Re: AUTO_CD (-J) with CDPATH problems

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxx>]

On Sep 28, 11:02am, Peter Stephenson wrote:
} Subject: Re: AUTO_CD (-J) with CDPATH problems
}
} The problem arises if the command name `prom' is hashed, i.e. in zsh's
} internal tables of where commands are to be found.  For some reason,
} this will happen even to subdirectories of a directory of $path ---
} the whole of a directory in $path, not just commands, are added to the
} command hash table.  [...]
} 
} I know the same feature has been causing trouble with completion for
} some time, but this seems to be the last straw.

This is even more annoying in the NT port of zsh, because of course the
DLLs and data files and whatnot all live in the same directories as the
associated executables, so you end up with a -huge- hash table stuffed
with useless junk.  (Unfortunately, a stat()-based fix is of limited
usefulness in that case, because executability is generally a property
of the filename extension only.)

} [...] did anybody ever check how
} much slower it was to stat() the entire directory when adding it to
} the command hash table?

It probably depends on whether some elements of the path are on NFS
servers, and various other local details.  I think it's best left alone,
or made an option (urk).

} I can make a minimal patch just for AUTO_CD when the single
} stat()/access() is cheap, of course (in fact I've got one), but I'd
} prefer to attack the root cause if possible.

There are a few possible approaches short of examining every file in
$path at hashing time.  One would be to examine only files for which
there is an equivalent name in $cdpath or later in $path, i.e., only
stat() when disambiguation is necessary.  Combined with the patch you
just described, that would also catch cases where a subdirectory was
added to a directory in $cdpath after hashing.  (Also, I'd avoid
putting in the command hash table anything that was already in the
named directory hash table, or that was directly included in $path or
$cdpath.)

Except for the above and stray non-commands showing up in completions,
are there other cases where junk in the command hash causes problems?

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com