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Posted 26 Jan 2012

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Alternative to Activator.CreateInstance

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26 Jan 2012CPOL
The final solution after much debate and optimization:public class DynamicInitializer { static readonly Dictionary> list = new Dictionary>(); public static T New() where T : class { return New(typeof...

The final solution after much debate and optimization:

public class DynamicInitializer
        static readonly Dictionary<string, Func<object>> list = new Dictionary<string, Func<object>>();

        public static T New<T>() where T : class 
            return New(typeof (T)) as T;

        public static object New(Type type)
            if (list.ContainsKey(type.Name)) return list[type.Name];

            Func<object> method = Expression.Lambda<Func<object>>(Expression.Block(type, new Expression[] { Expression.New(type) })).Compile();
            list.Add(type.Name, method);
            return method();


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Dean Oliver
Software Developer BBD Johannesburg
South Africa South Africa
Bsc (Hons) Business Information Systems.
MCTS: Web Applications Development with Microsoft .NET Framework 4
MCTS: Windows Communication Foundation Development with Microsoft .NET Framework 4
MCTS: Accessing Data with Microsoft .NET Framework 4
Microsoft Certified Professional Developer Certification.

Comments and Discussions

GeneralRe: Perhaps it would make it completely obvious looking at the c... Pin
Andrew Rissing26-Jan-12 7:46
MemberAndrew Rissing26-Jan-12 7:46 
GeneralRe: If you use TryGetValue, it uses an out parameter to set the ... Pin
Andrew Rissing26-Jan-12 7:33
MemberAndrew Rissing26-Jan-12 7:33 
GeneralRe: thanks Andrew appreciate that. Why is it quicker though? Pin
Dean Oliver26-Jan-12 6:50
MemberDean Oliver26-Jan-12 6:50 
GeneralRe: If you do update this, I'd recommend using "TryGetValue" rat... Pin
Andrew Rissing26-Jan-12 6:13
MemberAndrew Rissing26-Jan-12 6:13 
GeneralRe: No problem. Pin
Paulo Zemek26-Jan-12 6:02
mvaPaulo Zemek26-Jan-12 6:02 
GeneralI think this last version is almost OK. In fact, if you know... Pin
Paulo Zemek26-Jan-12 4:59
mvaPaulo Zemek26-Jan-12 4:59 
GeneralRe: Sorry Paulo I actually accidentally posted the incorrect ver... Pin
Dean Oliver26-Jan-12 5:42
MemberDean Oliver26-Jan-12 5:42 
Sorry Paulo I actually accidentally posted the incorrect version. This is the code I meant to post prior to the last iteration.
GeneralBased on a comment by nonexisto, I realized that the constra... Pin
Andrew Rissing26-Jan-12 4:49
MemberAndrew Rissing26-Jan-12 4:49 

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