Property Statement
A property, also called field or attribute, characterizes a given object or piece of information. Properties can be used to control access to data. It is common use to include instructions at setting or reading time of properties. Code can vary from simple assignment to complex context dependent routines. Using Get, Let or Set accessors enforces properties' consistency when necessary.
This statement requires Option Compatible to be placed before the executable program code in a module.
[Private | Public] Property Get name[char | As typename]
End Property
[Private | Public] Property [Let | Set] name[char] [([Optional [ByRef | ByVal]]value[char | As typename])] [As typename]
End Property
name: The property name.
argument: Value to be passed to the Property setter routine.
Property setters often use a single argument. Multiple arguments are equally accepted.
argument fragment
{[Optional [ByRef|ByVal]]|ParamArray} argument {{As typename|char}[ = expression]|[()]As Variant}
Parameters
Optional: The argument is not mandatory.
ByRef: The argument is passed by reference. ByRef is the default.
ByVal: The argument is passed by value. Its value can be modified by the called routine.
char: Type declaration character.
typename: Primitive data type name. Library or module defined types can also be specified.
= expression: Specify a default value for the argument, matching its declared type. Optional is necessary for each argument specifying a default value.
ParamArray: Use ParamArray when the number of parameters is undetermined. A typical scenario is that of a Calc user-defined function. Using ParamArray should be limited to the last argument of a routine.
UsingParamArray or = expression require Option Compatible to be placed before the executable program code in a module.
When using Option VBASupport 1, Optional arguments with no default value (= expression) are initialized according to their data type, except if Variant.
Examples
Option Compatible
Sub Main
ProductName = "Office"
Print ProductName ' displays "Collabora Office"
End Sub
Private _office As String
Property Get ProductName As String
ProductName = _office
End Property
Property Let ProductName(value As String)
_office = "Libre"& value
End Property
In the absence of Property Let or Property Set, Property Get helps define protected information, which can not be accidently altered by a foreign module:
Option Compatible
Public Property Get PathDelimiter As String ' Read-only variable
Static this As String
If this = "" Then : Select Case GetGuiType()
Case 1 : this = ";" ' Windows
Case 4 : this = ":" ' Linux or macOS
Case Else : Error 423 ' Property or method not defined: PathDelimiter
End Select : End If
PathDelimiter = this
End Property ' read-only PathDelimiter
Sub Main
PathDelimiter = "a sentence" ' does nothing
End Sub
Use Let or Set when handling UNO services or class objects:
Option Compatible
Sub Main
'Set anObject = CreateUnoService( "com.sun.star.frame.Desktop" )
anObject = CreateUnoService( "com.sun.star.frame.Desktop" )
Print anObject.SupportedServiceNames(0) ' displays "com.sun.star.frame.Frame"
End Sub
Property Get anObject As Object
Set anObject = _obj
End Property
Private _obj As Object
'Property Set anObject(value As Object)
'Set _obj = value.CurrentFrame
'End Property
Property Let anObject(value As Object)
Set _obj = value.CurrentFrame
End Property