Understanding Iterators, Part 2: Listing 3

The Visual Basic iterator property.

Public ReadOnly Iterator Property CoursesIteratorProperty(CategoryName As String) As IEnumerable(Of CourseWithModules)
    Get
        Dim iL As New IteratorsDemo.IteratorsLayer
        Dim svcUri As Uri = New Uri("http://www.pluralsight-training.net/odata/")
        Dim provider = New PluralsightService.CourseProvider(svcUri)
        Dim courses = iL.GetCoursesForCategory(CategoryName)
        For Each course In courses
            Dim CoursesIterator = New CourseWithModules _
                With {.Course = course, .Modules = iL.GetModulesForCourse(course.Name)}
            Yield CoursesIterator
        Next
    End Get
  End Property

  Public Sub CategoryClickProperty(CategoryName As String)
    lstCoursesAndModules.Items.Clear()
    Dim courseCount = 0
    Dim moduleCount = 0

	For Each item In CoursesIteratorProperty(CategoryName)
        lstCoursesAndModules.Items.Add(String.Empty)
        Dim CourseLine = String.Format("    {0}  ({1})", item.Course.Title, item.Course.Name)
        lstCoursesAndModules.Items.Add(CourseLine)
        courseCount += 1

        For Each moduleItem In item.Modules
            Dim ModuleLine = String.Format("        {0}  ({1})", moduleItem.Title, moduleItem.VideoLength)
            lstCoursesAndModules.Items.Add(ModuleLine)
            moduleCount += 1
        Next
        Application.DoEvents()
    Next

    Dim header = String.Format("There are {0} Courses With {1} Modules For Category {2}", courseCount, moduleCount, CategoryName)
    lstCoursesAndModules.Items.Insert(0, header)
  End Sub

About the Author

Joe Kunk is a Microsoft MVP in Visual Basic, three-time president of the Greater Lansing User Group for .NET, and developer for Dart Container Corporation of Mason, Michigan. He's been developing software for over 30 years and has worked in the education, government, financial and manufacturing industries. Kunk's co-authored the book "Professional DevExpress ASP.NET Controls" (Wrox Programmer to Programmer, 2009). He can be reached via email at [email protected].

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