Add --get-pref option

This allows reading specific preferences from the commandline.

Author: matthijskooijman

app/src/processing/app/Base.java

@@ -268,7 +268,7 @@ static protected void initRequirements() {
   }
 
 
-  protected static enum ACTION { GUI, VERIFY, UPLOAD, NOOP };
+  protected static enum ACTION { GUI, VERIFY, UPLOAD, NOOP, GET_PREF };
   public Base(String[] args) throws Exception {
     platform.init(this);
 
@@ -322,6 +322,7 @@ public Base(String[] args) throws Exception {
     ACTION action = ACTION.GUI;
     boolean doVerboseBuild = false;
     boolean doVerboseUpload = false;;
+    String getPref = null;
     String selectBoard = null;
     String selectPort = null;
     String currentDirectory = System.getProperty("user.dir");
@@ -332,6 +333,7 @@ public Base(String[] args) throws Exception {
     actions.put("--verify", ACTION.VERIFY);
     actions.put("--upload", ACTION.UPLOAD);
     actions.put("--noop", ACTION.NOOP);
+    actions.put("--get-pref", ACTION.GET_PREF);
 
     // Check if any files were passed in on the command line
     for (int i = 0; i < args.length; i++) {
@@ -342,6 +344,12 @@ public Base(String[] args) throws Exception {
           String mess = I18n.format(_("Can only pass one of: {0}"), PApplet.join(valid, ", "));
           showError(null, mess, 3);
         }
+        if (a == ACTION.GET_PREF) {
+          i++;
+          if (i >= args.length)
+            showError(null, _("Argument required for --get-pref"), 3);
+          getPref = args[i];
+        }
         action = a;
         continue;
       }
@@ -406,7 +414,7 @@ public Base(String[] args) throws Exception {
     if ((action == ACTION.UPLOAD || action == ACTION.VERIFY) && filenames.size() != 1)
       showError(null, _("Must specify exactly one sketch file"), 3);
 
-    if (action == ACTION.NOOP && filenames.size() != 0)
+    if ((action == ACTION.NOOP || action == ACTION.GET_PREF) && filenames.size() != 0)
       showError(null, _("Cannot specify any sketch files"), 3);
 
     if ((action != ACTION.UPLOAD && action != ACTION.VERIFY) && (doVerboseBuild || doVerboseUpload))
@@ -493,6 +501,15 @@ public Base(String[] args) throws Exception {
         // Do nothing (intended for only changing preferences)
         System.exit(0);
         break;
+      case GET_PREF:
+        String value = Preferences.get(getPref, null);
+        if (value != null) {
+          System.out.println(value);
+          System.exit(0);
+        } else {
+          System.exit(4);
+        }
+        break;
     }
   }
 

build/shared/manpage.adoc

@@ -149,6 +149,11 @@ OPTIONS
 	Immediately quit after processing the commandline. This can be
 	used to just set preferences with *--pref*.
 
+*--get-pref __preference__*::
+	Prints the value of the given preference to the standard output
+	stream. When the value does not exist, nothing is printed and
+	the exit status is set (see EXIT STATUS below).
+
 PREFERENCES
 -----------
 Arduino keeps a list of preferences, as simple name and value pairs.
@@ -185,6 +190,7 @@ EXIT STATUS
 *1*:: Build failed or upload failed
 *2*:: Sketch not found
 *3*:: Invalid (argument for) commandline option
+*4*:: Preference passed to *--get-pref* does not exist
 
 FILES
 -----