To goto or not to goto

PerlJam has asked for the wisdom of the Perl Monks concerning the following question:

Hi Everyone, I am writing a program that is going to send sales quotes and receive data to and from a ftp server. I am trying make it so that if the computer gets disonnected from our RAS it'll redial and then resend the quote that it failed on and all other quotes left in the array. I am wondering what the best way to do this would be. As you can see in the code below, when the transfer fails I call the routine to connect to the RAS. Now I was thinking of using a goto command here to jump back to the beginning of the current for loop after the connection is made. I am hesitant only because I know how goto's should be avoided unless necessary. Is this a good place to use one? or is there another method I should look into?

#
    # Loop through quotes array and upload each file in the array.
    #
    foreach my $quote (@quotes) {
        system("cls");
        emphasize("Sending quote: $quote");
        my $return = $ftp->put("$quote");
        #
        # If the upload completed $return should == $quote
        # and we can move the file to a backup folder.
        #
        if ($return == $quote) {                                      
+                       # Needs testing!!!!!!!!!!!!!!
            move("$quote", "${new_dir}\\$quote") or warn "move failed:
+ $!";
        }
        else {
            while ( &connect_ras() ) {}
            # ShouldI place a goto here and a label at the beginning?
        }

    }
    disconnect_ftp();
}
[download]

----
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Comment on To goto or not to goto Download Code

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Re: To goto or not to goto by dsheroh (Monsignor) on Jun 10, 2002 at 22:37 UTC
From `man perlfunc`: redo LABEL redo The "redo" command restarts the loop block without evaluating the conditional again. The "continue" block, if any, is not executed. If the LABEL is omitted, the command refers to the innermost enclosing loop. This command is normally used by programs that want to lie to themselves about what was just input:	[reply] [d/l]
Re: To goto or not to goto by FoxtrotUniform (Prior) on Jun 10, 2002 at 22:37 UTC
I'd rework the loop body like so: `foreach my $quote (@quotes) { my $return = 0; do { system("cls"); emphasize("Sending quote: $quote"); $return = $ftp->put($quote); if($return != $quote) { while(&connect_ras()) {} } } while($return != $quote); move($quote, "${new_dir}\\$quote") or warn "move failed: $!\n"; }` [download] The inner "do...while" loop test could use some work, but I think the loop expresses the idea "keep trying to send this quote until we succeed" better than a goto would. `-- The hell with paco, vote for Erudil! /msg me if you downvote this node, please. :wq`	[reply] [d/l]
Re: To goto or not to goto by DamnDirtyApe (Curate) on Jun 10, 2002 at 22:38 UTC
Perhaps a `next` would keep you from having to use a `goto` here. # # Loop through quotes array and upload each file in the array. # MY_LOOP: foreach my $quote (@quotes) { system("cls"); emphasize("Sending quote: $quote"); my $return = $ftp->put("$quote"); # # If the upload completed $return should == $quote # and we can move the file to a backup folder. # if ($return == $quote) { + # Needs testing!!!!!!!!!!!!!! move("$quote", "${new_dir}\\$quote") or warn "move failed: + $!"; } else { while ( &connect_ras() ) {} # ShouldI place a goto here and a label at the beginning? next MY_LOOP ; } } disconnect_ftp(); } [download] Note: this is untested, but I think it fits with your intent. Update: After reading the above posts, I'm not sure if you want `redo` or `next`. Use `redo` if you want to skip back to the start of the block without re-evaluating the conditional. Use `next` if you want to skip to the end of the block, so that the conditional is re-evaluated for the next iteration. Hope that makes sense. :-) _______________ D a m n D i r t y A p e Home Node \| Email	[reply] [d/l]
Re: To goto or not to goto by PerlJam (Sexton) on Jun 10, 2002 at 22:56 UTC
Makes perfect sense Ape... Thanks! I can't do the next as it would leave the quote that failed to go, behind. I'll try out the redo and the do while loop proposed. Thanks for the ideas guys!	[reply]
Re: Re: To goto or not to goto by Rich36 (Chaplain) on Jun 11, 2002 at 00:11 UTC
Also, if cross-platform compatibility is an issue (or you just want to avoid system calls), check out How do you clear the screen? instead of calling "cls". «Rich36»	[reply]


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