Re^2: "next" from within eval {} ?

Just realized that my solution is different with what you want. In mine, it will still execute do_bar, eventhough do_foo returns false. The only way that I can think to break from eval is to raise an exeception, e.g.:


#!/usr/bin/perl -lw
use strict;
use diagnostics;

sub do_foo { die "err" if $_==2;  $_!=4 }
sub do_bar { "..."; }

for (1..5) {
    eval {
        die 'next please' unless do_foo();
        die 'next please' unless do_bar();
    };
    if (my $e = $@) {
        warn $e if ($e !~ /^next please/);
        next;
    }
    print;
}
[download]

Hope this is what you are looking for

Comment on Re^2: "next" from within eval {} ? Download Code

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Re^3: "next" from within eval {} ? by Anonymous Monk on Dec 16, 2011 at 12:22 UTC
Thanks for your thoughts. Actually, your first suggestion was fine, and it looks like a reasonably elegant alternative to using `next`. Due to short-circuit evaluation, subsequent functions do in fact not execute, once the flag has become false: `sub do_foo { print "running foo"; die "err" if $_==2; $_!=4 } sub do_bar { print "running bar"; "..."; } for (1..5) { print "-----"; my $ok = 1; eval { $ok &&= do_foo(); $ok &&= do_bar(); }; if ($@) { warn $@; next; } next unless $ok; print; } __END__ ----- running foo running bar 1 ----- running foo err at ./test.pl line 5. ----- running foo running bar 3 ----- running foo ----- running foo running bar 5` [download] Still, I'm not sure what's wrong with using next from within eval. I mean, you don't generate warnings without a good reason...	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^3: "next" from within eval {} ?
by Anonymous Monk on Dec 16, 2011 at 12:22 UTC

Thanks for your thoughts.

Actually, your first suggestion was fine, and it looks like a reasonably elegant alternative to using next. Due to short-circuit evaluation, subsequent functions do in fact not execute, once the flag has become false:

sub do_foo { print "running foo"; die "err" if $_==2;  $_!=4 }
sub do_bar { print "running bar"; "..."; }

for (1..5) {
    print "-----";
    my $ok = 1;
    eval {
        $ok &&= do_foo();
        $ok &&= do_bar();
    };
    if ($@) {
        warn $@;
        next;
    }
    next unless $ok;
    print;        
}

__END__
-----
running foo
running bar
1
-----
running foo
err at ./test.pl line 5.

-----
running foo
running bar
3
-----
running foo
-----
running foo
running bar
5
[download]

Still, I'm not sure what's wrong with using next from within eval. I mean, you don't generate warnings without a good reason...

[reply]
[d/l]
[select]