Re: Finalization and Garbage Collection: a hole in the RM?

[mazzanti@iei.pi.cnr.it (Franco Mazzanti)]

Robert Dewar said:
 "Well anyone can use language any way they like, but in the normal English
 meaning of the word unpredictable (which is the proper one to be using,
 since unpredictable is not  technical term), of course bounded errors
 result in unpredictable program execution, in that you cannot predict
 what will happen. "

Probably a gave a too technical meaning to the term "predictable".
In effect, the RM index doen not contain the entry "unpredictable"
or "predictable" or "not predictable". And this is a sign that the
use of the term was not meant to be strictly "technical".

However, it is also true that the Reference Manual associates
the (normal English) term "unpredictable" (or "not predictable")
only to erroneous executions, and not to bounded errors.
Therefore encouraging, expecially to those people whose native language
is not English, the impression that it is correct to associate the
(normal English) term "unpredictable" only to erroneous executions.

Even more, in 13.9.1(11) it is explicitly said that the use of an invalid
value (which is probably the "least predictable" case of bounded errors)
does not lead to "unpredictable" execution.

Quoting RM 13.9.1(11):
    "If the representation of the object does not represent a value of
    the object's type, the semantics of operations on such
    representations is implementation-defined, but does not by itself
    lead to erroneous or unpredictable execution, or to other objects
    becoming abnormal."

I agree with Robert that "anyone can use language any way they like"
(also the authors of the Reference Manual), but I was not too wrong when
I said that the RM did not consider bounded errors as cases of true
"unpredictability" (whether or not this is correct from the point
of view of normal English usage of the term "predictable").

By the way, I completely agree that bounded-errors are not like
non-deterministic behaviour (just because they ARE errors).

Franco Mazzanti