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lnkohana/system/guide/kohana/conventions.md

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2013-04-22 04:09:50 +00:00
# Conventions and Coding Style
It is encouraged that you follow Kohana's coding style. This makes code more readable and allows for easier code sharing and contributing.
## Class Names and File Location
Class names in Kohana follow a strict convention to facilitate [autoloading](autoloading). Class names should have uppercase first letters with underscores to separate words. Underscores are significant as they directly reflect the file location in the filesystem.
The following conventions apply:
1. CamelCased class names should be used when it is undesirable to create a new directory level.
2. All class file names and directory names must match the case of the class as per [PSR-0](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md).
3. All classes should be in the `classes` directory. This may be at any level in the [cascading filesystem](files).
### Examples {#class-name-examples}
Remember that in a class, an underscore means a new directory. Consider the following examples:
Class Name | File Path
----------------------|-------------------------------
Controller_Template | classes/Controller/Template.php
Model_User | classes/Model/User.php
Model_BlogPost | classes/Model/BlogPost.php
Database | classes/Database.php
Database_Query | classes/Database/Query.php
Form | classes/Form.php
## Coding Standards
In order to produce highly consistent source code, we ask that everyone follow the coding standards as closely as possible.
### Brackets
Please use [BSD/Allman Style](http://en.wikipedia.org/wiki/Indent_style#BSD.2FAllman_style) bracketing.
#### Curly Brackets
Curly brackets are placed on their own line, indented to the same level as the control statement.
// Correct
if ($a === $b)
{
...
}
else
{
...
}
// Incorrect
if ($a === $b) {
...
} else {
...
}
#### Class Brackets
The only exception to the curly bracket rule is, the opening bracket of a class goes on the same line.
// Correct
class Foo {
// Incorrect
class Foo
{
#### Empty Brackets
Don't put any characters inside empty brackets.
// Correct
class Foo {}
// Incorrect
class Foo { }
#### Array Brackets
Arrays may be single line or multi-line.
array('a' => 'b', 'c' => 'd')
array(
'a' => 'b',
'c' => 'd',
)
##### Opening Parenthesis
The opening array parenthesis goes on the same line.
// Correct
array(
...
)
// Incorrect:
array
(
...
)
##### Closing parenthesis
###### Single Dimension
The closing parenthesis of a multi-line single dimension array is placed on its own line, indented to the same level as the assignment or statement.
// Correct
$array = array(
...
)
// Incorrect
$array = array(
...
)
###### Multidimensional
The nested array is indented one tab to the right, following the single dimension rules.
// Correct
array(
'arr' => array(
...
),
'arr' => array(
...
),
)
array(
'arr' => array(...),
'arr' => array(...),
)
##### Arrays as Function Arguments
// Correct
do(array(
...
))
// Incorrect
do(array(
...
))
As noted at the start of the array bracket section, single line syntax is also valid.
// Correct
do(array(...))
// Alternative for wrapping long lines
do($bar, 'this is a very long line',
array(...));
### Naming Conventions
Kohana uses under_score naming, not camelCase naming.
#### Classes
// Controller class, uses Controller_ prefix
class Controller_Apple extends Controller {
// Model class, uses Model_ prefix
class Model_Cheese extends Model {
// Regular class
class Peanut {
When creating an instance of a class, don't use parentheses if you're not passing something on to the constructor:
// Correct:
$db = new Database;
// Incorrect:
$db = new Database();
#### Functions and Methods
Functions should be all lowercase, and use under_scores to separate words:
function drink_beverage($beverage)
{
#### Variables
All variables should be lowercase and use under_score, not camelCase:
// Correct:
$foo = 'bar';
$long_example = 'uses underscores';
// Incorrect:
$weDontWantThis = 'understood?';
### Indentation
You must use tabs to indent your code. Using spaces for tabbing is strictly forbidden.
Vertical spacing (for multi-line) is done with spaces. Tabs are not good for vertical alignment because different people have different tab widths.
$text = 'this is a long text block that is wrapped. Normally, we aim for '
.'wrapping at 80 chars. Vertical alignment is very important for '
.'code readability. Remember that all indentation is done with tabs,'
.'but vertical alignment should be completed with spaces, after '
.'indenting with tabs.';
### String Concatenation
Do not put spaces around the concatenation operator:
// Correct:
$str = 'one'.$var.'two';
// Incorrect:
$str = 'one'. $var .'two';
$str = 'one' . $var . 'two';
### Single Line Statements
Single-line IF statements should only be used when breaking normal execution (e.g. return or continue):
// Acceptable:
if ($foo == $bar)
return $foo;
if ($foo == $bar)
continue;
if ($foo == $bar)
break;
if ($foo == $bar)
throw new Exception('You screwed up!');
// Not acceptable:
if ($baz == $bun)
$baz = $bar + 2;
### Comparison Operations
Please use OR and AND for comparison:
// Correct:
if (($foo AND $bar) OR ($b AND $c))
// Incorrect:
if (($foo && $bar) || ($b && $c))
Please use elseif, not else if:
// Correct:
elseif ($bar)
// Incorrect:
else if($bar)
### Switch Structures
Each case, break and default should be on a separate line. The block inside a case or default must be indented by 1 tab.
switch ($var)
{
case 'bar':
case 'foo':
echo 'hello';
break;
case 1:
echo 'one';
break;
default:
echo 'bye';
break;
}
### Parentheses
There should be one space after statement name, followed by a parenthesis. The ! (bang) character must have a space on either side to ensure maximum readability. Except in the case of a bang or type casting, there should be no whitespace after an opening parenthesis or before a closing parenthesis.
// Correct:
if ($foo == $bar)
if ( ! $foo)
// Incorrect:
if($foo == $bar)
if(!$foo)
if ((int) $foo)
if ( $foo == $bar )
if (! $foo)
### Ternaries
All ternary operations should follow a standard format. Use parentheses around expressions only, not around just variables.
$foo = ($bar == $foo) ? $foo : $bar;
$foo = $bar ? $foo : $bar;
All comparisons and operations must be done inside of a parentheses group:
$foo = ($bar > 5) ? ($bar + $foo) : strlen($bar);
When separating complex ternaries (ternaries where the first part goes beyond ~80 chars) into multiple lines, spaces should be used to line up operators, which should be at the front of the successive lines:
$foo = ($bar == $foo)
? $foo
: $bar;
### Type Casting
Type casting should be done with spaces on each side of the cast:
// Correct:
$foo = (string) $bar;
if ( (string) $bar)
// Incorrect:
$foo = (string)$bar;
When possible, please use type casting instead of ternary operations:
// Correct:
$foo = (bool) $bar;
// Incorrect:
$foo = ($bar == TRUE) ? TRUE : FALSE;
When casting type to integer or boolean, use the short format:
// Correct:
$foo = (int) $bar;
$foo = (bool) $bar;
// Incorrect:
$foo = (integer) $bar;
$foo = (boolean) $bar;
### Constants
Always use uppercase for constants:
// Correct:
define('MY_CONSTANT', 'my_value');
$a = TRUE;
$b = NULL;
// Incorrect:
define('MyConstant', 'my_value');
$a = True;
$b = null;
Place constant comparisons at the end of tests:
// Correct:
if ($foo !== FALSE)
// Incorrect:
if (FALSE !== $foo)
This is a slightly controversial choice, so I will explain the reasoning. If we were to write the previous example in plain English, the correct example would read:
if variable $foo is not exactly FALSE
And the incorrect example would read:
if FALSE is not exactly variable $foo
Since we are reading left to right, it simply doesn't make sense to put the constant first.
### Comments
#### One-line Comments
Use //, preferably above the line of code you're commenting on. Leave a space after it and start with a capital. Never use #.
// Correct
//Incorrect
// incorrect
# Incorrect
### Regular Expressions
When coding regular expressions please use PCRE rather than the POSIX flavor. PCRE is considered more powerful and faster.
// Correct:
if (preg_match('/abc/i', $str))
// Incorrect:
if (eregi('abc', $str))
Use single quotes around your regular expressions rather than double quotes. Single-quoted strings are more convenient because of their simplicity. Unlike double-quoted strings they don't support variable interpolation nor integrated backslash sequences like \n or \t, etc.
// Correct:
preg_match('/abc/', $str);
// Incorrect:
preg_match("/abc/", $str);
When performing a regular expression search and replace, please use the $n notation for backreferences. This is preferred over \\n.
// Correct:
preg_replace('/(\d+) dollar/', '$1 euro', $str);
// Incorrect:
preg_replace('/(\d+) dollar/', '\\1 euro', $str);
Finally, please note that the $ character for matching the position at the end of the line allows for a following newline character. Use the D modifier to fix this if needed. [More info](http://blog.php-security.org/archives/76-Holes-in-most-preg_match-filters.html).
$str = "email@example.com\n";
preg_match('/^.+@.+$/', $str); // TRUE
preg_match('/^.+@.+$/D', $str); // FALSE