On Fri, 2002-04-26 at 14:11, Allison Randal wrote:
> On Fri, Apr 26, 2002 at 08:49:23AM +1000, Damian Conway wrote:
> Hmmm... how about:
>
> for $results.get_next() {
> print $_;
> LAST { print "Done."; }
> ELSE { print "No results."; }
> }
>
> The "else" of a loop construct isn't really the same as the "else" of an
> C<if>. You can't use an C<elsif> for one thing. And the condition for
Why not? What would be wrong with:
for @x {
...
} elsif (stuff) {
...
} else {
...
}
Of course it brings other less wholesome things to mind like "elsfor"
and "elsloop" and "if ... elsfor" and "for ... elsif ... elsloop ...
else", but why not?
> reaching the "else" is different too, it isn't always a "false value",
Yes it is.
> sometimes it's "no values to iterate over" or "condition met before
> first execution of loop".
while(@x) { ... } / if (@x) { ... }
while($x) { ... } / if ($x) { ... }
These are different how? To my eye, the only difference is what happens
at the end of the block. In fact,
while ($x) { ... ; last; }
is an if.
> I can also think of some advantages to having the "else" within the
> scope of the loop. You might want your object to return a "false" value
> from .get_next() (one that C<for> will see as non-iterate-able) but that
> still contains some interesting properties that can be used by the
> "else". If the "else" followed the loop this value wouldn't be in scope.
This is something I had not considered, but sounds very cool.
sub alllines ($file) {
my $fh;
if ($fh = IO::File->new("<$file")) {
return $fh->getlines;
} else {
return $! but false;
}
}
while alllines("/etc/passwd") -> $_ {
...
} else {
die "/etc/passwd: $_";
}
Yeah... I like it.
