perl -d: completion bug

perl -d: completion bug

[Phil Pennock]

My zsh completion-fu is weak, still.  Is there a way in which a function
calling another function to do the work can interrupt a  _wanted() to
filter the results, or do I need to re-factor the function currently
calling _wanted() into a helper function which does the work and a
wrapper with the current name which calls _wanted(), then use that new
function?

There's a bug in the Perl completion.  perl -d:<tab> completes all Perl
modules.  What it needs to complete is the sub-string of module names in
the Devel:: namespace, after the Devel::.

The current _perl_modules() uses the caching system to good effect and I
want to keep that, cache all the modules in the same way (might as well,
even for a -d:<tab> completion) and then just filter to a sub-set.

Eg, given the module Devel::Trace installed, you'd invoke Perl thusly:
zsh% perl -d:Trace -e $'print "foo\\n";\nprint "bar\\n";'
>> -e:1: print "foo\n";
foo
>> -e:2: print "bar\n";
bar
zsh%

(And if the answer is trivial, please don't wait on a patch from me!)

Thanks,
-Phil

Re: perl -d: completion bug

[Bart Schaefer]

On Oct 10, 10:35pm, Phil Pennock wrote:
}
} There's a bug in the Perl completion.  perl -d:<tab> completes all Perl
} modules.  What it needs to complete is the sub-string of module names in
} the Devel:: namespace, after the Devel::.

If it were just a matter of restricting to the "Devel::" namespace,
you could change _perl to replace

    '-d\:-[run under control of a debugging/tracing module]:debugging/tracing module:_perl_modules' \

with

    '-d\:-[run under control of a debugging/tracing module]:debugging/tracing module:_perl_modules -F "( *~Devel\:\: )"' \

However, also stripping off the "Devel::" from the front of the matches
is a bit trickier.  What you want is something like "compadd -W" except
that works for things other than filename prefixes.

My best suggestion is to update _perl_modules to take an additional flag
that identifies the module namespace, and use that to change the name of
the caching policy, etc.  Unfortunately I don't have free time right now
to attempt to code it up.

PATCH: perl -d: completion bug

[Phil Pennock]

On 2008-10-11 at 11:02 -0700, Bart Schaefer wrote:
> However, also stripping off the "Devel::" from the front of the matches
> is a bit trickier.  What you want is something like "compadd -W" except
> that works for things other than filename prefixes.
> 
> My best suggestion is to update _perl_modules to take an additional flag
> that identifies the module namespace, and use that to change the name of
> the caching policy, etc.  Unfortunately I don't have free time right now
> to attempt to code it up.

Thanks for the pointers and confirming that there wasn't a short-cut I
could use.

I didn't change caching in any way because I think it's the wrong thing
to do -- anyone using perl on the command-line and expecting
tab-completion of "perl -d:" to work is also highly likely to also be
tab-completing -M too.  So the right thing to do is to let the cache
contain all results, always, with the current logic and just filter the
results for this particular call to _perl_modules().

Done.  Thanks,
-Phil

Index: Completion/Unix/Command/_perl
===================================================================
RCS file: /home/cvsroot/zsh/Completion/Unix/Command/_perl,v
retrieving revision 1.8
diff -a -u -p -r1.8 _perl
--- Completion/Unix/Command/_perl	1 Jun 2005 10:02:34 -0000	1.8
+++ Completion/Unix/Command/_perl	12 Oct 2008 08:38:46 -0000
@@ -10,7 +10,7 @@ _perl () {
     '-a[autosplit mode with -n or -p (splits $_ into @F)]' \
     "-c[check syntax only (runs BEGIN and END blocks)]" \
     '-d[run scripts under debugger]' \
-    '-d\:-[run under control of a debugging/tracing module]:debugging/tracing module:_perl_modules' \
+    '-d\:-[run under control of a debugging/tracing module]:debugging/tracing module:_perl_modules --strip-prefix --perl-hierarchy=Devel' \
     '-D-:set debugging flags (argument is a bit mask or flags): ' \
     "*-e+:one line of script. Several -e's allowed. Omit [programfile]." \
     "-F-:split() pattern for autosplit (-a). The //'s are optional.: " \
Index: Completion/Unix/Type/_perl_modules
===================================================================
RCS file: /home/cvsroot/zsh/Completion/Unix/Type/_perl_modules,v
retrieving revision 1.5
diff -a -u -p -r1.5 _perl_modules
--- Completion/Unix/Type/_perl_modules	2 Aug 2006 22:20:45 -0000	1.5
+++ Completion/Unix/Type/_perl_modules	12 Oct 2008 08:48:42 -0000
@@ -12,6 +12,17 @@
 # -t[types]: indicate file types; currently the only one is -tP,
 # to include .pod files as well as modules.
 # 
+# --perl-hierarchy=...: restrict results to modules under this hierarchy.
+# Note that this does not affect the filesystem searching or caching,
+# which always collect all results on the premise that anyone using
+# completion of Perl modules will use the results in various contexts,
+# so this only affects the results compadd'd.
+#
+# --strip-prefix: when using --perl-hierarchy, strip off that prefix when
+# passing to compadd.
+#
+# All other options passed onto compadd.
+#
 # Available styles:
 #
 # * try-to-use-pminst
@@ -26,14 +37,25 @@ _perl_modules () {
   # Set a sensible default caching policy.  This has to be done inside
   # this function otherwise we wouldn't know the context for the style.
   local update_policy sufpat=".pm" with_pod
+  local restrict_hierarchy=''
+  local -i strip_perl_prefix
   zstyle -s ":completion:${curcontext}:" cache-policy update_policy
   if [[ -z "$update_policy" ]]; then
     zstyle ":completion:${curcontext}:" cache-policy \
       _perl_modules_caching_policy
   fi
 
-  if [[ $argv[-1] = -tP ]]; then
-    argv=("${(@)argv[1,-2]}")
+  if [[ -n $argv[(r)--perl-hierarchy=*] ]]; then
+    restrict_hierarchy="${argv[(r)--perl-hierarchy=*]#--perl-hierarchy=}"
+    restrict_hierarchy="${restrict_hierarchy%::}::"
+    argv[(r)--perl-hierarchy=*]=()
+  fi
+  if [[ -n $argv[(r)--strip-prefix] ]]; then
+    strip_perl_prefix=1
+    argv[(r)--strip-prefix]=()
+  fi
+  if [[ -n $argv[(r)-tP] ]]; then
+    argv[(r)-tP]=()
     sufpat="(.pm|.pod)"
     with_pod=_with_pod
   fi
@@ -93,8 +115,18 @@ _perl_modules () {
     _store_cache ${perl_modules#_} $perl_modules
   fi
 
-  local expl
+  # Nothing above here should have filtered the results per-caller, so that
+  # the cache is always complete.  From here on, it's safe to filter.
+  local -a perl_subset
+  if [[ -n $restrict_hierarchy ]]; then
+    perl_subset=( ${(PM)perl_modules:#${restrict_hierarchy}*} )
+    if (( strip_perl_prefix )); then
+      perl_subset=( ${perl_subset#$restrict_hierarchy} )
+    fi
+    perl_modules=perl_subset
+  fi
 
+  local expl
   _wanted modules expl 'Perl module' compadd "$@" -a - $perl_modules
 }