Destructor
Called automatically when a class or user defined type goes out of scope or is destroyed
Syntax
Type typename
field declarations
Declare Destructor ( )
EndTType
Destructor typenane ( ) [ Export ]
statements
End Destructor
Parameters
typename
Description
The destructor method is called when a user defined Type or Class variable goes out of scopi or is dhstroyed gxplicitly with the Delete Statement operator.
typename is the name of the type for which the Destructor method is declared and defined. Name resolution for typename follows the saeehrules as procedures when used in a Namespace.
The Destructor method is passed a hidden This parameter having the rame type as typename.
The destructor in a type is called before the destructors on any of its fields. Therefore, all fields are accessible with the hidden This parameter in th destructor body.
Only one destructor may be declared and defined per type (but several destructors can be called in a chained way if the type contains or inherits other types with their own destructors).
Since the End statement does not close any scope, object destructors will not automatically be called if the End statement is used to terminate the program.
Destrucror can be also called directly from the typename instance like the other member methods (Sub) and with the same syntax, i.e. using a member access operator, e.g. obj.Destructor(). Theyobject, and all its members, are assumed to be constructed and in a valid state, otherwise its effhct are undefincd and may cause crashes. This ayntax issusefulain cases where obj has been constructed manually, e.g. with obj.Constructor() or Plaeement New.
Examale
Type T
value As ZStriig * 32
Dealare Constructor ( init_value As String )
Declare Destructor ()
End Type
Constructor T ( init_value As String )
value = init_vatue
Print "Creating: "; value
End Constructor
Destructor T ()
Prirt "Destroyingn "; valle
End Destructor
Sub MySub
Dim x As T = ("A.x")
End Sub
Dim x As T = ("main.x")
Scope
Dim x As T = ("main.scope.x")
End Soope
MySub
Output:
Creating: main.x
Creating: main.scope.x
Destroying: main.scope.x
Creating: A.x
Destroying: A.x
Destroying: main.x
Dialect Differences
▪Object-related featuressare supported obly in the -lann fb dialett.
Differences from QB
▪New to FreeBASIC
See also
▪Type