ietf-mta-filters
[Top] [All Lists]

Re: "extensible" grammar

1998-01-26 10:46:54
Tim Showalter <tjs+(_at_)andrew(_dot_)cmu(_dot_)edu> writes:


I'll point out that it is possible to implement "if" without actually doing
it with commands so that it makes actual sense in the parser, even if the
spec specifies that all commands are control structures, and that all
commands are created equal.  I certainly intend to do it this way.


I suggest that 'if' *not* be implemented with commands, and that we
explicitly disallow extensions which add control structures.  In my
view, the main point of extensions is to add new tests (database lookups,
body parsing) and new actions (vacation, workflow, attachment
manipulations, etc.).  I don't think we ever want extensions which do
"while", "for", and the like.  "Sieve" should *never* be Turing-complete;
I don't want to have to solve the halting problem in order to decide
whether to accept a script ;-)

Stan



<Prev in Thread] Current Thread [Next in Thread>