clewis@eci386.uucp (Chris Lewis) (02/08/90)
When you
do 'something';
And "something" isn't in your home directory (though it's directory is in
@INC), $! is set to "No such file or directory". Even though perl actually
did read the file, $@ is zero/null and definitions set therein can be
referenced. Sometimes this appears to depend on the contents of the
perl script, but I've not narrowed it down very far. Both Perl 2 and 3.
I suspect that this is actually errno being set on the first open attempt
(in your home directory), but isn't being reset on a later successful
open.
Have I missed something?
--
Chris Lewis, Elegant Communications Inc, {uunet!attcan,utzoo}!lsuc!eci386!clewis
Ferret mailing list: eci386!ferret-list, psroff mailing list: eci386!psroff-listlwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) (02/09/90)
In article <1990Feb7.190655.16030@eci386.uucp> clewis@eci386 (Chris Lewis) writes:
: When you
:
: do 'something';
:
: And "something" isn't in your home directory (though it's directory is in
: @INC), $! is set to "No such file or directory". Even though perl actually
: did read the file, $@ is zero/null and definitions set therein can be
: referenced. Sometimes this appears to depend on the contents of the
: perl script, but I've not narrowed it down very far. Both Perl 2 and 3.
:
: I suspect that this is actually errno being set on the first open attempt
: (in your home directory), but isn't being reset on a later successful
: open.
I think your analysis is correct. I don't think you should rely on the
value of $! at that point though. The fact that $@ is null means there
was no compilation error. To indicate successful execution of 'something'
I've been putting a 1; at the end of every 'something' I write. The you
can just say
do 'something' || die "Couldn't do something";
To specifically check for whether the file was found you could say
$foo = do 'something';
die "Couldn't find something" unless defined $foo;
die "Couldn't parse something: $@" if $@;
die "Couldn't run something" unless $foo;
$! is not meant to be anything more than what errno is. And errno just
reflects the last error on a system call. Something as complicated as
a path search does a number of system calls.
Larry