commit - e6eae0468089573a77abb012145073dd8d1c4402
commit + 19d28f97177c183d78bbce4642857db2ea27541f
blob - 7e552eddfecbe0b782dec4fa11b58fe32d9d2124
blob + fcbd49da45d37f494b7475ce90749039c3ab4052
--- exercise
+++ exercise
@@ -267,48 +267,41 @@ proc check_suite_counters {counters} {
 proc getopt {argvvar optstring optvar argvar} {
     upvar $argvvar argv $optvar opt $argvar arg
 
-    set hd [lindex $argv 0]
-    set opt [string index $hd 1]
-    if {$opt eq "" || [string index $hd 0] ne "-"} {	;# no option argument
-        return 0
+    set arg [lindex $argv 0]                    ;# "" if argv empty
+    set opt [string index $arg 1]               ;# "" if arg empty
+    if {$opt eq "" || [string index $arg 0] ne "-"} {
+        return 0                                ;# no option
     }
-    if {$hd eq "--"} {
-        set argv [lreplace $argv 0 0]           ;# remove hd
-        return 0
+    set argv [lreplace $argv 0 0]               ;# tentative consumption
+    if {$arg eq "--"} {
+        return 0                                ;# end of options
     }
 
     # consume option character
-    set hd [string replace $hd 1 1]
-    if {$hd ne "-"} {
-        set argv [lreplace $argv 0 0 $hd]       ;# replace hd
-    } else {
-        set argv [lreplace $argv 0 0]           ;# consume exhausted hd
+    set arg [string replace $arg 1 1]
+    if {$arg ne "-"} {                          ;# not yet exhausted?
+        set argv [linsert $argv 0 $arg]         ;# put it back for now
     }
 
+    # check if option is valid
     set idx [string first $opt $optstring]
     if {$idx == -1 || $opt eq ":"} {
-        puts stderr "$::argv0: unknown option -- $opt"
+        puts stderr "[file tail $::argv0]: unknown option -$opt"
         set opt "?"
-        return 1
+        return 1                                ;# could come back for more
     }
 
     # handle option arguments
-    if {[string index $optstring [expr $idx + 1]] ne ":"} {
-        return 1                                ;# no argument expected
-    }
-    if {$hd ne "-"} {
-        set arg [string replace $hd 0 0]        ;# rest of hd -> optarg
-        set argv [lreplace $argv 0 0]           ;# consume hd
-    } elseif {[llength $argv] > 0} {
-        set arg [lindex $argv 0]                ;# next arg -> optarg
+    if {[string index $optstring [expr $idx + 1]] eq ":"} {
+        if {$arg ne "-"} {
+            set arg [string range $arg 1 end]   ;# use the rest of arg
+        } elseif {[llength $argv] > 0} {
+            set arg [lindex $argv 0]            ;# use the next arg
+        } else {
+            puts stderr "[file tail $::argv0]: -$opt requires an argument"
+            set opt [expr {[string index $optstring 0] eq ":" ? ":" : "?"}]
+        }
         set argv [lreplace $argv 0 0]           ;# consume arg
-    } else {
-        puts stderr "$::argv0: option requires an argument -- $opt"
-        if {[string index $optstring 0] eq ":"} {
-            set opt ":"
-        } else {
-            set opt "?"
-        }
     }
 
     return 1