Re: Thoughts on a builtin read

[malte@TechFak.Uni-Bielefeld.DE]

[ rsalz@osf.org wrote ]:
    Anyhow, let's take a look at your idea.  That is,
            x=`foobar
    hould set $status to the exit value of foobar.  What should
            x=foobar
    set $status to?  Leave it unchanged?  What about
            x=*
    if the directory is empty?  And if it isn't? What about
            x=/foo/*
    when /foo doesn't exist?

Yes, an assignment leaves the status unchanged. Your file name expansion 
examples are just a shorthand for
	x = `{ glob /foo/* }	# glob == echo

Currently, neither "x=*" nor "x=`{ glob *}" sets $status to some reasonable
value, it is just 0 -- always!

    You are making a simple shell very complicated, don't you think?

Complicated is your word for it, I'd rather call it more usable. I have
frequently had the problem to distinguish between a failed backquote
command and a command producing no output. There may be better solutions then
this
	x = `{ foo || echo '!@#$%^&*()' }
	if( ~ $x '!@#$%^&*()' )
		...
but it seems to me to be a FAQ. The person who started this thread had
just this problem. I don't mean to offend anybody, but I have the impression
that because Tom Duff invented this shell there can't be anything wrong. But
if one takes a closer look, one sees quite a few sh'isms still in it, e.g
shift. I think rc in its original form and in its current form is an excellent
point to start a shell project. This is why I post all this to this list
and have it discussed instead of just implementing it for myself. Be assured
though, that I very much appreciate different opinions.

Back to the read problem: Currently there is no builtin which assigns
a value to a variable ( except for the special variables of course ).
There's been a discussion on shift shifting arbitrary lists with the
proposed syntax being "shift x 2" probably because "x = `{ shift x 2 }"
isn't too elegant. If this makes its way into rc, I don't mind if read
expects a variable as a command line parameter. But since I don't care
if some functionality is built into the shell, I'd prefer the
backquote substitution solution.

Malte