Double dispatch in C# 4.0 - dynamic keyword? - c#

I realise this has been asked before, but I didn't find a clear agreement on the best solution.
Is using dynamic (like below) the best way to do this?
I guess its best to avoid dynamic whenever possible to help catch problems at compile-time.
(classA1 and classA2 implement Interface A and likewise for B)
public static void Foo(InterfaceA a, InterfaceB b)
{
Foo((dynamic)a, (dynamic)b);
}
static void Foo(classA1 a, classB1 b) { //some code }
static void Foo(classA2 a, classB2 b) { //some code }
static void Foo(classA1 a, classB2 b) { //some code }
static void Foo(classA2 a, classB1 b) { //some code }
Or similarly...
public static void Foo(InterfaceA a, InterfaceB b)
{
((dynamic) a).Foo(b);
}
public classA1
{
void Foo(classB1 b) { //some code }
}
//repeated for other cases

Is using dynamic (like below) the best way to do this?
Well it's a way to do it - so long as the execution-time types will always end up with something that overload resolution will be happy with.
You might want to put a backstop method of
static void Foo(object x, object y)
in case none of the methods are applicable (e.g. a is a non-ClassA1/ClassA2 implementation). It's not going to help you if both values are null, mind you...
I would usually attempt to redesign so that this isn't required, but it's hard to know the best solution without more context.

Are 'classA1' and so on implementations of InterfaceA? If so then why not just declare the Foo functions as accepting InterfaceA and InterfaceB and cast them within to the concrete implementation expected by the function? E.g.,
static void Foo(InterfaceA a, InterfaceB b) {
classA1 c1 = a as classA1;
classB1 b1 = b as classB1;
// ... etc
}
Dynamic isn't intended to be used this way.

You could do something AWFUL with reflection - but I'm sure it's not better than doing dynamic:
void Main()
{
var a = "hello";//5;
var b = "hello";
var type1 = a.GetType();
var type2 = b.GetType();
var t = typeof(FooClass);
var methods = t.GetMethods();
foreach(var method in methods)
{
var parameters = method.GetParameters();
if(parameters.Length == 2)
{
if(parameters[0].ParameterType == type1
&& parameters[1].ParameterType == type2)
{
method.Invoke(this, new object[]{ a, b });
}
}
}
}
public static class FooClass
{
public static void Foo(int i, string s)
{
"Foo1".Dump();
}
public static void Foo(string s, string s2)
{
"Foo2".Dump();
}
}

C# has traditionally been a statically-typed language. The dynamic keyword adds dynamic typing to the language. The usual advice is to use "dynamic" sparingly. Here may be a case where you need it.
Generics won't cut it as this won't compile:
private void button1_Click(object sender, EventArgs e)
{
Foo(new classA1(), new classB2());
}
static void Foo<T, T1>(T a, T1 b) where T: InterfaceA
where T1: InterfaceB
{
Foo2(a, b);
}
static void Foo2(classA1 a, classB1 b) { }
static void Foo2(classA2 a, classB2 b) { }
static void Foo2(classA1 a, classB2 b) { }
static void Foo2(classA2 a, classB1 b) { }
interface InterfaceA { }
interface InterfaceB { }
class classA1 : InterfaceA { }
class classA2 : InterfaceA { }
class classB1 : InterfaceB { }
class classB2 : InterfaceB { }

Related

Create variable of class without the parameters of it's constructor

I have a BaseClass with a constructor and some parameters and then I want to do a strategy where depending of an enum, it creates one derived class or another (of that BaseClass), but with the same parameters. Is there any way to refactor this ? Thanks !
public enum GameMode
{
ModeA,
ModeB
}
public abstract class BaseClass
{
public BaseClass(int a, string b, char c)
{
}
}
public class FirstGameMode : BaseClass
{
public FirstGameMode(int a, string b, char c) : base(a, b, c)
{
}
}
public class SecondGameMode: BaseClass
{
public SecondGameMode(int a, string b, char c) : base(a, b, c)
{
}
}
public class TestingPurpose
{
private GameMode _gameMode;
private BaseClass _baseClass;
public void Init()
{
if (_gameMode == GameMode.ModeA)
{
// They use the same variables !
_baseClass = new FirstGameMode(5, "Hello", 'c');
}
else
{
// They use the same variables !
_baseClass = new SecondGameMode(5, "Hello", 'c');
}
}
}
I tried with some reflection but still I couldn't do it.
I would like to have something like
public void Init()
{
BaseMatchMode type;
if (_gameMode == GameMode.ModeA)
{
type = typeof(FirstGameMode);
}
else
{
type = typeof(SecondGameMode);
}
_baseClass = new type(5, "Hello", 'c');
}
You could use a factory delegate method;
Func<int a, string b, char c, BaseClass> factory;
if (_gameMode == GameMode.ModeA)
{
factory= (a, b, c) => new FirstGameMode(a, b, c);
}
else
{
factory= (a, b, c) => new SecondGameMode(a, b, c);
}
_baseClass = factory(5, "Hello", 'c');
For such an simple example it would probably be easier to just skip the factory method and create your objects directly. But this technique is sometimes useful if you want to add some abstraction between components.
You could also create a factory class instead of just using a delegate. There are also dependency injection (DI) / Inversion of Control (IoC) frameworks that are intended to solve the problem of specifying what implementation of interfaces/base classes other components should use.

How to call methods of data member through a generic method

Considering the classes below, I would like to be able to write:
B b = new B();
b.f(1); // calls b._a.f(int)
b.f("howdy!"); // calls b._a.f(string)
Class A cannot be modified.
public class A
{
public void f(int i) { }
public void f(string s) { }
}
public class B
{
public void f<T>(T v)
{
_a.f(v); // fails
}
A _a = new A();
}
If you really want to simplify your f pass-through down to a single method, you'll have to use run-time type checking. I don't see any other way around it. Generics aren't going to work here.
public void f(object v)
{
if (v is int i)
_a.f(i);
else if (v is string s)
_a.f(s);
else
throw new InvalidOperationException();
}
I gather that you are hesitant to just expose _a because there are some methods on it that you would rather not be accessible to the caller? Could you introduce an interface, or would that be considered a modification to class A?
public interface IFoo
{
void f(int i);
void f(string s);
}
public class A : IFoo
{
...
}
public class B
{
public IFoo A => _a;
}

C# - Passing all the method arguments to another method?

I've got a class, which has three overloaded methods. Let's say, there is:
class MyChildClass
{
public void myMethod(int i)
{ /* do something with i */ }
public void myMethod(int a, string b)
{ /* get i from a and b and call: */ myMethod(i); }
public void myMethod(string c, string d)
{ /* get i from c and d and call: */ myMethod(i); }
}
Now I'd like this class to be a private field in other (parent) class, but I need those three methods to be accessible. For now, I just did:
class MyBaseClass
{
private MyChildClass myObject = new myChildClass(); // or similar
public void myMethod(int i)
{ myObject.myMethod(i); }
public void myMethod(int a, string b)
{ myObject.myMethod(a, b); }
public void myMethod(string c, string s)
{ myObject.myMethod(c, d); }
}
Is there a way to implement it as one short method? Something which would look like:
public void myMethod(unknownListOfArgumentsOfDifferentTypes args)
{ myObject.myMethod(args); }
I tried to use public void myMethod(params object[] something) but it didn't work. Is it possible, or do I have to "project" every method into another?
EDIT: Child class has various methods and fields, which I want to be accessible for parent class only. That's why I don't want parent to derive after it. I didn't explain that, sorry if it looked like child class contains only those three methods. Those are the methods I want to be accessible as public methods of parent class.
Why don't you do
class MyChildClass : MyBaseClass
{
}
same effect, less code, and this way MyChildClass is a MyBaseClass
If you implement some sort of generic facade using reflection you'll just be reducing performance, bypassing the benefits of type safety and delaying the discovery of problems.
You'll also have have a "has a" relationship instead "is a" relationship which is incongruent with your class names.
If you want to give up this simplicty with its associated benefits you could make use the GetMethodBySig extension accepted in this post.
Something like this,
class SemiGenericFacade<T> where T : new()
{
private readonly t = new T();
public void CallVoidOnT(string name, params object[] parameters)
{
var paramTypes = parameters.Select(p => typeof(p))
var match = typeof(T).GetMethodBySig(typeof(void), paramTypes)
.Single(mi => mi.Name == name);
match.Invoke(this.t, parameters);
}
}
Following on from Piotr Justyna's comment, implementing and using this method results in the cat turning into a tiger and eating her kittens.
If you were to do this it would make sense to add to the linked extension
public static class Extensions
{
public static MethodInfo GetMethodByNameThenSig(
this Type type,
string name,
Type returnType,
params Type[] parameterTypes)
{
return type.GetMethods().Where((m) =>
{
if (m.Name != name)
{
return false;
}
if (m.ReturnType != returnType)
{
return false;
}
var parameters = m.GetParameters();
if ((parameterTypes == null || parameterTypes.Length == 0))
{
return parameters.Length == 0;
}
if (parameters.Length != parameterTypes.Length)
{
return false;
}
for (int i = 0; i < parameterTypes.Length; i++)
{
if (parameters[i].ParameterType != parameterTypes[i])
{
return false;
}
}
return true;
}).Single();
}
}
Which you could use like this,
class GenericFacade<T> where T : new()
{
private readonly t = new T();
public void CallOnInternal(string name, params object[] parameters)
{
var paramTypes = parameters.Select(p => typeof(p))
var match = typeof(T).GetMethodByNameThenSig(
name,
typeof(void),
paramTypes);
match.Invoke(this.t, parameters);
}
public TResult CallOnInternal<TResult>(string name, params object[] parameters)
{
var paramTypes = parameters.Select(p => typeof(p))
var match = typeof(T).GetMethodByNameThenSig(
name,
typeof(TResult),
paramTypes);
return (TResult)match.Invoke(this.t, parameters);
}
}
FINAL EDIT
Looking at the code involved to use reflection and considering the cost associated with the loss of type safety. I'd suggest its better to establish the "has-a" relationship explicitly in the traditional manner.
You can use public void myMethod(params object[] something) as in:
public static void Main()
{
UnknownArgumentsMethod1(1, 2, 3, "foo");
}
public static void UnknownArgumentsMethod1(params object[] list)
{
UnknownArgumentsMethod2(list);
}
public static void UnknownArgumentsMethod2(params object[] list)
{
foreach (object o in list)
{
if (o.GetType() == typeof(int))
{
Console.WriteLine("This is an integer: " + (int)o);
}
else if (o.GetType() == typeof(string))
{
Console.WriteLine("This is a string: " + (string)o);
}
}
}
The obvious answer would be to have inheritance.
In your case (even though the names of the classes suggest otherwise) the way to do it is by inheriting the ChildClass in the BaseClass and that way you would have the methods from the ChildClass exposed through the BaseClass.
ex:
class MyBaseClass: MyChildClass
{
}
If the classes are not related and you just want to have an instance of MyChildClass in MyBaseClass but only expose a certain set of methods but by not making the others private what you could do is expose the MyChildClass instance through an interface that only exposes the necessary fields like so:
public class BaseClass
{
public IChildClass ChildClassInstance = new ChildClass();
}
public class ChildClass : IChildClass
{
public void myMethod(int i)
{ /* do something with i */ }
public void myMethod(int a, string b)
{ /* get i from a and b and call: */ myMethod(i); }
public void myMethod(string c, string d)
{ /* get i from c and d and call: */ myMethod(i); }
}
public interface IChildClass
{
void myMethod(int i);
void myMethod(int a, string b);
}
and then you could access only the methods that you allow to be exposed through an instance of the base class:
BaseClass test = new BaseClass();
test.ChildClassInstance.myMethod(1);
test.ChildClassInstance.myMethod(1,"test");

Determine if two methods have the same base definition

I've just made the unfortunate (for my app at least) discovery that two methods declared inside a generic class do not have the same base definition, demonstrated best in code:
public static class Test
{
private class Generic<T> { public void Method() { } }
public static void TestBase()
{
var x = typeof(Generic<int>).GetMethod("Method");
var y = typeof(Generic<double>).GetMethod("Method");
Debug.Assert(x.GetBaseDefinition() == y.GetBaseDefinition()); // fails
}
}
Both x and y.IsGeneric is false, so GetGenericMethodDefinition cannot be used.
The only solution I've been able to think of so far is to compare their names and that their declaring types are the same generic type, but in the presence of overloads that seems very brittle..
So.. I don't suppose there's a helpful method I've missed in the reflection library that can tell me if these two methods have been first declared in the same class? Or a workaround?
EDIT:
To clarify, I want to make a method:
public bool DeclaredInSameClass(MethodInfo a, MethodInfo b);
which returns true if both a and b are both first declared in the same class.
Ignoring generics, this is simple: a.GetBaseDefinition() == y.GetBaseDefinition(), but how to handle methods declared within generic classes?
EDIT... one last try:
private class Generic<T> {
public void Method() { }
public void Method(string param) { }
public void OtherMethod() { }
}
private class NonGeneric { public void Method() { } }
static void Main(string[] args)
{
var x = typeof(Generic<int>).GetMethod("Method", new Type[]{});
var y = typeof(Generic<double>).GetMethod("Method", new Type[]{});
var a = typeof(Generic<double>).GetMethod("OtherMethod");
var b = typeof(NonGeneric).GetMethod("Method");
var c = typeof(Generic<int>).GetMethod("Method", new Type[] { typeof(string) });
Debug.Assert(DeclaredInSameClass(x, y));
Debug.Assert(!DeclaredInSameClass(x, a));
Debug.Assert(!DeclaredInSameClass(x, b));
Debug.Assert(!DeclaredInSameClass(x, c));
Debug.Assert(!DeclaredInSameClass(a, b));
}
public static bool DeclaredInSameClass(MethodInfo a, MethodInfo b)
{
if (a.DeclaringType.IsGenericType != b.DeclaringType.IsGenericType)
{
return false;
}
else if (a.DeclaringType.IsGenericType)
{
var x = a.DeclaringType.GetGenericTypeDefinition().GetMethod(a.Name, a.GetParameters().Select(p => p.ParameterType).ToArray());
var y = b.DeclaringType.GetGenericTypeDefinition().GetMethod(b.Name, b.GetParameters().Select(p => p.ParameterType).ToArray());
return x.Equals(y);
}
return a.GetBaseDefinition().Equals(b.GetBaseDefinition());
}

Improving methods with variable parameters using .NET Generics

I have a lot of functions which are currently overloaded to operate on int and string:
bool foo(int);
bool foo(string);
bool bar(int);
bool bar(string);
void baz(int p);
void baz(string p);
I then have a lot of functions taking 1, 2, 3, or 4 arguments of either int or string, which call the aforementioned functions:
void g(int p1) { if(foo(p1)) baz(p1); }
void g(string p1) { if(foo(p1)) baz(p1); }
void g(int p2, int p2) { if(foo(p1)) baz(p1); if(bar(p2)) baz(p2); }
void g(int p2, string p2) { if(foo(p1)) baz(p1); if(bar(p2)) baz(p2); }
void g(string p2, int p2) { if(foo(p1)) baz(p1); if(bar(p2)) baz(p2); }
void g(string p2, string p2) { if(foo(p1)) baz(p1); if(bar(p2)) baz(p2); }
// etc.
Note: The implementation of the g() family is just an example
More types than the current int or string might be introduced at any time. The same goes for functions with more arguments than 4. The current number of identical functions is barely manageable. Add one more variant in either dimension and the combinatoric explosion will be so huge, it might blow away the application.
In C++, I'd templatize g() and be done.
I understand that .NET generics are different. I have been fighting them for two hours now trying to come up with a solution that doesn't involve copy and pasting code, to no avail.
C# generics won't require me to type out identical code for a family of functions taking five arguments of either of three types?
What am I missing?
Edit: These functions are used to parse a bunch of arguments (currently either int or string) from some source. Imagine bar() and baz() being able to read both int or string, and the g() family specifying the type and number of arguments to parse (implicitly, by their arguments' types).
Consider using inheritance for this case. I am assuming that foo, bar and baz are inherent to the type (int or string in your case). If this is not true please correct or comment this answer.
using System;
namespace ConsoleApplication3
{
abstract class Param
{
public abstract bool Foo();
public abstract bool Bar();
public abstract void Baz();
public static IntParam Create(int value)
{
return new IntParam(value);
}
public static StringParam Create(string value)
{
return new StringParam(value);
}
}
abstract class Param<T> : Param {
private T value;
protected Param() { }
protected Param(T value) { this.value = value; }
public T Value {
get { return this.value; }
set { this.value = value; }
}
}
class IntParam : Param<int>
{
public IntParam() { }
public IntParam(int value) : base(value) { }
public override bool Foo() { return true; }
public override bool Bar() { return true; }
public override void Baz()
{
Console.WriteLine("int param value is " + this.Value);
}
}
class StringParam : Param<string>
{
public StringParam() { }
public StringParam(string value) : base(value) { }
public override bool Foo() { return true; }
public override bool Bar() { return true; }
public override void Baz()
{
Console.WriteLine("String param value is " + this.Value);
}
}
class Program
{
static void g(Param p1)
{
if (p1.Foo()) { p1.Baz(); }
}
static void g(Param p1, Param p2)
{
if (p1.Foo()) { p1.Baz(); }
if (p2.Bar()) { p2.Baz(); }
}
static void Main(string[] args)
{
Param p1 = Param.Create(12);
Param p2 = Param.Create("viva");
g(p1);
g(p2);
g(p1, p1);
g(p1, p2);
g(p2, p1);
g(p2, p2);
Console.ReadKey();
}
}
}
This would output:
int param value is 12
String param value is viva
int param value is 12
int param value is 12
int param value is 12
String param value is viva
String param value is viva
int param value is 12
String param value is viva
String param value is viva
For a new supported type you:
create a new class that supports the type and extends Param<T>;
implement Foo, Bar and Baz for that new type;
Create a new g method (just one) that has another parameter.
Specially for 3) this would greatly reduce explosion of methods. Now you write a single g method for any given number of parameters. With previous design you had to write, for n parameters, 2^n methods (n = 1 -> 2 methods, n = 2 -> 4 methods, n = 3 -> 8 methods, ..).
Your true problem here is most likely one of design, rather than something generics can be used for. Generics should be used for things that are actually type-agnostic, not as a catch-all to make life a bit easier. Perhaps try posting some actual example code you're using, and someone may have an idea about how to redesign your solution in a way that will allow you to extend it without so much headache.
As a teaser, consider something like this:
public void DoSomethingConditionally<T>(T key, Func<T, bool> BooleanCheck, Action<T> WhatToDo)
{
if (BooleanCheck(key)) WhatToDo(key);
}
And you could call it like this:
DoSomethingConditionally<String>("input", v => v == "hello", s => Console.WriteLine(s));
I've used lambda expressions here, but you could just as easily predefine a few Func<>s that perform some common expressions. This would be a much better pattern than method overloading, and would force you to handle new input types at design time.
Not as optimal as I would like... but what if foo, bar, and baz had generic versions as well?
static bool foo(int input)
{
return input > 5;
}
static bool foo(string input)
{
return input.Length > 5;
}
static void baz(int input)
{
Console.WriteLine(input);
}
static void baz(string input)
{
Console.WriteLine(input);
}
static bool foo<T>(T input)
{
if (input is int) return foo((int)(object)input);
if (input is string) return foo((string)(object)input);
return false;
}
static void baz<T>(T input)
{
if (input is int) baz((int)(object)input);
else if (input is string) baz((string)(object)input);
else throw new NotImplementedException();
}
static void g<T>(T input)
{
if (foo(input))
baz(input);
}
static void g<T, U>(T input, U inputU)
{
g(input);
g(inputU);
}
Use a list of objects.
In the case the number of parameters are unknown at planning time, just use a list of objects. Something like:
void g(params object[] args) {
foreach (object arg in args) {
if ((arg is int) && (foo((int)arg))) baz((int)arg) else
if ((arg is string) && (foo((string)arg))) baz((string)arg)
}
}
(Assuming you have bool foo(int), bool foo(string)...)
So you can call:
g(p1, p2);
g(p1);
g(p1, p2, p3)
with any combination of the types, since every reference derives from object (which it could be many more types than required, int and string, but could be handy in future to support more other types).
This is possible since you could use Reflection to recognize the type at runtime.
Another way to execute a sequence of operation is the use of interfaces, defining the action to execute at certain conditions, on certain objects.
interface IUpdatable {
void Update(object[] data);
}
class object1 : IUpdatable { public void Update(object data) { baz(data); } }
class object2 : IUpdatable { public void Update(object data) { baz(data); } }
void g(params IUpdatable[] args) {
foreach (IUpdatable arg in args) {
arg.Update(args);
}
}
But this way you have to model p1 and p2 (but also p3, as objects implementing an interface, which could be not possible.
I would have done this as a comment to #smink, but I don't have enough rep...
If you extend the Param base class to have implicit operators you are back to not having to wrap the contents in code (though the runtime still incurs the wrapping overhead)...
abstract class Param
{
...
public static implicit operator Param(int value)
{ return new IntParam(value); }
}
If you are using C# / .NET 4.0, you can achieve multiple dispatch using the dynamic feature so you only have to implement a single overload of g based on the number of arguments and the proper foo/bar/baz overloads by type inside each g implementation will be resolved at runtime.
void g(dynamic p1) { if (foo(p1)) baz(p1); }
void g(dynamic p1, dynamic p2) { if (foo(p1)) baz(p1); if (bar(p2)) baz(p2); }
Edit:
Even though you are unable to use C# / .NET 4.0, you can still use this approach using reflection. I've added another foo/bar/baz overload for double showing how well this generalizes and allows you to eliminate duplicate g implementations.
bool foo(int p) {Console.WriteLine("foo(int)=" + p); return p == 0;}
bool foo(string p) {Console.WriteLine("foo(string)=" + p); return p == "";}
bool foo(double p) { Console.WriteLine("foo(double)=" + p); return p == 0.0; }
bool bar(int p) {Console.WriteLine("bar(int)=" + p); return p == 1;}
bool bar(string p) { Console.WriteLine("bar(string)=" + p); return p == ""; }
bool bar(double p) { Console.WriteLine("bar(double)=" + p); return p == 1.1; }
void baz(int p) {Console.WriteLine("baz(int)=" + p);}
void baz(string p) { Console.WriteLine("baz(string)=" + p); }
void baz(double p) { Console.WriteLine("baz(double)=" + p); }
//these object overloads of foo/bar/baz allow runtime overload resolution
bool foo(object p)
{
if(p == null) //we need the type info from an instance
throw new ArgumentNullException();
//may memoize MethodInfo by type of p
MethodInfo mi = typeof(Program).GetMethod(
"foo",
BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic,
null,
new Type[] { p.GetType() },
null
);
if (mi.GetParameters()[0].ParameterType == typeof(object))
throw new ArgumentException("No non-object overload found");
return (bool)mi.Invoke(this, new object[] { p });
}
bool bar(object p)
{
if (p == null)
throw new ArgumentNullException();
MethodInfo mi = typeof(Program).GetMethod(
"bar",
BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic,
null,
new Type[] { p.GetType() },
null
);
if (mi.GetParameters()[0].ParameterType == typeof(object))
throw new ArgumentException("No non-object overload found");
return (bool)mi.Invoke(this, new object[] { p });
}
void baz(object p)
{
if (p == null)
throw new ArgumentNullException();
MethodInfo mi = typeof(Program).GetMethod(
"baz",
BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic,
null,
new Type[] { p.GetType() },
null
);
if (mi.GetParameters()[0].ParameterType == typeof(object))
throw new ArgumentException("No non-object overload found");
mi.Invoke(this, new object[] { p });
}
//now you don't need to enumerate your identical implementations of g by type
void g(object p1) { if (foo(p1)) baz(p1); }
void g(object p1, object p2) { if (foo(p1)) baz(p1); if (bar(p2)) baz(p2); }
Unfortunately, generics cannot handle this situation. At least, not well. If you make your methods generic, then just about any type can be passed into them. There won't be an adequate where clause on the generics to limit it to just string and int. If your methods are going to do specific int/string related operations inside them, then generics wont work at all.
Generics in C# are not nearly as powerful as templates in C++, and yes they can cause some major headaches at time. It just takes time to get used to them and get a feel for what they can and cannot do.
This might be a bit heavy handed, but would encapsulating the different parameters types as classes work?:
public abstract class BaseStuff
{
public abstract bool Foo();
public abstract bool Bar();
public abstract void Baz();
public void FooBaz()
{
if(Foo()) Baz();
}
public void BarBaz()
{
if(Bar()) Baz();
}
}
public class IntStuff : BaseStuff
{
private int input;
public IntStuff(int input)
{
this.input = input;
}
public bool Foo()
{
//logic using input for example
return input > 0;
}
//implement Bar and Baz using input
}
public class StringStuff : BaseStuff
{
private string input;
public IntStuff(string input)
{
this.input = input;
}
//Implement Foo, Bar and Baz
}
And then have some G methods somewhere:
public void G(BaseStuff stuff1)
{
stuff1.FooBaz();
}
public void G(BaseStuff stuff1, BaseStuff stuff2)
{
stuff1.FooBaz();
stuff2.BarBaz();
}
And you can then call with:
G(new IntStuff(10), new StringStuff("hello"));
G(new StringStuff("hello"), new StringStuff("world"));
You can use code generation to solve this.
Look at Reflection.Emit. You can also generate code with T4 in Visual Studio.
The types are really getting in the way here. You could also try to solve this with a dynamic language or with the C# 4 dynamic keyword.
If you are using c# 4.0 you can do this with the option parameter
Or you can use object
Foo(object o)
{
if (o is int){ }
else if (o is string){ }
}
Or you can use the generic method Foo<T>(T o){ }

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