Class/Static Constants in Delphi

Question

In Delphi, I want to be able to create an private object that\'s associated with a class, and access it from all instances of that class. In Java, I\'d use:

pub         


        

Answer 1

Two questions I think that need to be answered before you come up with a "perfect" solution..

• The first, is whether TLogLogger is thread-safe. Can the same TLogLogger be called from multiple threads without calls to "syncronize"? Even if so, the following may still apply
• Are class variables thread-in-scope or truly global?
• If class variables are truly global, and TLogLogger is not thread safe, you might be best to use a unit-global threadvar to store the TLogLogger (as much as I don't like using "global" vars in any form), eg

Code:

interface
type
  TMyObject = class(TObject)
  private
    FLogger: TLogLogger; //NB: pointer to shared threadvar
  public
    constructor Create;
  end;
implementation
threadvar threadGlobalLogger: TLogLogger = nil;
constructor TMyObject.Create;
begin
  if not Assigned(threadGlobalLogger) then
    threadGlobalLogger := TLogLogger.GetLogger(TMyObject); //NB: No need to reference count or explicitly free, as it's freed by Log4D
  FLogger := threadGlobalLogger;
end;

Edit: It seems that class variables are globally stored, rather than an instance per thread. See this question for details.