SimpleContainer not using the default constructor.

[adupontxpertdoc]

Hi,

SimpleContainer is calling the wrong constructor should call AddinOptionsModel() instead of AddinOptionsModel(string filename). Example of code:

public class AddinOptionsModel
{
    // Expected constructor to be called.
    public AddinOptionsModel()
        : this("Default")
    {
        // ...
    }

    // Actual constructor called with fileName = null crashing the application. 
    public AddinOptionsModel(string fileName)

    {
        // ...
    }

}

// In Bootstrap Configuration
this._container.Singleton<AddinOptionsModel, AddinOptionsModel>();

// In our code
this.AddinOptionsModel = IoC.Get();

Regards

[nigel-sampson]

Right now SimpleContainer is as the name says pretty simple. It simple matches on the public constructor with the most parameters irregardless of whether it can fulfill those dependencies.

It wouldn't be difficult to change this. I'd look at the SelectEligibleConstructor method of SimpleContainer. Happy to take a PR on this.

[jongleur1983]

What's the best strategy to implement here?
If I understand the current SimpleContainer implementation correct, it's currently using the constructor providing the most number of parameters.

static ConstructorInfo SelectEligibleConstructor(Type type) { return (from c in type.GetConstructors().Where(c => c.IsPublic) orderby c.GetParameters().Length descending select c).FirstOrDefault(); }

This is the best selection when we don't know anything about the parameters provided as it promises the largest flexibility to use all arguments.

But as far as I understand the SimpleContainer we know all parameters that can be reliably resolved.
While trying to implement that solution, I'm therefore happy to get feedback on this proposed strategy:

When selecting the right constructor (SeletEligibleConstructor), I propose to choose the public one with least unregistered parameters (types).

This is in fact a breaking change to what happens now, but if this issue should be implemented at all, I don't see how that should be possible without breaking changes.

[nigel-sampson]

I agree with the proposal around which constructor to use, also agree that it's a breaking change so will shift it to 4.0.0.