Stevan Little writes:
> Hello all,
>
> I am not even 100% sure these are bugs. I assume I should be able to do
> this, but I dont know for sure.
>
> These two test groups (taken from t/builtins/io/io_in_for_loop.t) below
> will fail with the error:
>
> pugs: tempfile: hGetLine: illegal operation (handle is closed)
>
> it seems that accessing the filehandle in the for loop is a bad thing.
>
> { # now read it in with the $fh controling the loop but call
> # the =$fh inside the loop inside parens (is this list context??)
> my $fh = open($filename);
> my $num = 1;
> for (=$fh) -> $line {
> is($line, "$num\n", '... got the right line ((=$fh) controlled
> loop)');
> $num++;
> my $line2 = =$fh;
> is($line2, "$num\n", '... got the right line2 ((=$fh)
> controlled loop)');
> $num++;
> }
> $fh.close();
> }
>
> { # now read it in with the $fh controling the loop but call
> # the =$fh inside the loop w/out parens (is this scalar context??)
> my $fh = open($filename);
> my $num = 1;
> for =$fh -> $line {
> is($line, "$num\n", '... got the right line (=$fh controlled
> loop)');
> $num++;
> my $line2 = =$fh;
> is($line2, "$num\n", '... got the right line2 (=$fh controlled
> loop)');
> $num++;
> }
> $fh.close();
> }
Hmm... I believe that the behavior in this case is undefined. It sure
would be nice if it worked, but you see:
for =$fh -> $line { ... }
Evaluates `=$fh` in list context. In an eager world, this eats up the
whole file in one go. In the ideal lazy world, it reads one line at a
time (which would allow this example to work... I think). And perhaps
that's how we need to define it. But currently, whether this works
depends on how lazy $fh is, and whether it does any thunks (thunks are
bad in this case).
Luke
