From 47cbb529f5723b246125ae083a193e11481b89ef Mon Sep 17 00:00:00 2001
From: George Halkiadakis <gchalkiadakis@sklavenitis.co.gr>
Date: Sun, 12 Mar 2023 07:01:30 +0200
Subject: initializing classroom structure using anom framework

---
 classes/Registry.php | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 classes/Registry.php

(limited to 'classes/Registry.php')

diff --git a/classes/Registry.php b/classes/Registry.php
new file mode 100644
index 0000000..df012e9
--- /dev/null
+++ b/classes/Registry.php
@@ -0,0 +1,129 @@
+<?php
+
+/** Registry
+ * ---
+ * Regisrty is a global repository of {key: value} pairs,
+ * where key is a friendly label, and...
+ * value can be anything (numbet|string|array|object etc)
+ *
+ * It has a central role in the framework.
+ * By default it holds the Request instance and several
+ * othe core instanses like database connections etc.
+ */
+class Registry
+{
+    /** STATIC PROPERTIES
+     * -------------------------------------------------------------------------
+     */
+
+    /** keeps all ready-to-use records
+     * ---
+     * These are all records defined via Registry::set(), and
+     * vow-records defined (Registry::vow()) AND called (Registry::use())
+     * (it does not include the vows that have not carried-out yet )
+     */
+    private static $records = Array();
+
+    /** keeps all records that will be carried-out later (if ever) 
+     * ---
+     * These are registered via Registry::vow()
+     */
+    private static $wish = Array();
+
+
+    /** METHODS
+     * -------------------------------------------------------------------------
+     */
+
+    /** set
+     * ---
+     * store $data to the registry undel the label $key
+     * @param $key (string)
+     * @param $data *
+     */
+    static function set($key, $data)
+    {
+        // TODO: not use if needed...
+        // you may include an explicit method for reseting the key
+        // or even reVOWing a wish;
+        // or it could be just a 3rd paremeter like
+        // function set($key, $data, $reset = false) {...}
+        // function set($key, $function, $reset = false) {...}
+
+        if (!isset(self::$records[$key])) {
+
+            self::$records[$key] = $data;
+            return true;
+
+        } else { return fasle; }
+    }
+
+
+    /** get
+     * ---
+     * get data from registry,
+     * stored under the label $key
+     * @param $key (string): the label
+     * @return data (mixed)
+     */
+    static function get($key)
+    {
+        // if defined and not beeing a vow/wish, serve
+        if (isset(self::$records[$key]) && (!isset(self::$wish[$key]))) {
+
+            return self::$records[$key];
+
+        } else { return false; }
+    }
+
+
+    /** vow
+     * ---
+     * implements a promise of a function operation
+     * when/if the registry label is called;
+     * it can store a function, an object handler etc.
+     * 
+     * example:
+     * Registry::vow('key', function(){ return new Obj(); })
+     * 
+     * The main advantage of using a 'vow' vs a 'set' is
+     * that a 'vow' will not use system resources to prepare
+     * the data/object/handler/etc until/if-ever is called.
+     * 
+     * @param $label (string): label / refference key
+     * @param function : 
+     */
+    static function vow($label, $function)
+    {
+        self::$wish[$label] = $function;
+    }
+
+    
+    /** use (some vow)
+     * ---
+     * this is the method that carries out
+     * the promissed function (with arguments)
+     */
+    static function use($label, $args=[])
+    {
+        // if already prepered (and is a wish) serve it
+        if (isset(self::$records[$label]) && isset(self::$wish[$label])) {
+
+            return self::$records[$label];
+
+        } else {
+            
+            // otherwise if is a wish/promise
+            if (array_key_exists($label, self::$wish)) {
+
+                // prepare, store and serve it
+                $carryOut = call_user_func_array(self::$wish[$label], $args);
+                self::$records[$label] = $carryOut;
+
+                return $carryOut;
+
+            } else { return false; }
+        }
+    }
+
+}
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