CODEWITHSUNDEEP
c#genericscollections
Blood-HaZaRd
Blood-HaZaRd

Reputation: 2124

using collection in generic function

I was trying to use a generic function for 2 kinds of Collections, in which I call the method Add.

So below my Code:

using System;
using System.Collections;

namespace CollectionsApplication
{
    class Program
    {
        static void AddElement<T>(ref T container, string key, string value)
        {
            container.Add(key, value);
        }

        static void Main(string[] args)
        {
            SortedList s1 = new SortedList();
            Hashtable  h1 = new Hashtable();

            AddElement<SortedList>(ref s1, "001", "Zara Ali");
            AddElement<Hashtable>(ref h1, "001", "Zara Ali");
        }
    }
}

and below the error :

error CS1061: 'T' does not contain a definition for 'Add' and no extension method 'Add' accepting a first argument of type 'T'

So Could this be performed and how to fix it if possible ?

Thank you in advance.

Upvotes: 1

Views: 57

Answers (3)

SᴇM
SᴇM

Reputation: 7213

Or create an extension method:

public static class MyExtensions
{
    public static void AddElement(this IDictionary container, string key, string value)
    {
        container.Add(key, value);
    }
}

And usage:

SortedList s1 = new SortedList();
Hashtable h1 = new Hashtable();

s1.AddElement("001", "Zara Ali");
h1.AddElement("001", "Zara Ali");

Upvotes: 2

smolchanovsky
smolchanovsky

Reputation: 1863

Why not make it easier, like so?

using System;
using System.Collections;

namespace CollectionsApplication
{
    class Program
    {
        static void AddElement(IDictionary container, string key, string value)
        {
            container.Add(key, value);
        }

        static void Main(string[] args)
        {
            SortedList s1 = new SortedList();
            Hashtable  h1 = new Hashtable();

            AddElement(s1, "001", "Zara Ali");
            AddElement(h1, "001", "Zara Ali");
        }
    }
}

Upvotes: 2

Robin Bennett
Robin Bennett

Reputation: 3231

The problem here is that T can be anything (e.g. an int) and isn't guaranteed to have an Add method.

You need to constrain T to something that has an Add method.

static void AddElement<T>(ref T container, string key, string value)
    where T : IDictionary 
{
    container.Add(key, value);
}

Upvotes: 3

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