new "delete block" primitive in sensing, experimental

HISTORY.md

@@ -19,6 +19,7 @@
     * new "label", "type", "scope", "slots", "defaults", "menus" and "editables" choices in the OF BLOCK block-attribute reporter's dropdown
     * new "set attribute of block" primitive, experimental
     * new "define block" primitive, experimental
+    * new "delete block" primitive, experimental
     * new "this script" primitive, experimental
     * new localization extension primitives in the "ide" category, hyperized
     * new extension primitive for importing a costume from a url
@@ -59,6 +60,7 @@
 * blocks, threads: new "editables" selector for block attributes (indicates read-only input slots)
 * German translation update for "editables"
 * blocks, threads: new "defaults" selector for block attributes
+* blocks, objects, threads: new "delete block" primitive in sensing
 
 ### 2022-06-27
 * threads: trim block label before identifying existing definition in DEFINE

snap.html

@@ -18,7 +18,7 @@
         <script src="src/widgets.js?version=2021-17-09"></script>
         <script src="src/blocks.js?version=2022-06-28"></script>
         <script src="src/threads.js?version=2022-06-28"></script>
-        <script src="src/objects.js?version=2022-06-23"></script>
+        <script src="src/objects.js?version=2022-06-28"></script>
         <script src="src/scenes.js?version=2022-03-03"></script>
         <script src="src/gui.js?version=2022-05-19"></script>
         <script src="src/paint.js?version=2021-07-05"></script>

src/blocks.js

@@ -13685,6 +13685,10 @@ ReporterSlotMorph.prototype.isEmptySlot = function () {
 
 ReporterSlotMorph.prototype.fixLayout = function () {
     var contents = this.contents();
+    if (!contents) {
+        contents = this.emptySlot();
+        this.add(contents);
+    }
     this.bounds.setExtent(contents.extent().add(
         this.edge * 2 + this.rfBorder * 2
     ));

src/objects.js

@@ -94,7 +94,7 @@ embedMetadataPNG*/
 
 /*jshint esversion: 6*/
 
-modules.objects = '2022-June-23';
+modules.objects = '2022-June-28';
 
 var SpriteMorph;
 var StageMorph;
@@ -927,6 +927,11 @@ SpriteMorph.prototype.initBlocks = function () {
             spec: 'set %byob of block %repRing to %s',
             defaults: [['label']]
         },
+        doDeleteBlock: {
+            type: 'command',
+            category: 'control',
+            spec: 'delete block %repRing'
+        },
         reportBlockAttribute: {
             type: 'reporter',
             category: 'control',
@@ -2658,6 +2663,7 @@ SpriteMorph.prototype.blockTemplates = function (
         blocks.push(block('doSwitchToScene'));
         blocks.push('-');
         blocks.push(block('doDefineBlock'));
+        blocks.push(block('doDeleteBlock'));
         blocks.push(block('doSetBlockAttribute'));
         blocks.push(block('reportBlockAttribute'));
         blocks.push(block('reportThisContext'));
@@ -9138,6 +9144,7 @@ StageMorph.prototype.blockTemplates = function (
         blocks.push(block('doSwitchToScene'));
         blocks.push('-');
         blocks.push(block('doDefineBlock'));
+        blocks.push(block('doDeleteBlock'));
         blocks.push(block('doSetBlockAttribute'));
         blocks.push(block('reportBlockAttribute'));
         blocks.push(block('reportThisContext'));

src/threads.js

@@ -6175,6 +6175,47 @@ Process.prototype.compileBlockReferences = function (context, varName) {
     }
 };
 
+Process.prototype.doDeleteBlock = function (context) {
+    // highly experimental & under construction
+    var rcvr = this.blockReceiver(),
+        ide = rcvr.parentThatIsA(IDE_Morph),
+        stage = ide.stage,
+        expr, def, method, idx;
+
+    this.assertType(context, ['command', 'reporter', 'predicate']);
+    expr = context.expression;
+    if (!expr.isCustomBlock) {
+        throw new Error('expecting a custom block\nbut getting a primitive');
+    }
+    def = expr.isGlobal ? expr.definition : rcvr.getMethod(expr.semanticSpec);
+    rcvr.deleteAllBlockInstances(def);
+    if (def.isGlobal) {
+        idx = stage.globalBlocks.indexOf(def);
+        if (idx !== -1) {
+            stage.globalBlocks.splice(idx, 1);
+        }
+    } else {
+        // delete local definition
+        idx = rcvr.customBlocks.indexOf(def);
+        if (idx !== -1) {
+            rcvr.customBlocks.splice(idx, 1);
+        }
+        // refresh instances of inherited method, if any
+        method = rcvr.getMethod(def.blockSpec);
+        if (method) {
+            rcvr.allDependentInvocationsOf(method.blockSpec).forEach(
+                block => block.refresh(method)
+            );
+        }
+    }
+
+    // update the IDE
+    ide.flushPaletteCache();
+    ide.categories.refreshEmpty();
+    ide.refreshPalette();
+    ide.recordUnsavedChanges();
+};
+
 Process.prototype.reportAttributeOf = function (attribute, name) {
     // hyper-dyadic
     // note: specifying strings in the left input only accesses