PROTECTED: (Access Control)


Specifies protected member access control in a Type or Class

Syntax:
Type typename
Protected:
member declarations
End Type

Parameters:
typename
name of the Type or Class
member declarations
declarations for fields, functions, or enumerations

Description:
Protected: indicates that member declarations following it have protected access. Protected members are accessible only from inside a member function for the Type or Class, and classes which are derived from the Type or Class.

member declarations following Protected: are protected until a different access control specifier is given, like Private: or Public:.

Members in a Type declaration are Public: by default if no member access control specifier is given.

NOTE: This keyword is useful only since fbc version 0.24 because inheritance is then supported.

Examples:
Type animal
  Dim As String animalName
  Protected:
    Dim As Integer serialNumber
End Type

Type dog Extends animal
  Dim As String masterName
  Declare Sub setSerialNumber ( ByVal number As Integer )
End Type

Sub dog.setSerialNumber ( ByVal number As Integer )
  '' This is OK. We're inside a member function of the derived type
  This.serialNumber = number
End Sub

Dim As dog d

'' This is OK, animalName is public
d.animalName = "Buddy"

'' this would generate a compile error:
'' - serialNumber is protected and we're trying to access it outside its type and the derived type
'' d.serialNumber = 123456789

' Example to illustrate the access control 'Protected' with a token provided by an admin right for an user right:
'    - The 'admin_right' type extends the 'user_right' type.
'    - Create directly an 'user_right' object is forbidden.
'         ('default user_right.constructor' access and 'copy user_right.constructor' access are 'Protected')
'    - The 'user_right' type has only the access right to get the token.
'         ('user_right.token' get-property access is 'Public' and 'user_right.token' set-property access is 'protected')
'    - The 'admin_right' type has the access rights to set and to get the token.
'         ('admin_right.token' get-property access and 'admin_right.token' set-property access are 'Public')
'
' An 'admin_right' object is created, and then a reference of type 'user_right' to this object is defined.
'    (create directly an 'user_right' object is forbidden)


Type user_right
  Public:
    Declare Property token () As String          '' 'Public' to authorize user_right token get
  Protected:
    Declare Constructor ()                       '' 'Protected' to forbid user_right object default-construction
    Declare Constructor (ByRef u As user_right)  '' 'Protected' to forbid user_right object copy-construction
    Declare Property token (ByRef s As String)   '' 'Protected' to forbid user_right token set
  Private:
    Dim As String user_right_token               '' 'Private' to forbid access from outside user_right
End Type

Constructor user_right ()  '' Default-constructor
End Constructor

Constructor user_right (ByRef u As user_right)  '' Protected copy-constructor
  This.user_right_token = u.user_right_token
End Constructor

Property user_right.token () As String  '' Public property user_right token get
  Return This.user_right_token
End Property

Property user_right.token (ByRef s As String)  '' Protected property user_right token set
  This.user_right_token = s
End Property


Type admin_right Extends user_right
  Public:
    Declare Property token () As String         '' 'Public' to authorize admin_right token get
    Declare Property token (ByRef s As String)  '' 'Public' to authorize admin_right token set
End Type

Property admin_right.token () As String  '' Public property admin_right token get
  Return Base.token                      '' 'Base.' to access to the base type property shadowed by this property name
End Property

Property admin_right.token (ByRef s As String)  '' Public property admin_right token set
  Base.token = s                                '' 'Base.' to access to the base type property shadowed by this property name
End Property


Dim As admin_right ar       '' Create an admin_right type object 'ar'
ar.token = "fxm123456789"   '' admin_right set the token for user_right
Print "'" & ar.token & "'"  '' admin_right get the user_right token
Print

Dim ByRef As user_right ur = ar  '' Create a user_right type reference 'ur' to the 'ar' instance of admin_right type
Print "'" & ur.token & "'"       '' user_right get its token
'ur.token = "fxm0"               '' Error: Illegal member access, USER_RIGHT.TOKEN.property.set (user_right cannot set its token)

'Dim As user_right ur1       '' Error: The default constructor has no public access
'Dim As user_right ur2 = ar  '' Error: Constructor has no public access

Sleep


Dialect Differences:
Differences from QB:
See also:
Back to User Defined Types
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