This illustrates how you can use Tcl to ensure that files get closed even when errors happen by combining catch, close and return (from the Tcl manual): pr

This illustrates how you can use Tcl to ensure that files get closed even when errors happen by combining catch, close and return (from the Tcl manual): proc withOpenFile {filename channelVar script} { upvar 1 $channelVar chan set chan [open $filename] catch { uplevel 1 $script } result options close $chan return -options $options $result }