Experimental “ForEach” primitive (hidden in dev mode)

objects.js

@@ -125,7 +125,7 @@ PrototypeHatBlockMorph*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.objects = '2014-December-03';
+modules.objects = '2014-December-04';
 
 var SpriteMorph;
 var StageMorph;
@@ -1151,6 +1151,13 @@ SpriteMorph.prototype.initBlocks = function () {
             category: 'lists',
             spec: 'map %repRing over %l'
         },
+        doForEach: {
+            dev: true,
+            type: 'command',
+            category: 'lists',
+            spec: 'for %upvar in %l %cs',
+            defaults: [localize('each item')]
+        },
 
         // Code mapping - experimental
         doMapCodeOrHeader: { // experimental
@@ -2063,6 +2070,8 @@ SpriteMorph.prototype.blockTemplates = function (category) {
             blocks.push(txt);
             blocks.push('-');
             blocks.push(block('reportMap'));
+            blocks.push('-');
+            blocks.push(block('doForEach'));
         }
 
     /////////////////////////////////
@@ -5198,6 +5207,8 @@ StageMorph.prototype.blockTemplates = function (category) {
             blocks.push(txt);
             blocks.push('-');
             blocks.push(block('reportMap'));
+            blocks.push('-');
+            blocks.push(block('doForEach'));
         }
 
     /////////////////////////////////

threads.js

@@ -83,7 +83,7 @@ ArgLabelMorph, localize, XML_Element, hex_sha512*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.threads = '2014-December-03';
+modules.threads = '2014-December-04';
 
 var ThreadManager;
 var Process;
@@ -1679,6 +1679,26 @@ Process.prototype.reportMap = function (reporter, list) {
     }
 };
 
+Process.prototype.doForEach = function (upvar, list, script) {
+    // perform a script for each element of a list, assigning the
+    // current iteration's element to a variable with the name
+    // specified in the "upvar" parameter, so it can be referenced
+    // within the script. Uses the context's - unused - fourth
+    // element as temporary storage for the current list index
+
+    if (isNil(this.context.inputs[3])) {this.context.inputs[3] = 1; }
+    var index = this.context.inputs[3];
+    this.context.outerContext.variables.addVar(upvar);
+    this.context.outerContext.variables.setVar(
+        upvar,
+        list.at(index)
+    );
+    if (index > list.length()) {return; }
+    this.context.inputs[3] += 1;
+    this.pushContext();
+    this.evaluate(script, new List(), true);
+};
+
 // Process interpolated primitives
 
 Process.prototype.doWait = function (secs) {