DotNet Conference: code smells

Fernando Escolar
@fernandoescolar
fernando.escolar@tokiota.com
Code Smells
Y
A
X B

public void CalculateTotalPrice()
{
//calculates taxes
var taxes = 0.0m;
foreach (var product in this.productLines)
{
// ...
taxes += product.Price / product.TaxesPercent * 100;
}
//calculates price
var price = 0.0m;
foreach (var product in this.productLines)
{
// ...
price += product.Price * product.Unit;
}
this.TotalPrice = price + taxes;
}

public void CalculateTotalPrice()
{
var taxes = this.CalculateTaxes();
var price = this.CalculatePrice();
this.TotalPrice = price + taxes;
}
public decimal CalculateTaxes()
{
// ...
return taxes;
}
public decimal CalculatePrice()
{
// ...
return price;
}

public class User
{
// ...
}
public class Product
{
// ...
}
public class ProductLine
{
// ...
}
public class Order
{
// ...
}

public class Customer
{
private string name;
private string lastName;
private string streetType;
private string streetName;
private string streetNumber;
private string floorNumber;
private string doorNumber;
private string postalCode;
private string city;
private string state;
private string country;
private string phone;
private string email;
}

public class Customer {
private string name;
private string lastname;
private string phone;
private string email;
private Address address;
}
public class Address {
private string streetType;
private string streetName;
private string streetNumber;
private string floorNumber;
private string doorNumber;
private string postalCode;
private string city;
private string state;
private string country;
}

public void Draw(int x, int y, int width, int heigth,
int borderSize,
Color borderColor, Color backgroundColor)
{
// ...
}

public void Draw(BorderedRectangle rectangle)
{
// ...
}
public class Rectangle
{
public int X { get; set; }
public int Y { get; set; }
public int Width { get; set; }
public int Height { get; set; }
public Color Color { get; set; }
}
public class BorderedRectangle : Rectangle
{
public int BorderSize { get; set; }
public Color BorderColor { get; set; }
}

class Rectangle
{
public void Draw(int x, int y, int width, int height,
int borderSize, Color borderColor, Color backgroundColor)
{
this.DrawRectable(x, y, width, height, backgroundColor);
this.DrawRectangleBorder(x, y, width, height, borderSize,
borderColor);
}
private void DrawRectable(int x, int y, int width, int height,
Color color)
{
// ...
}
private void DrawRectangleBorder(int x, int y, int width,
int height, int borderSize, Color color)
{
// ...
}

public class Rectangle
{
public int X { get; set; }
public int Y { get; set; }
public int Width { get; set; }
public int Height { get; set; }
public Color Color { get; set; }
public void Draw() { /* ... */ }
}
public class BorderedRectangle : Rectangle
{
public int BorderSize { get; set; }
public Color BorderColor { get; set; }
public void Draw() { base.Draw(); /* ... */ }
}

namespace MyTech
{
class MyTechConnection { }
class MyTechConnectionHndl { }
class Order {
public bool Order(OrderRequest request) { /* ... */ }
}
class Inv
{
int Do(int a, string s, double d) { /* ... */ }
}
}

namespace MyTechnology
{
class Connection { }
class ConnectionHandler { }
class OrderManager {
public bool Request(Order order) { /* ... */ }
}
class Invoice
{
bool Pay(int userId, string account, double price) {
/* ... */
}
}
}

private const decimal USDolarChange = 1.13845m;
private const decimal BritishPoundsChange = 0.739373275m;
public enum MoneyTypes { Euro, USDolar, BritishPounds };
public decimal ConvertValue(decimal money, MoneyTypes type)
{
switch (type)
{
case MoneyTypes.Euro:
return money;
case MoneyTypes.USDolar:
return money * USDolarChange;
case MoneyTypes.BritishPounds:
return money * BritishPoundsChange;
default:
return money;
}
}

public class Euro {
public decimal Value { get; set; }
public virtual decimal GetConvertedValue()
{
return this.Value;
}
}
public class USDolar : Euro {
public override decimal GetConvertedValue()
{
return this.Value * USDolarChange;
}
}
public class BritishPounds : Euro {
public override decimal GetConvertedValue()
{
return this.Value * BritishPoundsChange;
}
}

public decimal GetDiscount()
{
var basePrice = quantity * itemPrice;
if (quantity > 1000)
return basePrice * 0.95;
else if (quantity > 500)
return 20.0d;
}

public decimal GetDiscount()
{
if (quantity > 1000)
return CalculateBasePrice() * 0.95;
else if (quantity > 500)
return 20.0d;
}
private decimal CalculateBasePrice()
{
return quantity * itemPrice;
}

abstract class Membership
{
public abstract IEnumerable<User> GetUsers();
public abstract IEnumerable<Profile> GetProfiles();
public abstract User Auth(string user, string password);
public abstract IEnumerable<Profile> GetUserProfile(User user);
}
class MyMembership : Membership
{
public override IEnumerable<User> GetUsers() {
throw new NotImplementedException(); }
public override IEnumerable<Profile> GetProfiles() {
throw new NotImplementedException(); }
public override User Auth(string user, string password) {
// ...
}
public override IEnumerable<Profile> GetUserProfile(User user) {
// ...
}
}
¿Liskov?

abstract class Membership
{
public abstract User Auth(string user, string password);
public abstract IEnumerable<Profile> GetUserProfile(User user);
}
class MyMembership : Membership
{
public override User Auth(string user, string password)
{
// ...
}
public override IEnumerable<Profile> GetUserProfile(User user)
{
// ...
}
}

class TokiotaService
{
// ...
}
class MicrosoftService
{
// ...
}
public IEnumerable<TokiotaItem> GetTokiotaItems()
{
return this.tokiotaService.GetProyects();
}
public IEnumerable<MicrosoftItem> GetMicrosoftItems()
{
return this.microsoftService.GetPartnerCollaborations();
}

class Item { /* ... */ }
class IAdapter
{
IEnumerable<Item> GetItems();
}
class MicrosoftAdapter : IAdapter { /* ... */ }
class TokiotaAdapter : IAdapter { /* ... */ }
public IEnumerable<Item> GetItems(IAdapter adapter)
{
return adapter.GetItems();
}

public decimal CalculateTotalPrice() {
if (this.isChristmas) {
return this.CalculateChristmas();
}
else {
if (this.HasDiscount()) {
return this.CalculateDiscounted(this.GetDiscount());
}
else {
if (this.isTimeOfSale) {
return this.CalculateDiscounted(this.GetSalesDiscount());
}
else
{
return this.CalculateStandard();
}
}
}
}

public decimal CalculateTotalPrice()
{
if (this.isChristmas)
return this.CalculateChristmas();
if (this.HasDiscount())
return this.CalculateDiscounted(this.GetDiscount());
if (this.isTimeOfSale)
return this.CalculateDiscounted(this.GetSalesDiscount());
return this.CalculateStandard();
}

class Customer
{
public string Name { get; set; }
public string LastName { get; set; }
public string toXML()
{
return @"<Customer>" +
"<Name>" +
this.Name +
"</Name>" +
"<LastName>" +
this.LastName +
"</LastName>" +
"</Customer>";
}
}
Open-Close?

class Customer
{
private readonly CustomerXmlSerializer serializer = ...;
public string toXML()
{
return this.serializer.Serialize(this);
}
}
class CustomerXmlSerializer : XmlSerializer
{
public string Serialize(Customer c)
{
var sb = new StringBuilder();
sb.Append(this.StartTag("Customer"));
sb.Append(this.WriteTag("Name", c.Name));
sb.Append(this.WriteTag("LastName", c.LastName));
sb.Append(this.EndTag("Customer"));
}

class OrderManager
{
decimal CalculateOrderPrice(Product[] products, int[] units) {
/* ... */
}
}
class OrderViewModel
{
public Product[] Products { get; set; }
public int[] Units { get; set; }
}
class OrderService
{
void SendOrder(Product[] products, int[] units) { /* ... */ }
}
¿Y si queremos
añadir IVA?

class Order
{
public Product[] Products { get; set; }
public int[] Units { get; set; }
public decimal GetPrice() { /* ... */ }
}
class OrderManager
{
decimal CalculateOrderPrice(Order order) {
return order.GetPrice();
}
}
{
public Order Order { get; set; }
}
class OrderService
{
void SendOrder(Order order) { /* ... */ }
}

class Vehicle { }
class Car : Vehicle { }
class Truck : Vehicle { }
class Motorbike : Vehicle { }
class VehicleXmlSerializer { }
class CarXmlSerializer : VehicleXmlSerializer { }
class TruckXmlSerializer : VehicleXmlSerializer { }
class MotorbikeXmlSerializer : VehicleXmlSerializer { }
Vehicle
Class
Car
Truck
Motorbike
Xml
Car
Truck
MotorBike

class VehicleXmlSerializer
{
public VehicleXmlSerializer(IToXmlStrategy[] strategies) { }
}
interface IToXmlStrategy { }
interface IToXmlStrategy<T> where T : Vehicle { }
class CarToXmlStrategy : IToXmlStrategy<Car> { }
class TruckTOXmlStrategy : IToXmlStrategy<Truck> { }
class MotorbikeToXmlStrategy : IToXmlStrategy<Motorbike> { }

{
decimal CalculateTax() { return totalPrice * 0.21; }
}
class Invoice
{
decimal ShowTax() { return order.TotalPrice * 0.21; }
}
class ViewModel
{
public decimal Tax { get { return 21.0; } }
}

static class Globals
{
public const decimal TaxPercent = 21.0m;
public const decimal TaxDelta = TaxPercent / 100;
}
{
decimal CalculateTax() { return totalPrice * Globals.TaxDelta; }
}
class Invoice
{
decimal ShowTax() { return order.TotalPrice * Globals.TaxDelta; }
}
class ViewModel
{
public decimal Tax { get { return Globals.TaxPercent; } }
}

class LazyClass
{
public static string FormatName(string name,
string lastname, string surname)
{
return string.Format("{1}, {0} ({2})",
name, lastname, surname);
}
}
Solo un método
llamada desde
solo un lugar

class CustomerInfo
{
public string Surname { get; set; }
public override string ToString()
{
return string.Format("{1}, {0} ({2})",
this.Name,
this.LastName, this.Surname);
}
}

class Settings
{
public string Host { get; set; }
public bool UseSsl { get; set; }
public int NumerOfConnections { get; set; }
}
class SettingsManager
{
public void Save(Settings settings) { /* ... */ }
public Settings Load() { /* ... */ }
}
Una clase con las propiedades y
otra con los métodos

class Settings
{
public string Host { get; set; }
public bool UseSsl { get; set; }
public int NumerOfConnections { get; set; }
public void Save() { /* ... */ }
public void Load() { /* ... */ }
}

class MyClass
{
public int MyProperty { get; set; }
public void Process() { /* ... */ }
public void Send() { /* ... */ }
}
class MyClassOld
{
}

class MyClass
{
public int MyProperty { get; set; }
public void Send() { /* ... */ }
}

class CustomerController {
public ActionResult Edit(Customer customer) {
if (Model.IsValid) {
this.customerRepository.InsertOrUpdate(customer);
this.customerRepository.Save();
return RedirectToAction("Index");
}
return View();
}
}
class EmployeeController {
public ActionResult Edit(Employee employee) {
if (Model.IsValid) {
this.employeeRepository.InsertOrUpdate(employee);
this.employeeRepository.Save();
}
return View();
}
}

class ControllerBase<TEntity> where TEntity : IEntity
{
IRepository<Employee> repository;
public ActionResult Edit(TEntity entity)
{
if (Model.IsValid)
{
this.repository.InsertOrUpdate(entity);
this.repository.Save();
}
return View();
}
}
class CustomerController : ControllerBase<Customer> { }
class EmployeeController : ControllerBase<Employee> { }

public interface ITextFormatStrategy { string Format(string input); }
public class CommentTextFormatContext {
private ITextFormatStrategy strategy;
public CommentTextFormatContext(ITextFormatStrategy strategy) {
this.strategy = strategy;
}
public int ExecuteStrategy(string input) {
return strategy.Format(input);
}
}
public class RemoveHtmlTagsStrategy : ITextFormatStrategy {
public string Format(string input) {
return Regex.Replace(input, @"<[^>]*>", string.Empty);
}
}
¿Solo una estrategia? YAGNI

public class Comment
{
public void SetMessage(string message)
{
this.Text = Regex.Replace(message, @"<[^>]*>", string.Empty);
}
}

// calculates the total price of the order
public decimal Calculate()
{
// in christmas time
if (DateTime.Now >= new DateTime(DateTime.Now.Year, 12, 25)
&& DateTime.Now <= new DateTime(DateTime.Now.Year + 1, 1, 5))
{
// it has a discount of 10%
return this.TotalPrice * 0.9;
}
else
{
return thisw.TotalPrice;
}
}

public decimal CalculateOrderTotalPrice()
{
if (IsChirstmasTime()) {
return this.ApplyDiscountPercentage(10);
}
else {
return this.TotalPrice;
}
}
private decimal ApplyDiscountPercentage(int percentage)
{
return this.TotalPrice * (100 - percentage) / 100;
}
private static bool IsChirstmasTime()
{
return DateTime.Now >= new DateTime(DateTime.Now.Year, 12, 25)
&& DateTime.Now <= new DateTime(DateTime.Now.Year + 1, 1, 5);
}

public class Product
{
public bool HasBeenOrdered(Order order)
{
return order.Products.Contains(this);
}
}
public class Order
{
public List<Product> Products { get; set; }
}

public class Product { }
public class Order
{
public List<Product> Products { get; set; }
public bool HasBeenOrdered(Product product)
{
return this.Products.Contains(product);
}
}

{
public string PhoneNumber { get; set; }
public string Address { get; set; }
}
public class Order
{
private Customer customer;
public string GetSummary()
{
var summary = string.Format("{0} {1}n{2}n{3}",
this.customer.Name,
this.customer.LastName,
this.customer.PhoneNumber,
this.customer.Address);
summary += "n" + this.TotalPrice + " €";
return summary;
}
}

{
public string PhoneNumber { get; set; }
public string Address { get; set; }
public override string ToString() {
return string.Format("{0} {1}n{2}n{3}",
this.Name,
this.LastName,
this.PhoneNumber,
this.Address);
}
}
public class Order
{
private Customer customer;
public string GetSummary() {
return this.customer.ToString() + "n" + this.TotalPrice + " €";
}
}

{
/* ... */
if (this.Customer.Address.Country.IsEuropean)
{
/* ... */
}
/* ... */
}

{
/* ... */
if (this.Customer.IsEuropean)
{
/* ... */
}
/* ... */
}
{
public bool IsEuropean
{
get
{
return this.Address.IsEuropean;
}
}
}

class MyConnection
{
private SqlConnection connection = new SqlConnection();
public string ConnectionString
{
get { return this.connection.ConnectionString; }
}
public void Open()
{
this.connection.Open();
}
public MyCommand CreateCommand()
{
return new MyCommand(this.connection.CreateCommand());
}
}

SqlConnection connection = new SqlConnection();

class XmlSerializer
{
public string StartTagString { get; set; }
public string EndTagString { get; set; }
public XmlSerializer()
{
StartTagString = "<{0}>";
EndTagString = "</{0}>";
}
protected string WriteTag(string name, string value) {
return StartTag(name) + value + EndTag(name);
}
protected string StartTag(string name) {
return string.Format(StartTagString, name);
}
protected string EndTag(string name) {
return string.Format(EndTagString, name);
}
}

class XmlSerializer
{
private const string StartTagString = "<{0}>";
private const string EndTagString = "</{0}>";
protected string WriteTag(string name, string value)
{
return StartTag(name) + value + EndTag(name);
}
protected string StartTag(string name)
{
return string.Format(StartTagString, name);
}
protected string EndTag(string name)
{
return string.Format(EndTagString, name);
}
}

Fernando Escolar
@fernandoescolar
fernando.escolar@tokiota.com
¡¡¡Si te ha gustado no olvides
rellenar la encuesta!!!
Thanks
Y
A
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