Added more options. Can choose to use an sbt snapshot with -snapshot.

Now by default it refuses to run sbt in a directory with no sign it is
an sbt directory; give -create to force it.

.gitignore

@@ -5,4 +5,4 @@ target
 lib_managed
 src_managed
 /ext
-.lib/sbt-launch.jar
+.lib

sbt

@@ -5,9 +5,40 @@
 
 set -e
 
+jar_url () {
+  local where=$1  # releases or snapshots
+  local ver=$2
+  
+  echo "http://typesafe.artifactoryonline.com/typesafe/ivy-$where/org.scala-tools.sbt/sbt-launch/$ver/sbt-launch.jar"
+}
+jar_file () {
+  echo "$script_dir/.lib/$1/sbt-launch.jar"
+}
+
 # todo - make this dynamic
-launch_base=http://typesafe.artifactoryonline.com/typesafe/ivy-releases/org.scala-tools.sbt/sbt-launch
-launch_url=$launch_base/0.10.1/sbt-launch.jar
+sbt_release_version=0.10.1
+sbt_release_url=$(jar_url releases $sbt_release_version)
+sbt_release_jar=$(jar_file $sbt_release_version)
+sbt_snapshot_version=0.11.0-20110825-052147
+sbt_snapshot_url=$(jar_url snapshots $sbt_snapshot_version)
+sbt_snapshot_jar=$(jar_file $sbt_snapshot_version)
+
+# Falses made true via command line options
+useSnapshot=0
+createProject=0
+
+set_sbt_jar () {
+  if (( $useSnapshot )); then
+    sbt_version=$sbt_snapshot_version
+    sbt_url=$sbt_snapshot_url
+  else
+    sbt_version=$sbt_release_version
+    sbt_url=$sbt_release_url
+  fi
+
+  sbt_jar="$script_dir/.lib/$sbt_version/sbt-launch.jar"
+}
+
 
 # this seems to cover the bases on OSX, and someone will
 # have to tell me about the others.
@@ -26,11 +57,10 @@ get_script_path () {
 declare -r script_path=$(get_script_path "$BASH_SOURCE")
 declare -r script_dir="$(dirname $script_path)"
 declare -r script_name="$(basename $script_path)"
-declare -r default_sbt_jar="$script_dir/.lib/sbt-launch.jar"
 declare -r default_java_opts="-Dfile.encoding=UTF8"
 declare -r default_sbt_opts="-XX:+CMSClassUnloadingEnabled -XX:MaxPermSize=512m -Xmx2g -Xss2m"
-declare -r latest_28="2.8.1"
-declare -r latest_29="2.9.0-1"
+declare -r latest_28="2.8.2.RC1"
+declare -r latest_29="2.9.1.RC4"
 declare -r latest_210="2.10.0-SNAPSHOT"
 
 usage () {
@@ -38,43 +68,38 @@ usage () {
 Usage: $script_name [options]
 
   -help           prints this message
-  -nocolors       disable ANSI color codes
-  -debug          set sbt log level to debug
   -v | -verbose   this runner is chattier
-  -sbtjar <path>  location of sbt launcher (default: $default_sbt_jar)
+  -debug          set sbt log level to debug
+  -create         start sbt even in a directory with no project
+  -sbtjar <path>  location of sbt launcher (default: $(jar_file '<sbt version>'))
   -sbtdir <path>  location of global settings and plugins (default: ~/.sbt)
      -ivy <path>  local Ivy repository (default: ~/.ivy2)
   -shared <path>  shared sbt boot directory (default: none, no sharing)
 
-  # setting scala version
+  # setting scala and sbt versions
   -28           set scala version to $latest_28
   -29           set scala version to $latest_29
   -210          set scala version to $latest_210
   -local <path> set scala version to local installation at path
+  -snapshot     use a snapshot of sbt (otherwise, latest released version)
 
-  # passing options to jvm
-  JAVA_OPTS     environment variable  # default: "$default_java_opts"
-  SBT_OPTS      environment variable  # default: "$default_sbt_opts"
+  # jvm options and output control
+  JAVA_OPTS     environment variable, if unset uses "$default_java_opts"
+  SBT_OPTS      environment variable, if unset uses "$default_sbt_opts"
   -Dkey=val     pass -Dkey=val directly to the jvm
   -J-X          pass option -X directly to the jvm (-J is stripped)
+  -nocolors     disable ANSI color codes
 
-The defaults given for JAVA_OPTS and SBT_OPTS are only used if the
-corresponding variable is unset. In the case of a duplicated option,
-SBT_OPTS takes precedence over JAVA_OPTS, and command line options
-take precedence over both.
+In the case of a duplicated option, SBT_OPTS takes precedence over
+JAVA_OPTS, and command line options take precedence over both.
 EOM
 }
 
-# no args - alert them there's stuff in here
-[[ $# -gt 0 ]] || {
-  echo "Starting $script_name: invoke with -help for other options"
-}
-
 # pull -J and -D options to give to java.
 declare -a args
 declare -a java_args
 declare -a sbt_commands
-declare sbt_jar="$default_sbt_jar"
+declare sbt_jar=
 declare verbose=0
 
 addJava () {
@@ -91,7 +116,9 @@ while [ $# -gt 0 ]; do
          -ivy) addJava "-Dsbt.ivy.home=$2"; shift 2 ;;
       -shared) addJava "-Dsbt.boot.directory=$2"; shift 2 ;;
       -sbtdir) addJava "-Dsbt.global.base=$2"; shift 2 ;;
+    -snapshot) useSnapshot=1; shift ;;
     -nocolors) addJava "-Dsbt.log.noformat=true"; shift ;;
+      -create) createProject=1; shift ;;
 
           -D*) addJava "$1"; shift ;;
           -J*) addJava "${1:2}"; shift ;;
@@ -111,18 +138,36 @@ done
 # reset "$@" to the residual args
 set -- "${args[@]}"
 
+# verify this is an sbt dir or -create was given
+[[ -f "build.sbt" ]] || [[ -d "project" ]] || (( $createProject )) || {
+  cat <<EOM
+$(pwd) doesn't appear to be an sbt project.
+If you want to start sbt anyway, run:
+  $0 -create
+
+EOM
+  exit 1
+}
+
+# no args - alert them there's stuff in here
+[[ $# -gt 0 ]] || {
+  echo "Starting $script_name: invoke with -help for other options"
+}
+
 # pick up completion if present; todo
 [[ -f .sbt_completion.sh ]] && source .sbt_completion.sh
 
 # no jar? download it.
+[[ -f "$sbt_jar" ]] || set_sbt_jar
 [[ -f "$sbt_jar" ]] || {
-  echo "Downloading sbt launcher, this should only take a moment..."
+  echo "Downloading sbt launcher $sbt_version, this should only take a moment..."
 
-  if which curl >/dev/null; then
-    curl "$launch_url" --output "$sbt_jar"
-  elif which wget >/dev/null; then
-    wget "$launch_url" > "$sbt_jar"
-  fi
+  mkdir -p $(dirname "$sbt_jar") &&   
+    if which curl >/dev/null; then
+      curl --silent "$sbt_url" --output "$sbt_jar"
+    elif which wget >/dev/null; then
+      wget --quiet "$sbt_url" > "$sbt_jar"
+    fi
 }
 
 # still no jar? uh-oh.