Here is my generic method from which i want to return the class object
public class TestBase
{
public T NavigateandReturntheObject<T>() where T : new()
{
//do navigate to page stuff and return the page object
//previously it was - return new T();
//Now i want to do something like this
return PageObjectBase<T>.PageObject;
}
}
Above method calling the below static generic class which will handle object creation of a particular class
public static class PageObjectBase<T> where T : class, new()
{
private static T singleTonObject;
public static T PageObject
{
get
{
return InstanceCreation();
}
}
public static T InstanceCreation()
{
if (singleTonObject == null)
{
singleTonObject = new T();
}
return singleTonObject;
}
}
How can i call the PageObject property from my test base class please advice.
Note : I have searched forum and find answers relevant to generic method to another generic method calling.The same is achieved by reflection.Can we use reflection in my case too? If so how can we do it.
You can add another constraint 'class' to NavigateandReturntheObject
public T NavigateandReturntheObject<T>() where T : class,new()
Complete Code.
public class TestBase
{
public T NavigateandReturntheObject<T>() where T : class,new()
{
//do navigate to page stuff and return the page object
//previously it was - return new T();
//Now i want to do something like this
return PageObjectBase<T>.PageObject;
}
}
Demo Code
public class TestClass
{
public string Name{get;set;}
public TestClass()
{
Name = "Dummy Name";
}
}
var testBase = new TestBase();
var sample = testBase.NavigateandReturntheObject<TestClass>();
Console.WriteLine(sample.Name);
Output
Dummy Name
Related
I have the following code:
public interface IMyActionFactory
{
AbstractAction<T> CreateAction<T>(MyActionParamBase paramBase = null)
where T : MyActionParamBase;
}
public sealed class MergeActionParam : MyActionParamBase
{
}
public class MergeTest
{
private readonly IMyActionFactory _actionFactory = new DefaultMyActionFactory();
[Theory]
[PropertyData("MergeWorksData")]
public void MergeWorks(/*params here*/)
{
var param = new MergeActionParam();
// populate param here
var sut = _actionFactory.CreateAction<MergeActionParam>(param);
sut.DoAction();
}
}
I am getting an error
"..Error 10 Using the generic type 'IMyActionFactory' requires 1
type arguments..."
Why does the compiler expect a type to be passed to my IMyActionFactory, since I have declared the interface without a T? As far as the method is concerned its the only one to expect the type. Am I missing something here?
How can I make it work without redefining the interface signature?
EDIT:
Feeling a bit embarassed here, because the quick code I put down and ran seperately in a standalone online c# compiler doesnt give any compilation errors. However, going back to my original solution (tens of projects altogether) the error is still there.. Maybe has something to do with the XUnit ?..not sure
public interface IMyActionFactory
{
AbstractAction<T> CreateAction<T>(MyActionParamBase paramBase = null)
where T : MyActionParamBase;
}
public interface IAction
{
void DoAction();
}
public abstract class AbstractAction<T> : IAction
where T : MyActionParamBase
{
public void DoAction()
{
}
}
public class MyActionParamBase
{
public MyActionParamBase()
{
}
}
public sealed class MergeActionParam : MyActionParamBase
{
}
public class DefaultMyActionFactory : IMyActionFactory
{
public AbstractAction<T> CreateAction<T>(MyActionParamBase paramBase = null) where T : MyActionParamBase
{
return null;
}
}
public class MergeTest
{
private readonly IMyActionFactory _actionFactory = new DefaultMyActionFactory();
public void MergeWorks(/*params here*/)
{
var param = new MergeActionParam();
// populate param here
var sut = _actionFactory.CreateAction<MergeActionParam>(param);
sut.DoAction();
}
}
I'm sorry if this is poorly worded or if this has been asked before but I couldn't seem to find anything related to this and I'm quite tired.
Alright, so what I'm trying to do is get the value of of my trait in a subclass for situations where I need to reference an instance of a subclass but I don't have the information about what trait it will be using. This is easier for me to explain in code so here's what I'm trying to do.
public class TraitUser<T>
{
public void DoThingWithT(T thing)
{
thing.ToString();
}
}
public class TraitInspector
{
public void DoThing()
{
// This is where I run into my issue,
// I need to be able to get the trait that
// an instance of the TraitUser class is using to continue.
TraitUser<> tUser = GetRandomTraitUser()/*Imagine this returns an instance of TraitUser with a random trait, this is where my issue comes in.*/;
}
}
If I understand youright, you need get information about generic type T in TraitUser instance in TrairInspector.
public interface IGetTraitInfo
{
Type GetTraitObjectType();
object GetTraitObject();
}
public class TraitUser<T> : IGetTraitInfo
{
private T _thing;
public void DoThingWithT(T thing)
{
_thing = thing;
}
public Type GetTraintObjectType()
{
return typeof(T);
}
public Type GetTraitObject()
{
return _thing;
}
}
public class TrairInspector
{
public void InspectTraitUser(IGetTraitInfo traitUser)
{
Type traitType = traitUser.GetTraintObjectType();
object data = traitUser.GetTraitObject();
}
}
I didn't understand completely but this might help you.
public interface ITrait
{
string DoSomething();
}
public class Trait<T> where T : ITrait, new()
{
public string DoSomething()
{
ITrait trait = new T();
return trait.DoSomething();
}
}
public class TraitUser : ITrait
{
public string DoThing()
{
return "return something";
}
}
public class TrairInspector
{
public void DoThing()
{
Trait<TraitUser> traitUser = new Trait<TraitUser>();
traitUser.DoSomething();
}
}
This is what I want to do in C# (within class Helper - without generic arguments),
List<AbstractClass<dynamic>> data;
public void Add<T>(AbstractClass<T> thing)
{
this.data.Add((AbstractClass<dynamic>) thing);
}
This helper class would take and work with AbstractClass<> objects and give back AbstractClass<> of specific generic type. AbstractClass<T> contains many functions which return T / take in T like public T Invoke().
For Helper class T cannot be known beforehand. The Add<T>(.. thing) function is not in a class of type T.
To be used like this in Helper class's functions,
foreach(var c in data.Where(x => ...))
{
// public T Invoke() { ... } function within AbstractClass<T>
var b = c.Invoke();
// logic
}
This also fails,
List<AbstractClass<object>> data;
public void Add<T>(AbstractClass<T> thing)
{
this.data.Add((AbstractClass<object>) thing);
}
Now I think I can have,
List<dynamic> data; // or List<object> data;
public void Add<T>(AbstractClass<T> thing)
{
this.data.Add(thing);
}
but I want the constraint that List named data has only elements of type like
ConcreteClass : AbstractClass<OtherClass>
So we would know that there is an public T Invoke() function but we do not know what it returns. This is helpful to avoid mistakes of say misspelling Invocke and only knowing at run-time.
I want to avoid casting to dynamic every time to invoke functions that give back generic type T
To do what you want to do you are going to need to use a Contravariant interface
public class Program
{
static void Main()
{
var m = new Helper();
m.Add(new ConcreteClass());
m.Process();
}
class Helper
{
List<IAbstractClass<OtherClassBase>> data = new List<IAbstractClass<OtherClassBase>>();
public void Add(IAbstractClass<OtherClassBase> thing)
{
this.data.Add(thing);
}
public void Process()
{
foreach(var c in data.Where(x => x.ShouldBeProcessed()))
{
var b = c.Invoke();
Console.WriteLine(b.Question);
var castData = b as OtherClass;
if (castData != null)
Console.WriteLine(castData.Answer);
}
}
}
public interface IAbstractClass<out T>
{
bool ShouldBeProcessed();
T Invoke();
}
abstract class AbstractClass<T> : IAbstractClass<T>
{
public bool ShouldBeProcessed()
{
return true;
}
public abstract T Invoke();
}
class ConcreteClass : AbstractClass<OtherClass>
{
public override OtherClass Invoke()
{
return new OtherClass();
}
}
class OtherClassBase
{
public string Question { get { return "What is the answer to life, universe, and everything?"; } }
}
class OtherClass : OtherClassBase
{
public int Answer { get { return 42; } }
}
}
You do not need to tell Add what kind of class you are passing it, all that matters is it derives from the type specified. You could do public void Add(IAbstractClass<object> thing) and every class would work, but Invoke() would only return objects inside the foreach loop.
You need to figure out what is the most derived class you want Invoke() to return and that is what you set as the type in the list.
Maybe this will work for you:
public class Program
{
static void Main()
{
var m1 = new Helper<OtherClass>();
m1.Add(new ConcreteClass());
var m2 = new Helper<int>();
m2.Add(new ConcreteClass2());
}
class Helper<T>
{
List<AbstractClass<T>> data = new List<AbstractClass<T>>();
public void Add<T1>(T1 thing) where T1 : AbstractClass<T>
{
this.data.Add(thing);
}
}
class AbstractClass<T> { }
class OtherClass { }
class ConcreteClass : AbstractClass<OtherClass> { }
class ConcreteClass2 : AbstractClass<int> { }
}
I have the following:
List<IReport> myList = new List<IReport>();
Report myReport = TheirApi.GetReport();
myReport meets all the qualifications of IReport, but cannot implement IReport because I do not have access to the source of TheirApi. Casting to type IReport obviously results in null, and I read that I cannot cast an anonymous type to an interface.
Do I have any options here?
A wrapper class was just what the doctor ordered:
ReportServices.GetAllCustomReports().ToList().ForEach(customReport => _customReports.Add(new ReportWrapper(customReport)));
public class ReportWrapper : IReport
{
private Report inner;
public int ID
{
get { return inner.ID; }
set { inner.ID = value; }
}
public string Name
{
get { return inner.Name; }
set { inner.Name = value; }
}
public ReportWrapper(Report obj)
{
inner = obj;
}
}
You will need to wrap this object inside another one that implements the interface, and then you will need to implement it calling the inner object's properties and methods.
For example:
public class ReportWrapper : IReport
{
MyObjectIsLikeReport inner;
public ReportWrapper(MyObjectIsLikeReport obj) {
this.inner = obj;
}
public void ReportMethod(int value) {
this.inner.ReportMethod(value);
}
public int SomeProperty {
get { return this.inner.SomeProperty; }
set { this.inner.SomeProperty = value; }
}
}
To use it, you can do this:
List<IReport> myList = new List<IReport>();
MyObjectIsLikeReport myReport = TheirApi.GetReport();
myList.Add(new ReportWrapper(myReport));
Consider Adapter Design Pattern.
Definition: Convert the interface of a class into another interface
clients expect. Adapter lets classes work together that couldn't
otherwise because of incompatible interfaces.
good reference: http://www.dofactory.com/Patterns/PatternAdapter.aspx
interface IReport
{
void DoSomething();
}
class ReportApdapter : IReport
{
private readonly Report _report;
public ReportApdapter(Report report)
{
_report = report;
}
public void DoSomething()
{
_report.DoSomething();
}
}
class Report
{
public void DoSomething()
{
}
}
//You can use like this.
IReport report = new ReportApdapter(TheirApi.GetReport());
I need to have a wrapper class that exposes some properties of my entity class called ProfileEntity.
I tried doing it by deriving from this entity and then creating properties that return specific entity properties, but it says I cannot cast from ProfileEntity to ProfileEntityWrapper.
When I try to put the return values of a method that returns a 'ProfileEntity' into the wrapper I get the above error.
How do I create such a wrapper class that is castable?
Example
class ProfileEntityWrapper : ProfileEntity
{
public string Name
{
get
{
return this.ProfileEntityName;
}
}
}
public class Someclass
{
public ProfileEntity SomeMethod()
{
return ProfileEntity; // example of method returning this object
}
}
public class SomeOtherlClass
{
SomeClass sc = new SomeClass();
public void DoSomething()
{
ProfileEntityWrapper ew = (ProfileEntityWrapper)sc.SomeMethod(); // Cannot do this cast!!!
}
}
You cannot cast an object of ProfileEntity to ProfileEntityWrapper.
var entity = new ProfileEntity(); // this object is only of type ProfileEntity
var wrapper = new ProfileEntityWrapper(); // this object can be used as both ProfileEntityWrapper and ProfileEntity
You probably want to return a ProfileEntityWrapper in SomeMethod():
public class Someclass
{
public ProfileEntity SomeMethod()
{
return new ProfileEntityWrapper(); // it's legal to return a ProfileEntity
}
}
No, that is not possible.
To accomplish this problem you can maybe try this one:
public class ProfileEntity
{
public string ProfileEntityName { get; set; }
}
public class ProfileEntityWrapper
{
public ProfileEntityWrapper(ProfileEntity entity)
{
Entity = entity;
}
public ProfileEntity Entity { get; private set; }
public string Name
{
get
{
return Entity.ProfileEntityName;
}
}
}
public class SomeClass
{
public ProfileEntity SomeMethod()
{
// example of method returning this object
ProfileEntity temp = new ProfileEntity();
return temp;
}
}
public class SomeOtherClass
{
SomeClass sc = new SomeClass();
public void DoSomething()
{
//Create a new Wrapper for an existing Entity
ProfileEntityWrapper ew = new ProfileEntityWrapper(sc.SomeMethod());
}
}
If you are allowed to edit the ProfileEntity class, or if the ProfileEntity class is a generated partial class, you could add an interface instead of using a wrapper. You wouldn't need to do any casting with an interface either. Example:
public interface IProfile
{
string Name { get; }
}
public partial class ProfileEntity : IProfile
{
public string Name
{
get
{
return this.ProfileEntityName;
}
}
}
public class SomeClass
{
public ProfileEntity SomeMethod()
{
return ProfileEntity;
}
}
public class SomeOtherClass
{
SomeClass sc = new SomeClass();
public void DoSomething()
{
IProfile ew = sc.SomeMethod();
}
}
The IProfile instance will only provide access to the Name property.
This's no correct code from polymorphism aspect.
If we will take the famous polymorphism example when there're base Shape class and Circle, Polygon and Rectangle classes that extend the Shape class, your code will try to cast some shape into circle and as you understand this's invalid casting operation.
So to make this code work you must be sure that SomeClass.SomeMethod() will return instance of ProfileEntityWrapper or perform type check before the casting, like this:
ProfileEntity temp = sc.SomeMethod();
if(temp is ProfileEntityWrapper)
ProfileEntityWrapper ew = (ProfileEntityWrapper) temp;