Presentation from Leeds PHP 15/6/2016

1. Hello
@PeteJMcFarlane

2. Simple Made Easy

3. How to write code you
won't hate tomorrow
<!/> "#

4. KISS

5. KISS

6. KISS

7. KISS
Keep It Simple, Stupid

8. how do we measure code
quality?

9. how do we measure code quality?
4 number of classes
4 number of tests
4 using latest framework
4 PSR compliant
4 number of bugs shipped

10. how do we measure code quality?
can we:
4 read it easily
4 reason about it clearly
4 replace it quickly

11. readable
4 small functions/classes
4 good names
4 avoid nested code (ifs/loops) - extract methods
4 avoid else
4 return early or use a guard clause
4 avoid negation !

12. $data = $db->query("INSERT LONG, COMPLICATED SQL QUERY HERE");
echo '<ul>';
for ($i = 0; $i < count($data); $i++) {
echo "<li>$data[$i][0] - $data[$i][1]</li>";
}
echo '</ul>';

13. $people = $db->query("INSERT LONG, COMPLICATED SQL QUERY HERE");
echo '<ul>';
for ($i = 0; $i < count($people); $i++) {
echo "<li>$people[$i][0] - $people[$i][1]</li>";
}
echo '</ul>';

14. $people = $db->query("INSERT LONG, COMPLICATED SQL QUERY HERE");
echo '<ul>';
foreach ($people as $person) {
echo "<li>$person[0] - $person[1]</li>";
}
echo '</ul>';

15. $people = $db->query("INSERT LONG, COMPLICATED SQL QUERY HERE");
echo '<ul>';
foreach ($people as $person) {
echo "<li>{$person['name']} - {$person['email']}</li>";
}
echo '</ul>';

16. $people = $db->query("INSERT LONG, COMPLICATED SQL QUERY HERE");
$listElements = array_reduce($people, function ($html, $person) {
return $html . "<li>{$person['name']} - {$person['email']}</li>";
});
return '<ul>' . $listElements . '</ul>';

17. $people = $db->query("INSERT LONG, COMPLICATED SQL QUERY HERE");
return array_reduce($people, function ($html, $person) {
return $html . "<li>{$person['name']} - {$person['email']}</li>";
}, '<ul>') . '</ul>;

18. Input:
_ _ _ _ _ _ _ _
| | | _| _||_||_ |_ ||_||_|
|_| ||_ _| | _||_| ||_| _|
Output:
"0123456789"

19. return implode(array_map(function ($char) {
return $this->translate($char);
}, array_map('implode', transpose(array_map(function ($line) {
return str_split($line, 3);
}, explode("n", $ascii))))));

20. $lines = explode("n", $ascii);
$chunksOf3 = array_map(function ($line) {
return str_split($line, 3);
}, $lines);
$transposed = transpose($chunksOf3);
$characters = array_map('implode', $transposed);
$numbers = array_map(function ($char) {
return $this->translate($char);
}, $characters);
return implode($numbers);

21. if ($request->isValid()) {
$user = $request->getUser();
if ($user->hasPermissions()) {
foreach ($request->getUpdates() as $update) {
if ($update != null) {
$this->processUpdate($update);
}
}
} else {
throw new PermissionDeniedException;
}
} else {
throw new InvalidRequestException;
}

22. if (!$request->isValid()) {
throw new InvalidRequestException;
} else {
$user = $request->getUser();
if ($user->hasPermissions()) {
foreach ($request->getUpdates() as $update) {
if ($update != null) {
$this->processUpdate($update);
}
}
} else {
throw new PermissionDeniedException;
}
}

23. if (!$request->isValid()) {
throw new InvalidRequestException;
}
$user = $request->getUser();
if ($user->hasPermissions()) {
foreach ($request->getUpdates() as $update) {
if ($update != null) {
$this->processUpdate($update);
}
}
} else {
throw new PermissionDeniedException;
}

24. $this->guardAgainstInvalidRequest($request);
$user = $request->getUser();
if ($user->hasPermissions()) {
foreach ($request->getUpdates() as $update) {
if ($update != null) {
$this->processUpdate($update);
}
}
} else {
throw new PermissionDeniedException;
}

25. $this->guardAgainstInvalidRequest($request);
$user = $request->getUser();
if (!$user->hasPermissions()) {
throw new PermissionDeniedException;
}
foreach ($request->getUpdates() as $update) {
if ($update != null) {
$this->processUpdate($update);
}
}

26. $this->guardAgainstInvalidRequest($request);
$this->guardAuthorisedUser($request->getUser());
foreach ($request->getUpdates() as $update) {
if ($update != null) {
$this->processUpdate($update);
}
}

27. $this->guardAgainstInvalidRequest($request);
$this->guardAuthorisedUser($request->getUser());
$updates = array_filter($request->getUpdates());
$this->processUpdates($updates);

28. Good code doesn't just
emerge by accident
1
Me

29. function example()
{
$data = ...;
if (!$this->resultIsOK($data)) {
$result = false;
} else {
$result = true;
}
return $result;
}

30. function example()
{
$data = ...;
if ($this->resultIsOK($data)) {
$result = true;
} else {
$result = false;
}
return $result;
}

31. function example()
{
$data = ...;
if ($this->resultIsOK($data)) {
return true;
} else {
return false;
}
}

32. function example()
{
$data = ...;
if ($this->resultIsOK($data)) {
return true;
}
return false;
}

33. function example()
{
$data = ...;
return $this->resultIsOK($data) ? true : false;
}

34. function example()
{
$data = ...;
return $this->resultIsOK($data);
}

35. understandable
4 small, composable functions - that do one thing
4 hide complexity
4 good names - variables, functions, namespaces,
classes
4 small public API
4 TDD
4 Value objects

37. <?php
$d = 10;
$t = 3600;
$s = $d / t;
echo $s;

38. class Distance
{
private $km;
private function __construct() {}
public static function fromKm($km)
{
$d = new static;
$d->km = $km;
return $d;
}
public function asKm()
{
return $this->km;
}
}

39. class Time
{
private $seconds;
private function __construct() {}
public static function fromSeconds($seconds)
{
$t = new static;
$t->seconds = $seconds;
return $t;
}
public function inHours()
{
return $this->seconds / 3600;
}
}

40. class Speed
{
private $kmph;
public static function fromDistanceAndTime(Distance $d, Time $t)
{
$s = new static;
$s->kmph = $d->asKm() / $t->inHours();
return $s;
}
public function asMph()
{
return $this->kmph * 1.6093;
}
}

41. <?php
$d = Distance::fromKm(10); // 10 km
$t = Time::fromSeconds(3600); // 1 hr
$s = Speed::fromDistanceAndTime($d, $t); // 10 kmph
echo $s->asMph(); // will print 16.093

42. adaptable
4 Things change - new business knowledge/rules,
changing technologies
4 small functions/classes/modules
4 throw away code
4 dependency injection
4 be abstract, use interfaces

43. NO CODE IS SIMPLER
THAN NO CODE

44. Simple enables change = Opportunity

45. 4 do katas - readable, efficient, flexible
4 exercism.io, projecteuler.net
4 pair/mob program
4 code review
4 read others code bases
4 mentor at http://phpmentoring.org
4 attend/speak conferences & user groups
4 write a blog

46. Goodbye
@PeteJMcFarlane