Proposal: Generic parameter constructor parameter constraints

[ghost]

I propose to allow the definition of constructor parameter constraints for generics. Currently the new() constraint is permitted, but parameters cannot be specified.

Proposed syntax examples

public class Example<TThing> where TThing : ThingBase, new(string, bool)
{
    public void DoWork(string a, bool b)
    {
        TThing t = new TThing(a, b);

        t.Run();
    }
} 

A more practical example, which is useful when following a pattern of having a model filled by a data object.

public class Example2<TThing, TThingData> where TThing : new(TThingData)
{
    public TThing DoWork(int id)
    {
        var thingData = DataAccess.GetThingData(id);

        return new TThing(thingData);
    }
}

[vcsjones]

I think this has been discussed before and determined that it would require support from the CLR before C# could support it. Currently CLR only supports new().

[alrz]

Dup of #2206