How do i return an object from a function in Delphi without causing Access Violation?

Question

I have a delphi function that returns a TStringList, but when I return a value and try to use it I get a Access Violation Error i.e

myStringList := FuncStringLis         


        

Answer 1

A policy I have with such situations is to pass the stringlist content through the text property and just pass the string returned to the function. This way there's no need to discuss who release who. Of course, you have to do a little more coding, but it's safer. The example is an adaptation of the Ken White's one :

var
  SL: TStringList;
  Aux: String;
begin
  SL := TStringList.Create;
  try
    SL.Text := ProcToFillStringList;
    //Do something with populated list
  finally
    SL.Free;
  end;
end;

 // It receives a default param, in the case you have to deal with 
 // StringList with some previous content    
 function ProcToFillStringList(SListContent: String = ''):String;
 // Do the stuff you need to do with the content
end;

An exception is when all you have is the object and there's no way to retrieve the content on it through a safe type (in this case, strings); then I follow Ken White's idea.