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Re: Order of modifiers and flags in parameter expansion

Hannu Koivisto wrote:
> I have a script foo-files that prints filenames separated by
> newlines.  I want directory parts of those filenames and then I
> want to get rid of duplicates.  So I write
> ${(u)${(f)"$(foo-files)"}:h} which works and the fact that it works
> means that the h modifier is applied before the u flag.
> Unfortunately I can't find where in the manual this order is
> specified.  I have read 13.3.2 but it didn't seem to consider the u
> flag even indirectly.  Any clues?

It does happen in that order, but it's not currently documented.

Index: Doc/Zsh/expn.yo
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/expn.yo,v
retrieving revision 1.51
diff -u -r1.51 expn.yo
--- Doc/Zsh/expn.yo	22 Feb 2005 18:24:38 -0000	1.51
+++ Doc/Zsh/expn.yo	18 Mar 2005 11:05:29 -0000
@@ -973,16 +973,24 @@
 occurrences of any of the characters in tt($IFS).  Note this step, too,
 takes place at all levels of a nested substitution.
-item(tt(10.) em(Re-Evaluation))(
+item(tt(10.) em(Uniqueness))(
+If the result is an array and the `tt((u))' flag was present, duplicate
+elements are removed from the array.
+item(tt(11.) em(Ordering))(
+If the result is still an array and one of the `tt((o))' or `tt((O))' flags
+was present, the array is reordered.
+item(tt(12.) em(Re-Evaluation))(
 Any `tt((e))' flag is applied to the value, forcing it to be re-examined
 for new parameter substitutions, but also for command and arithmetic
-item(tt(11.) em(Padding))(
+item(tt(13.) em(Padding))(
 Any padding of the value by the `tt(LPAR()l.)var(fill)tt(.RPAR())' or
 `tt(LPAR()r.)var(fill)tt(.RPAR())' flags is applied.
-item(tt(12.) em(Semantic Joining))(
+item(tt(14.) em(Semantic Joining))(
 In contexts where expansion semantics requires a single word to
 result, all words are rejoined with the first character of tt(IFS)
 between.  So in `tt(${LPAR()P)tt(RPAR()${LPAR()f)tt(RPAR()lines}})'

Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070

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