ask: close #248

- fix `--required` causing infinite loop, this was due to `option_timeout` being empty, which causes `-t ''` to be send to `read` which causes it to exit immediately and try again for input
- clarified some comments

commands/ask

@@ -253,7 +253,7 @@ function ask_() (
 		fi
 	}
 	function do_prompt { # has sideffects: RESULT, ASKED
-		local programmatic_stdin input_prompt __read_status __input_result result_prompt result_prompt_row_count
+		local programmatic_stdin input_prompt __read_status __input_result result_prompt result_prompt_row_count clear='' p='' read_args=('-r')
 		if test ! -t 0; then
 			programmatic_stdin='yes'
 		else
@@ -267,19 +267,26 @@ function ask_() (
 			fi
 			input_prompt+="$style__icon_prompt"
 		fi
+		if test -n "$option_timeout"; then
+			read_args+=(
+				-t "$option_timeout"
+			)
+		fi
 
-		local clear='' p=''
 		ASKED='yes' # not local
 		while true; do
 			# reset
 			__read_status=0
 			__input_result=''
 
-			# test for stdin technique, as [read -i] does not support programatic stdin
+			# adapt according to read mode
 			if test "$programmatic_stdin" = 'yes'; then
-				# we have programatic stdin, so manually read the line without a tty prompt
-				# don't read multiple lines, as other lines are for subequent prompts, such as confirmations or the next program
-				IFS='' read -r -t "$option_timeout" __input_result || __read_status=$?
+				# read in programmatic stdin mode behaves differently, so we have to account for that:
+				# [-p <prompt>] is discarded, no prompt is shown
+				# [-i <default>] is discarded, no default value is handled
+				# as such, do not pass such to read, do not manually bother with a prompt, and handle the default value ourself
+				# trunk-ignore(shellcheck/SC2162)
+				IFS='' read "${read_args[@]}" __input_result || __read_status=$?
 				if test -z "$__input_result" -o "$__input_result" = $'\n'; then
 					# treat empty string and newline as default
 					:
@@ -300,7 +307,8 @@ function ask_() (
 				clear=''
 
 				# clear and prompt
-				IFS= read -r -t "$option_timeout" -ei "$RESULT" -p "$p" __input_result || __read_status=$?
+				# trunk-ignore(shellcheck/SC2162)
+				IFS= read "${read_args[@]}" -ei "$RESULT" -p "$p" __input_result || __read_status=$?
 
 				# update the value on successful read, and prepare the clear
 				# note if there was a default value, pressing enter will set [__input_result] to it
@@ -328,7 +336,7 @@ function ask_() (
 				# ask again
 				continue
 			else
-				# no result, optional, set value to empty, and proceed
+				# no result, optional, set value to empty, exit read loop, and continue with program
 				RESULT=''
 				break
 			fi