Re^3: how to loop

Um... so if you edit the script so that $mode is set to something other than "running", the loop will execute just once, and the script exits; but if you edit the script so that $mode is set to "running", the script loops indefinitely until you kill it (^C or whatever). And that's the intended design?

I would have expected that either (a) the value assigned to $mode would depend on @ARGV (or %ENV, or some other external input), or (b) there would be something inside the loop that could change the value of $mode, or else (c) each time you edit the script to change its behavior, rather than editing a variable assignment, you would just edit the loop condition -- e.g. do {...} while(0); vs. do {...} while(1);, or something to that effect. (Note that the former "do" block will execute exactly once, whereas the block in while(0){...} never executes.)

As it is, I tend to share muba's puzzlement.

(updated to fix spelling)

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Re^4: how to loop by rsiedl (Friar) on Feb 21, 2007 at 07:57 UTC
yep, that was the intended design. the scripts purpose is to randomly select a wallpaper and set it in gnome2. i can then add it to my startup scripts, and it'll change the wallpaper, either once at login, or continuously while i am logged in, depending upon what i've set $mode to. i've modified it a bit more though, so maybe this makes more sense... Read more... (2 kB)	[reply] [d/l]
Re^5: how to loop by graff (Chancellor) on Feb 21, 2007 at 08:13 UTC
Yes, that does make more sense. Just one word of caution though... Instead of this: `# Interval to change at if we want $mode = "running" my $interval = $ARGV[0]; # Change the mode if we have been passed an interval $mode = "running" if ($interval);` [download] something like this would be more prudent: `my $interval = 0; if ( @ARGV ) { ( $interval ) = ( $ARGV[0] =~ /(\d+)/ ) or die "Usage: $0 [m]\n m: number of minutes between color cha +nges\n"; } $mode = "running" if ( $interval );` [download] That makes sure that you don't try to do arithmetic on a non-numeric string, or sleep for a negative number of seconds. (update -- minor nit-pick -- since you now have an "interval" variable that is either true or false, you don't really need a "mode" variable, do you?)	[reply] [d/l] [select]