Memoization

Intent

Cache result after computing it.

Motivation

Eliminate repeated database queries

Implementation

Simply cache the result into an array or other appropriate type

Examples

with functions

function db_get_something( $x ) {
  static $cache = array();

  if(empty($cache[$x])) { 
    $cache[$x] = //some db query result;
  }
  return $cache[$x];
}

with objects

class db_get_somethning {
  private $cache = array();

  function func() {
    if(empty($this->cache[$x])) 
this->cache[$x] = //some db query result;
    return $this->cache[$x];
  }
}

Complications

cache lifetime, size, invalidation