optional-parameters

I come with this: (defn string->integer [str & [base]] (Integer/parseInt str (if (nil? base) 10 base))) (string->integer "10") (string->integer "FF" 16) But it must be a better way to do this. A function can have multiple signatures if the signatures differ in arity. You can use that to supply default values. (defn string->integer ([s] (string->integer s 10)) ([s base] (Integer/parseInt s base))) Note that assuming false and nil are both considered non-values, (if (nil? base) 10 base) could be shortened to (if base base 10) , or further to (or base 10) . You can also destructure rest arguments

How can I declare a managed method in C++/CLI that has an optional parameter when used from C#? I've decorated the parameter with both an Optional and a DefaultParameterValue attribute (see: How default parameter values are encoded ), but only the Optional attribute seems to be honored. C++/CLI: public ref class MyClass1 { public: MyClass1([System::Runtime::InteropServices::Optional] [System::Runtime::InteropServices::DefaultParameterValue(2)] int myParam1) ↑ { System::Console::WriteLine(myParam1); } }; C#: var myInstance1 = new MyClass1(); // compiles and runs Output : 0 Expected Output: 2

You can declare optional parameters in an interface method but implementing classes are not required to declare the parameters as optional, as Eric Lippert explained . Conversely, you can declare a parameter as optional in an implementing class but not in the interface. So is there any reason to declare optional parameters in an interface? If not, why is it allowed? Examples: public interface IService1 { void MyMethod(string text, bool flag = false); } public class MyService1a : IService1 { public void MyMethod(string text, bool flag) {} } public class MyService1b : IService1 { public void

I need to provide following functionality for one of the web sites. http://www.example.com/ [sponsor] /{controller}/{action} Depending on the [sponsor], the web page has to be customized. I tried combination of registering the routes with Application_Start and Session_Start but not able to get it working. public static void RegisterRoutes(RouteCollection routes, string sponsor) { if (routes[sponsor] == null) { routes.MapRoute( sponsor, // Route name sponsor + "/{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional } //

I am developing a framework, where in I am a calling stored procedure with dynamically created parameters. I am building parameter collection at the runtime. The problem occurs when I am passing a parameter to stored procedure, but stored proc doesn't accept such parameter. For example, my stored procedure is: CREATE PROCEDURE GetTaskEvents @TaskName varchar(50) AS BEGIN -- SP Logic END Calling stored procedure as: EXEC GetTaskEvents @TaskName = 'TESTTASK', @ID = 2 This throws below error: Msg 8144, Level 16, State 2, Procedure GetTaskEvents, Line 0 Procedure or function GetTaskEvents has too

I wish to say: public void Problem(Guid optional = Guid.Empty) { } But the compiler complains that Guid.Empty is not a compile time constant. As I don’t wish to change the API I can’t use: Nullable<Guid> Meligy Solution You can use new Guid() instead public void Problem(Guid optional = new Guid()) { // when called without parameters this will be true var guidIsEmpty = optional == Guid.Empty; } You can also use default(Guid) default(Guid) also will work exactly as new Guid() . Because Guid is a value type not reference type, so, default(Guid) is not equal to null for example, instead, it's