public bool Extends(Constructor constructor)
{
bool result = true;
foreach (string name in constructor._parameterNames.Where(name => !_parameterNames.Contains(name)))
result = false;
return result;
}
/// <summary>
/// Returns an instance of a derived class of the base class <!--typeparamref name="T" /-->.
/// Constructor parameters for the derived class should be stored in the <paramref name="parameterDictionary"/>.
/// </summary>
/// <param name="parameterDictionary">
/// A dictionary of parameters to be passed to subclass constructors, which are registered using <see cref="RegisterConstructorAttribute"/>.
/// Keys should be named in accordance with the <see cref="FactoryParameterAttribute"/>.
/// </param>
/// <returns></returns>
public static T GetInstance <T>(Dictionary <string, object> parameterDictionary)
{
var name = (string)parameterDictionary["name"];
Assembly assembly = Assembly.GetAssembly(typeof(T));
// loop through all the types in the assembly
Type[] types = assembly.GetTypes();
bool foundRegisteredClass = false;
Type matchingType = null;
foreach (Type type in types)
{
// type should be derived from base class T, or should implement interface T.
if (!typeof(T).IsAssignableFrom(type))
{
continue;
}
var registerClassAttributes = (RegisterClassAttribute[])type.GetCustomAttributes(typeof(RegisterClassAttribute), false);
if (registerClassAttributes.Any(registerClassAttribute => registerClassAttribute.RegisteredName == name))
{
foundRegisteredClass = true;
}
if (!foundRegisteredClass)
{
continue;
}
matchingType = type;
break;
}
if (matchingType == null)
{
throw new Exception("Factory can't find a class with the registered name " + name + " in the assembly " + assembly.GetName() + ".");
}
// look through the class's constructors
ConstructorInfo[] constructorInfos = matchingType.GetConstructors();
var matchingConstructors = new List <Constructor>();
Constructor constructor;
foreach (ConstructorInfo constructorInfo in constructorInfos)
{
constructor = new Constructor(constructorInfo, parameterDictionary);
if (!constructor.Match)
{
continue;
}
bool addConstructor = true;
foreach (Constructor matchingConstructor in matchingConstructors)
{
if (matchingConstructor.Extends(constructor))
{
addConstructor = false; // we already have a better constructor
break;
}
if (constructor.Extends(matchingConstructor))
{
matchingConstructors.Remove(matchingConstructor); // matchingConstructor is superceded by constructor
}
}
if (addConstructor)
{
matchingConstructors.Add(constructor);
}
}
#if strict
if (!constructor.UsedAllParameters)
{
throw new Exception("Not used all parameters");
}
#endif
if (matchingConstructors.Count == 0)
{
throw new Exception("Couldn't find a constructor which matches the given parameters");
}
if (matchingConstructors.Count > 1)
{
throw new Exception("More than one constructor matches the given parameters");
}
constructor = matchingConstructors[0];
return((T)constructor.GetInstance());
}
