The Seven Steps To
Better PHP Code
Stefan Priebsch,
e-novative GmbH

Who I am
• PHP enthusiast since 2000
• IT and PHP Consultant
• From Munich, Germany
• University Degree in
Computer Science
• Writer (Books and Articles)
• Blog: http://inside.e-novative.de
• Email: stefan.priebsch@e-
novative.de
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 2

Step 1
Consistently
Format Source
Code
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 3

Format Source Code
• It's easy to code for computers,
but hard to code for humans
• Code is read more often than written
• Code should be human-readable
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 4

Unredable Code
#include <stdio.h>#define y
for(c=0,i=54;i>=0;c=(s[i]+=a[i]+c)/11,s[i]=s[i]%11
,i--);#define z for(i=0main(){char s[55],a[55];int
c,i,d;for(;;){z;i<55;s[i++]=0);for(;(d=getchar())!
='\\n';){d=d>58?(d>77?d-87:d-55):d-
48;z;i<55;a[i]=s[i],i++);y
z;i<54;s[i]=s[i+1],i++);s[54]=0;y
z;i<53;a[i++]=0);a[53]=d/11;a[54]=d%11;y}z;i<54&&s
[i]==0;i++);for(;i<55;i++)printf(\"%c\",s[i]<10?s[i]
+48:32);printf(\"\\n\");}}

Unredable Code
<?php
$bool = ($i<7&&$j>8||$k==4);
if ($a == $b) {
if ($b > 4){
do_something(); }
} else {
do_something_else();
}
?>

Format Source Code
• Format source code consistently
• Establish a coding standard
▪ How to indent
▪ Where to put whitespace
▪ Capitalization
• Reuse existing coding standards
• Use a code beautifer
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 7

Step 2
Establish
Naming
Conventions
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 8

Naming Conventions
• Establish a naming scheme
▪ Capitalization
▪ Consistent names
▪ Make the purpose clear
• Keep file names simple
(alphanumeric chars, blanks,
underscores)
• Prefix names in global namespace
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 9

Naming Conventions
processData()
doIt()
innerLoop()
$del_pos
checkConnection() vs. isConnected()
$filename vs. $fileName
open_connection($a, $b, $c, $d);
ftp_connect($server, $port, ...);

Step 3
Create
API
Documentation
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 11

API Documentation
• Document public interfaces
• Code assumptions instead of
commenting
• Are inline comments necessary?
▪ Code should communicate its purpose
▪ The better the names, the fewer
comments
• PHPDoc, derived from JavaDoc
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 12

API Documentation
• Special Comment Blocks
/**
* ...
*/
• Special @tags
(@author, @version, @param,
@returns, …)
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 13

Naming Conventions
/**
* This is what the class does.
*
* @package PackageName
* @author Your Name
* @version 1.0.0RC2
*/
class myFooClass
{
/**
* @param $aBar the Bar
* @param $aBaz the Baz
* @return bool success
*/
public function doFoo($aBar, $aBaz)

Step 4
Eliminate
Redundant
Redundant
Redundant
Code
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 15

Eliminate Redundant Code
• Avoid duplicate or similar code
• The Goal is: Make code changes in
just one spot
• Create parametrized functions and
methods („helper functions“)
• Do not over-generalize when
programming, use Refactoring
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 16

Eliminate Duplicate Code
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$q = $db->query('SELECT quantity FROM data WHERE item=\\'' . $_REQUEST['item'] . '\\'');
$quantity = $q->current(SQLITE_NUM);
$quantity = $quantity[0];
$quantity++;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
if ('remove' == $_REQUEST['action'])
{
$q = $db->query('SELECT quantity FROM data WHERE item=\\'' . $_REQUEST['item'] . '\\'');
$quantity = $q->current(SQLITE_NUM);
$quantity = $quantity[0];
if ($quantity > 0) $quantity--;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
}

Eliminate Duplicate Code
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$q = $db->query('SELECT quantity FROM data WHERE item=\\'' . $_REQUEST['item'] . '\\'');
$quantity = $q->current(SQLITE_NUM);
$quantity = $quantity[0];
$quantity++;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
if ('remove' == $_REQUEST['action'])
{
$q = $db->query('SELECT quantity FROM data WHERE item=\\'' . $_REQUEST['item'] . '\\'');
$quantity = $q->current(SQLITE_NUM);
$quantity = $quantity[0];
if ($quantity > 0) $quantity--;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
}

Eliminate Duplicate Code
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
$quantity++;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
if ('remove' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
if ($quantity > 0) $quantity--;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
}
function get_quantity($aItem)
{
$db = new SQLiteDatabase('report.sqlite');
$q = $db->query('SELECT quantity FROM data WHERE item=\\'' . $aItem . '\\'');
$result = $q->current(SQLITE_NUM);
return $result[0];
}

Eliminate Duplicate Code
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
$quantity++;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
if ('remove' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
if ($quantity > 0) $quantity--;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
}

Eliminate Duplicate Code
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
$quantity++;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
if ('remove' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
if ($quantity > 0) $quantity--;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
}

Eliminate Duplicate Code
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
$quantity++;
update_quantity($_REQUEST['item'], $quantity);
}
if ('remove' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
if ($quantity > 0) $quantity--;
update_quantity($_REQUEST['item'], $quantity);
}
}
function update_quantity($aItem, $aQuantity)
{
$db = new SQLiteDatabase('report.sqlite');
$q = $db->queryExec('UPDATE data SET quantity=\\'' . $aQuantity . '\\' ' .
'WHERE item=\\'' . $aItem . '\\'');
}

Before
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$q = $db->query('SELECT quantity FROM data WHERE item=\\'' . $_REQUEST['item'] . '\\'');
$quantity = $q->current(SQLITE_NUM);
$quantity = $quantity[0];
$quantity++;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
if ('remove' == $_REQUEST['action'])
{
$q = $db->query('SELECT quantity FROM data WHERE item=\\'' . $_REQUEST['item'] . '\\'');
$quantity = $q->current(SQLITE_NUM);
$quantity = $quantity[0];
if ($quantity > 0) $quantity--;
$q = $db->queryExec('UPDATE data SET quantity=' . $quantity . ' WHERE item=\\'' .
$_REQUEST['item'] . '\\'');
}
}

After
if (isset($_REQUEST['action']))
{
if ('add' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
$quantity++;
update_quantity($_REQUEST['item'], $quantity);
}
if ('remove' == $_REQUEST['action'])
{
$quantity = get_quantity($_REQUEST['item']);
if ($quantity > 0) $quantity--;
update_quantity($_REQUEST['item'], $quantity);
}
}

Step 5
Shorten
Code
Blocks
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 25

Shorten Code Blocks
• Break down code into little pieces
• A method or function should fit on
the screen without scrolling
• When the code needs (too many)
inline comments, it may be too
complex
• No more than three nesting levels
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 26

The 30 Second Rule
• If you don't understand a function or
method in 30 seconds, it is probably
too complex
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 27

Step 6
Separate
Different
Concerns
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 28

Separate Concerns
• Three-Tier architecture:
▪ Presentation
▪ Business Logic
▪ Data Access
• Functionality (add, remove, modify)
• Input (pre)processing
• No SQL near HTML
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 29

Separate Concerns
• Makes Unit Testing easier, because
logic is decoupled from data source
and presentation
• Allows much more code reuse
• Code becomes easier to read
because you can focus on one aspect
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 30

Separate Concerns
$q = $db->query('SELECT * from data ORDER BY ' . $order);
print '<table><tr><td><b><a href=\"?sort=item\">Item</a></b></td><td><b><a
href=\"?sort=barcode\">Barcode</a></b></td><td><b><a href=\"?sort=shelf\">Shelf</a></b></td><td><b><a
href=\"?sort=quantity\">Quantity</a></b></td></tr>';
while($q->valid())
{
$r = $q->current(SQLITE_ASSOC);
print '<tr>';
$first = true;
foreach ($r as $key => $value)
{
if ($first)
{
$item = $value;
$first = false;
}
print '<td>' . $value . '</td>';
if ('quantity' == $key) $sum += $value;
}
print '<td>[<a href=\"?sort=' . $order . '&action=add&item=' . $item . '\">+</a>]</td><td>[<a
href=\"?sort=' . $order . '&action=remove&item=' . $item . '\">-</a>]</td></tr>';
$q->next();
}
print '<tr><td></td><td></td><td>Total:</td><td><b>' . $sum . '</b></td></tr></table>';

Data Access
$q = $db->query('SELECT * from data ORDER BY ' . $order);
print '<table><tr><td><b><a href=\"?sort=item\">Item</a></b></td><td><b><a
href=\"?sort=barcode\">Barcode</a></b></td><td><b><a href=\"?sort=shelf\">Shelf</a></b></td><td><b><a
href=\"?sort=quantity\">Quantity</a></b></td></tr>';
while($q->valid())
{
$r = $q->current(SQLITE_ASSOC);
print '<tr>';
$first = true;
foreach ($r as $key => $value)
{
if ($first)
{
$item = $value;
$first = false;
}
print '<td>' . $value . '</td>';
if ('quantity' == $key) $sum += $value;
}
print '<td>[<a href=\"?sort=' . $order . '&action=add&item=' . $item . '\">+</a>]</td><td>[<a
href=\"?sort=' . $order . '&action=remove&item=' . $item . '\">-</a>]</td></tr>';
$q->next();
}
print '<tr><td></td><td></td><td>Total:</td><td><b>' . $sum . '</b></td></tr></table>';

Logic
$q = $db->query('SELECT * from data ORDER BY ' . $order);
print '<table><tr><td><b><a href=\"?sort=item\">Item</a></b></td><td><b><a
href=\"?sort=barcode\">Barcode</a></b></td><td><b><a href=\"?sort=shelf\">Shelf</a></b></td><td><b><a
href=\"?sort=quantity\">Quantity</a></b></td></tr>';
while($q->valid())
{
$r = $q->current(SQLITE_ASSOC);
print '<tr>';
$first = true;
foreach ($r as $key => $value)
{
if ($first)
{
$item = $value;
$first = false;
}
print '<td>' . $value . '</td>';
if ('quantity' == $key) $sum += $value;
}
print '<td>[<a href=\"?sort=' . $order . '&action=add&item=' . $item . '\">+</a>]</td><td>[<a
href=\"?sort=' . $order . '&action=remove&item=' . $item . '\">-</a>]</td></tr>';
$q->next();
}
print '<tr><td></td><td></td><td>Total:</td><td><b>' . $sum . '</b></td></tr></table>';

Presentation
$q = $db->query('SELECT * from data ORDER BY ' . $order);
print '<table><tr><td><b><a href=\"?sort=item\">Item</a></b></td><td><b><a
href=\"?sort=barcode\">Barcode</a></b></td><td><b><a href=\"?sort=shelf\">Shelf</a></b></td><td><b><a
href=\"?sort=quantity\">Quantity</a></b></td></tr>';
while($q->valid())
{
$r = $q->current(SQLITE_ASSOC);
print '<tr>';
$first = true;
foreach ($r as $key => $value)
{
if ($first)
{
$item = $value;
$first = false;
}
print '<td>' . $value . '</td>';
if ('quantity' == $key) $sum += $value;
}
print '<td>[<a href=\"?sort=' . $order . '&action=add&item=' . $item . '\">+</a>]</td><td>[<a
href=\"?sort=' . $order . '&action=remove&item=' . $item . '\">-</a>]</td></tr>';
$q->next();
}
print '<tr><td></td><td></td><td>Total:</td><td><b>' . $sum . '</b></td></tr></table>';

Separate Data Access
function get_data($aSort)
{
$db = new SQLiteDatabase('report.sqlite');
$q = $db->query('SELECT * from data ORDER BY ' . $aSort);
$result = array();
while($q->valid())
{
$result[] = $q->current(SQLITE_ASSOC);
$q->next();
}
return $result;
}

Separate Logic
function get_total()
{
$db = new SQLiteDatabase('report.sqlite');
$q = $db->query('SELECT SUM(quantity) from data');
$result = $q->current(SQLITE_NUM);
return $result[0];
}

Putting it together
print '<table>';
print '<tr><td><b><a href=\"?sort=item\">Item</a></b></td><td><b><a
href=\"?sort=barcode\">Barcode</a></b></td><td><b><a href=\"?sort=shelf\">Shelf</a></b></td><td><b><a
href=\"?sort=quantity\">Quantity</a></b></td></tr>';
foreach (get_data() as $r)
{
print '<tr>';
$first = true;
foreach ($r as $key => $value)
{
if ($first)
{
$item = $value;
$first = false;
}
print '<td>' . $value . '</td>';
}
print '<td>[<a href=\"?sort=' . $order . '&action=add&item=' . $item . '\">+</a>]</td><td>[<a
href=\"?sort=' . $order . '&action=remove&item=' . $item . '\">-</a>]</td>';
print '</tr>';
}
print '<tr><td></td><td></td><td>Total:</td><td><b>' . get_total() . '</b></td></tr></table>';

New Possibilities
print create_good_old_HTML_table(get_data(), get_total());
print create_fancy_AJAX_user_interface(get_data(), get_total());
export_data_to_a_really_really_special_format(get_data());

Step 7
Replace
Implementations
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 39

Replace Implementations
• Use native PHP instead of an old
extension
• Use components (PEAR, Zend
Framework, ezComponents)
• Use PHP extensions
(XMLWriter, SOAP)
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 40

Replace Implementations
• Rewrite ugly functions/methods
• Keep the API
• If you don't rely on global variables,
this should not affect the rest of the
application
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 41

The Seven Steps
1. Consistently Format Source Code
2. Establish Naming Conventions
3. Create API Documenation
4. Eliminate Redundant Code
5. Shorten Code Blocks
6. Separate Different Concerns
7. Replace Implementations
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 42

What is Refactoring?
• Changing code
▪ to improve readability
▪ to simplify the structure
• Without changing the results
• Not adding new functionality
• 'Clean Up' the code
• Improve the design
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 43

What is Refactoring?
• important part of agile methods
• not only suited for OOP
• an interesting experience
• and fun to do!
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 44

Why Refactor
• The world constantly changes
▪ environment changes
▪ terminology changes
▪ requirements change
• Software design decays over time
• We never get things right
the first time
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 45

When To Refactor
• Before you add new functionality
▪ Refactor until it becomes obvious how to
add a feature
• When you don't understand the code
▪ Make code more readable
• When you fix a bug
• After a code review
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 46

How To Refactor
• Run tests to make sure things work
• Refactor, one step at a time
• Rerun tests to make sure things still
work
• Automated Refactoring support
starts showing up in PHP IDEs
▪ Automation does not replace thinking
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 47

Testing
• xUnit Framework for PHP
▪ PHPUnit (www.phpunit.de)
▪ SimpleTest (www.simpletest.org)
• Not only for object-oriented code
• If you don't have tests, create them
as you go
• At least, run a Lint check:
php -l <filename>
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 48

Resources
• The definitive book on Refactoring:
Martin Fowler: Refactoring. Improving the
Design of Existing Code
• www.refactoring.com
• http://c2.com/cgi/wiki?WhatIsRefactoring
• How to write unmaintainable code
http://mindprod.com/jgloss/unmain.html
• Slides will be made available at
http://inside.e-novative.de
The Seven Steps To Better PHP Code - Stefan Priebsch, e-novative GmbH 49

The Seven Steps To
Better PHP Code
Thank you for listening.
stefan.priebsch@e-novative.de