user_guide_src/source/general/styleguide.rst - code-igniter-v3-giggi - Gitiles

 ########################
 General Style and Syntax
 ########################

 The following page describes the use of coding rules adhered to when
 developing CodeIgniter.

 .. contents:: Table of Contents

 File Format
 ===========

 Files should be saved with Unicode (UTF-8) encoding. The BOM should
 *not* be used. Unlike UTF-16 and UTF-32, there's no byte order to
 indicate in a UTF-8 encoded file, and the BOM can have a negative side
 effect in PHP of sending output, preventing the application from being
 able to set its own headers. Unix line endings should be used (LF).

 Here is how to apply these settings in some of the more common text
 editors. Instructions for your text editor may vary; check your text
 editor's documentation.

 TextMate
 ''''''''

 #. Open the Application Preferences
 #. Click Advanced, and then the "Saving" tab
 #. In "File Encoding", select "UTF-8 (recommended)"
 #. In "Line Endings", select "LF (recommended)"
 #. *Optional:* Check "Use for existing files as well" if you wish to
    modify the line endings of files you open to your new preference.

 BBEdit
 ''''''

 #. Open the Application Preferences
 #. Select "Text Encodings" on the left.
 #. In "Default text encoding for new documents", select "Unicode (UTF-8,
    no BOM)"
 #. *Optional:* In "If file's encoding can't be guessed, use", select
    "Unicode (UTF-8, no BOM)"
 #. Select "Text Files" on the left.
 #. In "Default line breaks", select "Mac OS X and Unix (LF)"

 PHP Closing Tag
 ===============

 The PHP closing tag on a PHP document **?>** is optional to the PHP
 parser. However, if used, any whitespace following the closing tag,
 whether introduced by the developer, user, or an FTP application, can
 cause unwanted output, PHP errors, or if the latter are suppressed,
 blank pages. For this reason, all PHP files should **OMIT** the closing
 PHP tag, and instead use a comment block to mark the end of file and
 it's location relative to the application root. This allows you to still
 identify a file as being complete and not truncated.

 ::

 	INCORRECT: <?php  echo "Here's my code!";  ?>  CORRECT: <?php  echo "Here's my code!";  /* End of file myfile.php */ /* Location: ./system/modules/mymodule/myfile.php */

 Class and Method Naming
 =======================

 Class names should always start with an uppercase letter. Multiple words
 should be separated with an underscore, and not CamelCased. All other
 class methods should be entirely lowercased and named to clearly
 indicate their function, preferably including a verb. Try to avoid
 overly long and verbose names.

 ::

 	INCORRECT: class superclass class SuperClass  CORRECT: class Super_class

 ::

 	class Super_class {      function __construct()     {      } }

 Examples of improper and proper method naming::

 	INCORRECT: function fileproperties()       // not descriptive and needs underscore separator function fileProperties()       // not descriptive and uses CamelCase function getfileproperties()        // Better!  But still missing underscore separator function getFileProperties()        // uses CamelCase function get_the_file_properties_from_the_file()    // wordy  CORRECT: function get_file_properties()  // descriptive, underscore separator, and all lowercase letters

 Variable Names
 ==============

 The guidelines for variable naming is very similar to that used for
 class methods. Namely, variables should contain only lowercase letters,
 use underscore separators, and be reasonably named to indicate their
 purpose and contents. Very short, non-word variables should only be used
 as iterators in for() loops.

 ::

 	INCORRECT: $j = 'foo';       // single letter variables should only be used in for() loops $Str            // contains uppercase letters $bufferedText       // uses CamelCasing, and could be shortened without losing semantic meaning $groupid        // multiple words, needs underscore separator $name_of_last_city_used // too long  CORRECT: for ($j = 0; $j < 10; $j++) $str $buffer $group_id $last_city

 Commenting
 ==========

 In general, code should be commented prolifically. It not only helps
 describe the flow and intent of the code for less experienced
 programmers, but can prove invaluable when returning to your own code
 months down the line. There is not a required format for comments, but
 the following are recommended.

 `DocBlock <http://manual.phpdoc.org/HTMLSmartyConverter/HandS/phpDocumentor/tutorial_phpDocumentor.howto.pkg.html#basics.docblock>`_
 style comments preceding class and method declarations so they can be
 picked up by IDEs::

 	/**  * Super Class  *  * @package Package Name  * @subpackage  Subpackage  * @category    Category  * @author  Author Name  * @link    http://example.com  */ class Super_class {

 ::

 	/**  * Encodes string for use in XML  *  * @access  public  * @param   string  * @return  string  */ function xml_encode($str)

 Use single line comments within code, leaving a blank line between large
 comment blocks and code.

 ::

 	// break up the string by newlines $parts = explode("\n", $str);  // A longer comment that needs to give greater detail on what is // occurring and why can use multiple single-line comments.  Try to // keep the width reasonable, around 70 characters is the easiest to // read.  Don't hesitate to link to permanent external resources // that may provide greater detail: // // http://example.com/information_about_something/in_particular/  $parts = $this->foo($parts);

 Constants
 =========

 Constants follow the same guidelines as do variables, except constants
 should always be fully uppercase. *Always use CodeIgniter constants when
 appropriate, i.e. SLASH, LD, RD, PATH_CACHE, etc.*

 ::

 	INCORRECT: myConstant  // missing underscore separator and not fully uppercase N       // no single-letter constants S_C_VER     // not descriptive $str = str_replace('{foo}', 'bar', $str);   // should use LD and RD constants  CORRECT: MY_CONSTANT NEWLINE SUPER_CLASS_VERSION $str = str_replace(LD.'foo'.RD, 'bar', $str);

 TRUE, FALSE, and NULL
 =====================

 **TRUE**, **FALSE**, and **NULL** keywords should always be fully
 uppercase.

 ::

 	INCORRECT: if ($foo == true) $bar = false; function foo($bar = null)  CORRECT: if ($foo == TRUE) $bar = FALSE; function foo($bar = NULL)

 Logical Operators
 =================

 Use of **\|\|** is discouraged as its clarity on some output devices is
 low (looking like the number 11 for instance). **&&** is preferred over
 **AND** but either are acceptable, and a space should always precede and
 follow **!**.

 ::

 	INCORRECT: if ($foo || $bar) if ($foo AND $bar)  // okay but not recommended for common syntax highlighting applications if (!$foo) if (! is_array($foo))  CORRECT: if ($foo OR $bar) if ($foo && $bar) // recommended if ( ! $foo) if ( ! is_array($foo))

 Comparing Return Values and Typecasting
 =======================================

 Some PHP functions return FALSE on failure, but may also have a valid
 return value of "" or 0, which would evaluate to FALSE in loose
 comparisons. Be explicit by comparing the variable type when using these
 return values in conditionals to ensure the return value is indeed what
 you expect, and not a value that has an equivalent loose-type
 evaluation.

 Use the same stringency in returning and checking your own variables.
 Use **===** and **!==** as necessary.
 ::

 	INCORRECT: // If 'foo' is at the beginning of the string, strpos will return a 0, // resulting in this conditional evaluating as TRUE if (strpos($str, 'foo') == FALSE)  CORRECT: if (strpos($str, 'foo') === FALSE)

 ::

 	INCORRECT: function build_string($str = "") {     if ($str == "") // uh-oh!  What if FALSE or the integer 0 is passed as an argument?     {      } }  CORRECT: function build_string($str = "") {     if ($str === "")     {      } }


 See also information regarding
 `typecasting <http://us3.php.net/manual/en/language.types.type-juggling.php#language.types.typecasting>`_,
 which can be quite useful. Typecasting has a slightly different effect
 which may be desirable. When casting a variable as a string, for
 instance, NULL and boolean FALSE variables become empty strings, 0 (and
 other numbers) become strings of digits, and boolean TRUE becomes "1"::

 	$str = (string) $str; // cast $str as a string

 Debugging Code
 ==============

 No debugging code can be left in place for submitted add-ons unless it
 is commented out, i.e. no var_dump(), print_r(), die(), and exit()
 calls that were used while creating the add-on, unless they are
 commented out.

 ::

 	// print_r($foo);

 Whitespace in Files
 ===================

 No whitespace can precede the opening PHP tag or follow the closing PHP
 tag. Output is buffered, so whitespace in your files can cause output to
 begin before CodeIgniter outputs its content, leading to errors and an
 inability for CodeIgniter to send proper headers. In the examples below,
 select the text with your mouse to reveal the incorrect whitespace.

 **INCORRECT**::

 	 <?php     // ...there is whitespace and a linebreak above the opening PHP tag     // as well as whitespace after the closing PHP tag ?>

 **CORRECT**::

 	<?php     // this sample has no whitespace before or after the opening and closing PHP tags ?>

 Compatibility
 =============

 Unless specifically mentioned in your add-on's documentation, all code
 must be compatible with PHP version 5.1+. Additionally, do not use PHP
 functions that require non-default libraries to be installed unless your
 code contains an alternative method when the function is not available,
 or you implicitly document that your add-on requires said PHP libraries.

 Class and File Names using Common Words
 =======================================

 When your class or filename is a common word, or might quite likely be
 identically named in another PHP script, provide a unique prefix to help
 prevent collision. Always realize that your end users may be running
 other add-ons or third party PHP scripts. Choose a prefix that is unique
 to your identity as a developer or company.

 ::

 	INCORRECT: class Email     pi.email.php class Xml       ext.xml.php class Import        mod.import.php  CORRECT: class Pre_email     pi.pre_email.php class Pre_xml       ext.pre_xml.php class Pre_import    mod.pre_import.php

 Database Table Names
 ====================

 Any tables that your add-on might use must use the 'exp\_' prefix,
 followed by a prefix uniquely identifying you as the developer or
 company, and then a short descriptive table name. You do not need to be
 concerned about the database prefix being used on the user's
 installation, as CodeIgniter's database class will automatically convert
 'exp\_' to what is actually being used.

 ::

 	INCORRECT: email_addresses     // missing both prefixes pre_email_addresses // missing exp_ prefix exp_email_addresses // missing unique prefix  CORRECT: exp_pre_email_addresses

 **NOTE:** Be mindful that MySQL has a limit of 64 characters for table
 names. This should not be an issue as table names that would exceed this
 would likely have unreasonable names. For instance, the following table
 name exceeds this limitation by one character. Silly, no?
 **exp_pre_email_addresses_of_registered_users_in_seattle_washington**
 One File per Class
 ==================

 Use separate files for each class your add-on uses, unless the classes
 are *closely related*. An example of CodeIgniter files that contains
 multiple classes is the Database class file, which contains both the DB
 class and the DB_Cache class, and the Magpie plugin, which contains
 both the Magpie and Snoopy classes.

 Whitespace
 ==========

 Use tabs for whitespace in your code, not spaces. This may seem like a
 small thing, but using tabs instead of whitespace allows the developer
 looking at your code to have indentation at levels that they prefer and
 customize in whatever application they use. And as a side benefit, it
 results in (slightly) more compact files, storing one tab character
 versus, say, four space characters.

 Line Breaks
 ===========

 Files must be saved with Unix line breaks. This is more of an issue for
 developers who work in Windows, but in any case ensure that your text
 editor is setup to save files with Unix line breaks.

 Code Indenting
 ==============

 Use Allman style indenting. With the exception of Class declarations,
 braces are always placed on a line by themselves, and indented at the
 same level as the control statement that "owns" them.

 ::

 	INCORRECT: function foo($bar) {     // ... }  foreach ($arr as $key => $val) {     // ... }  if ($foo == $bar) {     // ... } else {     // ... }  for ($i = 0; $i < 10; $i++)     {     for ($j = 0; $j < 10; $j++)         {         // ...         }     }  CORRECT: function foo($bar) {     // ... }  foreach ($arr as $key => $val) {     // ... }  if ($foo == $bar) {     // ... } else {     // ... }  for ($i = 0; $i < 10; $i++) {     for ($j = 0; $j < 10; $j++)     {         // ...     } }

 Bracket and Parenthetic Spacing
 ===============================

 In general, parenthesis and brackets should not use any additional
 spaces. The exception is that a space should always follow PHP control
 structures that accept arguments with parenthesis (declare, do-while,
 elseif, for, foreach, if, switch, while), to help distinguish them from
 functions and increase readability.

 ::

 	INCORRECT: $arr[ $foo ] = 'foo';  CORRECT: $arr[$foo] = 'foo'; // no spaces around array keys   INCORRECT: function foo ( $bar ) {  }  CORRECT: function foo($bar) // no spaces around parenthesis in function declarations {  }   INCORRECT: foreach( $query->result() as $row )  CORRECT: foreach ($query->result() as $row) // single space following PHP control structures, but not in interior parenthesis

 Localized Text
 ==============

 Any text that is output in the control panel should use language
 variables in your lang file to allow localization.

 ::

 	INCORRECT: return "Invalid Selection";  CORRECT: return $this->lang->line('invalid_selection');

 Private Methods and Variables
 =============================

 Methods and variables that are only accessed internally by your class,
 such as utility and helper functions that your public methods use for
 code abstraction, should be prefixed with an underscore.

 ::

 	convert_text()        // public method _convert_text()     // private method

 PHP Errors
 ==========

 Code must run error free and not rely on warnings and notices to be
 hidden to meet this requirement. For instance, never access a variable
 that you did not set yourself (such as $_POST array keys) without first
 checking to see that it isset().

 Make sure that while developing your add-on, error reporting is enabled
 for ALL users, and that display_errors is enabled in the PHP
 environment. You can check this setting with::

 	if (ini_get('display_errors') == 1) {     exit "Enabled"; }

 On some servers where display_errors is disabled, and you do not have
 the ability to change this in the php.ini, you can often enable it with::

 	ini_set('display_errors', 1);

 **NOTE:** Setting the
 `display_errors <http://us.php.net/manual/en/ref.errorfunc.php#ini.display-errors>`_
 setting with ini_set() at runtime is not identical to having it enabled
 in the PHP environment. Namely, it will not have any effect if the
 script has fatal errors

 Short Open Tags
 ===============

 Always use full PHP opening tags, in case a server does not have
 short_open_tag enabled.

 ::

 	INCORRECT: <? echo $foo; ?>  <?=$foo?>  CORRECT: <?php echo $foo; ?>

 One Statement Per Line
 ======================

 Never combine statements on one line.

 ::

 	INCORRECT: $foo = 'this'; $bar = 'that'; $bat = str_replace($foo, $bar, $bag);  CORRECT: $foo = 'this'; $bar = 'that'; $bat = str_replace($foo, $bar, $bag);

 Strings
 =======

 Always use single quoted strings unless you need variables parsed, and
 in cases where you do need variables parsed, use braces to prevent
 greedy token parsing. You may also use double-quoted strings if the
 string contains single quotes, so you do not have to use escape
 characters.

 ::

 	INCORRECT: "My String"                 // no variable parsing, so no use for double quotes "My string $foo"                // needs braces 'SELECT foo FROM bar WHERE baz = \'bag\''   // ugly  CORRECT: 'My String' "My string {$foo}" "SELECT foo FROM bar WHERE baz = 'bag'"

 SQL Queries
 ===========

 MySQL keywords are always capitalized: SELECT, INSERT, UPDATE, WHERE,
 AS, JOIN, ON, IN, etc.

 Break up long queries into multiple lines for legibility, preferably
 breaking for each clause.

 ::

 	INCORRECT: // keywords are lowercase and query is too long for // a single line (... indicates continuation of line) $query = $this->db->query("select foo, bar, baz, foofoo, foobar as raboof, foobaz from exp_pre_email_addresses ...where foo != 'oof' and baz != 'zab' order by foobaz limit 5, 100");  CORRECT: $query = $this->db->query("SELECT foo, bar, baz, foofoo, foobar AS raboof, foobaz                 FROM exp_pre_email_addresses                 WHERE foo != 'oof'                 AND baz != 'zab'                 ORDER BY foobaz                 LIMIT 5, 100");

 Default Function Arguments
 ==========================

 Whenever appropriate, provide function argument defaults, which helps
 prevent PHP errors with mistaken calls and provides common fallback
 values which can save a few lines of code. Example::

 	function foo($bar = '', $baz = FALSE)
	########################
	General Style and Syntax
	########################

	The following page describes the use of coding rules adhered to when
	developing CodeIgniter.

	.. contents:: Table of Contents

	File Format
	===========

	Files should be saved with Unicode (UTF-8) encoding. The BOM should
	not be used. Unlike UTF-16 and UTF-32, there's no byte order to
	indicate in a UTF-8 encoded file, and the BOM can have a negative side
	effect in PHP of sending output, preventing the application from being
	able to set its own headers. Unix line endings should be used (LF).

	Here is how to apply these settings in some of the more common text
	editors. Instructions for your text editor may vary; check your text
	editor's documentation.

	TextMate
	''''''''

	#. Open the Application Preferences
	#. Click Advanced, and then the "Saving" tab
	#. In "File Encoding", select "UTF-8 (recommended)"
	#. In "Line Endings", select "LF (recommended)"
	#. Optional: Check "Use for existing files as well" if you wish to
	modify the line endings of files you open to your new preference.

	BBEdit
	''''''

	#. Open the Application Preferences
	#. Select "Text Encodings" on the left.
	#. In "Default text encoding for new documents", select "Unicode (UTF-8,
	no BOM)"
	#. Optional: In "If file's encoding can't be guessed, use", select
	"Unicode (UTF-8, no BOM)"
	#. Select "Text Files" on the left.
	#. In "Default line breaks", select "Mac OS X and Unix (LF)"

	PHP Closing Tag
	===============

	The PHP closing tag on a PHP document ?> is optional to the PHP
	parser. However, if used, any whitespace following the closing tag,
	whether introduced by the developer, user, or an FTP application, can
	cause unwanted output, PHP errors, or if the latter are suppressed,
	blank pages. For this reason, all PHP files should OMIT the closing
	PHP tag, and instead use a comment block to mark the end of file and
	it's location relative to the application root. This allows you to still
	identify a file as being complete and not truncated.

	::

	INCORRECT: <?php echo "Here's my code!"; ?> CORRECT: <?php echo "Here's my code!"; /* End of file myfile.php / / Location: ./system/modules/mymodule/myfile.php */

	Class and Method Naming
	=======================

	Class names should always start with an uppercase letter. Multiple words
	should be separated with an underscore, and not CamelCased. All other
	class methods should be entirely lowercased and named to clearly
	indicate their function, preferably including a verb. Try to avoid
	overly long and verbose names.

	::

	INCORRECT: class superclass class SuperClass CORRECT: class Super_class

	::

	class Super_class { function __construct() { } }

	Examples of improper and proper method naming::

	INCORRECT: function fileproperties() // not descriptive and needs underscore separator function fileProperties() // not descriptive and uses CamelCase function getfileproperties() // Better! But still missing underscore separator function getFileProperties() // uses CamelCase function get_the_file_properties_from_the_file() // wordy CORRECT: function get_file_properties() // descriptive, underscore separator, and all lowercase letters

	Variable Names
	==============

	The guidelines for variable naming is very similar to that used for
	class methods. Namely, variables should contain only lowercase letters,
	use underscore separators, and be reasonably named to indicate their
	purpose and contents. Very short, non-word variables should only be used
	as iterators in for() loops.

	::

	INCORRECT: $j = 'foo'; // single letter variables should only be used in for() loops $Str // contains uppercase letters $bufferedText // uses CamelCasing, and could be shortened without losing semantic meaning $groupid // multiple words, needs underscore separator $name_of_last_city_used // too long CORRECT: for ($j = 0; $j < 10; $j++) $str $buffer $group_id $last_city

	Commenting
	==========

	In general, code should be commented prolifically. It not only helps
	describe the flow and intent of the code for less experienced
	programmers, but can prove invaluable when returning to your own code
	months down the line. There is not a required format for comments, but
	the following are recommended.

	`DocBlock <http://manual.phpdoc.org/HTMLSmartyConverter/HandS/phpDocumentor/tutorial_phpDocumentor.howto.pkg.html#basics.docblock>`_
	style comments preceding class and method declarations so they can be
	picked up by IDEs::

	/** * Super Class * * @package Package Name * @subpackage Subpackage * @category Category * @author Author Name * @link http://example.com */ class Super_class {

	::

	/** * Encodes string for use in XML * * @access public * @param string * @return string */ function xml_encode($str)

	Use single line comments within code, leaving a blank line between large
	comment blocks and code.

	::

	// break up the string by newlines $parts = explode("\n", $str); // A longer comment that needs to give greater detail on what is // occurring and why can use multiple single-line comments. Try to // keep the width reasonable, around 70 characters is the easiest to // read. Don't hesitate to link to permanent external resources // that may provide greater detail: // // http://example.com/information_about_something/in_particular/ $parts = $this->foo($parts);

	Constants
	=========

	Constants follow the same guidelines as do variables, except constants
	should always be fully uppercase. *Always use CodeIgniter constants when
	appropriate, i.e. SLASH, LD, RD, PATH_CACHE, etc.*

	::

	INCORRECT: myConstant // missing underscore separator and not fully uppercase N // no single-letter constants S_C_VER // not descriptive $str = str_replace('{foo}', 'bar', $str); // should use LD and RD constants CORRECT: MY_CONSTANT NEWLINE SUPER_CLASS_VERSION $str = str_replace(LD.'foo'.RD, 'bar', $str);

	TRUE, FALSE, and NULL
	=====================

	TRUE, FALSE, and NULL keywords should always be fully
	uppercase.

	::

	INCORRECT: if ($foo == true) $bar = false; function foo($bar = null) CORRECT: if ($foo == TRUE) $bar = FALSE; function foo($bar = NULL)

	Logical Operators
	=================

	Use of \\|\\| is discouraged as its clarity on some output devices is
	low (looking like the number 11 for instance). && is preferred over
	AND but either are acceptable, and a space should always precede and
	follow !.

	::

	INCORRECT: if ($foo \|\| $bar) if ($foo AND $bar) // okay but not recommended for common syntax highlighting applications if (!$foo) if (! is_array($foo)) CORRECT: if ($foo OR $bar) if ($foo && $bar) // recommended if ( ! $foo) if ( ! is_array($foo))

	Comparing Return Values and Typecasting
	=======================================

	Some PHP functions return FALSE on failure, but may also have a valid
	return value of "" or 0, which would evaluate to FALSE in loose
	comparisons. Be explicit by comparing the variable type when using these
	return values in conditionals to ensure the return value is indeed what
	you expect, and not a value that has an equivalent loose-type
	evaluation.

	Use the same stringency in returning and checking your own variables.
	Use === and !== as necessary.
	::

	INCORRECT: // If 'foo' is at the beginning of the string, strpos will return a 0, // resulting in this conditional evaluating as TRUE if (strpos($str, 'foo') == FALSE) CORRECT: if (strpos($str, 'foo') === FALSE)

	::

	INCORRECT: function build_string($str = "") { if ($str == "") // uh-oh! What if FALSE or the integer 0 is passed as an argument? { } } CORRECT: function build_string($str = "") { if ($str === "") { } }


	See also information regarding
	`typecasting <http://us3.php.net/manual/en/language.types.type-juggling.php#language.types.typecasting>`_,
	which can be quite useful. Typecasting has a slightly different effect
	which may be desirable. When casting a variable as a string, for
	instance, NULL and boolean FALSE variables become empty strings, 0 (and
	other numbers) become strings of digits, and boolean TRUE becomes "1"::

	$str = (string) $str; // cast $str as a string

	Debugging Code
	==============

	No debugging code can be left in place for submitted add-ons unless it
	is commented out, i.e. no var_dump(), print_r(), die(), and exit()
	calls that were used while creating the add-on, unless they are
	commented out.

	::

	// print_r($foo);

	Whitespace in Files
	===================

	No whitespace can precede the opening PHP tag or follow the closing PHP
	tag. Output is buffered, so whitespace in your files can cause output to
	begin before CodeIgniter outputs its content, leading to errors and an
	inability for CodeIgniter to send proper headers. In the examples below,
	select the text with your mouse to reveal the incorrect whitespace.

	INCORRECT::

	<?php // ...there is whitespace and a linebreak above the opening PHP tag // as well as whitespace after the closing PHP tag ?>

	CORRECT::

	<?php // this sample has no whitespace before or after the opening and closing PHP tags ?>

	Compatibility
	=============

	Unless specifically mentioned in your add-on's documentation, all code
	must be compatible with PHP version 5.1+. Additionally, do not use PHP
	functions that require non-default libraries to be installed unless your
	code contains an alternative method when the function is not available,
	or you implicitly document that your add-on requires said PHP libraries.

	Class and File Names using Common Words
	=======================================

	When your class or filename is a common word, or might quite likely be
	identically named in another PHP script, provide a unique prefix to help
	prevent collision. Always realize that your end users may be running
	other add-ons or third party PHP scripts. Choose a prefix that is unique
	to your identity as a developer or company.

	::

	INCORRECT: class Email pi.email.php class Xml ext.xml.php class Import mod.import.php CORRECT: class Pre_email pi.pre_email.php class Pre_xml ext.pre_xml.php class Pre_import mod.pre_import.php

	Database Table Names
	====================

	Any tables that your add-on might use must use the 'exp\_' prefix,
	followed by a prefix uniquely identifying you as the developer or
	company, and then a short descriptive table name. You do not need to be
	concerned about the database prefix being used on the user's
	installation, as CodeIgniter's database class will automatically convert
	'exp\_' to what is actually being used.

	::

	INCORRECT: email_addresses // missing both prefixes pre_email_addresses // missing exp_ prefix exp_email_addresses // missing unique prefix CORRECT: exp_pre_email_addresses

	NOTE: Be mindful that MySQL has a limit of 64 characters for table
	names. This should not be an issue as table names that would exceed this
	would likely have unreasonable names. For instance, the following table
	name exceeds this limitation by one character. Silly, no?
	exp_pre_email_addresses_of_registered_users_in_seattle_washington
	One File per Class
	==================

	Use separate files for each class your add-on uses, unless the classes
	are closely related. An example of CodeIgniter files that contains
	multiple classes is the Database class file, which contains both the DB
	class and the DB_Cache class, and the Magpie plugin, which contains
	both the Magpie and Snoopy classes.

	Whitespace
	==========

	Use tabs for whitespace in your code, not spaces. This may seem like a
	small thing, but using tabs instead of whitespace allows the developer
	looking at your code to have indentation at levels that they prefer and
	customize in whatever application they use. And as a side benefit, it
	results in (slightly) more compact files, storing one tab character
	versus, say, four space characters.

	Line Breaks
	===========

	Files must be saved with Unix line breaks. This is more of an issue for
	developers who work in Windows, but in any case ensure that your text
	editor is setup to save files with Unix line breaks.

	Code Indenting
	==============

	Use Allman style indenting. With the exception of Class declarations,
	braces are always placed on a line by themselves, and indented at the
	same level as the control statement that "owns" them.

	::

	INCORRECT: function foo($bar) { // ... } foreach ($arr as $key => $val) { // ... } if ($foo == $bar) { // ... } else { // ... } for ($i = 0; $i < 10; $i++) { for ($j = 0; $j < 10; $j++) { // ... } } CORRECT: function foo($bar) { // ... } foreach ($arr as $key => $val) { // ... } if ($foo == $bar) { // ... } else { // ... } for ($i = 0; $i < 10; $i++) { for ($j = 0; $j < 10; $j++) { // ... } }

	Bracket and Parenthetic Spacing
	===============================

	In general, parenthesis and brackets should not use any additional
	spaces. The exception is that a space should always follow PHP control
	structures that accept arguments with parenthesis (declare, do-while,
	elseif, for, foreach, if, switch, while), to help distinguish them from
	functions and increase readability.

	::

	INCORRECT: $arr[ $foo ] = 'foo'; CORRECT: $arr[$foo] = 'foo'; // no spaces around array keys INCORRECT: function foo ( $bar ) { } CORRECT: function foo($bar) // no spaces around parenthesis in function declarations { } INCORRECT: foreach( $query->result() as $row ) CORRECT: foreach ($query->result() as $row) // single space following PHP control structures, but not in interior parenthesis

	Localized Text
	==============

	Any text that is output in the control panel should use language
	variables in your lang file to allow localization.

	::

	INCORRECT: return "Invalid Selection"; CORRECT: return $this->lang->line('invalid_selection');

	Private Methods and Variables
	=============================

	Methods and variables that are only accessed internally by your class,
	such as utility and helper functions that your public methods use for
	code abstraction, should be prefixed with an underscore.

	::

	convert_text() // public method _convert_text() // private method

	PHP Errors
	==========

	Code must run error free and not rely on warnings and notices to be
	hidden to meet this requirement. For instance, never access a variable
	that you did not set yourself (such as $_POST array keys) without first
	checking to see that it isset().

	Make sure that while developing your add-on, error reporting is enabled
	for ALL users, and that display_errors is enabled in the PHP
	environment. You can check this setting with::

	if (ini_get('display_errors') == 1) { exit "Enabled"; }

	On some servers where display_errors is disabled, and you do not have
	the ability to change this in the php.ini, you can often enable it with::

	ini_set('display_errors', 1);

	NOTE: Setting the
	`display_errors <http://us.php.net/manual/en/ref.errorfunc.php#ini.display-errors>`_
	setting with ini_set() at runtime is not identical to having it enabled
	in the PHP environment. Namely, it will not have any effect if the
	script has fatal errors

	Short Open Tags
	===============

	Always use full PHP opening tags, in case a server does not have
	short_open_tag enabled.

	::

	INCORRECT: <? echo $foo; ?> <?=$foo?> CORRECT: <?php echo $foo; ?>

	One Statement Per Line
	======================

	Never combine statements on one line.

	::

	INCORRECT: $foo = 'this'; $bar = 'that'; $bat = str_replace($foo, $bar, $bag); CORRECT: $foo = 'this'; $bar = 'that'; $bat = str_replace($foo, $bar, $bag);

	Strings
	=======

	Always use single quoted strings unless you need variables parsed, and
	in cases where you do need variables parsed, use braces to prevent
	greedy token parsing. You may also use double-quoted strings if the
	string contains single quotes, so you do not have to use escape
	characters.

	::

	INCORRECT: "My String" // no variable parsing, so no use for double quotes "My string $foo" // needs braces 'SELECT foo FROM bar WHERE baz = \'bag\'' // ugly CORRECT: 'My String' "My string {$foo}" "SELECT foo FROM bar WHERE baz = 'bag'"

	SQL Queries
	===========

	MySQL keywords are always capitalized: SELECT, INSERT, UPDATE, WHERE,
	AS, JOIN, ON, IN, etc.

	Break up long queries into multiple lines for legibility, preferably
	breaking for each clause.

	::

	INCORRECT: // keywords are lowercase and query is too long for // a single line (... indicates continuation of line) $query = $this->db->query("select foo, bar, baz, foofoo, foobar as raboof, foobaz from exp_pre_email_addresses ...where foo != 'oof' and baz != 'zab' order by foobaz limit 5, 100"); CORRECT: $query = $this->db->query("SELECT foo, bar, baz, foofoo, foobar AS raboof, foobaz FROM exp_pre_email_addresses WHERE foo != 'oof' AND baz != 'zab' ORDER BY foobaz LIMIT 5, 100");

	Default Function Arguments
	==========================

	Whenever appropriate, provide function argument defaults, which helps
	prevent PHP errors with mistaken calls and provides common fallback
	values which can save a few lines of code. Example::

	function foo($bar = '', $baz = FALSE)