CleanCodeObjectClass.cs

//--------------------------------------------------------------------------------------
// 5. Objects, Data Structures, Classes  - Đối tượng, cấu trúc dữ liệu, lớp 
//--------------------------------------------------------------------------------------

//--------------------------------------------------------------------------------------
// Sử dụng getters và setters 
// Bad
class BankAccount
{
    public double Balance = 1000;
}

var bankAccount = new BankAccount();

// Fake buy shoes...
bankAccount.Balance -= 100;
// Good
class BankAccount
{
    private double _balance = 0.0D;

    pubic double Balance {
        get {
            return _balance;
        }
    }

    public BankAccount(balance = 1000)
    {
       _balance = balance;
    }

    public void WithdrawBalance(int amount)
    {
        if (amount > _balance)
        {
            throw new Exception('Amount greater than available balance.');
        }

        _balance -= amount;
    }

    public void DepositBalance(int amount)
    {
        _balance += amount;
    }
}

var bankAccount = new BankAccount();

// Buy shoes...
bankAccount.WithdrawBalance(price);

// Get balance
balance = bankAccount.Balance;


//--------------------------------------------------------------------------------------
// Hạn chế tối đa public setters 
// Bad
class Employee
{
    public string Name { get; set; }

    public Employee(name)
    {
        Name = name;
    }
}
// Good
class Employee
{
    public string Name { get; }

    public Employee(string name)
    {
        Name = name;
    }
}

//--------------------------------------------------------------------------------------
// Sử dụng các method chaining 
// Bad

// Good
public static class ListExtensions
{
    public static List<T> FluentAdd<T>(this List<T> list, T item)
    {
        list.Add(item);
        return list;
    }

    public static List<T> FluentClear<T>(this List<T> list)
    {
        list.Clear();
        return list;
    }

    public static List<T> FluentForEach<T>(this List<T> list, Action<T> action)
    {
        list.ForEach(action);
        return list;
    }

    public static List<T> FluentInsert<T>(this List<T> list, int index, T item)
    {
        list.Insert(index, item);
        return list;
    }

    public static List<T> FluentRemoveAt<T>(this List<T> list, int index)
    {
        list.RemoveAt(index);
        return list;
    }

    public static List<T> FluentReverse<T>(this List<T> list)
    {
        list.Reverse();
        return list;
    }
}

internal static void ListFluentExtensions()
{
    var list = new List<int>() { 1, 2, 3, 4, 5 }
        .FluentAdd(1)
        .FluentInsert(0, 0)
        .FluentRemoveAt(1)
        .FluentReverse()
        .FluentForEach(value => value.WriteLine())
        .FluentClear();
}


//--------------------------------------------------------------------------------------
// Khuyến khích dùng composition thay vì kế thừa 
// Bad
class Employee
{
    private string Name { get; set; }
    private string Email { get; set; }

    public Employee(string name, string email)
    {
        Name = name;
        Email = email;
    }

    // ...
}

// Bad because Employees "have" tax data.
// EmployeeTaxData is not a type of Employee

class EmployeeTaxData : Employee
{
    private string Name { get; }
    private string Email { get; }

    public EmployeeTaxData(string name, string email, string ssn, string salary)
    {
         // ...
    }

    // ...
}
// Good
class EmployeeTaxData
{
    public string Ssn { get; }
    public string Salary { get; }

    public EmployeeTaxData(string ssn, string salary)
    {
        Ssn = ssn;
        Salary = salary;
    }

    // ...
}

class Employee
{
    public string Name { get; }
    public string Email { get; }
    public EmployeeTaxData TaxData { get; }

    public Employee(string name, string email)
    {
        Name = name;
        Email = email;
    }

    public void SetTax(string ssn, double salary)
    {
        TaxData = new EmployeeTaxData(ssn, salary);
    }

    // ...
}