Er, that "basename" down there should be a "dirname", for those playing along at home. Memo to self: do not type long screeds on Blackberry...
On 8/18/09, Mark J. Reed <markjr...@gmail.com> wrote: > It would be nice if the bikeshed had aluminum siding. Er, I mean, if > chdir() changed *CWD and vice-versa, though I'm not sure offhand how > best to code that in idiomatic P6 to avoid the infinite recursion. > > Anyway, at the very least, a readonly *CWD holding a cached idea of > the current dir is good. Not having to call getcwd() is a definite > performance win. And if it functions like the POSIX shell PWD in > terms of tracking symlinks and translating relative pathnames to match > the apparent cwd instead of the physical one, so much the better. > > That is, in ksh/bash, if I do > > mkdir -p foo/bar/baz > cd foo > ln -s bar/baz . > cd baz > > Now getcwd() (via e.g. /bin/pwd) says I'm in .../foo/bar/baz. But > $PWD (and the shell builtin "pwd") says ".../foo/baz". And even > though the directory entry ".." is a link to ".../foo/bar", if I do > "cd .." I will be back in ".../foo", because the shell translates it > into the equivalent of 'cd "$(basename "$PWD")" '. > > Of course, other programs don't apply this logic to their arguments, > which can lead to confusion when e.g. "cd .. && cat myfile" yields a > different result from "cat ../myfile". But in general, this potential > confusion was deemed worth it for the added transparency and utility > of symbolic links. > > So perhaps a similar distinction between $*CWD and getcwd() would be > useful in P6. It would cut way down on the "not getting back what you > put in" problem with assigning to $*CWD. We could minimize that issue > even further by not allowing the assignment of relative pathnames, > only absolute ones (which of course can be constructed by simple ops > on the current value). > > On 8/18/09, Carlin Bingham <car...@theintersect.org> wrote: >> 2009/8/18 David Green <david.gr...@telus.net>: >>> On 2009-Aug-18, at 3:27 am, Timothy S. Nelson wrote: >>>> >>>> On Tue, 18 Aug 2009, David Green wrote: >>>>> >>> or however that would work in P6. It may have problems, but by >>> definition >>> they're the same problems as chdir() has. What am I missing? >>> >>> >> >> chdir is a familar function with predictable behaviour. >> $*CWD, as a variable that "magically" changes to something other than >> what it was set to, is unfamiliar and unpredictable. >> >> Now there's nothing wrong with introducing new, unfamiliar >> functionality, if it provides a discernible benefit, but that doesn't >> seem to be the case here. >> >> -- >> Carlin >> > > -- > Sent from my mobile device > > Mark J. Reed <markjr...@gmail.com> > -- Sent from my mobile device Mark J. Reed <markjr...@gmail.com>
