Question

I have a structure something like this

struct MyStructure
    :IFoo
{
}

and a method like this:

public BarThisFoo(IFoo a)
{

}

my question is does passing the structure into that method “box” the structure, thus causing a garbage allocation?

Addendum:
Before anyone says it, garbage collection is not free in this application, it’s actually very sensitive to garbage collections, so allocation free code is important.

Answer 1

Yes, it does. Boxing occurs whenever you convert from:

• a value type to an object reference
• a value type to a System.ValueType reference
• a value type to a reference to an interface implemented by the value type
• an enum type to a System.Enum reference

This is case III, obviously. You can read a more thorough example here.