MDL-62891 core: Introduce new get_callable_name() function

lib/moodlelib.php

@@ -10149,3 +10149,22 @@ class lang_string {
         return $this->component;
     }
 }
+
+/**
+ * Get human readable name describing the given callable.
+ *
+ * This performs syntax check only to see if the given param looks like a valid function, method or closure.
+ * It does not check if the callable actually exists.
+ *
+ * @param callable|string|array $callable
+ * @return string|bool Human readable name of callable, or false if not a valid callable.
+ */
+function get_callable_name($callable) {
+
+    if (!is_callable($callable, true, $name)) {
+        return false;
+
+    } else {
+        return $name;
+    }
+}

lib/tests/moodlelib_test.php

@@ -4065,4 +4065,57 @@ class core_moodlelib_testcase extends advanced_testcase {
             ],
         ];
     }
+
+    /**
+     * Test that {@link get_callable_name()} describes the callable as expected.
+     *
+     * @dataProvider callable_names_provider
+     * @param callable $callable
+     * @param string $expectedname
+     */
+    public function test_get_callable_name($callable, $expectedname) {
+        $this->assertSame($expectedname, get_callable_name($callable));
+    }
+
+    /**
+     * Provides a set of callables and their human readable names.
+     *
+     * @return array of (string)case => [(mixed)callable, (string|bool)expected description]
+     */
+    public function callable_names_provider() {
+        return [
+            'integer' => [
+                386,
+                false,
+            ],
+            'boolean' => [
+                true,
+                false,
+            ],
+            'static_method_as_literal' => [
+                'my_foobar_class::my_foobar_method',
+                'my_foobar_class::my_foobar_method',
+            ],
+            'static_method_of_literal_class' => [
+                ['my_foobar_class', 'my_foobar_method'],
+                'my_foobar_class::my_foobar_method',
+            ],
+            'static_method_of_object' => [
+                [$this, 'my_foobar_method'],
+                'core_moodlelib_testcase::my_foobar_method',
+            ],
+            'method_of_object' => [
+                [new lang_string('parentlanguage', 'core_langconfig'), 'my_foobar_method'],
+                'lang_string::my_foobar_method',
+            ],
+            'function_as_literal' => [
+                'my_foobar_callback',
+                'my_foobar_callback',
+            ],
+            'function_as_closure' => [
+                function($a) { return $a; },
+                'Closure::__invoke',
+            ],
+        ];
+    }
 }