On 11/30/05, Chip Salzenberg <[EMAIL PROTECTED]> wrote: > On Wed, Nov 30, 2005 at 12:02:08PM -0800, Jonathan Sillito wrote: > > I have some clarification questions about the new pdd20 > > > 1. What is expected to be in P0 in: > > .lex "$a", P0 > > The ".lex" directive is compile-time only, and has no runtime effect > on the contents of P0. (Of course, once a register is available with > a lexical name, "store_lex" may modify it.)
OK, so this directive makes "$a" an alias for P0. > > 2. Should we provide a way for a compiler to provide depths to the > > find_lex and store_lex ops if it chooses to? > > Maximum depths, you mean? I know of no use case for it. Not maximum depth but the exact depth for a given lexical variable in the case of closures. The reason would simply be performance, though maybe insignificant in the common case (i.e. shallow nesting). > > 5. Thinking about closure support vs. outer support - the difference > > and the need for both mechanisms is not clear to me. > > Could you unpack this, please? Well, using :outer allows the look up algorithm to walk through enclosing lexical scopes ($sub = $sub.outer). In the case of closures the LexEnv is populated with the enclosing LexPads which I assume come from enclosing lexical scopes, which allows the the look up to do the same thing, no? I must be missing something here. > Chip Salzenberg <[EMAIL PROTECTED]> Thanks, Jonathan
