Not only can you use a while loop but you can also use goto in a better way. Perl has two distinct forms of goto. The first (as you are doing here) is a classic goto. Just a jump, all state preserved, messy. Don't do it.

The second is a tail call form. If you goto &sub it leaves the current stack frame and re-enters with the existing values of @_ re-aliased. This means you have clean scope. This is very useful for retries. So in this case we could:

for my $router (@routers) {
    get_config($router, 0);
}

....

sub get_config {
    my ($router, $retries) = @_;
    my $output = `expect -f show_running_config.exp $router->[$IP]`;
    die "Failed to get config for $router->[$NAME] at $router->[
+$IP]: $output\n" if $retries > 3 and $?;
    unless ($?) {
        sleep 5;
        $_[2] = $_[2] + 1;
        goto &get_config;
    return write_config($output, "$router->[$NAME].cfg");
}

[download]

Here goto gives you an effective restart condition, but with a clean state (i.e. all locally scoped variables, such as $output get cleared on each retry. It is very nice in the sense it gives you a clean restart on the function without the extra stack overhead (though since you are only retrying 5 times, recursion may be another option).

In reply to Re: Wait and retry loop without goto by einhverfr
in thread Wait and retry loop without goto by samuelk1

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