From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23253 invoked from network); 10 Jun 2002 12:05:55 -0000 Received: from sunsite.dk (130.225.247.90) by ns1.primenet.com.au with SMTP; 10 Jun 2002 12:05:55 -0000 Received: (qmail 3016 invoked by alias); 10 Jun 2002 12:05:45 -0000 Mailing-List: contact zsh-workers-help@sunsite.dk; run by ezmlm Precedence: bulk X-No-Archive: yes X-Seq: 17309 Received: (qmail 3001 invoked from network); 10 Jun 2002 12:05:43 -0000 To: zsh-workers@sunsite.dk (Zsh hackers list) Subject: The sh substitution problem. Date: Mon, 10 Jun 2002 13:05:14 +0100 Message-ID: <24097.1023710714@csr.com> From: Peter Stephenson namely ${1+"$@"} when using `sh' word-spliting makes a scalar out of "$@" and splits it later on, with consequent undesirable effects. I thought I had a way of doing the important cases (i.e. the ones required for POSIX) simply but it turns out it doesn't work. We just have a completely different notion of how a command line word is formed (because ours is more logical :-)). So I've given that up. I have a vague plan for doing it `properly' but it doesn't fill me with delight: - When calling prefork() from multsub(), don't remove nulls (hence preserving information about quotes, which are retained as Snull, Dnull and Bnull). - In multsub(), handle arrays properly, i.e. stick the results in what is currently its second argument. This will have knock-on effects since paramsubst() messes around with val and aval all the time. The way mult_isarr has been hacked in to avoid the calling sequence may make this more difficult. (Ideally we would replace mult_isarr by making multsub() always return arrays. This is probably even harder, but I don't understand the details of mult_isarr, which handles nested substitutions, well enough to say.) [It might be possible to keep val and aval as a pair in a structure, a sort of pseudo-parameter, and only convert between scalar and array when really necessary with a `forcescalar' or `forcearray' function/macro.] - Avoid joining words before splitting them (unless it is a forced join with a given string). This changes the current rules but is inevitable for getting this to work at all. This probably also means handling certain types of scalar result by joining arrays at this point instead of before (even if they are not going to be split). This is also probably tricky because there are umpteen different ways of ending up with a scalar. This is probably where we would have to do any joining due to letting multsub() always return an array. I used the word `probably' three times in that paragraph. - When splitting, handle a loop over multiple array elements and keep track of quotes. This also fixes: % ARGV0=sh zsh $ set word $ print -l ${1+'this should not be split'} this should not be split This is tricky and I have no idea of its detailed feasibility. If anyone wants to try they should. Otherwise just make comments. -- Peter Stephenson Software Engineer CSR Ltd., Science Park, Milton Road, Cambridge, CB4 0WH, UK Tel: +44 (0)1223 392070 ********************************************************************** The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer. **********************************************************************