Dušan Kasan - Zrefaktoruj cykly na kolekce

ZREFAKTORUJ CYKLY NA KOLEKCIEDUŠAN KASAN


github.com/DusanKasan

twitter.com/DusanKasan

[email protected]




[email protected]




[email protected]


O com to bude?• Aký máme problém?

• Čo sú kolekcie

• Kolekcie v PHP

• Práca s kolekciami

• Funkcionálny prístup v PHP

• Otázky

Problém | Kolekcie | PHP | Ukážky | FP

ˇ


Aký máme problém?


$likedPosts = [];foreach ($users as $user) { if ($user['verified']) { $userId = $user['id']; foreach ($user['posts'] as $post) { if (count($post['likes'])) { $likedPosts[$userId][] = $post; } } }}


Aký máme problém?


$likedPosts = [];foreach ($users as $user) { if ($user['verified']) { $userId = $user['id']; foreach ($user['posts'] as $post) { if (count($post['likes'])) { $likedPosts[$userId][] = $post; } } }} 4 úrovne odsadenia

ťažšie na pochopenie

kandidát na refaktoring


Refaktoring - viac funkcií?


$likedPosts = [];foreach ($users as $user) { if ($user['verified']) { $userId = $user['id']; foreach ($user['posts'] as $post) { if (count($post['likes'])) { $likedPosts[$userId][] = $post; } } }} private function getLikedPosts(array $posts)

{ $likedPosts = []; foreach ($posts as $post) { if (count($post['likes'])) { $likedPosts[] = $post; } } return $likedPosts; }


Refaktoring - viac funkcií?


$likedPosts = [];foreach ($users as $user) { $likedPosts = $this->getLikedPosts($user['posts']); if ($user['verified'] && count($likedPosts)) { $likedPosts[$user['id']] = $likedPosts; }}

• “OK” riešenie

• Meno čiastkových funkcií nesie dostatočný význam

• Pre úplné pochopenie treba skákať medzi funkciami


Refaktoring - built-in array funkcie?


$indexedUsers = [];foreach ($users as $user) { $indexedUsers[$user['id']] = $user; }$verifiedUsers = array_filter( $indexedUsers, function ($user) { return $user['verified']; });

$likedPosts = array_map( function($verifiedUser) { return array_filter( $verifiedUser['posts'], function($post) {return count($post['likes']);} ); }, $verifiedUsers);




To je hnus

velebnosti,

já jdu blejt.




$indexedUsers = [];foreach ($users as $user) { $indexedUsers[$user['id']] = $user; }$verifiedUsers = array_filter( $indexedUsers, function ($user) { return $user['verified']; });

$likedPosts = array_map( function($verifiedUser) { return array_filter( $verifiedUser['posts'], function($post) {return count($post['likes']);} ); }, $verifiedUsers);


Kolekcie



Kolekcie


• Čo je kolekcia?

• Skupina prvkov, resp. dvojíc kľúč - hodnota

• Collection pipeline

• Návrhový vzor

• Sekvenčné spájanie operácií nad kolekciou

• Operácie napr.: filter, map alebo reduce

• Bežný pri FP, ale aj v OO jazykoch, ktoré majú lambdy

• Výhody?


Kolekcie - funkcie


append, combine, concat, contains, countBy, cycle, diff, distinct,

drop, dropLast, dropWhile, each, every, except, extract, filter, find,

first, flatten, flip, frequencies, get, getOrDefault, groupBy,

groupByKey, has, indexBy, interleave, interpose, intersect, isEmpty,

isNotEmpty, keys, last, map, mapcat, only, partition, partitionBy,

prepend, realize, reduce, reduceRight, reductions, reject, replace,

reverse, second, shuffle, size, slice, some, sort, splitAt, splitWith,

take, takeNth, takeWhile, transform, toArray, zip,


Refaktoring - Kolekcie




Refaktoring - Kolekcie



$likedPosts = Collection::from($users) ->filter(function ($user) {return $user['verified'];}) ->indexBy(function($user) {return $user['id'];}) ->map(function($user) { return Collection::from($user['posts']) ->filter(function($post) {return count($post['likes']);}); }) ->reject(function($posts) {return isEmpty($posts);});


Kedy použit kolekcie


• Práca so zložitými dátovými štruktúrami

• API

• Import CSV so zložitejšou logikou

• Transformácie datasetov

• Refaktoring vnorených cyklov pre ľahšie porozumenie

'


Kolekcie v PHP - knižnice


• CakePHP Collection (github.com/cakephp/collection)

• Laravel Collections (github.com/illuminate/support)

• PHP-Collection (github.com/emonkak/php-collection)

• Knapsack (github.com/DusanKasan/Knapsack)


Kolekcie v PHP - nedostatky


$collection->map(function($item) { return $item->field; });




$collection->map(function($item) {return $item->field;});






$collection->map($item ~> $item->field);






$collection->map($item ~> $item->field);


$collection->map(function($item) => $item->field);

RFC pre PHP 7.1


Ako to vyzerá v reálnom kóde?


$oldRouteData = Collection::from($oldRoutes) ->map(function(array $oldRoute) { return toArray(only($oldRoute, ['title', 'url'])); });$routeData = Collection::from($routes) ->filter(function(Route $route) { $methods = $route->getMethods(); $isGet = empty($methods) || in_array('GET', $methods); $excludeFromSitemap = $route->getOption('excludeFromSitemap') === TRUE; return $isGet && !$excludeFromSitemap; }) ->indexBy(function(Route $route, $routeName) { return $route->getOption('routeTitle') ?: ucwords(str_replace('_', ' ', $routeName)); }) ->map(function (Route $route) { return $route->compile(); }) ->filter(function(CompiledRoute $compiledRoute) { return empty($compiledRoute->getPathVariables()); }) ->map(function(CompiledRoute $compiledRoute, $routeTitle) { return [ 'title' => $routeTitle, 'url' => $compiledRoute->getStaticPrefix() ]; }) ->concat($oldRoutes);


Ako to vyzerá v reálnom kóde?


$file->setFlags(SplFileObject::READ_CSV);$parts = Collection::from($file)->splitAt(2);$header = $parts->first()->toArray();if ($header != $this->header) { throw InvalidCsvFormat::invalidHeader();} $packages = $parts ->second() ->reject( function (array $row) { return $this->isEmptyLine($row); } ) ->map( function ($row) use ($customer) { return $this->buildIncorporation($customer, $row); } ) ->realize() ->map( function (CompanyIncorporation $incorporation) use ($order, $packageId, $customer) { $this->saveIncorporation($incorporation); $package = $this->buildPackage($packageId, $incorporation->getCompany()); $this->savePackageToOrder($package, $order); $this->printedDocumentResolver ->resolveDocuments($package->getId(), $customer, $package->getCompanyEntity()); return $package; } ) ->toArray();


Funkcionálne v PHP


• Collection functions

• github.com/DusanKasan/Knapsack

• Transducers

• github.com/mtdowling/transducers.php


Viac info?


• Martin Fowler (martinfowler.com)

• Adam Wathan (adamwathan.me/refactoring-to-collections)

• Dokumentácia a testy ku knižniciam


Date post:	22-Jan-2018
Category:	Software
Upload:	konference-phplive
View:	390 times
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Dušan Kasan - Zrefaktoruj cykly na kolekce

Software