status of `{} commands

status of `{} commands

[Chris Siebenmann]

could rc make $status after a `{} command the status of the last command
in the backquotes, especially in the context of 'var=`{command(s)}'? It
would make unnecessary a number of annoying hacks, like:
	var=`` $nl {line; echo $status}
	if (! ~ $#var 2 || ! ~ $var(2) 0)
		break;	# EOF or error
	var=`{echo $var(1)}
for a workable first pass at read that notices EOF.

	- cks

Re: status of `{} commands

[Byron Rakitzis]

Unfortunately, `{} is not a command, it is a construct that exapands to a list.
Let's leave it that way.

The only time I can see you being interested in the exit status of a command
in backquotes is when assigning variables, otherwise the very meaning of
$status becomes distorted. i.e.,

	echo `{/bin/false}

should set status to true, in my opinion. Allowing ` to set $status would
clutter the semantics of `, imho.

I'm not sure what to do in the case of assignments. Would it not be possible
to write a function which takes a command and a variable name as arguments
and performs the assignment while overriding $status?

e.g.,

	fn assigncc {
		tmp = `` $nl {eval $2; echo $status}
		if (~ $#tmp 2 && ~ $tmp(2) 0) {
			$1 = `{echo $tmp(1)}
		} else {
			return 1
		}
	}

to be used as

	assigncc foo 'echo hi'

I will agree that this option would be more feasible if you could pass
pieces of rc code as arguments. The eval and the quoting of the command
to be executed is definitely problematic.