Question

I’ve run into a little difficulty and I’m not sure how best to solve this issue.

I wrote a class that expects data type to be specified upon the creation of a new instance. Much like in the same way as the System.Collections.Generic.List<T> class that stores a number of items of a specified type. However my class doesn’t has the same or similar function as the List<T> class does.

Upon creation of a new instance of my class, for example:

string phrase = "Some string type data.";
MyClass<string> data = new MyClass<string>( () => phrase );

Afterwards my class would provide a number of methods that would give a result regardless of the type of data being imparted into MyClass<T> (where T is the data type). Doesn’t matter if it is string, bool, int, or any kind.

I’ve tested my class and it works as expected, now how can I store a number of elements of MyClass but each element with different imparted data type, inside a collection class such as List<>.

Let me exemplify (code will contain syntax errors since I’m not sure how to write correctly):

// My intent... Not sure how to do it.
string phrase = "Some string data type.";
int number = 23;
bool boolData = false;

List<MyClass<T>> list = new List<MyClass<T>>();

list.Add( new MyClass<string>( () => phrase ) );
list.Add( new MyClass<int>( () => number ) );
list.add( new MyClass<bool>( () => boolData ) );

As you see I don’t know how to store a number of element of MyClass with different imparted data types, if they were all the same imparted data type, I wouldn’t be having this issue.

For example:

// How it should be done. But not what I need.
string phrase1 = "Hello Phrase 1.";
string phrase2 = "Hello Phrase 2.";

List<MyClass<string>> list = new List<MyClass<string>>();

list.Add(new MyClass<string>( () => phrase1) );
list.Add(new MyClass<string>( () => phrase2) );

If this was what I wanted to accomplish, I wouldn’t have a problem, but since I want to accomplish what I exemplified before this last example, I’m just not sure how to best do it.

Basically thats my issue, I’ve provided a few basic examples because I believe my question might be a bit odd, and to be honest my terminology wouldn’t not be adequate I think.

This is probably quite simple for some of you. My thanks for your help.

Answer 1

Typically you’d create a non-generic base class (or interface) for the generic type:

abstract class MyClass // Or interface
{
    // Anything useful but non-generic here
}

class MyClass<T> : MyClass
{
    // Anything using T
}

Then you can just create a List<MyClass>. Of course to get at any of the members within MyClass<T> you’ll need to know the right T to cast to, but I think that’s unavoidable.

Of course this doesn’t help much if you don’t control MyClass<T> and it doesn’t provide a useful base class – but there’s nothing in C# to help you with this situation.