Re: WGLC on draft-freed-sieve-ihave-02.txt

Stephan Bosch writes:
> Given the fact that most extensions introduce new language elements, 
> the compiler must have some means of ignoring/discarding the regions 
> of the script that need the obscure extensions.
Most extensions do not extend the grammar. They only add new commands, 
tests, etc., which follow the basic Sieve grammar.
> Alternatively, doing the actual ihave test at runtime requires that 
> the compiler can distinguish between erroneous language features and 
> features that would have been introduced by the unknown extension (in 
> order to produce compile time errors or runtime errors respectively). 
> This would require knowledge about that obscure extension.
I think there's an unstated requirement there: in order to be used with 
ihave, an extension must obey the grammar on page 36 of RFC 5228.
Arnt