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In article <102618@linus.UUCP> duncant@mbunix.mitre.org (Thomson) writes:

Thomson> I am surprised at the use of the phrase "more powerful
Thomson> amiga-style wildcards".  More powerful than what?

On 18 Mar 90 18:55:35 GMT, peter@sugar.hackercorp.com (Peter da Silva) said:

Peter> Suppose you want to match all file names ending with .c, .h, or
Peter> .bak, and beginning with an underscore or "ck" or containing
Peter> the string "test".

Peter> In UNIX, you have to use several expressions:

Peter> 	_*.[ch] _*.bak ck*.[ch] ck*.bak *test*.[ch] *test*.bak

For csh users:  {_,ck,*test}*.{[ch],bak}

Peter> On the Amiga, you have a single expression:

Peter> 	((_|ck)#?|#?test#?).(c|h|bak)

Peter> The Amiga wildcards are more complex, but they're also a lot
Peter> more powerful.

AmigaDOS's (x|y|z) syntax is directly analogous to csh's {x,y,z}.

Thomson> I never understood where the AmigaDos wildcard conventions
Thomson> came from.

Peter> The syntax is unconventional, but the use of a closure rather
Peter> than a wildcard has been around for a long time.

Granted, AmigaDOS wildcards are flexible and powerful, but I find them
less convenient to use than Unix wildcards, under most circumstances.
While it is mor flexible to be able to match foo and foooo with f#o,
it's not something I find myself using on any regular basis.

What is more difficult, for example, is the fact that the copy program
only accepts a single source and single destination argument.  Yes,
you can do "copy (foo|bar|baz) dir" instead of "copy foo bar baz dir",
but the former notation is more cumbersome to type, and introduces
another disadvantage, namely that it is a _wildcard_.

This means the entire directory must be scanned for matches.  You lose
the speed advantage of the hashed directory lookups, and pay the
penalty for a directory scan, even if you know exactly what files you
want to copy.  The only way to avoid this is to run the copy program
once for each program to be copied.  This is also inconvenient.  The
problem is most noticable if you want to copy a half dozen or so files
from a LARGE directory on a floppy.  My C: directory takes on the
order of 20-30 seconds to scan (maybe longer) and it should not be
necessary for a simple list of files.

I realize that this problem can be solved by using a different copy
program which accepts arguments in a fashion more like that of Unix
cp.  That's not the point.  The point is that in _practice_, the
flexible wildcards which AmigaDOS offer are not necessarily the boon
they may seem.  They are awkward to use, and can shift focus from some
strengths of AmigaDOS (hashed lookups) to some weaknesses (directory
scans).

As for solutions, accepting multiple filename arguments instead of a
single one in places like the copy program would be an improvement.

In response to Dave Haynie's note that "*" has special meaning to
AmigaDOS:  point taken.  But there are times it can be determined from
context whether "*" should be the console or a wildcard.  Of course,
there are situations where it is indeterminable.  Offering the user a
configurable option of whether or not to treat "*" as a wildcard, and
permit it to be escaped with \ or even *.  That is, in a wildcard
context, treat "*" as "#?" and "**" as "*".  Thoughts?

Deven
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