Re: constant from variable

["Tanel Tammik" <keevitaja@xxxxxxxxx>]

"Nathan Rixham" <nrixham@xxxxxxxxx> wrote in message 
news:4C097083.3080803@xxxxxxxxxxxx
> Tanel Tammik wrote:
>> ""Tanel Tammik"" <keevitaja@xxxxxxxxx> wrote in message 
>> news:31.A3.00596.0D7590C4@xxxxxxxxxxxxxxx
>>> "Ashley Sheridan" <ash@xxxxxxxxxxxxxxxxxxxx> wrote in message 
>>> news:1275678975.2217.83.camel@xxxxxxxxxxxx
>>>> On Fri, 2010-06-04 at 22:07 +0300, Tanel Tammik wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> define('MYCONST', 'something');
>>>>>
>>>>> $my = 'my';
>>>>> $const = 'const';
>>>>>
>>>>>
>>>>> is it possible to get the value of MYCONST using variables $my and 
>>>>> $const_
>>>>>
>>>>> Br
>>>>> Tanel
>>>>>
>>>>>
>>>>>
>>>>
>>>> I don't really see how you can? The only correlation at all is that the
>>>> two variables use the same letters combined as their values as the name
>>>> of the constant but in a different case. Variables and constants in PHP
>>>> are case-sensitive.
>>>>
>>>> Why are you trying to do this anyway? Perhaps there's a better way than
>>>> what you are trying to do.
>>>>
>>>> Thanks,
>>>> Ash
>>>> http://www.ashleysheridan.co.uk
>>>>
>>>>
>>>>
>>> <?php
>>> define('PERFIX', 'dbperfix_');
>>> define('DB_MYTABLE', PERFIX . 'mytable');
>>>
>>> abstract class Database {
>>>  private static function table_name() {
>>>    $table_name = strtolower(get_called_class());
>>>    return constant('DB_' . strtoupper($table_name));
>>>  }
>>>
>>>  public static function return_query() {
>>>    return "select * from " . static::table_name() . " where 
>>> something='value'";
>>>  }
>>> }
>>>
>>> class MyTable extends Database {
>>> }
>>>
>>> echo MyTable::return_query();
>>> ?>
>>>
>>> i know i could just do return PERFIX . $table_name. -  i'm using it that 
>>> way. i was just curious if the other way is possible. might come handy 
>>> some day!
>>>
>>> Br
>>> Tanel
>>>
>>
>> this is better:
>>
>> <?php
>> define('PERFIX', 'dbperfix_');
>> define('DB_MYTABLE', PERFIX . 'mytable');
>>
>> abstract class Database {
>>   private static function table_name() {
>>     return constant('DB_' . strtoupper(get_called_class()));
>>   }
>>
>>   public static function return_query() {
>>     return "select * from " . static::table_name() . " where 
>> something='value'";
>>   }
>> }
>>
>> class MyTable extends Database {
>> }
>>
>> echo MyTable::return_query();
>> ?>
>
> I'm jumping a few steps here, but you may be interested in looking at this 
> pattern :)
>
> http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html
>
>

i'm using also somekind of patter... don't have a name for it!

<?php
abstract class DatabaseObject {
  public static function table_name() {
    $table_name = strtoupper(end(explode('\\', get_called_class())));
    return constant('DB_' . $table_name);
  }

  public static function find_by_sql($query) {
    global $db;

    $rows = array();
    $result = $db->query($query);

    while($row = $db->fetch_assoc($result)) {
      $rows[] = static::init($row);
    }

    return $rows;
  }

  public static function find_by_id($id = 0) {
    $result_array = static::find_by_sql("select * from " . 
static::table_name() . " where id='" . (int)$id . "' limit 1");
    return (!empty($result_array)) ? array_shift($result_array) : false;
  }

  public static function find_all($order_by = 'id') {
    $result_array = static::find_by_sql("select * from " . 
static::table_name() . " order by " . $order_by);
    return $result_array;
  }

  protected static function table_fields() {
    global $db;

    $result = $db->query("show columns from " . static::table_name());
    while($row = $db->fetch_array($result)) {
      $table_fields[] = array_shift($row);
    }

    return $table_fields;
  }

  protected static function init($row) {
    global $db;

    $obj = new static;

    foreach($row as $field => $value) {
      $obj->$field = $value;
    }

    return $obj;
  }

  protected function attributes() {
    global $db;

    $attributes = array();

    foreach(static::table_fields() as $field) {
      if(property_exists($this, $field)) {
        $attributes[$field] = $db->escape_value($this->$field);
      }
    }

    return $attributes;
  }

  public function save() {
    return isset($this->id) ? $this->update() : $this->create();
  }

  public function create() {
    global $db;

    $attributes = $this->attributes();

    $query  = "insert into " . static::table_name() . " (";
    $query .= join(', ', array_keys($attributes));
    $query .= ") values('";
    $query .= join("', '", array_values($attributes));
    $query .= "')";

    if($db->query($query)) {
      return $db->insert_id();
    }
  }

  public function update() {
    global $db;

    $attributes = $this->attributes();

    foreach($attributes as $key => $value) {
      $attribute_pairs[] = "{$key} = '$value'";
    }

    $query  = "update " . static::table_name() . " set ";
    $query .= join(', ', $attribute_pairs);
    $query .= " where id='" . (int)$this->id . "'";

    if($db->query($query)) {
      return $this->id;
    }
  }

  public function delete() {
    global $db;

    $query = "delete from " . static::table_name() . " where id='" 
.(int)$this->id. "'";

    if($db->query($query)) {
      return true;
    }
  }
}

class MyTable extends DatabaseObject {
}

$myrow = MyTable::find_by_id($id);
$myrow->name = $name;
$myrow->save();

$newrow = new MyTable;
$newrow->name = $name;
$newrow->save();

PHP 5.3 is fun! With namespaced i can autoload all classes in different 
folders as well using namespace corresponding to the path to the class file!

Br
Tanel 



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