Clear PHP is a coding reference for all of us. It tracks recommendations to write clear code, avoiding the classic traps, keeping options opened for the future and preventing decayed code. Those recommendations are above coding conventions, that focuses on code writing, and code architecture, with its design patterns and conceptions. This is the first time in history where an effort was made to collect all those rules, so every project can choose among them, and define exactly his own coding standard.

1. he clearPHP
reference
Amsterdam, the Netherlands. May 21st 2015
T

2. Agenda
clearPHP reference
Focus on PHP
Make your own

3. Speaker
Damien Seguy
CTO at exakat
"Ik ben een boterham" : I'm a recent resident
Automated code audit services

4. Something wrong?
<?php
function f($a, $a, $a) {
echo $a;
}
f('b', 'c', 'd');
?>
Won’t work in PHP
7
W
ill work in Python
clearPHP : all-unique-arguments

5. Coding standards
Symfony
Wordpress
Drupal
Typo3
Atoum
CakePHP
PEAR
PSR
Rafael Dohms
…

6. Wordpress Standards
Single and Double Quotes
Indentation
Brace Style
Regular Expressions
No Shorthand PHP Tags
Remove Trailing Spaces
Space Usage
Formatting SQL statements
Database Queries
Naming Conventions
Self-Explanatory Flag Values for Function
Arguments
Ternary Operator
Yoda Conditions
Clever Code
Error Control Operator @
Don’t extract()

7. Coding conventions
Conception
PHP coding
reference

8. PHP gotcha

9. Something wrong?
<?php
class w extends v {
function f($a, $b = 2, $c) {
echo $a;
}
}
?>
Still works in PHP
7
clearPHP : argument-with-default-at-the-end

10. Something to avoid ?
<?php
if (($h = file_get_contents($uri)) == '') {
print "Error : couldn't access siten";
} else {
process_html($h);
}
?>
clearPHP : strict-comparisons

11. Something to avoid ?
• array_search
• collator_compare
• collator_get_sort_key
• current
• fgetc
• file_get_contents
• file_put_contents
• iconv_strpos
• iconv_strrpos
• imagecolorallocate
• imagecolorallocatealpha
• mb_strlen
• next
• pcntl_getpriority
• preg_match
• preg_match_all
• prev
• readdir
• stripos
• strpos
• strripos
• strrpos
• strtok
clearPHP : strict-comparisons

12. Something to trip on ?
<?php
$array = array('a', 'b');
$array2 = array('c', 'd');
foreach ($array as &$f) { }
foreach ($array2 as $f) { }
print_r($array);
print_r($array2);
clearPHP : no-dangling-reference

13. Something to avoid ?
Array
(
[0] => a
[1] => d
)
Array
(
[0] => c
[1] => d
)
clearPHP : no-dangling-reference

14. Something to trip on ?
<?php
$array = array('a', 'b');
$array2 = array('c', 'd');
foreach ($array as &$f) { }
unset($f);
foreach ($array2 as $f) { }
print_r($array);
print_r($array2);
clearPHP : no-dangling-reference

15. Something to trap you ?
<?php
$x = true;
$y = false;
$z = $x and $y;
$z = $x && $y;
?>
clearPHP : no-letter-logical

17. Something wrong ?
<?php
try {
} catch (UnresolvedClass $e) {
} catch (NotAnException $e) {
}
this is dead code too
clearPHP : no-unresolved-catch
this is dead code too

18. Something wrong ?
<?php
namespace X;
try {
} catch (Exception $e) {
}
?>
this is still dead code
clearPHP : no-unresolved-catch

19. Something wrong ?
<?php
if ($x instanceof SomeKlasse) {
$y = $x->convert();
}
?>
Unresolved classes are not notified :
this is dead code
clearPHP : no-unresolved-instanceof

20. Performances

21. Something slow ?
<?php
define('DAY_IN_SECONDS', 24 * 60 * 60);
define('DAY_IN_SECONDS', 86400);
const DAY_IN_SECONDS = 86400;
?>
clearPHP : always-preprocess

22. Something slow ?
<?php
$x = [];
$x['id'] = 0;
$x['username'] = 'bibi';
$x['creation'] = time();
?>
clearPHP : always-preprocess
<?php
$x = [ 'id' => 0,
'username' => 'bibi',
'creation' => time(),
];
?>

23. Something slow ?
<?php
echo "<p>";
echo $paragraph;
echo "</p>";
?>
clearPHP : no-repeated-print

24. Something slow ?
<?php
$array = $source->fetchData();
$array = array_unique($array);
?>
clearPHP : avoid-those-slow-functions
<?php
$array = $database->fetchData();
$array = array_keys(
array_count_values($array));
?>

25. Something slow ?
clearPHP : no-array_merge-in-loop
<?php
$merged = [];
foreach($array as $id => $row) {
$array[$id][4] = VAT * $row[2];
$merged = array_merge($merged, $row);
}
?>
<?php
foreach($array as &$row) {
$row[4] = VAT * $row[2];
}
unset($row);
$merged = array_merge($merged, $array);
?> clearPHP : use-reference-to-alter-in-foreach

26. PHP tricks

27. Something wrong ?
<?php
switch ($x) {
default :
// something useful
break;
default :
// something else and useful
break;
}
this is still dead code
clearPHP : no-switch-with-multiple-defaultWon’t work in PHP
7

28. Something wrong ?
<?php
switch ($x) {
case 1 :
// something useful
break;
case 1 :
// something useful
break;
}
this is still dead code
clearPHP : no-duplicate-case

29. Something wrong ?
<?php
$array = ['png' => 'image/png',
'jpg' => 'image/jpg',
'jpeg' => 'image/jpeg',
'gif' => 'image/gif',
'webp' => 'image/webp',
'wbmp' => 'image/wbmp',
'png' => 'image/png',
];
?>clearPHP : no-duplicate-key

30. Something wrong ?
<?php
$array = [ 1 => 2,
'1' => 4,
5 => 6,
7 => 8,
9 => 10,
11 => 12,
1.3 => 14
];
two of
them
is
dead
code
clearPHP : no-duplicate-key

31. Something insane
<?php
$content = @file_get_contents($uri);
?>
clearPHP : no-noscream

32. Something insane
<?php
class user {
public static getName() {
return $this->name;
}
}
?>
clearPHP : no-static-this Still works in PHP
7

33. Not so specific to PHP

34. Something insane ?
<?php
$credit = ( !is_array($_credit)) ?
PtoBR(propre($_credit)) :
( $_credit['url'] ? '<a href="' .
$_credit['url'] . '">' : '') .
$_credit['nom'] . ( $_credit['url'] ?
'</a>' : '');
?>
clearPHP : no-nested-ternary

35. Something hardcoded
<?php
$ftp_user = 'foo';
$ftp_pass = 'bar';
// set up a connection
$conn_id = ftp_connect('ftp.example.nl');
// authentication
ftp_login($conn_id, $ftp_user, $ftp_pass);
?>
clearPHP : no-hardcoded-credential

36. Something weird
<?php
class user {
public static countReal($array) {
return count(array_filter(
$array,
function ($x) { return !empty($x);}
);
}
}
?>
clearPHP : not-a-method

37. Something useless
<?php
interface i { function getI(); }
class x implements i {
function getI() { return rand(0, 10); }
}
?>
clearPHP : no-useless-interfaces

38. Something useless
<?php
function negateI(i $x) {
return - $x->getI();
}
function sumI(array $a) {
$r = 0;
foreach($a as $b) {
if ($x instanceof i) {
$r += $x->getI();
}
}
return $r;
}
clearPHP : no-useless-interfaces

39. clearPHP
https://github.com/
dseguy/clearPHP
109 rules for clear
coding in PHP

40. clearPHP
Name
Explanations
Examples
Do and don't
More reading material

41. Single and Double Quotes
Indentation
Brace Style
[Regular Expressions]
no-short-tags
Remove Trailing Spaces
Space Usage
Formatting SQL statements
Database Queries -
(always-prepare-statement)
Naming Conventions
Self-Explanatory Flag Values for Function
Arguments
[Ternary Operator]
yoda-condition
No-implied-if
No-scream
Know-your-variables
Wordpress Standards

42. Sources
PHP Manual
Articles
Common practices
Feedback on clearPHP's repo

43. Something greedy ?
<?php
echo ("<p>" . $paragraph . "</p>");
?>

44. Something greedy ?
<?php
echo "<p>" . $paragraph . "</p>";
?>
clearPHP : no-parenthesis-for-language-construct

45. Something greedy ?
<?php
echo "<p>", $paragraph, "</p>";
?>
clearPHP : no-unnecessary-string-concatenation

46. Build your own reference
Read the reference
Cherry pick the rules
you like
Ignore the rules you
don't like
Herald this as your own
reference

47. More rules to come
Do not use the 'else' keyword
Do not use 'else if' but make it one else if
Do wash your hands before hitting the keyboard

48. Texte
Thanks!
@faguo, dseguy@exakat.com,
https://github.com/dseguy/clearPHP

50. clearPHP
Rules to write good PHP code
Rules to write PHP code
Largest list of recommendations
Cherry pick your selection

52. No one knows why
Looks like old PHP 4
Bad for performance
Bad for security
Bad for maintenance
Newbie mistake
Bad for testing