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Task/Singleton/FreeBASIC/singleton.basic

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+REM Sacado del forum de FreeBASIC (https://www.freebasic.net/forum/viewtopic.php?t=20432)
+
+Type singleton
+    Public :
+    Declare Static Function crearInstancia() As singleton Ptr
+    Declare Destructor ()
+    Dim i As Integer
+    Private :
+    Declare Constructor()
+    Declare Constructor(Byref rhs As singleton)
+    Declare Static Function instancia(Byval crear As Integer) As singleton Ptr
+End Type
+
+Static Function singleton.crearInstancia() As singleton Ptr
+    Return singleton.instancia(1)
+End Function
+
+Static Function singleton.instancia(Byval crear As Integer) As singleton Ptr
+    Static ref As singleton Ptr = 0
+    Function = 0
+    If crear = 0 Then
+        ref = 0
+    Elseif ref = 0 Then
+        ref = New singleton
+        Function = ref
+    End If
+End Function
+
+Constructor singleton ()
+End Constructor
+
+Destructor singleton()
+singleton.instancia(0)
+End Destructor
+
+'-----------------------------------------------------------------------------
+Dim As singleton Ptr ps1 = singleton.crearinstancia()
+ps1->i = 1234
+Print ps1, ps1->i
+
+Dim As singleton Ptr ps2 = singleton.crearinstancia()
+Print ps2
+
+Delete ps1
+
+Dim As singleton Ptr ps3 = singleton.crearinstancia()
+Print ps3, ps3->i
+Delete ps3
+Sleep