On Mon, 29 Jul 2002, Dan Sugalski wrote:
> If I thought anyone'd do control flow with it, I'd have a version of
> the op for that, but I don't think we're going to see that, and perl
> doesn't do it, so...
Okay, writing this email has convinced me that maybe we don't need these
ops. If Perl's going to do things like this:
$x = 1; $y = 2; $z = "grape";
if $z < $x < $y lt $z { print "strange, but true" }
then it seems like they'll be used for control flow just like anything
else. The alternative would be to do this with the Ix versions like so:
cmpn I0, Px, Py
unless I0, -1, l_false
Or with the current set of ops, through temps like so:
set N0, Px
set N1, Py
ge N0, N1, l_false
Actually, since with this version we can keep the num/string temporaries
around to reuse them in comparison chains and only do the conversion once,
the other might not be so great -- strtod is painful. cmp{n,s} save us
one instruction per compare (two for the branching versions), so they'd
probably be a win on single comparisons, but they're not as useful as I
naively thought.
How useful do people think these are?
/s
