Constructor on type '###' not found

Question

I have a type that accepts these parameters:

public SmaSeries(ISeries<decimal> parent, int periods, TierKind? runOnTier = null) 

I am trying to create an instance of this type using Activator.CreateInstance (the overload that accepts type and args) by passing object[] in the args parameter:

 new object[] 
 {
    new DecimalSeries(),
    20,
    new Nullable<TierKind>(TierKind.Client)
 }

//DecimalSeries implements ISeries<decimal>

Getting back Constructor on type 'SmaSeries' not found.

Is there a way to fix the args so the activator finds the constructor?

Thanks.

Solution 1

Works fine in .NET 4.5, and even 2.0

using System;

class SmaSeries
{
    public SmaSeries(ISeries<decimal> parent, int periods,
         TierKind? runOnTier = null) { }
    static void Main()
    {
        object[] args = new object[] 
         {
            new DecimalSeries(),
            20,
            new Nullable<TierKind>(TierKind.Client)
         };

        object obj = Activator.CreateInstance(typeof(SmaSeries), args);
    }
}
enum TierKind { Client }
interface ISeries<T> { }
class DecimalSeries : ISeries<decimal> { }

I think perhaps: is your constructor or one of the types maybe not public?

Solution 2

Sure enough it was a bug. I was creating List of Object in order to dynamically add parameters and then just forgot to do ToArray when calling the activator, and since the args is params object[], it took the list instead of taking its members. Sorry for wasting your time and thanks to all who replied/commented on this post.

Comments

[Alex Mendez]

I don't think 2.0 allows specifying default values on parameters.

[Marc Gravell]

@AlexMendez actually, it does... I'm talking about the .NET platform 2.0, not the C# compiler. The attribute used has been there forever, courtesy of VB.NET; if you use a later compiler version to target an earlier .NET version, it works fine. How Activator.CreateInstance works is entirely down to the .NET version (not the C# version). What you are talking about (optional parameters) is largely a compiler feature, not a runtime feature (although it is a bit more complex than that... isn't everything)

[Alex Mendez]

I knew about VB, but did not know you could compile with the later compiler to 2.0 and still use default values in parameters in c#. Also, I don't think I said anything about optional parameters. It was default values on parameters. Good to know. Thanks.

[Marc Gravell]

@AlexMendez optional parameters, and parameters with default values, are basically synonymous

[Oleg Sakharov]

Mate, you just saved me from few hours of debugging.