From -4390622934731575100 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,e94695845965b249 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 1992-12-12 09:07:15 PST Newsgroups: comp.std.c++ Path: sparky!uunet!munnari.oz.au!metro!extro.ucc.su.OZ.AU!maxtal From: maxtal@extro.ucc.su.OZ.AU (John MAX Skaller) Subject: Re: Zero-length structures and pointer comparisons Message-ID: <1992Dec12.162211.5076@ucc.su.OZ.AU> Sender: news@ucc.su.OZ.AU Nntp-Posting-Host: extro.ucc.su.oz.au Organization: MAXTAL P/L C/- University Computing Centre, Sydney References: <9234601.10277@mulga.cs.mu.OZ.AU> <1992Dec11.231131.10956@microsoft.com> <24392@alice.att.com> Date: Sat, 12 Dec 1992 16:22:11 GMT Lines: 51 In article <24392@alice.att.com> ark@alice.UUCP () writes: >In article <1992Dec11.231131.10956@microsoft.com> jimad@microsoft.com (Jim Adcock) writes: > >> So that taking the address of a nested function in different scopes >> causes differing trampolines to be created, and differing pointers returned? > >It shouldn't need to do that. At most one trampoline is ever necessary >for a given nested function during its lifetime, namely the one that >binds the lexically surrounding context that was current when the >block containing the definition of that function was entered. Are you saying that if I have a recursive function with a nested function in it, and store the address of the nested function in scope at the time of entering the n'th recursion into an array in slot n, then executing the j'th slot will access the n'th activation record and not the j'th one? (I.e. all the functions in the array access the most recent activation record?) > >Moreover, that trampoline address is unique until the corresponding >function has gone out of scope, at which point the address is moot. Irrespective of how it is implemented, and even if taking the address of a nested function is allowed, I would like to see C++ allow nested functions. There are several levels to which this could be done: 1) Same as non-nested function: no access to environment, BUT the name is function local, also no address taking. 2) Allow access to environment, but not taking address. 3) Full hog: allow address taking. One could also restricted nesting to one level. Andrew, Would any of these be likely to be accepted by the committee? Do you personally favour nested functions? If not, why not? Anyone else? Anyone with GNU actually using them? Anyone hate them? -- ;---------------------------------------------------------------------- JOHN (MAX) SKALLER, maxtal@extro.ucc.su.oz.au Maxtal Pty Ltd, 6 MacKay St ASHFIELD, NSW 2131, AUSTRALIA ;--------------- SCIENTIFIC AND ENGINEERING SOFTWARE ------------------