Best practices for naming conventions

$instance = new Class()
$var_name = 5;
$x = get_x();

class TestThing
{
    public $objectProperty;

    public function methodName() {
    }
}

function function_name( $argument = null ) {
}

$variable_name = 'hi'; //Non-object
$TestThing = new TestThing; //Object

<?php
/*
 * This file is part of the psYiiExtensions package.
 *
 * @copyright Copyright &copy; 2009 Pogostick, LLC
 * @link http://www.pogostick.com Pogostick, LLC.
 * @license http://www.pogostick.com/licensing
 */

/**
 * Provides a base class for code lookup tables in your database
 *
 * @package     psYiiExtensions
 * @subpackage  models
 *
 * @author      Jerry Ablan <[email protected]>
 * @version     SVN: $Id: CPSCodeTableModel.php 402 2010-09-11 23:00:16Z [email protected] $
 * @since       v1.0.6
 *
 * @filesource
 */
class CPSCodeTableModel extends CPSModel
{
    //********************************************************************************
    //* Constants
    //********************************************************************************

    /***
    * The name of our code table DDL
    */
    const DDL_NAME = 'code_t.sql';
    const DDL_TABLE_NAME = 'code_t';
    const DDL_DATA_NAME = 'code_install_data.sql';

    //********************************************************************************
    //* Private Members
    //********************************************************************************

    /**
     * @var integer A value filter
     */
    protected $_valueFilter = null;
    public function getValueFilter() { return $this->_valueFilter; }
    public function setValueFilter( $value ) { $this->_valueFilter = $value; }

    /**
     * @var string The column name for our "active" attribute.
     */
    protected $_activeAttributeName = 'active_ind';

    /**
     * @var string The class name of our "code" model
     */
    protected $_modelClass = 'Codes';

    //********************************************************************************
    //* Public Methods
    //********************************************************************************

    public function init()
    {
        parent::init();

        //  Get our model class
        $this->_modelClass = self::_findModelClass();
    }

    /**
    * Installs a standard code table into the database.
    *
    * @param CDbConnection $dbConnection Defaults to PS::_a()->db
    * @param string $name The code table name. Defaults to 'code_t'
    * @returns boolean
    */
    public static function install( $dbConnection = null, $name = self::DDL_TABLE_NAME )
    {
        $_db = PS::nvl( $dbConnection, PS::_db() );

        if ( $name && $_db )
        {
            $_path = Yii::getPathOfAlias( 'pogostick.templates.ddl' );

            $_sql = file_get_contents( $_path . self::DDL_NAME );
            if ( strlen( $_sql ) )
            {
                $_sql = str_ireplace( '%%TABLE_NAME', $name, $_sql );
                $_command = $_db->createCommand( $_sql );
                if ( $_command->execute() )
                {
                    $_sql = file_get_contents( $_path . self::DDL_DATA_NAME );

                    //  Load some codes...
                    if ( strlen( $_sql ) )
                    {
                        $_sql = str_ireplace( '%%TABLE_NAME', $name, $_sql );
                        $_command = $_db->createCommand( $_sql );
                        $_command->execute();
                    }
                }

                return true;
            }
        }

        return false;
    }

    /**
    * Get code rows
    * @param int $codeId Specific code ID to retrieve
    * @param string $codeType Retrieves all codes that are of this type
    * @param string $codeAbbreviation Retrieves all codes that are of this abbreviation. If type specicifed, further filters return set
    * @param string $sortOrder Optional sort order of result set. Defaults to PK (i.e. id)
    * @return array|string Depending on the parameters supplied, either returns a code row, an array of code rows, or a string.
    */
    protected static function getCodes( $codeId = null, $codeType = null, $codeAbbreviation = null, $sortOrder = null, $activeCodesOnly = true, $valueFilter = null )
    {
        $_criteria = null;
        $_modelClass = self::_findModelClass();
        $_model = call_user_func( array( $_modelClass, 'model' ) );

        if ( null === $sortOrder ) $sortOrder = $_model->primaryKey;

        //  Get a single code...
        if ( null !== $codeId ) return $_model->valueFilter( $valueFilter )->active( $activeCodesOnly )->findByPk( $codeId );

        $_condition = array();
        $_params = array();

        //  Get a specific code by type/abbr
        if ( null !== $codeType )
        {
            $_condition[] = 'code_type_text = :code_type_text';
            $_params[':code_type_text'] = $codeType;
        }

        if ( null !== $codeAbbreviation )
        {
            $_condition[] = 'code_abbr_text = :code_abbr_text';
            $_params[':code_abbr_text'] = $codeAbbreviation;
        }

        //  No conditions? Bail...
        if ( empty( $_condition ) )
            return null;

        $_criteria = array(
            'condition' => implode( ' AND ', $_condition ),
            'params' => $_params,
            'order' => PS::nvl( $sortOrder ),
        );

        return $_model->valueFilter( $valueFilter )->active( $activeCodesOnly )->findAll( $_criteria );
    }

    /**
    * @return array validation rules for model attributes.
    */
    public function rules()
    {
        return array(
            array( 'code_type_text', 'length', 'max' => 60 ),
            array( 'code_abbr_text', 'length', 'max' => 60 ),
            array( 'code_desc_text', 'length', 'max' => 255 ),
            array( 'assoc_text', 'length', 'max' => 255 ),
            array( 'id, active_ind, code_type_text, code_abbr_text, code_desc_text, create_date, lmod_date', 'required' ),
            array( 'id, active_ind, parnt_code_id', 'numerical', 'integerOnly' => true ),
            array( 'assoc_value_nbr', 'numerical' ),
        );
    }

    /**
     * @return array customized attribute labels (name=>label)
     */
    public function attributeLabels()
    {
        return array(
            'id' => 'Id',
            'code_type_text' => 'Type',
            'code_abbr_text' => 'Abbreviation',
            'code_desc_text' => 'Description',
            'parnt_code_id' => 'Parent Code Id',
            'assoc_value_nbr' => 'Associated Number',
            'assoc_text' => 'Associated Text',
            'active_ind' => 'Active',
            'create_date' => 'Created On',
            'lmod_date' => 'Modified On',
        );
    }

    //********************************************************************************
    //* Statics
    //********************************************************************************

    /**
    * Returns the static model of the specified AR class.
    * @return CActiveRecord the static model class
    */
    public static function model( $sClassName = __CLASS__ )
    {
        return parent::model( $sClassName );
    }

    /**
    * Find a code by type
    *
    * @param string $codeType
    * @return array
    * @static
    */
    public static function findAllByType( $codeType, $sortOrder = 'code_desc_text', $valueFilter = null )
    {
        return self::getCodes( null, $codeType, null, $sortOrder, true, $valueFilter );
    }

    /**
    * Find a code by type
    *
    * @param string $codeType
    * @return array
    * @static
    */
    public static function findAllByAbbreviation( $codeAbbreviation, $codeType = null, $sortOrder = 'code_desc_text' )
    {
        return self::getCodes( null, $codeType, $codeAbbreviation, $sortOrder );
    }

    /**
    * Finds a single code by code_id
    *
    * Duplicates findByPk, but wanted to be consistent.
    *
    * @param integer $iCodeId
    * @return CActiveRecord
    * @static
    */
    public static function findById( $iCodeId )
    {
        return self::getCodes( $iCodeId );
    }

    /**
    * Retrieves the associated value for a code
    *
    * @param int $codeId
    * @return double
    */
    public function valueFilter( $value = null )
    {
        //  Nothing? Move along...
        if ( null === $value )
            return $this;

        //  Not an array? Make one...
        if ( ! is_array( $value ) ) $value = array( $value );

        //  No items?
        if ( empty( $value ) )
            return $this;

        //  Make string...
        if ( count( $value ) == 1 )
            $_condition = '( assoc_value_nbr is null or assoc_value_nbr = ' . $value[0] . ')';
        else
            $_condition = '( assoc_value_nbr is null or assoc_value_nbr in (' . implode( ',', $value ) . '))';

        $this->getDbCriteria()->mergeWith( array( 'condition' => $_condition ) );
        return $this;
    }

    /**
    * Returns a code's description
    *
    * @param int $codeId
    * @return string
    */
    public static function getCodeDescription( $codeId )
    {
        $_code = self::getCodes( $codeId );
        return $_code ? $_code->code_desc_text : null;
    }

    /**
    * Returns a code's abbreviation
    *
    * @param int $codeId
    * @return string
    */
    public static function getCodeAbbreviation( $codeId )
    {
        $_code = self::getCodes( $codeId );
        return $_code ? $_code->code_abbr_text : null;
    }

    /**
    * Returns a code's id given a type and abbreviation
    *
    * @param string $codeType
    * @param string $codeAbbreviation
    * @return integer
    */
    public static function getCodeFromAbbreviation( $codeType, $codeAbbreviation )
    {
        $_codeList = self::getCodes( null, $codeType, $codeAbbreviation );
        return ! empty( $_codeList )  ? $_codeList[0]->id : null;
    }

    /**
    * Retrieves the associated text for a code
    *
    * @param int $codeId
    * @return string
    */
    public static function getAssociatedText( $codeId )
    {
        $_code = self::getCodes( $codeId );
        return $_code ? $_code->assoc_text : null;
    }

    /**
    * Retrieves the associated value for a code
    *
    * @param int $codeId
    * @return double
    */
    public static function getAssociatedValue( $codeId )
    {
        $_code = self::getCodes( $codeId );
        return $_code ? $_code->assoc_value_nbr : null;
    }

    /**
    * Returns all rows based on type/abbr given
    * If it's a specific request, (i.e. type & abbr given) a single row is returned.
    *
    * @param string $codeType
    * @param string $codeAbbreviation
    * @return int|CPSCodeTableModel|array
    */
    public static function lookup( $codeType, $codeAbbreviation = null, $returnIdOnly = true )
    {
        $_code = self::getCodes( null, $codeType, $codeAbbreviation );
        return $_code ? ( $returnIdOnly ? $_code->id : $_code ) : null;
    }

    /**
     * Only return active code records as designated by the active_ind
     * @returns CPSCodeTableModel
     */
    public function active( $activeOnly = true )
    {
        if ( $activeOnly && $this->hasAttribute( $this->_activeAttributeName ) ) $this->getDbCriteria()->mergeWith( array( 'condition' => 'active_ind = :active_ind', 'params' => array( ':active_ind' => 1 ) ) );
        return $this;
    }

    /**
     * Finds and sets the model class for this object.
     * If your model class is not "Codes" and you're not running PHP 5.3.x+, override
     * this method to provide your own model name.
     *
     * @return string The name of the model class
     */
    protected static function _findModelClass()
    {
        $_modelClass = 'Codes';

        //  Can't really use get_called_class with 5.2...
        if ( version_compare( PHP_VERSION, '5.3.0' ) >= 0 )
            $_modelClass = get_called_class();

        return $_modelClass;
    }
}