Add machine-processible mode so people can adapt to their own players

README.md

@@ -67,7 +67,7 @@ On the bright side, though, youtube-dl downloads most songs in Opus, which has i
 
 **Q**: Why isn't my music player supported?
 
-**A**: Open a bug report/pull request.
+**A**: Open a bug report/pull request. Alternatively, use `ptgdp -m` and some glue.
 
 ## Bugs
 

ptgdp

@@ -27,6 +27,7 @@ declare _optconfigfile="${XDG_CONFIG_HOME:-$HOME/.config}/${_name}.conf"
 declare -i _optautoplay=0
 declare -i _optdlonly
 declare -i _opthelp
+declare -i _optmachinemode
 declare -i _optverbose
 # Working variables
 declare -a _queue
@@ -41,15 +42,23 @@ log() {
 	# loglevel 1: Detailed but not quite debugging
 	# loglevel 2: Definitely debugging
 	[ -z "$1" ] && return 1
+	local -i outstream=1
+	[ -n "$_optmachinemode" ] && outstream=2
 	if (( _optverbose >= ${2:-0} )); then
-		printf "%s\\n" "$1"
+		printf "%s\\n" "$1" >&"$outstream"
 	fi
 }
 warn() {
 	# Print a yellow line to the terminal, respecting _optverbose
 	[ -z "$1" ] && return 1
+	local -i outstream=1
+	[ -n "$_optmachinemode" ] && outstream=2
 	if (( _optverbose >= ${2:-0} )); then
-		printf "\\e[33m%s\\e[0m\\n" "$1"
+		if [ -t "$outstream" ]; then
+			printf "\\e[33m%s\\e[0m\\n" "$1" >&"$outstream"
+		else
+			printf "WARN: %s\\n" "$1" >&"$outstream"
+		fi
 	fi
 }
 error() {
@@ -247,6 +256,9 @@ given plaintext files with only search queries
   -c [FILE]		Load the given file in place of the usual config file
   -d			Download songs but don't queue them up
   -h			Print this help text
+  -m			Machine-processible mode. Output all log text to STDERR
+			and print only the final list of songs to STDOUT,
+			separated by newlines.
   -p			Play the queue after it's built
   -v			Print more status messages. Stacks
 
@@ -285,14 +297,20 @@ playlist() {
 			continue
 		fi
 	done < "$1"
-	backend-execqueue
+	if [ -n "$_optmachinemode" ]; then
+		for file in "${_queue[@]}"; do
+			printf "$file\\n"
+		done
+	else
+		backend-execqueue
+	fi
 	log "Finished: $dlcache cached, $dlsuccess downloaded, $dlerr failed"
 }
 
 # Main
 main() {
 	# Getopts before anything else
-	while getopts ":c:dhpv" opt; do
+	while getopts ":c:dhmpv" opt; do
 		case $opt in
 			c)
 				_optconfigfile="$OPTARG"
@@ -303,6 +321,9 @@ main() {
 			h)
 				_opthelp=1
 				;;
+			m)
+				_optmachinemode=1
+				;;
 			p)
 				_optautoplay=1
 				;;