Web Development & Stuff » Eco friendly / green computing

Reset PHP array key values

admin — Sat, 16 May 2009 11:17:19 +0000

To reset the key values in a PHP array you can do this:

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$things = array('a','b','c','d');

unset($things[0]);

print_r($things); 

#outputs

#Array

#(

#    [1] => b

#    [2] => c

#    [3] => d

#)

# Actually do the reset.

$things = array_values($things);

print_r($things);

#outputs 

#Array

#(

#    [0] => b

#    [1] => c

#    [2] => d

#)

Dynamic object attributes / member variables with specific visibility not possible with PHP

admin — Wed, 06 May 2009 09:48:53 +0000

Ran into an interesting situation yesterday. I wanted to create some dynamic (overloading) object attributes (object member variables) in PHP with private visibility. Forcing encapsulation via getter methods. It seems this is not possible, as dynamic attributes are only ever public (see the PHP documentation).

There is however, as always, a work around! If you set a private containing array for your dynamic attributes you can get almost the same behaviour:

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class TestClass {

    private $dynamic_attribute_container = array();

    # This method is used to set new attributes.

    public SettingMethod($variable_name, $variable_value){

        $this->dynamic_attribute_container[$this->variable_name] = $this->variable_value;

    }

    # This method is used to return the attributes from within the private array container.

    public GettingMethod($attribute_name){

        # Encapsulation code.

        $output = strtolower($this->dynamic_attribute_container[$attribute_name]);

        return $output;

    }

}

$object = new TestClass();

$object->SettingMethod('foo','bar');

$object->foo; # This will error.

$object->GettingMethod('foo'); # This will return bar.

If anyone else has any thoughts on this subject I’d love to hear them.

MySQL indexes – query performance increase

admin — Wed, 25 Feb 2009 11:54:41 +0000

Today I had a log table report query that contained a nested query. It was taking ages (5mins) to complete. I investigated indexes which I had been meaning to look at for a while. Anyway I managed to bring down the query to 0.04s – I now have much love for indexes!!

Basic MySQL syntax:

1	CREATE INDEX index_name ON table_name(column_name);

You can also create indexes when you create a table. In this example I’m indexing id,landing_id,page_id and action_id with INDEX (id,landing_id,page_id,action_id):

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CREATE TABLE IF NOT EXISTS visitor_actions (

  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,

  landing_id INT UNSIGNED NOT NULL,

  page_id TINYINT UNSIGNED NOT NULL,

  action_id TINYINT UNSIGNED NOT NULL,

  dwell_time MEDIUMINT UNSIGNED NULL,

  start TINYINT UNSIGNED NOT NULL,

  created_at DATETIME NOT NULL,

  INDEX (id,landing_id,page_id,action_id)

) ENGINE=INNODB;

I’ll add to this post when I spend some more time looking at the different index types.

Eco friendly (green) PC power supply units

admin — Wed, 26 Mar 2008 22:54:05 +0000

A little off topic but hey it does say ‘& stuff’ in the Blog title!

I’m turning into a bit of an energy conservationalist, if there’s such a word!

I was dong a bit of reading about energy efficient power supply units for PC’s. I suddenly thought about the cheap 350w Jeantech unit I had in my machine purchased in PC World. I don’t usually buy stuff from there but there’s one down the road and I needed it quick.

I checked it out and it had a 65% energy conversion rating. Apparently this means that if 100w is being used by the PSU 65w actually get delivered at the output stage. I thought this was pretty poor.

Anyways I did some research and after a while I came across Coirsair and there new range of units offers an 85% conversion.

I am now the proud owner of one of the 450w models and must say it’s a very nice unit, well made with loads of neatly bound connections. It was only £35 too.

So I’m saving 20% on my PC electricity costs, should pay for itself soon, cool! Highly recommended to anyone. I’ll be using these or better rated PSU units in all future system builds.

If anyone has any more information on this subject including better rated units please leave a comment.