <soap:operation soapAction="http://GETIVRINFO/IVR/IVRINFO/GetIVRinfo" style="document"/> <wsdl:input> <soap:body use="literal"/> </wsdl:input> <wsdl:output> <soap:body use="literal"/> </wsdl:output> </wsdl:operation> </wsdl:binding> <wsdl:service name="IVR"> <wsdl:port name="SXSPort" binding="tns:SXSBinding"> <soap:address location="http://GETIVRINFO/IVR/IVRINFO"/> </wsdl:port> </wsdl:service> </wsdl:definitions>

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  • C# reflection instantiation

    - by NickLarsen
    I am currently trying to create a generic instance factory for which takes an interface as the generic parameter (enforced in the constructor) and then lets you get instantiated objects which implement that interface from all types in all loaded assemblies. The current implementation is as follows:     public class InstantiationFactory     {         protected Type Type { get; set; }         public InstantiationFactory()         {             this.Type = typeof(T);             if (!this.Type.IsInterface)             {                 // is there a more descriptive exception to throw?                 throw new ArgumentException(/* Crafty message */);             }         }         public IEnumerable GetLoadedTypes()         {             // this line of code found in other stack overflow questions             var types = AppDomain.CurrentDomain.GetAssemblies()                 .SelectMany(a = a.GetTypes())                 .Where(/* lambda to identify instantiable types which implement this interface */);             return types;         }         public IEnumerable GetImplementations(IEnumerable types)         {             var implementations = types.Where(/* lambda to identify instantiable types which implement this interface */                 .Select(x = CreateInstance(x));             return implementations;         }         public IEnumerable GetLoadedImplementations()         {             var loadedTypes = GetLoadedTypes();             var implementations = GetImplementations(loadedTypes);             return implementations;         }         private T CreateInstance(Type type)         {             T instance = default(T);             var constructor = type.GetConstructor(Type.EmptyTypes);             if (/* valid to instantiate test */)             {                 object constructed = constructor.Invoke(null);                 instance = (T)constructed;             }             return instance;         }     } It seems useful to me to have my CreateInstance(Type) function implemented as an extension method so I can reuse it later and simplify the code of my factory, but I can't figure out how to return a strongly typed value from that extension method. I realize I could just return an object:     public static class TypeExtensions     {         public object CreateInstance(this Type type)         {             var constructor = type.GetConstructor(Type.EmptyTypes);             return /* valid to instantiate test */ ? constructor.Invoke(null) : null;         }     } Is it possible to have an extension method create a signature per instance of the type it extends? My perfect code would be this, which avoids having to cast the result of the call to CreateInstance():     Type type = typeof(MyParameterlessConstructorImplementingType);     MyParameterlessConstructorImplementingType usable = type.CreateInstance();

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