public LateBoundCtor CreateCtor(Type type)
{
LateBoundCtor ctor = _ctorCache.GetOrAdd(type, t =>
{
//handle valuetypes
if (!type.IsClass)
{
var ctorExpression = Expression.Lambda <LateBoundCtor>(Expression.Convert(Expression.New(type), typeof(object)));
return(ctorExpression.Compile());
}
else
{
var constructors = type.GetConstructors(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
//find a ctor with only optional args
var ctorWithOptionalArgs = constructors.FirstOrDefault(c => c.GetParameters().All(p => p.IsOptional));
if (ctorWithOptionalArgs == null)
{
throw new ArgumentException("Type needs to have a constructor with 0 args or only optional args", "type");
}
//get all optional default values
var args = ctorWithOptionalArgs
.GetParameters()
.Select(p => Expression.Constant(p.DefaultValue, p.ParameterType)).ToArray();
//create the ctor expression
var ctorExpression = Expression.Lambda <LateBoundCtor>(Expression.Convert(Expression.New(ctorWithOptionalArgs, args), typeof(object)));
return(ctorExpression.Compile());
}
});
return(ctor);
}
public void Test_with_value_object_create_ctor()
{
var sourceType = typeof(ValueSource);
LateBoundCtor ctor = DelegateFactory.CreateCtor(sourceType);
var target = ctor();
target.ShouldBeType <ValueSource>();
}
public void Test_with_create_ctor()
{
var sourceType = typeof(Source);
LateBoundCtor ctor = DelegateFactory.CreateCtor(sourceType);
var target = ctor();
target.ShouldBeInstanceOf <Source>();
}
public static LateBoundCtor CreateCtor(Type type)
{
LateBoundCtor ctor = _ctorCache.GetOrAdd(type, t =>
{
var ctorExpression = Expression.Lambda <LateBoundCtor>(Expression.Convert(Expression.New(type), typeof(object)));
return(ctorExpression.Compile());
});
return(ctor);
}
