I am trying to find the right design pattern for the below scenario.
I have a dataaccess class that can access different datasource. So I have designed to have an implementation class for each datasource(DataAccessMongo, DataAccesssql).
Based on the configuration change the data source must be switched. I believe the right way to do this is to use dependency injection and the data access class that have must accept an interface as a dependency. In the below scenario all the methods are static and I am unable to have a static method in an interface. So for now I am using a enum to check what is the data access type and call the corresponding method. If there are more data sources then definitely I should add more conditions for each data source. I would like a to arrive at a better design pattern. Please suggest what will be the best patter for this scenario. Thanks.
//Implementation class for Mongo
Public Class DataAccessMongo
{
public static string FindById(string itemId)
{
...
}
public static string FindByName(string itemId)
{
...
}
public static string FindByLastName(string itemId)
{
...
}
}
//Implementation class for Sql
Public Class DataAccessSql
{
public static string FindById(string itemId)
{
...
}
public static string FindByName(string itemId)
{
...
}
public static string FindByLastName(string itemId)
{
...
}
}
Public Class DataAccess
{
public static string FindById(string id)
{
string result = string.Empty;
if (databaseType == EnumDb.Mongo)
{
result = DataAccessMongo.FindById(id);
}
else if (databaseType == EnumDb.Sql){
result = DataAccessSql.FindById(id);
}
return result;
}
public static string FindByName(string itemId)
{
string result = string.Empty;
if (databaseType == EnumDb.Mongo)
{
result = DataAccessMongo.FindByName(id);
}
else if (databaseType == EnumDb.Sql){
result = DataAccessSql.FindByName(id);
}
return result;
}
public static string FindByLastName(string itemId)
{
string result = string.Empty;
if (databaseType == EnumDb.Mongo)
{
result = DataAccessMongo.FindByLastName(id);
}
else if (databaseType == EnumDb.Sql){
result = DataAccessSql.FindByLastName(id);
}
return result;
}
}
Note: These methods serve the web API methods.
Related
I have created an interface that in theory should be able to return multiple generic lists of different types to provide the client with various information. When I attempt to loop through the results of the list it is only able to return first collection, can you help me to understand how I should be returning results from the following:
Interface class:
public interface IExampleInterface{}
public class ExampleType : IExampleInterface
{
public int First;
public int Last;
}
public class ExampleAmount : IExampleInterface
{
public decimal Amount;
public decimal TotalFee;
}
public class ExampleFacts : IExampleInterface
{
public bool TooLow;
public bool TooHigh;
}
Interface provider:
public class ExampleInterfaceProvider
{
private static readonly string conn = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
public static List<IExampleInterface> ExampleResults(int id)
{
//declare variables, read from database query using ExecuteReader...
var sT = new ExampleType
{
First = first;
Last = last;
}
var sA = new ExampleAmount
{
Amount = amount;
TotalFee = totalFee;
}
var sF = new ExampleFacts
{
TooHigh = tooHigh;
TooLow = tooLow;
}
var exampleResults = new List<IExampleInterface> {sT, sA, sF};
return exampleResults;
}
}
On the page I need to return the data:
foreach (dynamic item in ExampleResults(0))
{
Response.Write(item.First.ToString())
Response.Write(item.Last.ToString())
//The first two for 'sT' read fine, it breaks here
Response.Write(item.Amount.ToString())
//... And so on
}
Any help would be much appreciated,
Thanks
I think, there is no another solution except comparing implementations;
foreach (IExampleInterface item in ExampleResults(0))
{
if (item is ExampleType)
{
var exampleType = (ExampleType)item;
Response.Write(exampleType.First.ToString())
Response.Write(exampleType.Last.ToString())
}
else if (item is ExampleAmount)
{
var exampleAmount = (ExampleAmount)item;
Response.Write(exampleAmount.Amount.ToString())
}
//... And so on
}
If you are using C# 7, you can perform it as switch case
foreach (IExampleInterface item in ExampleResults(0))
{
switch (item)
{
case ExampleType c:
Response.Write(c.First.ToString());
Response.Write(c.Last.ToString());
break;
case ExampleAmount c:
Response.Write(c.Amount.ToString());
break;
default:
break;
}
//... And so on
}
You can find the documentation.
So basically, the items implementing IExampleInterface should all be written to a Response in a way that is somewhat specific to the actual type implementing the interface?
Then how about this:
public interface IExampleInterface
{
void WriteTo(Response response);
}
public class ExampleType : IExampleInterface
{
public int First;
public int Last;
public void WriteTo(Response response)
{
response.Write(First.ToString());
response.Write(Last.ToString());
}
}
public class ExampleAmount : IExampleInterface
{
public decimal Amount;
public decimal TotalFee;
public void WriteTo(Response response)
{
response.Write(Amount.ToString());
response.Write(TotalFee.ToString());
}
}
public class ExampleFacts : IExampleInterface
{
public bool TooLow;
public bool TooHigh;
public void WriteTo(Response response)
{
response.Write(TooLow.ToString());
response.Write(TooHigh.ToString());
}
}
And then:
foreach (IExampleInterface item in ExampleResults(0))
{
item.WriteTo(Response);
}
Assuming that Response is a variable holding an instance of the response rather than a static class.
I can't get Moq to mock an object that gets created in a static method.
Here is my moq and code
code:
public interface IConfigHelper
{
string GetConfiguration(string sectionName, string elementName);
}
public class ConfigHelper : IConfigHelper
{
public ConfigHelper() { }
public virtual string GetConfiguration(string sectionName, string elementName)
{
string retValue = String.Empty;
//Does things to get configuration and return a value
return retValue;
}
}
public class myRealClass
{
public myRealClass(){}
public string myworkingMethod()
{
var retValue = String.Empty;
retValue = utilSvc.GetConfigurationValue();
return retValue;
}
}
public static class utilSvc
{
public static string GetConfigurationValue()
{
ConfigHelper configUtil = new ConfigHelper(); //NOT BEING MOCKED
return configUtil.GetConfiguration("sectionName/sectionElement", "ClinicalSystem");
}
}
the Test using Moq
[TestFixture(TestName = "Tests")]
public class Tests
{
private Mock<IConfigHelper> configHelperMOCK;
[SetUp]
public void Setup()
{
configHelperMOCK = new Mock<IConfigHelper>();
}
[Test]
public void serviceIsBPManagementForValidSource()
{
//Arrange
string sectionName = "sectionName/sectionElement";
string clinicalElementName = "ClinicalSystem";
string clinicalElementValue = "Zedmed";
configHelperMOCK.Setup(s => s.GetConfiguration(sectionName, clinicalElementName)).Returns(clinicalElementValue);
//act
// the call to myRealClass
//assert
// test assertions
}
}
The issue that I am having is with this line:
ConfigHelper configUtil = new ConfigHelper(); //NOT BEING MOCKED
I cannot get the moq to Mock the object.
I do not want the code to read the config file. I wish to moq away this instance of ConfigHelper
You can't wrap the static class/method but you can redirect it
public static class UtilSvc
{
static UtilSvc()
{
CreatorFunc = () => new ConfigHelper();
}
public static Func<IConfigHelper> CreatorFunc { get; set; }
public static string GetConfigurationValue()
{
var configUtil = CreatorFunc();
return configUtil.GetConfiguration("sectionName/sectionElement",
"ClinicalSystem");
}
}
and then in the test
//...
private Mock<IConfigHelper> configHelperMOCK;
[SetUp]
public void Setup()
{
configHelperMOCK = new Mock<IConfigHelper>();
UtilService.CreatorFunc = () => configHelperMOCK.Object;
}
//...
You cannot mock static class. I would rather propose to inject that IConfigHelper into the myRealClass. That is the usual way how to decouple dependencies and use DI.
public class myRealClass
{
private IConfigHelper _configHelper;
public myRealClass(IConfigHelper configHelper)
{
_configHelper = configHelper;
}
public string myworkingMethod()
{
var retValue = String.Empty;
retValue = _configHelper.GetConfigurationValue();
return retValue;
}
}
Avoid coupling your code to static classes, which in most cases cause you code be to difficult to maintain and test.
Follow the Explicit Dependencies Principle
Methods and classes should explicitly require (typically through
method parameters or constructor parameters) any collaborating objects
they need in order to function correctly.
Give the article a read. It is short and very informative.
If you want to keep the static class then you wrap the static class behind an abstraction.
public interface IUtilSvc {
string GetConfigurationValue();
}
public class utilSvcWrapper : IUtilSvc {
public string GetConfigurationValue() {
return utilSvc.GetConfigurationValue(); //Calling static service
}
}
Or another option is that utlSvc does not have to be static if can be injected into dependent classes
public class utilSvc : IUtilScv {
private readonly IConfigHelper configUtil;
public utilSvc(IConfigHelper configHelper) {
configUtil = configHelper;
}
public string GetConfigurationValue() {
return configUtil.GetConfiguration("sectionName/sectionElement", "ClinicalSystem");
}
}
Inject the IUtilScv into the dependent class so that it is no longer dependent on static class.
public class myRealClass {
private readonly IUtilScv utilSvc;
//Explicit dependency inject via constructor
public myRealClass(IUtilScv utilSvc) {
this.utilSvc = utilSvc;
}
public string myworkingMethod() {
var retValue = utilSvc.GetConfiguration();
return retValue;
}
}
In that case you don't even need IConfigHelper when testing as it has also been abstracted away. And you only need to mock the dependencies needed for the test.
[TestFixture(TestName = "Tests")]
public class Tests {
private Mock<IUtilScv> utilScvMOCK;
[SetUp]
public void Setup() {
utilScvMOCK = new Mock<IUtilScv>();
}
[Test]
public void serviceIsBPManagementForValidSource() {
//Arrange
var expectedClinicalElementValue = "Zedmed";
utilScvMOCK
.Setup(s => s.GetConfiguration())
.Returns(expectedClinicalElementValue)
.Verifiable();
var sut = new myRealClass(utilScvMOCK.Object);
//Act
var actualClinicalElementValue = sut.myworkingMethod();
//Assert
configHelperMOCK.Verify();
Assert.AreEqual(expectedClinicalElementValue, actualClinicalElementValue);
}
}
Looking for design guidelines for the following problem.
I'm receiving two string values - action and message and have to call appropriate method which processes string message (processM1MessageVer1, processM1MessageVer2, processM2MessageVer1...). The method I have to call depends on the given string action. There are 2 versions (but in future there might be more) of each processing method. The version of method I have to call is determined by global variable version. Every method returns object of different type (ResultObject1, ResultObject2...). The result has to be serialized, converted to base64 and returned back.
Is there more elegant way of writing this (eliminate duplicate code, make possible future changes easier, reduce code...):
string usingVersion = "ver1";
public string processRequest(string action, string message)
if (usingVersion == "ver1"){
processRequestVer1(action, message);
}
else{
processRequestVer2(action, message);
}
}
//version 1
public string processRequestVer1(string action, string message){
string result = "";
switch (action){
case "m1":
ResultObject1 ro = processM1MessageVer1(message);
result = serialize(ro);
result = convertToB64(result);
case "m2":
ResultObject2 ro = processM2MessageVer1(message);
result = serialize(ro);
result = convertToB64(result);
case "m3":
ResultObject3 ro = processM3MessageVer1(message);
result = serialize(ro);
result = convertToB64(result);
}
return result;
}
//version 2
public string processRequestVer2(string action, string message){
string result = "";
switch (action){
case "m1":
ResultObject1 ro = processM1MessageVer2(message);
result = serialize(ro);
result = convertToB64(result);
case "m2":
ResultObject2 ro = processM2MessageVer2(message);
result = serialize(ro);
result = convertToB64(result);
case "m3":
ResultObject3 ro = processM3MessageVer2(message);
result = serialize(ro);
result = convertToB64(result);
}
return result;
}
It would be simplier if messages that have to be processed are of different object types instead of strings so that appropriate method could be called polymorphically. The fact that every process method returns different object type also complicates things even more. But these don't depend on me and I cannot change it.
My approach (make it more object oriented, and you should justify whether it's appropriate to create class structure depending on how complex your processing logic is. If your processing logic is only little then maybe this is over-engineering):
For serialize and convert to base 64, I assume you have some logic to do those tasks in a generic way. If not, move those to sub class also
public interface IRequestProcessorFactory
{
IRequestProcessor GetProcessor(string action);
}
public class FactoryVersion1 : IRequestProcessorFactory
{
public IRequestProcessor GetProcessor(string action)
{
switch(action)
{
case "m1":
return new M1Ver1RequestProcessor();
case "m2":
return new M2Ver1RequestProcessor();
case "m3":
return new M3Ver1RequestProcessor();
default:
throw new NotSupportedException();
}
}
}
public class FactoryVersion2 : IRequestProcessorFactory
{
public IRequestProcessor GetProcessor(string action)
{
switch(action)
{
case "m1":
return new M1Ver2RequestProcessor();
case "m2":
return new M2Ver2RequestProcessor();
case "m3":
return new M3Ver2RequestProcessor();
default:
throw new NotSupportedException();
}
}
}
public interface IRequestProcessor
{
string ProcessRequest(string message);
}
public class RequestProcessorBase<T>
{
public string ProcessRequest(string message)
{
T result = Process(message);
string serializedResult = Serialize(result);
return ConvertToB64(serializedResult);
}
protected abstract T Process(string message);
private string Serialize(T result)
{
//Serialize
}
private string ConvertToB64(string serializedResult)
{
//Convert
}
}
public class M1Ver1RequestProcessor : RequestProcessorBase<ResultObject1>
{
protected ResultObject1 Process(string message)
{
//processing
}
}
public class M2Ver1RequestProcessor : RequestProcessorBase<ResultObject2>
{
protected ResultObject2 Process(string message)
{
//processing
}
}
public class M3Ver1RequestProcessor : RequestProcessorBase<ResultObject3>
{
protected ResultObject3 Process(string message)
{
//processing
}
}
public class M1Ver2RequestProcessor : RequestProcessorBase<ResultObject1>
{
protected ResultObject1 Process(string message)
{
//processing
}
}
public class M2Ver2RequestProcessor : RequestProcessorBase<ResultObject2>
{
protected ResultObject2 Process(string message)
{
//processing
}
}
public class M3Ver2RequestProcessor : RequestProcessorBase<ResultObject3>
{
protected ResultObject3 Process(string message)
{
//processing
}
}
Usage:
string action = "...";
string message = "...";
IRequestProcessorFactory factory = new FactoryVersion1();
IRequestProcessor processor = factory.GetProcessor(action);
string result = processor.ProcessRequest(message);
The switch is still there in factory class, but it only returns processor and doesn't do actual work so it's fine for me
First - define interface that suit you best, like this
public interface IProcessMessage
{
string ActionVersion { get; }
string AlgorithmVersion { get; }
string ProcessMessage(string message);
}
Then create as many implementation as you need
public class processorM1Ver1 : IProcessMessage
{
public string ProcessMessage(string message)
{
ResultObject1 ro1 = processM1MessageVer1(message);
var result = serialize(ro1);
result = convertToB64(result);
return result;
}
public string ActionVersion {get { return "m1"; }}
public string AlgorithmVersion {get { return "ver1"; }}
}
public class processorM2Ver1 : IProcessMessage
{
public string ActionVersion {get { return "m2"; }}
public string AlgorithmVersion {get { return "ver1"; }}
public string ProcessMessage(string message)
{
ResultObject1 ro1 = processM2MessageVer1(message);
var result = serialize(ro1);
result = convertToB64(result);
return result;
}
}
public class processorM1Ver2 : IProcessMessage
{
public string ActionVersion {get { return "m1"; }}
public string AlgorithmVersion {get { return "ver2"; }}
public string ProcessMessage(string message)
{
ResultObject1 ro1 = processM1MessageVer2(message);
var result = serialize(ro1);
result = convertToB64(result);
return result;
}
}
Now you need something that know which implementation is best in current context
public class MessageProcessorFactory
{
private MessageProcessorFactory() { }
private static readonly MessageProcessorFactory _instance = new MessageProcessorFactory();
public static MessageProcessorFactory Instance { get { return _instance; }}
private IEnumerable<IProcessMessage> _processorCollection;
IEnumerable<IProcessMessage> ProcessorCollection
{
get
{
if (_processorCollection == null)
{
//use reflection to find all imlementation of IProcessMessage
//or initialize it manualy
_processorCollection = new List<IProcessMessage>()
{
new processorM1Ver1(),
new processorM2Ver1(),
new processorM1Ver2()
};
}
return _processorCollection;
}
}
internal IProcessMessage GetProcessor(string action)
{
var algorithVersion = ReadAlgorithVersion();
var processor = ProcessorCollection.FirstOrDefault(x => x.AlgorithmVersion == algorithVersion && x.ActionVersion == action);
return processor;
}
private string ReadAlgorithVersion()
{
//read from config file
//or from database
//or where this info it is kept
return "ver1";
}
}
It can be use in such way
public class Client
{
public string ProcessRequest(string action, string message)
{
IProcessMessage processor = MessageProcessorFactory.Instance.GetProcessor(action);
return processor.ProcessMessage(message);
}
}
I was just working on some application architecture and this may sound like a stupid question but please explain to me how the following works:
Interface:
public interface IMatterDAL
{
IEnumerable<Matter> GetMattersByCode(string input);
IEnumerable<Matter> GetMattersBySearch(string input);
}
Class:
public class MatterDAL : IMatterDAL
{
private readonly Database _db;
public MatterDAL(Database db)
{
_db = db;
LoadAll(); //Private Method
}
public virtual IEnumerable<Matter> GetMattersBySearch(string input)
{
//CODE
return result;
}
public virtual IEnumerable<Matter> GetMattersByCode(string input)
{
//CODE
return results;
}
Controller:
public class MatterController : ApiController
{
private readonly IMatterDAL _publishedData;
public MatterController(IMatterDAL publishedData)
{
_publishedData = publishedData;
}
[ValidateInput(false)]
public JsonResult SearchByCode(string id)
{
var searchText = id; //better name for this
var results = _publishedData.GetMattersBySearch(searchText).Select(
matter =>
new
{
MatterCode = matter.Code,
MatterName = matter.Name,
matter.ClientCode,
matter.ClientName
});
return Json(results);
}
This works, when I call my controller method from jquery and step into it, the call to the _publishedData method, goes into the class MatterDAL.
I want to know how does my controller know to go to the MatterDAL implementation of the Interface IMatterDAL. What if I have another class called MatterDAL2 which is based on the interface. How will my controller know then to call the right method?
I am sorry if this is a stupid question, this is baffling me.
EDIT:
Based on the responses, it seems like this is where the dependency is being resolved:
This is a ninject call:
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<ICpdMatterDAL>().To<CachedCpdData>();
}
Where CachedCpdData is:
public class CachedCpdData : ICpdMatterDAL
{
private static readonly object CacheLockObject = new object();
private readonly MatterDAL _matterData;
public CachedCpdData()
{
_matterData = DomainModel.DataAccessManager.Instance.Matters;
}
public IEnumerable<Matter> GetMattersForAutoCompleteByCode(string input)
{
var cacheKey = string.Format("matter-search-{0}", input ?? "");
var result = HttpRuntime.Cache[cacheKey] as IEnumerable<Matter>;
if (result == null)
{
lock (CacheLockObject)
{
result = HttpRuntime.Cache[cacheKey] as IEnumerable<Matter>;
if (result == null)
{
result = _matterData.GetMattersForAutoCompleteByCode(input).ToList();
HttpRuntime.Cache.Insert(cacheKey, result, null, DateTime.Now.AddSeconds(60), TimeSpan.Zero);
}
}
}
return result;
}
public IEnumerable<Matter> GetMattersByMatterCodeSearch(string input)
{
return _matterData.GetMattersByMatterCodeSearch(input);
}
}
The rason why your code is using the right implementation of IMatterDAL is because it's being passed as a parameter in the constructor of MatterController. I'm almost sure that your code is using some Dependency Injection framework to resolve IMatterDAL.
In fact Ninject is a DI Framework. Your code should have something like
kernel.Bind<IMatterDAL>().To<MatterDAL >();
I have following C# code. It works fine; but the GetDestination() method is cluttered with multiple if conditions by using is operator.
In .Net 4.0 (or greater) what is the best way to avoid these “if” conditions?
EDIT: Role is part of the business model, and the destination is purely an artifact of one particular application using that business model.
CODE
public class Role { }
public class Manager : Role { }
public class Accountant : Role { }
public class Attender : Role { }
public class Cleaner : Role { }
public class Security : Role { }
class Program
{
static string GetDestination(Role x)
{
string destination = #"\Home";
if (x is Manager)
{
destination = #"\ManagerHomeA";
}
if (x is Accountant)
{
destination = #"\AccountantHomeC";
}
if (x is Cleaner)
{
destination = #"\Cleaner";
}
return destination;
}
static void Main(string[] args)
{
string destination = GetDestination(new Accountant());
Console.WriteLine(destination);
Console.ReadLine();
}
}
REFERENCES
Dictionary<T,Delegate> with Delegates of different types: Cleaner, non string method names?
Jon Skeet: Making reflection fly and exploring delegates
if-else vs. switch vs. Dictionary of delegates
Dictionary with delegate or switch?
Expression and delegate in c#
Having virtual property which would be overriden in derived classes should do the trick:
class Role
{
public virtual string Destination { get { return "Home"; } }
}
class Manager : Role
{
public override string Destination { get { return "ManagerHome;"; } }
}
class Accountant : Role
{
public override string Destination { get { return "AccountantHome;"; } }
}
class Attender : Role
{
public override string Destination { get { return "AttenderHome;"; } }
}
class Cleaner : Role
{
public override string Destination { get { return "CleanerHome;"; } }
}
class Security : Role { }
I didn't make the property abstract, to provide default Home value when it's not overriden in derived class.
Usage:
string destination = (new Accountant()).Destination;
Console.WriteLine(destination);
Console.ReadLine();
Here's one option:
private static readonly Dictionary<Type, string> DestinationsByType =
new Dictionary<Type, string>
{
{ typeof(Manager), #"\ManagerHome" },
{ typeof(Accountant), #"\AccountantHome" },
// etc
};
private static string GetDestination(Role x)
{
string destination;
return DestinationsByType.TryGetValue(x.GetType(), out destination)
? destination : #"\Home";
}
Note:
This doesn't cope with null parameters. It's not clear whether or not you actually need it to. You can easily add null handling though.
This doesn't copy with inheritance (e.g. class Foo : Manager); you could do that by going up the inheritance hierarchy if necessary
Here's a version which does deal with both of those points, at the cost of complexity:
private static string GetDestination(Role x)
{
Type type = x == null ? null : x.GetType();
while (type != null)
{
string destination;
if (DestinationsByType.TryGetValue(x.GetType(), out destination))
{
return destination;
}
type = type.BaseType;
}
return #"\Home";
}
EDIT: It would be cleaner if Role itself had a Destination property. This could either be virtual, or provided by the Rolebase class.
However, it could be that the destination is really not something the Role should concern itself with - it could be that Role is part of the business model, and the destination is purely an artifact of one particular application using that business model. In that sort of situation, you shouldn't put it into Role, as that breaks separation of concerns.
Basically, we can't tell which solution is going to be most suitable without knowing more context - as is so often the way in matters of design.
Approach 1 (Selected): Using dynamic keyword to implement multimethods / double dispatch
Approach 2: Use a dictionary to avoid if blocks as mentioned in Jon Skeet’s answer below.
Approach 3: Use a HashList with delegates if there is condition other than equality (For example, if input < 25). Refer how to refactor a set of <= , >= if...else statements into a dictionary or something like that
Apporach 4: Virtual Functions as mentioned in MarcinJuraszek’s answer below.
MultiMethods / Double Dispatch approach using dynamic keyword
Rationale: Here the algorithm changes based on the type. That is, if the input is Accountant, the function to be executed is different than for Manager.
public static class DestinationHelper
{
public static string GetDestinationSepcificImplm(Manager x)
{
return #"\ManagerHome";
}
public static string GetDestinationSepcificImplm(Accountant x)
{
return #"\AccountantHome";
}
public static string GetDestinationSepcificImplm(Cleaner x)
{
return #"\CleanerHome";
}
}
class Program
{
static string GetDestination(Role x)
{
#region Other Common Works
//Do logging
//Other Business Activities
#endregion
string destination = String.Empty;
dynamic inputRole = x;
destination = DestinationHelper.GetDestinationSepcificImplm(inputRole);
return destination;
}
static void Main(string[] args)
{
string destination = GetDestination(new Security());
Console.WriteLine(destination);
Console.WriteLine("....");
Console.ReadLine();
}
}
This is a strongly typed, imperative language so if statements and type checking are going to happen.
Having said that, have you considered a virtual method on Role that can be overridden to provide a destination string?
A further alternative, a lookup table!
Dictionary<Type, string> paths = new Dictionary<TYpe, string>()
{
{ typeof(Manager), #"\ManagerHomeA" }
{ typeof(Accountant), #"\AccountantHomeC" }
{ typeof(Cleaner), "Cleaner" }
}
string path = #"\Home";
if(paths.ContainsKey(x.GetType())
path = paths[x];
One way to do it would be to use a map instead of an if:
//(psuedocode)
private Dictionary<Type, string> RoleMap;
void SomeInitializationCodeThatRunsOnce()
{
RoleMap.Add(typeof(Manager), #"\ManagerHome");
RollMap.Add(typeof(Accountant), #"\AccountantHome");
// ect...
}
string GetDestination(Role x)
{
string destination;
if(!RoleMap.TryGet(x.GetType(), out destination))
destination = #"\Home";
return destination;
}
Further reading: http://www.hanselman.com/blog/BackToBasicsMovingBeyondForIfAndSwitch.aspx
Role should have a virtual function that would return destination:
public virtual string GetDestination()
{
return "Home";
}
And all the classes should override this function and return the correct string. Then in the code you would have:
var role = new Accountant();
string destination = role.GetDestination();
I hope that helps. There may be typos, I am writing from head.
you can either use an interface definition or an abstract method / property
with interface:
public interface IDestinationProvider
{
sting Destination { get; }
}
string GetDestination(Role role)
{
var provider = role as IDestinationProvider;
if (provider != null)
return provider.Destination;
return "Default";
}
with an abstract base class
abstract class Role
{
public abstract string GetDestination();
}
class Manager : Role
{
public virtual string GetDestination() { return "ManagerHomeA"; }
}
string GetDestination(Role role)
{
return #"\" + role.GetDestination();
}
or with attributes:
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class DestinationAttribute : Attribute
{
public DestinationAttribute() { this.Path = #"\Home"; }
public string Path { get; set; }
}
[Destination(Path = #"\ManagerHome")]
public class Manager : Role { }
string GetDestination(Role role)
{
var destination = role.GetType().GetCustomAttributes(typeof(DestinationAttribute), true).FirstOrDefault();
if (destination != null)
return destination.Path;
return #"\Home";
}