Abstract classes C# - c#

I have an interface
using ClassAbstractFactory;
public interface IPlugin
{
AbstractFactory GetFactory();
}
and an AbstractFactory
public abstract class AbstractFactory
{
public abstract AbstractCake CreateCake();
public abstract AbstractBox CreateBox();
}
public abstract class AbstractCake
{
public abstract void Interact(AbstractBox box);
}
public abstract class AbstractBox
{
}
and I have .dll that inherit AbstractCake
public class ChocolateCake : AbstractCake
{
private bool _isPacked;
private bool _isDecorated;
private string _nameOfCake;
public ChocolateCake()
{
_isPacked = false;
_isDecorated = false;
_nameOfCake = "Шоколадный";
}
public bool IsPacked
{
get { return _isPacked; }
}
public bool IsDecorated
{
get { return _isDecorated; }
}
public string NameOfCake { get; set; }
public override void Interact(AbstractBox box)
{
_isPacked = true;
}
}
I load dll like this:
public IPlugin LoadAssembly(string assemblyPath)
{
Assembly ptrAssembly = Assembly.LoadFile(assemblyPath);
foreach (Type item in ptrAssembly.GetTypes())
{
if (!item.IsClass) continue;
if (item.GetInterfaces().Contains(typeof(IPlugin)))
{
return (IPlugin)Activator.CreateInstance(item);
}
}
throw new Exception("Invalid DLL, Interface not found!");
}
List<IPlugin> list = new List<IPlugin>();
foreach (var assemblyPath in GetPathsListToDll())
{
list.Add(LoadAssembly(assemblyPath));
}
How can I acess to attributes in my ChocolateCake,to use them like
foreach (var str in list)
{
Boolean a = str.GetFactory().GetCake().CreateCake().IsPacked;
}
or like this
string a = str.GetFactory().GetCake().CreateCake().NameOfCake;
or like this
str.GetFactory().GetCake().CreateCake().NameOfCake("Something");
or like this
str.GetFactory().GetCake().CreateCake().IsDecorated(true);

The problem here is that the AbstractFactory has a method that returns AbstractCake, and AbstractCake itself has no properties at all. As it stands, you would need to downcast the Cake (direct, or with the as keyword) to a ChocolateCake prior to accessing any of its properties, which is really messy:
string a = (ChocolateCake)(str.GetFactory().CreateCake()).NameOfCake;
Here are some considerations:
Move the properties which are common to all types of cake into AbstractCake, e.g. NameOfCake, IsPacked and IsDecorated
Given that the AbstractFactory and AbstractCake classes do not have any implementation at all, consider changing these to interfaces instead of abstract classes, i.e. ICakeFactory and ICake. Concrete implementations will be ChocolateCakeFactory and ChocolateCake as before.
Consumers of the factory and the cake should now only access what is exposed on the interfaces (ICakeFactory, ICake and IBox), and not need to do any down casting or make any assumptions about the actual concrete type of Cake etc.
i.e.
public interface ICake
{
void Interact(IBox box);
bool IsPacked { get; }
bool IsDecorated { get; }
string NameOfCake { get; set; }
}
public class ChocolateCake : ICake
{
private bool _isPacked;
private bool _isDecorated;
private string _nameOfCake;
public ChocolateCake() // ctor is not on the interface and is implementation detail
{
_isPacked = false;
_isDecorated = false;
_nameOfCake = "Шоколадный";
}
public void Interact(IBox box) {...}
public bool IsPacked { get { return _isPacked; } }
public bool IsDecorated { get { return _isDecorated; } }
// ...
}
public interface ICakeFactory
{
ICake CreateCake();
IBox CreateBox();
}
public class ChocolateCakeFactory : ICakeFactory
{
public ICake CreateCake() {return new ChocolateCake();}
public IBox CreateBox() {return new ChocolateCakeBox();}
}
Re : Usage
It is highly unlikely that you would ever do this:
string a = str.GetFactory().GetCake().CreateCake().NameOfCake;
str.GetFactory().GetCake().CreateCake().NameOfCake = "Something"; // Prop setter
as this would create a new cake instance each time (and discard the instance). How about:
class Bakery
{
private readonly ICakeFactory _cakeFactory;
public Bakery(ICakeFactory cakeFactory)
{
Contract.Requires(cakeFactory != null);
cakeFactory = _cakeFactory;
}
bool BakeStuff()
{
var cake = _cakeFactory.CreateCake();
cake.NameOfCake = "StackOverflow";
return cake.IsDecorated && cake.IsPacked;
}
}
Edit, Re Raise change Events
This involves implementing INotifyPropertyChanged
public interface ICake : INotifyPropertyChanged
Which you can then raise on your mutable properties, e.g.
public string NameOfCake
{
get { return _nameOfCake} ;
set {
var propChanged = PropertyChanged;
if (propChanged != null && value != _nameOfCake)
{
propChanged(this, new PropertyChangedEventArgs("NameOfCake"));
}
_nameOfCake = value;
}
}
And subscribe like so
var cake = new ChocolateCake();
cake.PropertyChanged += (sender, eventArgs)
=> Console.WriteLine("Property {0} has changed", eventArgs.PropertyName);

Would this work?
public abstract class AbstractFactory
{
public abstract TCake CreateCake<TCake>() where TCake : AbstractCake, new();
public abstract AbstractBox CreateBox();
}
...
var cake = str.GetFactory().CreateCake<ChocolateCake>();

Related

Convert to use dependency injection?

I have the following example code:
namespace ConsoleApp3
{
public interface IPriceList
{
double GetPrice();
}
public class PriceList : IPriceList
{
public double GetPrice()
{
return 2.3;
}
}
public interface ISensorValue
{
double GetValue();
}
public class SensorValue : ISensorValue
{
public double GetValue()
{
return 20.5;
}
}
public abstract class Condition
{
public abstract bool IsTrue();
}
public class PriceCondition : Condition
{
private IPriceList _priceList;
public PriceCondition(IPriceList priceList)
{
_priceList = priceList;
}
public override bool IsTrue() { return _priceList.GetPrice() > 4.4; }
}
public class SensorCondition : Condition
{
private ISensorValue _sensorValue;
public SensorCondition(ISensorValue sensorValue)
{
_sensorValue = sensorValue;
}
public override bool IsTrue() { return _sensorValue.GetValue() > 20.4; }
}
public class ScheduleManager
{
private List<Condition> _conditions = new List<Condition>();
public ScheduleManager(IPriceList priceList, ISensorValue sensorValue)
{
Condition condition = new PriceCondition(priceList);
_conditions.Add(condition);
condition = new SensorCondition(sensorValue);
_conditions.Add(condition);
}
}
internal class Program
{
static void Main(string[] args)
{
PriceList priceList = new PriceList();
SensorValue sensorValue = new SensorValue();
ScheduleManager deviceScheduleManager = new ScheduleManager(priceList, sensorValue);
}
}
}
I would like to convert this to using dependency injection with the following changes:
I don't want to pass any dependencies to ScheduleManager (they are only used to be be passed down to PriceCondition and SensorCondition. All the subclasses of Condition may have different set of dependencies and the number of dependencies which then needs to be passed through the constructor of ScheduleManager would become large. The dependencies needed by each Condition subclass should somehow be injected at that level.
The code in the ScheduleManager class which creates the two different Condition objects is just a simplified example. In the real case, Condition objects will be created dynamically based on the content of a JSON file.

How can I cause Simple Injector to use different concrete classes for the same interface, but with different classes

I can do this with StructureMap using Constructor Injection. However I cannot find a way to do this with Simple Injector. Here is some code that illustrates this (sorry for the length)
I've looked at the lambda in the Register method, but can't seem to understand how to call a single application wide instance of the container to get the one instance I need.
These are the object graphs I wish to construct:
var bannerTalker =
new LoudMouth(
new ConsoleShouter(), // Implements IConsoleVoicer
new ObnoxiousBannerGenerator());
var plainTalker =
new TimidSpeaker(
new ConsoleWhisperer()); // Implements IConsoleVoicer
Here's the code:
``` c#
public interface IConsoleVoicer
{
void SaySomething(string whatToSay);
}
public class ConsoleWhisperer : IConsoleVoicer
{
public void SaySomething(string whatToSay)
{
Console.WriteLine(whatToSay?.ToLower());
}
}
public class ConsoleShouter : IConsoleVoicer
{
public void SaySomething(string whatToSay)
{
Console.WriteLine(whatToSay?.ToUpper());
}
}
public interface IBannerGenerator
{
string GetBanner();
}
public class ObnoxiousBannerGenerator : IBannerGenerator
{
public string GetBanner()
{
return "OBNOXIOUS";
}
}
public interface IBannerTalker
{
void SayWithBanner(string somethingToSay);
}
public class LoudMouth : IBannerTalker
{
private IConsoleVoicer Voicer { get; set; }
private IBannerGenerator BannerGenerator { get; set; }
public LoudMouth(
IConsoleVoicer concoleVoicer, IBannerGenerator bannerGenerator)
{
Voicer = concoleVoicer;
BannerGenerator = bannerGenerator;
}
public void SayWithBanner(string somethingToSay)
{
Voicer.SaySomething(string.Format("{0}:{1}",
BannerGenerator.GetBanner(), somethingToSay));
}
}
public interface IPlainTalker
{
void SayIt(string somethingToSay);
}
public class TimidSpeaker : IPlainTalker
{
private IConsoleVoicer Voicer { get; set; }
public TimidSpeaker(IConsoleVoicer concoleVoicer)
{
Voicer = concoleVoicer;
}
public void SayIt(string somethingToSay)
{
Voicer.SaySomething(somethingToSay);
}
}
And this is what I've tried:
static void Main(string[] args)
{
var container = new Container();
container.Register<IBannerGenerator, ObnoxiousBannerGenerator>();
container.Register<IPlainTalker, TimidSpeaker>();
container.Register<IBannerTalker, LoudMouth>();
//HERE IS THE DILEMMA! How do I assign
// to IBannerTalker a A LoudMouth contructed with a ConsoleShouter,
// and to IPlainTalkerTalker a A TimidSpeaker contructed with a ConsoleWhisperer
//container.Register<IConsoleVoicer, ConsoleShouter>();
container.Register<IConsoleVoicer, ConsoleWhisperer>();
var bannerTalker = container.GetInstance<IBannerTalker>();
var plainTalker = container.GetInstance<IPlainTalker>();
bannerTalker.SayWithBanner("i am a jerk");
plainTalker.SayIt("people like me");
}
Ric .Net is right in pointing you at the RegisterConditional methods. The following registrations complete your quest:
container.Register<IBannerGenerator, ObnoxiousBannerGenerator>();
container.Register<IPlainTalker, TimidSpeaker>();
container.Register<IBannerTalker, LoudMouth>();
container.RegisterConditional<IConsoleVoicer, ConsoleShouter>(
c => c.Consumer.ImplementationType == typeof(LoudMouth));
container.RegisterConditional<IConsoleVoicer, ConsoleWhisperer>(
c => c.Consumer.ImplementationType == typeof(TimidSpeaker));

Casting a Parent to its Generic Child

I have the following setup:
public class Child<T>: BaseClass
{
public T Value;
}
public class IntChild: Child<int> { }
public class BoolChild: Child<bool> { }
public class FloatChild: Child<float> { }
public class MyProgram
{
public BaseClass Source;
public void SetValue(object val)
{
// I want to do something like the following
// ((Child) Source).Value = (val.GetType()) val;
// Instead, I have to do it like this
string temp = val.ToString();
switch (Source.GetType())
{
case "IntChild":
((IntChild) Source).Value = int.Parse(val.ToString());
break;
case "BoolChild":
((BoolChild) Source).Value = bool.Parse(val.ToString());
break;
case "FloatChild":
((FloatChild) Source).Value = float.Parse(val.ToString());
break;
}
}
}
I cannot modify the BaseClass (I could only overwrite ToString()).
How can I replace the switch with a simpler line of code? I want to do something like the following
((Child) Source).Value = (val.GetType()) val;
,instead of the switch. Is this even possible?
You should use the visitor pattern:
public abstract class BaseClassWithVisitor : BaseClass {
void AcceptVisitor(BaseClassVisitor visitor);
}
This means Child<T> become abstract too.
Make all Child<T> children class implements BaseClassWithVisitor.AcceptVisitor() method, so they are not abstract:
public class IntChild : Child<int> {
...
/// This method should be implemented in all Child<T> descendant classes
public override void AcceptVisitor(BaseClassVisitor visitor) { visitor.Visit(this); }
...
}
Then define the BaseClassVisitor interface :
public interface BaseClassVisitor {
void Visit(IntChild intChild);
void Visit(...); // all the other possible types
...
}
Then eventually create an implementation of the BaseClassVisitor that will do the operation you wanted:
public class SetValueVisitor : BaseClassVisitor {
void Visit(IntChild intChild) { intChild.Value = 1; }
void Visit(BoolChild boolChild) { boolChild.Value = false; }
...
}
Here is a complete example to make things clearer:
using System;
using System.Globalization;
namespace Visitor
{
class BaseClass
{
}
abstract class BaseClassWithVisitor : BaseClass
{
public abstract void AcceptVisitor(Visitor visitor);
}
abstract class Child<T> : BaseClassWithVisitor
{
public T Value;
}
class IntChild : Child<int>
{
public override void AcceptVisitor(Visitor visitor)
{
visitor.Visit(this);
}
}
class FloatChild : Child<float>
{
public override void AcceptVisitor(Visitor visitor)
{
visitor.Visit(this);
}
}
class StringChild : Child<string>
{
public override void AcceptVisitor(Visitor visitor)
{
visitor.Visit(this);
}
}
class Visitor
{
public object Value;
public void Visit(IntChild intChild)
{
intChild.Value = int.Parse(Value.ToString());
}
public void Visit(FloatChild floatChild)
{
floatChild.Value = float.Parse(Value.ToString(), CultureInfo.InvariantCulture);
}
public void Visit(StringChild stringChild)
{
stringChild.Value = Value.ToString();
}
}
class Program
{
static void Main(string[] args)
{
var visitor = new Visitor { Value = "12345" };
var intChild = new IntChild();
intChild.AcceptVisitor(visitor);
visitor = new Visitor { Value = "1.2345" };
var floatChild = new FloatChild();
floatChild.AcceptVisitor(visitor);
visitor = new Visitor { Value = "Hello World" };
var stringChild = new StringChild();
stringChild.AcceptVisitor(visitor);
Console.WriteLine("intChild.Value = {0}", intChild.Value);
Console.WriteLine("floatChild.Value = {0}", floatChild.Value);
Console.WriteLine("stringChild.Value = {0}", stringChild.Value);
}
}
}
This will output:
intChild.Value = 12345
floatChild.Value = 1,2345
stringChild.Value = Hello World
You can do it via reflection without classes modifying at all:
public void SetValue(object val)
{
Source.GetType().GetProperty("Value").SetValue(Source, value);
}
Small variation of answer already provided by Slava Utesinov
// Only set value if implementation of Child<>.
// If any other derived class of BaseClass with value field, then dont set
if(source.GetType().BaseType != null
&& source.GetType().BaseType.IsGenericType
&& source.GetType().BaseType.GetGenericTypeDefinition() == typeof(Child<>))
{
Console.WriteLine("Is implementation of Child<>");
source.GetType().GetField("Value").SetValue(source, val);
}
else
{
Console.WriteLine("Not implementation of Child<>");
}
One option to consider:
public void SetValue(object val)
{
dynamic dynamicSource = Source;
dynamicSource.Value = val;
}
It is a similar approach to the reflection based approaches, but a little more concise.

How can i avoid breaking LSP in this example? C#

I have a base class called Message like this:
public abstract class Message
{
protected int m_id;
protected bool m_localized;
protected string m_metaData;
public int GetID() { return m_id; }
public bool GetLocalized() { return m_localized; }
public string GetMetadata() { return m_metaData; }
}
Then, i have two more classes that inherit from Message for example:
public class ClassicMessage : Message
{
private string m_title;
private string m_content;
public void SetTitle(string title) { m_title = title; }
public void SetContent(string content) { m_content = content; }
public string GetTitle() { return m_title; }
public string GetContent() { return m_content; }
}
public class MessageWithCustomContent : Message
{
private List<CustomContent> m_content;
public MessageWithCustomContent()
{
m_content = new List<CustomContent>();
}
public List<CustomContent> GetContent()
{
return m_content;
}
public CustomContent GetContentEntry(int id)
{
return m_content.find(x => x.ID.Equals(id));
}
}
public class CustomContent
{
private int m_id;
public int ID { get; set { m_id = value; } }
private string m_body;
public string Body { get { return m_body; } set { m_body = value; }
private Image m_image;
public Image Image { get { return m_image; } set { m_image = value; } }
}
In a case like this, how can i unify the app interface if the derived classes has similar methods but these methods have different return types? (even when the methods try to do the same)
I know that with the example i'm breaking the Liskov Substitution Principle and the Open/Closed principle, what's the best approach to get around with that?
Thanks for your help!
Edit:
For more clarity, what i'm trying to achieve is to create a common interface to manage all the possible messages as the base "Message", because i want to avoid using typeof in the consumer class.
for example:
if(message is MessageWithCustomContent)
{
// do something with the contents.
}
else if(message is MessageWithCustomContent)
{
// do another thing with the contents.
}
etc...
You could change Message to be generic, and the T would specify the Content return type. See example below.
Edit
You could use a "IMessage" and a "Message: IMessage" as base.
You would then be able to create a IMessage list like so
var messages = new List<IMessage>
{
new ClassicMessage(),
new MessageWithCustomContent()
};
foreach (var message in messages)
{
message.GetContent();
}
Below is how the implementation of IMessagecould be done.
public interface IMessage
{
int GetID();
bool GetLocalized();
string GetMetadata();
object GetContent();
}
public abstract class Message<T> : IMessage
{
protected int m_id;
protected bool m_localized;
protected string m_metaData;
public int GetID() { return m_id; }
public bool GetLocalized() { return m_localized; }
public string GetMetadata() { return m_metaData; }
object IMessage.GetContent()
{
return GetContent();
}
public abstract T GetContent();
}
public class ClassicMessage : Message<string>
{
private string m_title;
private string m_content;
public void SetTitle(string title) { m_title = title; }
public void SetContent(string content) { m_content = content; }
public string GetTitle() { return m_title; }
public override string GetContent()
{
return m_content;
}
}
public class MessageWithCustomContent : Message<List<CustomContent>>
{
private List<CustomContent> m_content;
public MessageWithCustomContent()
{
m_content = new List<CustomContent>();
}
public CustomContent GetCustomContent(int id)
{
return null;
}
public override List<CustomContent> GetContent()
{
return m_content;
}
}
public class CustomContent
{
private int m_id;
public int ID { get; set; }
private string m_body;
public string Body
{
get { return m_body; }
set { m_body = value; }
}
}
I will explain how you break LSP below but before I do that, you are not really doing any inheriting. Yes you are declaring your classes to be inheriting but you are not really inheriting anything. So before learning LSP, perhaps you need to get a grip on inheritance firstly.
How do I know if I am breaking LSP?
Lest say your Message class was like this, notice the virtual and abstract methods:
public abstract class Message
{
protected int m_id;
protected bool m_localized;
protected string m_metaData;
public virtual int GetID() { return m_id; }
public virtual bool GetLocalized() { return m_localized; }
public abstract string GetMetadata();
}
Create a list like this:
var messages = new List<Message>();
Then add concrete types to that list of all the inheriting types. Then do this:
foreach(var thisMessage in messages)
{
var id = thisMessage.GetID();
var loc = GetLocalized();
var meta = GetMetadata();
}
If you get no exception thrown because one of the inheriting classes decided it does not need one of those methods, then you have not broken LSP. The idea is that if something is inheriting Message, then it should inherit everything. Otherwise, we cannot safely and with confidence substitute the inherited one for the parent one.
The reason this principle is important is because there may be existing code which is using Message, as shown in the foreach above, where it is treating all the types polymorphically and a developer decides to inherit it like this:
public abstract class BadMessage
{
public override int GetID()
{
throw new InvalidOperationException
("This method is not needed for BadMessage and should not be called");
}
public override bool GetLocalized() { ... }
public override string GetMetadata() { ... }
}
You see this will break existing code. And the worst part is, the compiler will not even be able to catch it, until it surfaces like an ugly bug in production.
Well, you're missing the interface methods in de base class. Abstract functions, that get implemented in the derivative classes. If you get a Message, not knowing what kind it is, how would you request its contents?
You could add derivative-specific methods to your base, but you'd have to implement an not_implemented exception in a virtual implementation in the base class to compensate for all derivatives not implementing it, and add exception handling. But then you should ask yourself: " is this class really a derivative? What do I want to achieve."

Inherit in generic classes C#

My brain is gonna to explode. :) So I would like to get help from you.
Please, think about my question like about just programmer puzzle. (Actually. perhaps it is very easy question for you, but not for me.)
It is needed to create array of objects. For example List where T is class. (I will describe Class T below). Also it is needed create “container” that will contain this array and some methods for work with this array. For example Add(), Remove(int IndexToRemove).
Class T must have field "Container", this way each elements of our array would be able to know where is it contained and has access its container's fields and methods. Notice, that in this case Class T should have type parameter. Indeed, it is not known beforehand which container's type is used.
Let us denote this class container as A and class element (class T) as AUnit.
Code:
class Program
{
static void Main(string[] args)
{
A a = new A();
a.Add();
a.Units[0].SomeField +=100;
Console.ReadKey();
}
}
class A
{
public List<AUnit> Units;
public A()//ctor
{
Units = new List<AUnit>();
}
public void Add()
{
this.Units.Add(new AUnit(this));
}
}
class AUnit
{
public int SomeField;
public A Container;
public string Name { get; private set; }
public AUnit(A container)
{
this.SomeField = 43;
this.Container = container;
this.Name = "Default";
}
}
Public fields should be protected or private of course, but let think about this later.
You can ask “why we create public A Container field in AUnit”? We create field public string Name{get;private set;} (actually property but nevermind). And also we would like to be able to change value of this field for example method [Class AUnit] public bool Rename(string newName)();. The main idea of this method is changing Name field only that case if no one element in array (public List Units; ) has the same name like newName. But to achieve this, Rename method has to have access to all names that is currently used. And that is why we need Container field.
Code of extended version AUnit
class AUnit
{
public int SomeField;
public A Container;
public string Name { get; private set; }
public AUnit(A container)
{
this.SomeField = 43;
this.Container = container;
this.Name = "Default";
}
public bool Rename(String newName)
{
Boolean res = true;
foreach (AUnit unt in this.Container.Units)
{
if (unt.Name == newName)
{
res = false;
break;
}
}
if (res) this.Name = String.Copy(newName);
return res;
}
}
Ok. If you still read it let's continue. Now we need to create Class B and class BUnit which will be very similar like Class A and Class Aunit. And finally the main question of this puzzle is HOW WE CAN DO IT? Of course, I can CopyPaste and bit modify A and AUnit and create this code.
class B
{
public List<BUnit> Units; //Only Type Changing
public B()//ctor Name changing...
{
Units = new List<BUnit>();//Only Type Changing
}
public void Add()
{
this.Units.Add(new BUnit(this));//Only Type Changing
}
}
class BUnit
{
public int SomeField;
public B Container;//Only Type Changing
public string Name { get; private set; }
public A a; //NEW FIELD IS ADDED (just one)
public BUnit(B container) //Ctor Name and arguments type changing
{
this.SomeField = 43;
this.Container = container;
this.Name = "Default";
this.a=new A(); //New ROW (just one)
}
public bool Rename(String newName)
{
Boolean res = true;
foreach (BUnit unt in this.Container.Units) //Only Type Changing
{
if (unt.Name == newName)
{
res = false;
break;
}
}
if (res) this.Name = String.Copy(newName);
return res;
}
}
And I can to use this classes this way.
static void Main(string[] args)
{
B b = new B();
b.Add();
b.Units[0].a.Add();
b.Units[0].a.Units[0].SomeField += 100;
bool res= b.Units[0].a.Units[0].Rename("1");
res = b.Units[0].a.Units[0].Rename("1");
Console.ReadKey();
}
This construction is can be used to create “non-homogeneous trees”.
Help, I need somebody help, just no anybody…. [The Beatles]
I created B and BUnit using CopyPaste.
But how it can be done using “macro-definitions” or “Generic”, inherit or anything else in elegant style? (C# language)
I think that there is no reason to describe all my unsuccessful attempts and subquestions. Already topic is too long. : )
Thanks a lot if you still read it and understand what I would like to ask.
You need to implement a base type, lets call it UnitBase, with all common functionality. I'd structure your code the following way:
Create an interface for your container, this way you can change implementation to more performant solutions without modifying the elements you will be adding to the container.
public interface IContainer
{
Q Add<Q>() where Q : UnitBase, new();
IEnumerable<UnitBase> Units { get; }
}
Following the idea stated in 1, why not make the search logic belong to the container? It makes much more sense, as it will mostly depend on how the container is implemented:
public interface IContainer
{
Q Add<Q>() where Q : UnitBase, new();
IEnumerable<UnitBase> Units { get; }
bool Contains(string name);
}
A specific implementation of IContainer could be the following:
public class Container : IContainer
{
public Container()
{
list = new List<UnitBase>();
}
private List<UnitBase> list;
public Q Add<Q>() where Q: UnitBase, new()
{
var newItem = Activator.CreateInstance<Q>();
newItem.SetContainer(this);
list.Add(newItem);
return newItem;
}
public IEnumerable<UnitBase> Units => list.Select(i => i);
public bool Contains(string name) =>
Units.Any(unit => unit.Name == name);
}
Create a base class for your AUnit and BUnit types condensing all common functionality:
public abstract class UnitBase
{
protected UnitBase()
{
}
public IContainer Container { get; private set; }
public int SomeField;
public string Name { get; private set; }
public void SetContainer(IContainer container)
{
Container = container;
}
public bool Rename(String newName)
{
if (Container.Contains(newName))
return false;
this.Name = newName; //No need to use String.Copy
return true;
}
}
Implement your concrete types:
public class BUnit : UnitBase
{
public int SpecificBProperty { get; private set; }
public BUnit()
{
}
}
Shortcomings of this approach? Well, the container must be of type <UnitBase>, I've removed the generic type because it really wasn't doing much in this particular case as it would be invariant in the generic type.
Also, keep in mind that nothing in the type system avoids the following:
myContainer.Add<BUnit>();
myContainer.Add<AUnit>();
If having two different types in the same container is not an option then this whole set up kind of crumbles down. This issue was present in the previous solution too so its not something new, I simply forgot to point it out.
InBetween , I am very thankful to you for your advices. Actually I can't say that I understood your answer in full, but using your ideas I have done what I want.
Looks like my variant works well. However I would like to hear your (and everyone) opinions about code described below. The main goal of this structure is creating non-homogeneous trees. So could you estimate it from this side.
First of all. We need to create interfaces for both classes. We describe there all "cross-used" functions.
public interface IUnit<T>
{
string Name { get;}
void SetContainer(T t);
bool Rename(String newName);
}
public interface IContainer
{
bool IsNameBusy(String newName);
int Count { get; }
}
Next. Create Base for Unit Classes for future inheritance. We will use in this inheritors methods from Container Base so we need generic properties and IUnit interface.
class UnitBase<T> : IUnit<T> where T : IContainer
Unfortunately I don't know yet how to solve the problem with Constructor parameters. That is why I use method
SetContainer(T container).
Code:UnitBase
class UnitBase<T> : IUnit<T> where T : IContainer
{
protected T Container;
public string Name { get; private set; }
public UnitBase()
{
this.Name = "Default";
}
public void SetContainer(T container)
{
this.Container = container;
}
public bool Rename(String newName)
{
bool res = Container.IsNameBusy(newName);
if (!res) this.Name = String.Copy(newName);
return !res;
}
}
Next. Create ContainerBase
ContainerBase should:
1) has IContainer interface.
2)has information about what it will contain:
... where U : IUnit<C>, new()
3)and .... has information about what itself is. This information we need to pass as parameter to SetContainer() method.
Code ContainerBase:
class ContainerBase<U, C> : IContainer //U - Unit Class. C-Container Class
where U : IUnit<C>, new()
where C : ContainerBase<U, C>
{
protected List<U> Units;
public U this[int index] { get { return Units[index]; } }
public ContainerBase()//ctor
{
this.Units = new List<U>();
}
public void Add()
{
this.Units.Add(new U());
this.Units.Last().SetContainer(((C)this));//may be a bit strange but actualy this will have the same type as <C>
}
public bool IsNameBusy(String newName)
{
bool res = false;
foreach (var unt in this.Units)
{
if (unt.Name == newName)
{
res = true;
break;
}
}
return res;
}
public int Count { get { return this.Units.Count; } }
}
Cast ((TContainer)(this)) may be is a bit strange. But using ContainerBase we always should use NewInheritorContainer. So this cast is just do nothing…looks like...
Finally. This classes can be used like in this example.
class SheetContainer : ContainerBase<SheetUnit,SheetContainer> {public SheetContainer(){}}
class SheetUnit : UnitBase<SheetContainer>
{
public CellContainer Cells;
public PictureContainer Pictures;
public SheetUnit()
{
this.Cells = new CellContainer();
this.Pictures = new PictureContainer();
}
}
class CellContainer : ContainerBase<CellUnit, CellContainer> { public CellContainer() { } }
class CellUnit : UnitBase<CellContainer>
{
public string ValuePr;//Private Field
private const string ValuePrDefault = "Default";
public string Value//Property for Value
{
//All below are Just For Example.
get
{
return this.ValuePr;
}
set
{
if (String.IsNullOrEmpty(value))
{
this.ValuePr = ValuePrDefault;
}
else
{
this.ValuePr = String.Copy(value);
}
}
}
public CellUnit()
{
this.ValuePr = ValuePrDefault;
}
}
class PictureContainer : ContainerBase<PictureUnit, PictureContainer> { public PictureContainer() { } }
class PictureUnit : UnitBase<PictureContainer>
{
public int[,] Pixels{get;private set;}
public PictureUnit()
{
this.Pixels=new int[,]{{10,20,30},{11,12,13}};
}
public int GetSizeX()
{
return this.Pixels.GetLength(1);
}
public int GetSizeY()
{
return this.Pixels.GetLength(0);
}
public bool LoadFromFile(string path)
{
return false;
}
}
static void Main(string[] args)
{
SheetContainer Sheets = new SheetContainer();
Sheets.Add();
Sheets.Add();
Sheets.Add();
Sheets[0].Pictures.Add();
Sheets[1].Cells.Add();
Sheets[2].Pictures.Add();
Sheets[2].Cells.Add();
Sheets[2].Cells[0].Value = "FirstTest";
bool res= Sheets[0].Rename("First");//res=true
res=Sheets[2].Rename("First");//res =false
int res2 = Sheets.Count;
res2 = Sheets[2].Pictures[0].Pixels[1, 2];//13
res2 = Sheets[2].Pictures.Count;//1
res2 = Sheets[1].Pictures.Count;//0
res2 = Sheets[0].Pictures[0].GetSizeX();//3
Console.ReadKey();
}
Looks like it works like I want. But I didn’t test it full.
Let me say Thank you again, InBetween.

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