Front page | perl.perl5.porters |
Postings from May 2004
On Wed, Apr 28, 2004 at 11:17:43PM -0000, Yitzchak Scott-Thoennes wrote:
> exiting an eval BLOCK via last when there is no loop block there
> sends control to the wrong place:
>
> This is correct:
>
> $ perl -we'{eval { print "1"; last; print "2" }; print "3"} print "4";'
> Exiting eval via last at -e line 1.
> 14
[snip]
> This is also correct:
>
> $ perl -we'{eval { print "1"; last; print "2" }; print "3"} print "4";'
> Exiting eval via last at -e line 1.
> 14
They both look identical to me?
> The following is just plain weird. Once it's printed "3", why is it then
> "Exiting subroutine via last"? It should give both warnings plus the
> Can't "last" outside a loop block warning, and only print "1":
>
> $ perl -we'sub foo { eval { print "1"; last; print "2" }; print "3"} foo;
> print "4";'
> Exiting eval via last at -e line 1.
> Exiting subroutine via last at -e line 1.
> 134
The eval { } is trapping the fatal error C<Can't "last" outside a loop block>
Although frankly I think that last-ing out of a sub should be a fatal
error too rather than just a warning; otherwise you get the following
spooky action at a distance:
$ ./perl -wle' sub f { redo if $_[0] > 2 } for (1..5) { print $_; f($_) }'
1
2
3
Exiting subroutine via redo at -e line 1.
3
Exiting subroutine via redo at -e line 1.
3
Exiting subroutine via redo at -e line 1.
3
...
ie you can control the loop that calls the sub from within the sub!
--
Spock (or Data) is fired from his high-ranking position for not being able
to understand the most basic nuances of about one in three sentences that
anyone says to him.
-- Things That Never Happen in "Star Trek" #19
Thread Previous
|
Thread Next