[Lazarus] thread safe

[Hans-Peter Diettrich]

Martin schrieb:

>> As stated in my former messages in this thread, IMHO, the "official" 
>> definition of thread-safe-ness does not make much sense with objects, 
>> but a more complex definition covering several cases of use is necessary.
> 
> Why? Where does the definition conflict with the above?
>   "A piece of code is *thread-safe* if it can be safely invoked by 
> multiple threads at the same time"

That's the definition of reentrant subroutines only.

> "Save invocation" includes that the function returns a "correct" 
> result(output) for any "input".
> 
> Where "input":
> - is not limited to the parameters passed in the parameter list, not 
> even to limited to parameters passed implicitly (such as the object 
> instance)
> - input includes the entire state of the system (that can be global 
> vars, available and unavailable resources of any kind, and much more)
> The same applies to "result", or "output".

This would mean that a thread-safe procedure has to lock *all* input 
that it - or one of its called procedures - wants to read or update, 
before starting at all. The best scenario for an unrecoverable deadlock :-(

> This part of "Save invocation" is not limited to thread safeness. It 
> applies to any piece of code.

Your attempt to re-interpret above definition is of no use :-(

DoDi