MVC Model 亂談

Strut 首推 Service to worker pattern (http://java.sun.com/blueprints/corej2eepatterns/Patterns/ServiceToWorker.html) 來取代傳統的 dispatcher view pattern。仔細想想後，發現還可介於兩者之間，如 asp 2 master pages 同時使用兩者的功能。

State Pattern 小畫家設計圖

State Pattern 的運作情況，即右圖，內容是一個小畫家的程式利用 State Pattern 構造。客戶首先必須選取一個按鈕，並於畫紙上拖拉出相對的圖形

Controller，也就是小畫家的 Business Logic 或稱 Model，在此我並沒有計劃用 Modular 的模式，單純地使用 Mediate Pattern 的設計方案來增加效能 (在我的假設裡，VTable Lookup 較 Hash Table 來的有效率，好管理 OO 在設計是 Big Plus)

其它還可以在 2 流程內加入Commander Pattern来實現 Undo 和 Redo

printf / sprintf in PHP

Most programmers are familiar with printf/sprinf in languages such as C/C++.
They have the following benefits
1. Ease of use and clarity - the flexablility to define a format string such as "%d, %s"
2. Maximum efficiency (ability to directly use existing buffers)
and drawbacks
3. Length safety
4. Type safety
5. Templatability

#3.,#4. #5. doesn't apply to PHP language in general, therefore its a good idea to use printf/sprintf exclusively. Question is how? How to enhance printf without going through much work?

First we look at what kind of enhancement could be done? We can obviously enhance #1. by creating a new string symbol, for example %dbs, %dbs would work like %s, except it would perform mysql_escape_string implicitly.

The perl regular expression and callback comes to rescue.
The following is a snap from drupal source.

/**
 * Helper function for db_query().
 */
function _db_query_callback($match, $init = FALSE) {
  static $args = NULL;
  if ($init) {
    $args = $match;
    return;
  }

  switch ($match[1]) {
    case '%d': // We must use type casting to int to convert FALSE/NULL/(TRUE?)
      return (int) array_shift($args); // We don't need db_escape_string as numbers are db-safe
    case '%s':
      return db_escape_string(array_shift($args));
    case '%%':
      return '%';
    case '%f':
      return (float) array_shift($args);
    case '%b': // binary data
      return db_encode_blob(array_shift($args));
  }
}

/**
 * Indicates the place holders that should be replaced in _db_query_callback().
 */
define('DB_QUERY_REGEXP', '/(%d|%s|%%|%f|%b)/');

/**
 * Runs a basic query in the active database.
 *
 * User-supplied arguments to the query should be passed in as separate
 * parameters so that they can be properly escaped to avoid SQL injection
 * attacks.
 *
 * @param $query
 *   A string containing an SQL query.
 * @param ...
 *   A variable number of arguments which are substituted into the query
 *   using printf() syntax. Instead of a variable number of query arguments,
 *   you may also pass a single array containing the query arguments.

 *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
 *   in '') and %%.
 *
 *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
 *   and TRUE values to decimal 1.
 *
 * @return
 *   A database query result resource, or FALSE if the query was not
 *   executed correctly.
 */
function db_query($query) {
  $args = func_get_args();
  array_shift($args);
  $query = db_prefix_tables($query);
  if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
    $args = $args[0];
  }
  _db_query_callback($args, TRUE);
  $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
  return _db_query($query);
}

Happy Coding!

Banner 圖片

打開 Photoshop 把數張圖貼上去，用 Ctrl+T 將它們改變大小，記得每張圖分別放在一個層，之後用遮罩把它們弄的朦朧

卡通人物手繪

幻想一下角度，直接畫就出來了