experimental "width of _" reporter relabelling option for "length of _"

HISTORY.md

@@ -6,6 +6,7 @@
     * hyperized image attribute reporter primitive (monadic)
     * when constructing a costume from a pixel list handle single values as greyscale
     * experimental "column _ of _" reporter relabelling option for "item _ of _"
+    * experimental "width of _" reporter relabelling option for "length of _"
 * **Notable Fixes:**
     * fixed a glitch in the animation library's "sine in-out" easing function 
     * fixed a postMessage glitch in the API, thanks, Bernat!
@@ -15,6 +16,7 @@
 ### 2021-01-26
 * threads: handle single values as greyscale when constructing a costume from a pixel list
 * threads, objects experimental "column _ of _" reporter relabelling option for "item _ of _"
+* threads, objects experimental "width of _" reporter relabelling option for "length of _"
 
 ### 2021-01-25
 * threads: hyperized image attribute reporter primitive (monadic)

src/objects.js

@@ -1334,6 +1334,11 @@ SpriteMorph.prototype.initBlocks = function () {
             category: 'lists',
             spec: 'length of %l'
         },
+        reportTableWidth: {
+            type: 'reporter',
+            category: 'lists',
+            spec: 'width of %l'
+        },
         reportListContainsItem: {
             type: 'predicate',
             category: 'lists',
@@ -1719,6 +1724,8 @@ SpriteMorph.prototype.blockAlternatives = {
     // lists
     reportListItem: ['reportTableColumn'],
     reportTableColumn: ['reportListItem'],
+    reportListLength: ['reportTableWidth'],
+    reportTableWidth: ['reportListLength'],
 
     // HOFs
     reportMap: ['reportKeep', 'reportFindFirst'],

src/threads.js

@@ -2006,19 +2006,20 @@ Process.prototype.reportItems = function (indices, list) {
     }
 };
 
-// Process - other basic list accessors
+// Process - experimental tabular list accessors
+
+Process.prototype.reportTableWidth = function (list) {
+    // experimental - answer the length of the longest sub-list
+    this.assertType(list, 'list');
+    return Math.max(...list.itemsArray().map(row =>
+        row instanceof List ? row.length() : 0)
+    );
+};
 
 Process.prototype.reportTableColumn = function (index, list) {
     // experimental and probably controversial as a primitive,
     // because it's so nice and easy to write in Snap!
     var col;
-
-    function columns() {
-        return Math.max(...list.itemsArray().map(row =>
-            row instanceof List ? row.length() : 0)
-        );
-    }
-
     if (!this.isMatrix(list)) {
         throw new Error(
             'expecting ' + 'table' + ' but getting ' + this.reportTypeOf(list)
@@ -2028,15 +2029,17 @@ Process.prototype.reportTableColumn = function (index, list) {
         return new List(new Array(list.length()));
     }
     if (this.inputOption(index) === 'any') {
-        col = this.reportBasicRandom(1, columns());
+        col = this.reportBasicRandom(1, this.reportTableWidth(list));
         return list.map(row => row.at(col));
     }
     if (this.inputOption(index) === 'last') {
-        return list.map(row => row.at(columns()));
+        return list.map(row => row.at(this.reportTableWidth(list)));
     }
     return list.map(row => row.at(index));
 };
 
+// Process - other basic list accessors
+
 Process.prototype.reportListLength = function (list) {
     this.assertType(list, 'list');
     return list.length();