Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cme!libes
From: libes@cme.nist.gov (Don Libes)
Newsgroups: comp.lang.perl
Subject: Re: Expect.pl, alpha release
Message-ID: <7749@muffin.cme.nist.gov>
Date: 2 Nov 90 03:06:40 GMT
References: <1990Nov2.003228.22744@iwarp.intel.com>
Organization: National Institute of Standards and Technology
Lines: 38

In article <1990Nov2.003228.22744@iwarp.intel.com> merlyn@iwarp.intel.com (Randal Schwartz) writes:
>The motivation for writing this package is the fact
>that Don Libes doesn't like Perl. :-)

I've never said anything like that, nor is it true (although I will admit
that I've had a lot of trouble learning Perl.)  Fact is, I've written
several Perl hacks, at least one of which is used daily at my site.

>The matchup of expect<->tcl and expect.pl<->Perl made for some weird
>design tradeoffs.  I may start from mostly scratch and do everything
>right.  That is probably why I hesitate to implement the rest of the
>functions... they really don't fit in a Perl environment.

Actually, I discussed these issues with several people during the
development of expect.  The approach I took effectively sealed off the
user from the underlying C implementation, substituting the more shell-
like Tcl language and reducing the ability to screw themselves somehow.

In the approach you took, the user language IS Perl, which provides
incredible power and flexibility.  The primary disadvantage is that
the user may have to learn Perl, which is hard.

Also, as you noticed, some of the features (like logging) are a problem
for Perl.  Oh, and as you suspected, recursive invocations are useful -
consider writing scripts that are half automated and half interactive,
like the fsck script I showed at the LISA conference.

Please don't get me wrong.  I think Perl is very useful.  I desperately
want a copy of your book.  And I consider it a compliment that you
followed my implementation as faithfully as you did.  Though, I did
think some of your Perl code pretty weird!

Actually, in my USENIX paper I stated that I fully expected someone to
incorporate the expect primitives into a shell, Perl, whatever.  I was
just showing proof of concept.  It just happened to turn out really nice.
In fact, I owe a lot for it to John Ousterhout who wrote Tcl.

Don Libes          libes@cme.nist.gov      ...!uunet!cme-durer!libes