Can anonymous class implement interface

Question

Is it possible to have an anonymous type implement an interface   I ve got a piece of code that I would like to work  but don t know how to do this   I ve had a couple of answers that either say no  or create a class that implements the interface construct new instances of that  This isn t really ideal  but I m wondering if there is a mechanism to create a thin dynamic class on top of an interface which would make this simple   public interface DummyInterface       string A   get        string B   get       public class DummySource       public string A   get  set        public string C   get  set        public string D   get  set       public class Test       public void WillThisWork                 var source   new DummySource 0           var values   from value in source                      select new                                                 A   value A                           B   value C         value D                                  DoSomethingWithDummyInterface values               public void DoSomethingWithDummyInterface IEnumerable lt DummyInterface gt  values                foreach  var value in values                        Console WriteLine  A     0    B     1     value A  value B                       I ve found an article Dynamic interface wrapping that describes one approach  Is this the best way of doing this

User · Answer

Casting anonymous types to interfaces has been something I've wanted for a while but unfortunately the current implementation forces you to have an implementation of that interface.

The best solution around it is having some type of dynamic proxy that creates the implementation for you. Using the excellent LinFu project you can replace

select new
{
  A = value.A,
  B = value.C + "_" + value.D
};

with

 select new DynamicObject(new
 {
   A = value.A,
   B = value.C + "_" + value.D
 }).CreateDuck<DummyInterface>();

User · Answer

No  anonymous types cannot implement an interface  From the C  programming guide      Anonymous types are class types that consist of one or more public read-only properties  No other kinds of class members such as methods or events are allowed  An anonymous type cannot be cast to any interface or type except for object

User · Answer

No  an anonymous type can t be made to do anything except have a few properties  You will need to create your own type  I didn t read the linked article in depth  but it looks like it uses Reflection Emit to create new types on the fly  but if you limit discussion to things within C  itself you can t do what you want

User · Answer

Another option is to create a single  concrete implementing class that takes lambdas in the constructor   public interface DummyInterface       string A   get        string B   get           Generic  implementing class public class Dummy   DummyInterface       private readonly Func lt string gt   getA      private readonly Func lt string gt   getB       public Dummy Func lt string gt  getA  Func lt string gt  getB                 getA   getA           getB   getB             public string A   gt   getA         public string B   gt   getB       public class DummySource       public string A   get  set        public string C   get  set        public string D   get  set       public class Test       public void WillThisWork                 var source   new DummySource 0           var values   from value in source                      select new Dummy    Syntax changes slightly                                                 getA       gt  value A                           getB       gt  value C         value D                                  DoSomethingWithDummyInterface values               public void DoSomethingWithDummyInterface IEnumerable lt DummyInterface gt  values                foreach  var value in values                        Console WriteLine  A     0    B     1     value A  value B                       If all you are ever going to do is convert DummySource to DummyInterface  then it would be simpler to just have one class that takes a DummySource in the constructor and implements the interface   But  if you need to convert many types to DummyInterface  this is much less boiler plate

User · Answer

The answer to the question specifically asked is no  But have you been looking at mocking frameworks  I use MOQ but there s millions of them out there and they allow you to implement stub  partially or fully  interfaces in-line  Eg   public void ThisWillWork         var source   new DummySource 0       var mock   new Mock lt DummyInterface gt          mock SetupProperty m   gt  m A  source Select s   gt  s A        mock SetupProperty m   gt  m B  source Select s   gt  s C         s D         DoSomethingWithDummyInterface mock Object

User · Answer

No  anonymous types cannot implement an interface  From the C  programming guide      Anonymous types are class types that consist of one or more public read-only properties  No other kinds of class members such as methods or events are allowed  An anonymous type cannot be cast to any interface or type except for object

User · Answer

The best solution is just not to use anonymous classes   public class Test       class DummyInterfaceImplementor   IDummyInterface               public string A   get  set            public string B   get  set               public void WillThisWork                 var source   new DummySource 0           var values   from value in source                      select new DummyInterfaceImplementor                                                   A   value A                           B   value C         value D                                  DoSomethingWithDummyInterface values Cast lt IDummyInterface gt                  public void DoSomethingWithDummyInterface IEnumerable lt IDummyInterface gt  values                foreach  var value in values                        Console WriteLine  A     0    B     1     value A  value B                       Note that you need to cast the result of the query to the type of the interface  There might be a better way to do it  but I couldn t find it

User · Answer

Casting anonymous types to interfaces has been something I've wanted for a while but unfortunately the current implementation forces you to have an implementation of that interface.

The best solution around it is having some type of dynamic proxy that creates the implementation for you. Using the excellent LinFu project you can replace

select new
{
  A = value.A,
  B = value.C + "_" + value.D
};

with

 select new DynamicObject(new
 {
   A = value.A,
   B = value.C + "_" + value.D
 }).CreateDuck<DummyInterface>();

User · Answer

The best solution is just not to use anonymous classes   public class Test       class DummyInterfaceImplementor   IDummyInterface               public string A   get  set            public string B   get  set               public void WillThisWork                 var source   new DummySource 0           var values   from value in source                      select new DummyInterfaceImplementor                                                   A   value A                           B   value C         value D                                  DoSomethingWithDummyInterface values Cast lt IDummyInterface gt                  public void DoSomethingWithDummyInterface IEnumerable lt IDummyInterface gt  values                foreach  var value in values                        Console WriteLine  A     0    B     1     value A  value B                       Note that you need to cast the result of the query to the type of the interface  There might be a better way to do it  but I couldn t find it

User · Answer

No  anonymous types cannot implement an interface  From the C  programming guide      Anonymous types are class types that consist of one or more public read-only properties  No other kinds of class members such as methods or events are allowed  An anonymous type cannot be cast to any interface or type except for object

User · Answer

Using Roslyn  you can dynamically create a class which inherits from an interface  or abstract class   I use the following to create concrete classes from abstract classes  In this example  AAnimal is an abstract class  var personClass   typeof AAnimal  CreateSubclass  quot Person quot     Then you can instantiate some objects  var person1   Activator CreateInstance personClass   var person2   Activator CreateInstance personClass    Without a doubt this won t work for every case  but it should be enough to get you started  using Microsoft CodeAnalysis  using Microsoft CodeAnalysis CSharp  using System  using System Collections Generic  using System IO  using System Linq  using System Reflection   namespace Publisher       public static class Extensions               public static Type CreateSubclass this Type baseType  string newClassName  string newNamespace    quot Magic quot                           todo  handle ref  out etc              var concreteMethods   baseType                                      GetMethods                                        Where method   gt  method IsAbstract                                       Select method   gt                                                                                var parameters   method                                                              GetParameters                                                                Select param   gt    quot  param ParameterType FullName   param Name  quot                                                                ToString  quot    quot                                             var returnTypeStr   method ReturnParameter ParameterType Name                                          if  returnTypeStr Equals  quot Void quot    returnTypeStr    quot void quot                                            var methodString      quot                                          public override  returnTypeStr   method Name   parameters                                                                                          Console WriteLine  quot  quot  newNamespace   newClassName   method Name    was called quot  quot                                               quot                                            return methodString Trim                                                                                ToList                 var concreteMethodsString   concreteMethods                                          ToString Environment NewLine   Environment NewLine                var classCode      quot              using System               namespace  newNamespace                                 public class  newClassName    baseType FullName                                         public  newClassName                                                                        concreteMethodsString                                                 quot  Trim                 classCode   FormatUsingRoslyn classCode                                var assemblies   new                                 MetadataReference CreateFromFile typeof object  Assembly Location                   MetadataReference CreateFromFile baseType Assembly Location                                              var assemblies   AppDomain                          CurrentDomain                          GetAssemblies                            Where a   gt   string IsNullOrEmpty a Location                            Select a   gt  MetadataReference CreateFromFile a Location                            ToArray                 var syntaxTree   CSharpSyntaxTree ParseText classCode                var compilation   CSharpCompilation                                  Create newNamespace                                   AddSyntaxTrees syntaxTree                                   AddReferences assemblies                                   WithOptions new CSharpCompilationOptions OutputKind DynamicallyLinkedLibrary                 using  var ms   new MemoryStream                                  var result   compilation Emit ms                     compilation Emit   quot C   Temp   newNamespace  dll quot                     if  result Success                                        ms Seek 0  SeekOrigin Begin                       Assembly assembly   Assembly Load ms ToArray                          var newTypeFullName     quot  newNamespace   newClassName  quot                        var type   assembly GetType newTypeFullName                       return type                                    else                                       IEnumerable lt Diagnostic gt  failures   result Diagnostics Where diagnostic   gt                          diagnostic IsWarningAsError                            diagnostic Severity    DiagnosticSeverity Error                        foreach  Diagnostic diagnostic in failures                                                Console Error WriteLine  quot  0    1  quot   diagnostic Id  diagnostic GetMessage                                                return null                                                     public static string ToString this IEnumerable lt string gt  list  string separator                        string result   string Join separator  list               return result                     public static string FormatUsingRoslyn string csCode                        var tree   CSharpSyntaxTree ParseText csCode               var root   tree GetRoot   NormalizeWhitespace                var result   root ToFullString                return result

User · Answer

No  anonymous types cannot implement an interface  From the C  programming guide      Anonymous types are class types that consist of one or more public read-only properties  No other kinds of class members such as methods or events are allowed  An anonymous type cannot be cast to any interface or type except for object

User · Answer

While the answers in the thread are all true enough  I cannot resist the urge to tell you that it in fact is possible to have an anonymous class implement an interface  even though it takes a bit of creative cheating to get there  Back in 2008 I was writing a custom LINQ provider for my then employer  and at one point I needed to be able to tell  quot my quot  anonymous classes from other anonymous ones  which meant having them implement an interface that I could use to type check them  The way we solved it was by using aspects  we used PostSharp   to add the interface implementation directly in the IL  So  in fact  letting anonymous classes implement interfaces is doable  you just need to bend the rules slightly to get there

User · Answer

Casting anonymous types to interfaces has been something I've wanted for a while but unfortunately the current implementation forces you to have an implementation of that interface.

The best solution around it is having some type of dynamic proxy that creates the implementation for you. Using the excellent LinFu project you can replace

select new
{
  A = value.A,
  B = value.C + "_" + value.D
};

with

 select new DynamicObject(new
 {
   A = value.A,
   B = value.C + "_" + value.D
 }).CreateDuck<DummyInterface>();

User · Answer

The best solution is just not to use anonymous classes   public class Test       class DummyInterfaceImplementor   IDummyInterface               public string A   get  set            public string B   get  set               public void WillThisWork                 var source   new DummySource 0           var values   from value in source                      select new DummyInterfaceImplementor                                                   A   value A                           B   value C         value D                                  DoSomethingWithDummyInterface values Cast lt IDummyInterface gt                  public void DoSomethingWithDummyInterface IEnumerable lt IDummyInterface gt  values                foreach  var value in values                        Console WriteLine  A     0    B     1     value A  value B                       Note that you need to cast the result of the query to the type of the interface  There might be a better way to do it  but I couldn t find it

User · Answer

No  an anonymous type can t be made to do anything except have a few properties  You will need to create your own type  I didn t read the linked article in depth  but it looks like it uses Reflection Emit to create new types on the fly  but if you limit discussion to things within C  itself you can t do what you want

User · Answer

The answer to the question specifically asked is no  But have you been looking at mocking frameworks  I use MOQ but there s millions of them out there and they allow you to implement stub  partially or fully  interfaces in-line  Eg   public void ThisWillWork         var source   new DummySource 0       var mock   new Mock lt DummyInterface gt          mock SetupProperty m   gt  m A  source Select s   gt  s A        mock SetupProperty m   gt  m B  source Select s   gt  s C         s D         DoSomethingWithDummyInterface mock Object

User · Answer

Casting anonymous types to interfaces has been something I've wanted for a while but unfortunately the current implementation forces you to have an implementation of that interface.

The best solution around it is having some type of dynamic proxy that creates the implementation for you. Using the excellent LinFu project you can replace

select new
{
  A = value.A,
  B = value.C + "_" + value.D
};

with

 select new DynamicObject(new
 {
   A = value.A,
   B = value.C + "_" + value.D
 }).CreateDuck<DummyInterface>();

User · Answer

Anonymous types can implement interfaces via a dynamic proxy   I wrote an extension method on GitHub and a blog post http   wblo gs feE to support this scenario    The method can be used like this   class Program       static void Main string   args                var developer   new   Name    Jason Bowers              PrintDeveloperName developer DuckCast lt IDeveloper gt               Console ReadKey               private static void PrintDeveloperName IDeveloper developer                Console WriteLine developer Name            public interface IDeveloper       string Name   get

User · Answer

Another option is to create a single  concrete implementing class that takes lambdas in the constructor   public interface DummyInterface       string A   get        string B   get           Generic  implementing class public class Dummy   DummyInterface       private readonly Func lt string gt   getA      private readonly Func lt string gt   getB       public Dummy Func lt string gt  getA  Func lt string gt  getB                 getA   getA           getB   getB             public string A   gt   getA         public string B   gt   getB       public class DummySource       public string A   get  set        public string C   get  set        public string D   get  set       public class Test       public void WillThisWork                 var source   new DummySource 0           var values   from value in source                      select new Dummy    Syntax changes slightly                                                 getA       gt  value A                           getB       gt  value C         value D                                  DoSomethingWithDummyInterface values               public void DoSomethingWithDummyInterface IEnumerable lt DummyInterface gt  values                foreach  var value in values                        Console WriteLine  A     0    B     1     value A  value B                       If all you are ever going to do is convert DummySource to DummyInterface  then it would be simpler to just have one class that takes a DummySource in the constructor and implements the interface   But  if you need to convert many types to DummyInterface  this is much less boiler plate

User · Answer

No  an anonymous type can t be made to do anything except have a few properties  You will need to create your own type  I didn t read the linked article in depth  but it looks like it uses Reflection Emit to create new types on the fly  but if you limit discussion to things within C  itself you can t do what you want

User · Answer

Anonymous types can implement interfaces via a dynamic proxy   I wrote an extension method on GitHub and a blog post http   wblo gs feE to support this scenario    The method can be used like this   class Program       static void Main string   args                var developer   new   Name    Jason Bowers              PrintDeveloperName developer DuckCast lt IDeveloper gt               Console ReadKey               private static void PrintDeveloperName IDeveloper developer                Console WriteLine developer Name            public interface IDeveloper       string Name   get

User · Answer

No  an anonymous type can t be made to do anything except have a few properties  You will need to create your own type  I didn t read the linked article in depth  but it looks like it uses Reflection Emit to create new types on the fly  but if you limit discussion to things within C  itself you can t do what you want

User · Answer

Using Roslyn  you can dynamically create a class which inherits from an interface  or abstract class   I use the following to create concrete classes from abstract classes  In this example  AAnimal is an abstract class  var personClass   typeof AAnimal  CreateSubclass  quot Person quot     Then you can instantiate some objects  var person1   Activator CreateInstance personClass   var person2   Activator CreateInstance personClass    Without a doubt this won t work for every case  but it should be enough to get you started  using Microsoft CodeAnalysis  using Microsoft CodeAnalysis CSharp  using System  using System Collections Generic  using System IO  using System Linq  using System Reflection   namespace Publisher       public static class Extensions               public static Type CreateSubclass this Type baseType  string newClassName  string newNamespace    quot Magic quot                           todo  handle ref  out etc              var concreteMethods   baseType                                      GetMethods                                        Where method   gt  method IsAbstract                                       Select method   gt                                                                                var parameters   method                                                              GetParameters                                                                Select param   gt    quot  param ParameterType FullName   param Name  quot                                                                ToString  quot    quot                                             var returnTypeStr   method ReturnParameter ParameterType Name                                          if  returnTypeStr Equals  quot Void quot    returnTypeStr    quot void quot                                            var methodString      quot                                          public override  returnTypeStr   method Name   parameters                                                                                          Console WriteLine  quot  quot  newNamespace   newClassName   method Name    was called quot  quot                                               quot                                            return methodString Trim                                                                                ToList                 var concreteMethodsString   concreteMethods                                          ToString Environment NewLine   Environment NewLine                var classCode      quot              using System               namespace  newNamespace                                 public class  newClassName    baseType FullName                                         public  newClassName                                                                        concreteMethodsString                                                 quot  Trim                 classCode   FormatUsingRoslyn classCode                                var assemblies   new                                 MetadataReference CreateFromFile typeof object  Assembly Location                   MetadataReference CreateFromFile baseType Assembly Location                                              var assemblies   AppDomain                          CurrentDomain                          GetAssemblies                            Where a   gt   string IsNullOrEmpty a Location                            Select a   gt  MetadataReference CreateFromFile a Location                            ToArray                 var syntaxTree   CSharpSyntaxTree ParseText classCode                var compilation   CSharpCompilation                                  Create newNamespace                                   AddSyntaxTrees syntaxTree                                   AddReferences assemblies                                   WithOptions new CSharpCompilationOptions OutputKind DynamicallyLinkedLibrary                 using  var ms   new MemoryStream                                  var result   compilation Emit ms                     compilation Emit   quot C   Temp   newNamespace  dll quot                     if  result Success                                        ms Seek 0  SeekOrigin Begin                       Assembly assembly   Assembly Load ms ToArray                          var newTypeFullName     quot  newNamespace   newClassName  quot                        var type   assembly GetType newTypeFullName                       return type                                    else                                       IEnumerable lt Diagnostic gt  failures   result Diagnostics Where diagnostic   gt                          diagnostic IsWarningAsError                            diagnostic Severity    DiagnosticSeverity Error                        foreach  Diagnostic diagnostic in failures                                                Console Error WriteLine  quot  0    1  quot   diagnostic Id  diagnostic GetMessage                                                return null                                                     public static string ToString this IEnumerable lt string gt  list  string separator                        string result   string Join separator  list               return result                     public static string FormatUsingRoslyn string csCode                        var tree   CSharpSyntaxTree ParseText csCode               var root   tree GetRoot   NormalizeWhitespace                var result   root ToFullString                return result

User · Answer

While the answers in the thread are all true enough  I cannot resist the urge to tell you that it in fact is possible to have an anonymous class implement an interface  even though it takes a bit of creative cheating to get there  Back in 2008 I was writing a custom LINQ provider for my then employer  and at one point I needed to be able to tell  quot my quot  anonymous classes from other anonymous ones  which meant having them implement an interface that I could use to type check them  The way we solved it was by using aspects  we used PostSharp   to add the interface implementation directly in the IL  So  in fact  letting anonymous classes implement interfaces is doable  you just need to bend the rules slightly to get there

User · Answer

The best solution is just not to use anonymous classes   public class Test       class DummyInterfaceImplementor   IDummyInterface               public string A   get  set            public string B   get  set               public void WillThisWork                 var source   new DummySource 0           var values   from value in source                      select new DummyInterfaceImplementor                                                   A   value A                           B   value C         value D                                  DoSomethingWithDummyInterface values Cast lt IDummyInterface gt                  public void DoSomethingWithDummyInterface IEnumerable lt IDummyInterface gt  values                foreach  var value in values                        Console WriteLine  A     0    B     1     value A  value B                       Note that you need to cast the result of the query to the type of the interface  There might be a better way to do it  but I couldn t find it

[c#] Can anonymous class implement interface?

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