On Sat, Nov 5, 2011 at 3:04 PM, Shawn H Corey <shawnhco...@gmail.com> wrote:
> On 11-11-05 01:49 PM, Uri Guttman wrote:
>
>> readline isn't a system call so it can't set $!.
>>
>> $! maps to the errno of system calls and has both the text and numeric
>> values of the actual error (only if one happens) of the last system
>> call. perl itself can trigger errors in system calls easily but the
>> internal errors don't set $! (they do set errno internally). e.g.
>> loading a file that doesn't exist will generate a perl error (which can
>> be caught with eval BLOCK) but the value of $! will still be meaningless.
>>
>
> I sorry but the function readline() will set $! on error.
Yes.
> See `perldoc readline`. $! will be undefined if no error occurs.
>
>
No.
Neither of these two are very portable, and may actually succeed on some
architectures. But eh.
For the latter:
use 5.014;
use Devel::Peek;
pipe $in, $out;
$out->autoflush;
say { $out } "eeyup";
Dump $!;
scalar readline($in);
Dump $!;
As you can see, readline() doesn't touch $! on success. Meanwhile, on error:
use 5.014;
use Devel::Peek;
open my $dh, "."; #Open directory as file
Dump $!;
readline( $dh );
Dump $!;
It does set $! -- Though strangely enough I can't get it to work with <>,
which smells like a bug.
