The definition of a virtual table can now be given as a closure, which is lazy evaluated

Author: rkrx

doc/virtual-tables.md

@@ -11,12 +11,14 @@ $vt1 = $db->select()
 ->field('a.field1')
 ->from('a', 'tableA');
 
-$vt2 = $db->select()
-->field('a.field1')
-->from('a', 'tableA');
-
 $db->getVirtualTables()->add('virt_table1', $vt1);
-$db->getVirtualTables()->add('virt_table2', $vt2);
+
+// Lazy evaluated
+$db->getVirtualTables()->add('virt_table2', function () {
+	return $db->select()
+	->field('a.field1')
+	->from('a', 'tableA');
+});
 ```
 
 Then use it as needed:

src/Tools/VirtualTables.php

@@ -9,10 +9,10 @@ class VirtualTables {
 
 	/**
 	 * @param string $tableName
-	 * @param Select $select
+	 * @param Select|\Closure $select
 	 * @return $this
 	 */
-	public function add($tableName, Select $select) {
+	public function add($tableName, $select) {
 		$this->virtualTables[$tableName] = $select;
 		return $this;
 	}
@@ -31,7 +31,11 @@ public function has($tableName) {
 	 */
 	public function get($tableName) {
 		if($this->has($tableName)) {
-			return $this->virtualTables[$tableName];
+			$table = $this->virtualTables[$tableName];
+			if($table instanceof \Closure) {
+				return call_user_func($table);
+			}
+			return $table;
 		}
 		return null;
 	}

tests/Builder/SelectTest.php

@@ -347,13 +347,13 @@ public function testVirtualTables() {
 		->field('a.field1')
 		->from('a', 'tableA');
 
-		$vt2 = TestSelect::create()
-		->field('a.field1')
-		->from('a', 'tableA');
-		
 		$db = new TestDB();
 		$db->getVirtualTables()->add('virt_table1', $vt1);
-		$db->getVirtualTables()->add('virt_table2', $vt2);
+		$db->getVirtualTables()->add('virt_table2', function () {
+			return TestSelect::create()
+			->field('a.field1')
+			->from('a', 'tableA');
+		});
 
 		$query = TestSelect::create($db)
 		->field('t.field1')