Update visitor pattern examples

Author: nemanjarogic

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Company.cs

@@ -5,23 +5,19 @@ namespace VisitorLibrary.CompanyExample;
 
 public class Company
 {
-    private readonly List<Employee> _employees = new List<Employee>();
+    private readonly List<Employee> _employees = new();
 
-    public void Hire(Employee employee)
-    {
+    public void Hire(Employee employee) =>
         _employees.Add(employee);
-    }
 
-    public void LayOff(Employee employee)
-    {
+    public void LayOff(Employee employee) =>
         _employees.Remove(employee);
-    }
 
     public void ReviewEmployeesAtEndOfTheYear(IPerformanceReview performanceReview)
     {
-        foreach (Employee employee in _employees)
+        foreach (var employee in _employees)
         {
             employee.Evaluate(performanceReview);
         }
     }
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/CompanyExecutor.cs

@@ -15,10 +15,12 @@ public static void Execute()
         company.Hire(new ProductOwner());
         company.Hire(new ProjectManager());
 
-        company.ReviewEmployeesAtEndOfTheYear(new IncomeRegulation());
+        Console.WriteLine("\nIt's time for annual performance reviews...\n");
 
-        Console.WriteLine("\nStarting second phase of performance review...\n");
+        Console.WriteLine("\nStarting review for the income regulation...\n");
+        company.ReviewEmployeesAtEndOfTheYear(new IncomeRegulation());
 
+        Console.WriteLine("\nStarting review for the vacation regulation...\n");
         company.ReviewEmployeesAtEndOfTheYear(new VacationRegulation());
     }
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Elements/Common/Employee.cs

@@ -9,16 +9,19 @@ public Employee(string name, double annualSalary, int vacationDays)
         Name = name;
         AnnualSalary = annualSalary;
         VacationDays = vacationDays;
+
+        Console.WriteLine(
+            "{0} {1} has annual salary of {2:C} and {3} vacation days",
+            GetType().Name,
+            Name,
+            AnnualSalary,
+            VacationDays);
     }
 
     public string Name { get; set; }
-
     public double AnnualSalary { get; set; }
-
     public int VacationDays { get; set; }
 
-    public void Evaluate(IPerformanceReview performanceReview)
-    {
+    public void Evaluate(IPerformanceReview performanceReview) =>
         performanceReview.Appraise(this);
-    }
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Elements/Common/IEmployeeEvaluation.cs

@@ -5,4 +5,4 @@ namespace VisitorLibrary.CompanyExample.Elements.Common;
 public interface IEmployeeEvaluation
 {
     void Evaluate(IPerformanceReview performanceReview);
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Elements/Developer.cs

@@ -8,4 +8,4 @@ public Developer()
         : base("Marc Murray", 80000, 25)
     {
     }
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Elements/ProductOwner.cs

@@ -8,4 +8,4 @@ public ProductOwner()
         : base("Arnold Aster", 75000, 25)
     {
     }
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Elements/ProjectManager.cs

@@ -8,4 +8,4 @@ public ProjectManager()
         : base("Anna Dover", 82000, 27)
     {
     }
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Visitors/Common/IPerformanceReview.cs

@@ -5,4 +5,4 @@ namespace VisitorLibrary.CompanyExample.Visitors.Common;
 public interface IPerformanceReview
 {
     void Appraise(IEmployeeEvaluation employeeEvaluation);
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Visitors/IncomeRegulation.cs

@@ -7,7 +7,10 @@ public class IncomeRegulation : IPerformanceReview
 {
     public void Appraise(IEmployeeEvaluation employeeEvaluation)
     {
-        var employee = employeeEvaluation as Employee;
+        if (employeeEvaluation is not Employee employee)
+        {
+            throw new ArgumentException("Appraise method works only with Employee objects");
+        }
 
         // We've had a great year, so 10% pay raises for everyone!
         // In case that we need different rules for pay raise, we would change IPerformanceReview interface
@@ -20,4 +23,4 @@ public void Appraise(IEmployeeEvaluation employeeEvaluation)
             employee.Name,
             employee.AnnualSalary);
     }
-}
+}

src/BehavioralPatterns/Visitor/VisitorLibrary/CompanyExample/Visitors/VacationRegulation.cs

@@ -7,10 +7,13 @@ public class VacationRegulation : IPerformanceReview
 {
     public void Appraise(IEmployeeEvaluation employeeEvaluation)
     {
-        var employee = employeeEvaluation as Employee;
+        if (employeeEvaluation is not Employee employee)
+        {
+            throw new ArgumentException("Appraise method works only with Employee objects");
+        }
 
         // And because you all helped have such a great year,
-        // all my employees get three extra paid time off days each!
+        // all employees will get three extra paid time off days!
         employee.VacationDays += 3;
 
         Console.WriteLine(
@@ -19,4 +22,4 @@ public void Appraise(IEmployeeEvaluation employeeEvaluation)
             employee.Name,
             employee.VacationDays);
     }
-}
+}