exiting an eval block inside a loop?

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Gurus,

I've looked in the Camel and Leopard, and they're mum on this topic. Is
it possible/permitted to exit an eval block that's running inside a loop,
or will that break something? Quickie example code:

LABEL: until ($foo eq q{}) {
$foo = $array{$ndx++};

eval {
for ($foo) {
/^abc/o && do {
next LABEL if ($_ =~ /ZZZ$/); # CAN I DO THIS?
# do something
};
/^def/o && do {
next LABEL if ($_ =~ /RST$/);
# do something else
};
}
};
$@ and die "Error in string value";
}

Deane Rothenmaier
Systems Architect
Walgreens Corp.
847-914-5150

"On two occasions I have been asked [by members of Parliament], 'Pray, Mr.
Babbage, if you put into the machine wrong figures, will the right answers
come out?' I am not able rightly to apprehend the kind of confusion of
ideas that could provoke such a question." -- Charles Babbage
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Gurus,



I've looked in the Camel and Leopard, and they're mum on this topic.  Is it possible/permitted to exit an eval block that's running inside a loop, or will that break something?  Quickie example code:



LABEL: until ($foo eq q{}) {

   $foo = $array{$ndx++};

 

   eval {

      for ($foo) {

         /^abc/o && do {

            next LABEL if ($_ =~ /ZZZ$/);  # CAN I DO THIS?

            # do something

         };

         /^def/o && do {

            next LABEL if ($_ =~ /RST$/);

            # do something else

         };

      }

   };

   $@ and die "Error in string value";

}



Deane Rothenmaier

Systems Architect

Walgreens Corp.

847-914-5150



"On two occasions I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question." -- Charles Babbage
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RE: exiting an eval block inside a loop?

From: activeperl-bounces@listserv.ActiveState.com
[mailto:activeperl-bounces@listserv.ActiveState.com] On Behalf Of
Deane.Rothenmaier@walgreens.com
Sent: 02 March 2007 16:29
To: activeperl@listserv.ActiveState.com
Subject: exiting an eval block inside a loop?

> Gurus, =

> =

> I've looked in the Camel and Leopard, and they're mum on this topic.
Is it possible/permitted to exit an eval > block that's running inside a
loop, or will that break something? Quickie example code: =

> =

> LABEL: until ($foo eq q{}) { =

> $foo =3D $array{$ndx++}; =

> =

> eval { =

> for ($foo) { =

> /^abc/o && do { =

> next LABEL if ($_ =3D~ /ZZZ$/); # CAN I DO THIS? =

> # do something =

> }; =

> /^def/o && do { =

> next LABEL if ($_ =3D~ /RST$/); =

> # do something else =

> }; =

> } =

> }; =

> $@ and die "Error in string value"; =

> } =


The documentation ('perldoc -f eval') addresses this issue to some
extent. The second from last paragraph (on my installation, at least)
discusses this.

However, you could also have just tried it (the suck-it-and-see approach
is one of the things that Perl is good at). If you did you would have
seen the warning that it causes (you do have warnings enabled, don't
you). You can inhibit the warning (see following example), but it is
better to avoid code that generates warnings as far as possible. If you
really must do it, please make sure that you document what you are doing
and why.

------------------------------------
use strict;
use warnings;

for my $i (1..10) {
# Try with and without the following statement.
no warnings qw{exiting};
eval {
print "i=3D$i\n";
next;
print "bottom of loop\n";
};
die $@ if $@;
}
------------------------------------

HTH

-- =

Brian Raven =


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RE: exiting an eval block inside a loop?

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"Suck-it-and-see"?

Okay, tried that, and got the warning you alluded to. Think I'll leave
things the way they are--two separate for switches, one in the eval to do
the work, and one before it to screen. Less elegant, perhaps, but it
doesn't throw hissy fits.

Thanks to all who even thought of answering this dopey question.... B-)

Deane Rothenmaier
Systems Architect
Walgreens Corp.
847-914-5150

"On two occasions I have been asked [by members of Parliament], 'Pray, Mr.
Babbage, if you put into the machine wrong figures, will the right answers
come out?' I am not able rightly to apprehend the kind of confusion of
ideas that could provoke such a question." -- Charles Babbage
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"Suck-it-and-see"?  



Okay, tried that, and got the warning you alluded to. Think I'll leave things the way they are--two separate for switches, one in the eval to do the work, and one before it to screen. Less elegant, perhaps, but it doesn't throw hissy fits.



Thanks to all who even thought of answering this dopey question....  B-)



Deane Rothenmaier

Systems Architect

Walgreens Corp.

847-914-5150



"On two occasions I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question." -- Charles Babbage
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