Nested classes with dynamic array

[falcontra]

Hi,
How can i define a dynamic array of a class object in another class?
Beneath you can find a demo code, what did I forget / wrong?

Main:

Sub
Dim library as Collection
Dim book as clsBook
Set library = New Collection

'add books to library
For i=0 to 5
Set book = New clsBook
book.title = "title"

'add pages to book
For j = 0 to 5
book.page(j).pagenr = "P" & j
Next j

library.Add book
Next i
End Sub

clsBook:
Dim title as String
Dim pages() as clsPage '??? How to create a dynamic array of the class clsPage


clsPage:
Dim pagenr as Integer

[Paul_Hossler]

I'd do it a little different - this might give you some ideas


Main sub in standard module

Option Explicit




Sub Main()
    Dim i As Long, j As Long
    Dim BookLibrary As Collection
    Dim oBook As clsBook
    Dim oPage As clsPage
    Dim s As String
    
    Set BookLibrary = New Collection


    'add books to BookLibrary
    For i = 1 To 5      '   Collection Items start at 1
        Set oBook = New clsBook
        oBook.BookTitle = "Book Title " & i


        'add pages to book
        For j = 1 To 5
            Set oPage = New clsPage
            oPage.PageNumber = j
            oPage.PageText = "This is text for " & oBook.BookTitle & " Page " & CStr(j)
            Call oBook.BookPages.Add(oPage, CStr(j))
        Next j
            
        BookLibrary.Add oBook, oBook.BookTitle
    
    
    Next i


    MsgBox BookLibrary(1).BookTitle
    MsgBox BookLibrary(5).BookTitle
    MsgBox BookLibrary(3).BookPages(1).PageText




    For Each oBook In BookLibrary
        s = s & oBook.BookTitle & vbCrLf
    Next
    
    MsgBox s


    s = ""
    For Each oPage In BookLibrary("Book Title 3").BookPages
        s = s & oPage.PageNumber & " -- " & oPage.PageText & vbCrLf
    Next
    
    MsgBox s
End Sub

clsBook:

Option Explicit


Private m_Title As String
Private m_Pages As Collection


Private Sub Class_Initialize()
    Set m_Pages = New Collection
End Sub


Private Sub Class_Terminate()
    Set m_Pages = Nothing
End Sub


Property Get BookTitle() As String
    BookTitle = m_Title
End Property
Property Let BookTitle(s As String)
    m_Title = s
End Property


Property Get BookPages() As Collection
    Set BookPages = m_Pages
End Property


Property Get BookPage(Nbr As Long) As clsPage
    Set BookPage = m_Pages(CStr(Nbr))
End Property

clsPage:

Option Explicit


Private m_PageNumber As Long
Private m_PageText As String


Property Get PageNumber() As Long
    PageNumber = m_PageNumber
End Property
Property Let PageNumber(n As Long)
    m_PageNumber = n
End Property


Property Get PageText() As String
    PageText = m_PageText
End Property
Property Let PageText(s As String)
    m_PageText = s
End Property

If you just wanted to add pages sequentially, then maybe something like this

        For j = 1 To 5            Set oPage = New clsPage
            oPage.PageNumber = oBook.BookPages.Count + 1
            oPage.PageText = "This is text for " & oBook.BookTitle & " Page " & CStr(oPage.PageNumber)
            Call oBook.BookPages.Add(oPage, CStr(oPage.PageNumber))
        Next j

[SamT]

Falcontr,

That's a bad example.

ClsChapter

Private pChapTitle as String

'How to read the chapter Title
Public Property Get Title() As String
   Title = pChapTitle
End Property

'How to write the chapter Title
Public Property Let Title(Chapter_Title As String)
   pChapTitle = Chapter_Title
End Property)

ClsBook

Private pChapters As Collection
Private pBook_Title As String

'Write the Book's Title
Public Property Let Title(BookTitle) As String
   pBook_Title = Title
End Property

'Read the Book's Title
Public Property Get Title() As String
   Title = pBook_Title
End Property

'Add a Chapter to the Book
Public Function AddChapter(ChapterTitle As String)
   Dim X as New ClsChapter
   X.Title = ChapterTitle
   pChapters.Add X
   set X = Nothing
End Function

'How many Chapters in Book
Public Property Get Count() As long
   Count = pChapters.Count
End Property

'What is Particular Chapter Title
Public Property Get ChapterTitle(ChapterNumber As long) As String
   ChapterTitle = pChapters(ChapterNumber).Title
End Property

Classes should only interact with the outside via Public Properties and Methods (Functions and Subs). The convention is that Properties only read and write Variables, and Methods perform actions. Another convention is that Class Variable used by Properties are prefixed with a special character. I use "p" for Property usage and "m" for Method usage, YMMV. The "Me" Keyword allows the internal use of Public Properties and Methods