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Modernising the Legacy
Marek Matulka
UK
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Marek Matulka
Software Engineer
SensioLabs UK
@super_marek
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Legacy
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What is legacy code?
- someone else’s code
- your old code
- an old framework you don’t know
- or too coupled to the framework
- built over years
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What is legacy code?
Old code where...
- most of it is procedural
- no namespaces used
- no code convention
- no separation of concerns
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What is legacy code?
Old code where...
- PHP mixed with HTML, CSS
- overused Global variables
- collection of include files
- *.inc files in public folder
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What is legacy code?
Old code where...
- no concept of environments
- no error reporting
- no logging
- no version control system used
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What is legacy code?
Any code...
- without tests
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It’s too hard
- understand the logic
- add new features
- debug
- fix bugs
- adopt new technologies
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How do we get
out of legacy?
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Start with the goal
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Why?
Business goal
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Why?
Who?
Who?
Actors
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Why?
Who?
Who?
How?
How?
How?
Impacts
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Why?
Who?
Who?
How?
How?
How?
What?
What?
What?
What?
What?
What?
Deliverables
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Why?
Who?
Who?
How?
How?
How?
What?
What?
What?
What?
What?
What?
Prioritise
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Goal: Reduce drop-outs by 10%
In order to see the total cost of order
As a shopper
I want to see postage cost
Example
Why? Who? How? What?
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Write scenarios
Feature: Shopper can see postage cost
In order to see the total cost of order
As a shopper
I want to see a postage cost
Scenario: Shopper can see a postage cost
Given I have added a "Clean Code" book priced £34.50 to the basket
And the postage cost for one book is £3.50
When I check the basket
Then I should see the postage cost of £3.50
And the total of the basket should be £38.00
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Implement scenarios
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Given-When-Then
Feature: Shopper can see postage cost
In order to see the total cost of order
As a shopper
I want to see a postage cost
Scenario: Shopper can see a postage cost
Given I have added a "Clean Code" book priced £34.50 to the basket
And the postage cost for one book is £3.50
When I check the basket
Then I should see the postage cost of £3.50
And the total of the basket should be £38.00
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Write a failing scenario
(feature)
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Write a failing scenario
(feature)
Write a failing test
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Write a failing scenario
(feature)
Write a failing test
Make your test pass
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Write a failing scenario
(feature)
Write a failing test
Make your test pass
Refactor your code
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Write a failing scenario
(feature)
Write a failing test
Make your test pass
Refactor your code
Repeat the fail-pass-refactor cycle as necessary
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Write a failing scenario
(feature)
Write a failing test
Make your test pass
Refactor your code
Make your
scenario pass
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Write a failing scenario
(feature)
Write a failing test
Make your test pass
Refactor your code
Make your
scenario pass
BDD
TDD
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Write a failing scenario
(feature)
Write a failing test
Make your test pass
Refactor your code
Make your
scenario pass
BDD
TDD
External Quality
Internal Quality
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(everything?)
What to test?
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Unit tests
Acceptance tests
Integration tests
Smoke tests
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Unit tests
Acceptance tests
Integration tests
Smoke tests
Manual
Automated
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Unit tests
Acceptance tests
Integration tests
Smoke tests
Slowest
Fastest
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Why test?
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Why test?
- code level documentation
- features described through examples
- clean code
- you’re not afraid to change your code
- peace of mind
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Why test?
delivered features
project’s life
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Why use
Symfony
components?
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Symfony Components
The standard foundation on which the best
PHP applications are built.
- fully tested
- decoupled
- reusable
- de-facto standard
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Symfony Components
Build a micro
framework.
Use components
you need
in your application.
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symfony/dependency-injection
Dependency Injection
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Dependency Injection
In software engineering, dependency injection is a
software design pattern that implements inversion of
control for resolving dependencies. Dependency injection
means giving an object its instance variables. Really. That's
it.
https://en.wikipedia.org/wiki/Dependency_injection
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Dependency Injection
PostageCalculator PostageRepository
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Dependency Inversion
PostageCalculator PostageRepository
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Dependency Inversion
PostageCalculator PostageRepository
PostageSqliteRepository
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Dependency Inversion
PostageCalculator PostageRepository
PostageSqliteRepository
PostageDoctrineRepository
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Install dependency injection
$ composer require symfony/dependency-injection
$ composer require symfony/config
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Create container.php
load('services.yml');
$container->compile();
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Create container.php
load('services.yml');
$container->compile();
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Create container.php
load('services.yml');
$container->compile();
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Create container.php
load('services.yml');
$container->compile();
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Create container.php
load('services.yml');
$container->compile();
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Create container.php
load('services.yml');
$container->compile();
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# app/config/services.yml
services:
acme.postage.repository:
class: Acme\Infrastructure\Sqlite\PostageSqliteRepository
acme.postage.calculator:
class: Acme\Basket\PostageCalculator
arguments:
- @acme.postage.repository
Create services.yml
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# app/config/services.yml
services:
acme.postage.repository:
class: Acme\Infrastructure\Sqlite\PostageSqliteRepository
acme.postage.calculator:
class: Acme\Basket\PostageCalculator
arguments:
- @acme.postage.repository
Create services.yml
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# app/config/services.yml
services:
acme.postage.repository:
class: Acme\Infrastructure\Sqlite\PostageSqliteRepository
acme.postage.calculator:
class: Acme\Basket\PostageCalculator
arguments:
- @acme.postage.repository
Create services.yml
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Use container
require '../_inc/db.php';
require '../app/container.php';
// ...
$postageCalculator = $container->get('acme.postage.calculator');
if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) {
$postage = $postage->toView();
echo sprintf("
Estimated postage for %d item(s): £%1.02f.
", $postage['quantity'], $postage['price'] ); } // ...Slide 56
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Use container
require '../_inc/db.php';
require '../app/container.php';
// ...
$postageCalculator = $container->get('acme.postage.calculator');
if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) {
$postage = $postage->toView();
echo sprintf("
Estimated postage for %d item(s): £%1.02f.
", $postage['quantity'], $postage['price'] ); } // ...Slide 57
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Use container
require '../_inc/db.php';
require '../app/container.php';
// ...
$postageCalculator = $container->get('acme.postage.calculator');
if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) {
$postage = $postage->toView();
echo sprintf("
Estimated postage for %d item(s): £%1.02f.
", $postage['quantity'], $postage['price'] ); } // ...Slide 58
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Dependency Injection
with Drupal 7?
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container.php
load('services.yml');
$container->compile();
$conf['di_container'] = $container;
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container.php
load('services.yml');
$container->compile();
$conf['di_container'] = $container;
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depot_locator.module
get('acme.depot_locator')->locateDepot($postcode);
$depot = $depotEntity->toArray();
set_depot_cookies($depot);
return ['depot' => $depot];
}
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twig/twig
Twig
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What is twig?
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Install twig
$ composer require twig/twig
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How to use twig?
$loader = new Twig_Loader_Filesystem('/path/to/templates');
$twig = new Twig_Environment($loader);
echo $twig->render('index.html', ['variable' => 'value']);
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# app/config/services.yml
parameters:
twig.paths:
- app/Resources/views
services:
twig.template_loader:
class: Twig_Loader_Filesystem
arguments:
- %twig.paths%
twig.renderer:
class: Twig_Environment
arguments:
- @twig.template_loader
Enabling twig in DI container
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# app/config/services.yml
parameters:
twig.paths:
- app/Resources/views
services:
twig.template_loader:
class: Twig_Loader_Filesystem
arguments:
- %twig.paths%
twig.renderer:
class: Twig_Environment
arguments:
- @twig.template_loader
Enabling twig in DI container
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# app/config/services.yml
parameters:
twig.paths:
- app/Resources/views
services:
twig.template_loader:
class: Twig_Loader_Filesystem
arguments:
- %twig.paths%
twig.renderer:
class: Twig_Environment
arguments:
- @twig.template_loader
Enabling twig in DI container
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# app/config/services.yml
parameters:
twig.paths:
- app/Resources/views
services:
twig.template_loader:
class: Twig_Loader_Filesystem
arguments:
- %twig.paths%
twig.renderer:
class: Twig_Environment
arguments:
- @twig.template_loader
Enabling twig in DI container
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Use twig
$basketViewData = $container->get('acme.basket.view')
->toView($_SESSION['basket']);
$basketView = $container->get('twig.renderer')
->render(
'basket.twig.html',
$basketViewData
);
echo $basketView;
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symfony/console
Add console commands
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Install console component
$ composer require symfony/console
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class ImportAndPersistCommand extends Command
{
private $action;
public function __construct(ImportAndPersistActionHandler $action)
{
$this->action = $action;
parent::__construct();
}
protected function configure()
{
$this->setName('products:import');
}
protected function execute(InputInterface $input, OutputInterface $output)
{
$startTime = microtime(true);
$this->action->importAndPersistProducts();
$executionTime = microtime(true) - $startTime;
$output->writeln(
sprintf("Products import completed in %1.02fs.", $executionTime)
);
}
}
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app/console
#!/usr/bin/php
addCommands([
$container->get('acme.command.import_products'),
$container->get('acme.command.delete_products'),
$container->get('acme.command.depot_locate'),
]);
$application->run();
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symfony/http-foundation
Decouple from global state
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Http application’s flow
Controller
Request Response
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Install HttpFoundation component
$ composer require symfony/http-foundation
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De-coupling from global state
# /public/index.php
get('acme.basket_view.controller')
->viewAction($request);
$response->send();
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De-coupling from global state
# /public/index.php
get('acme.basket_view.controller')
->viewAction($request);
$response->send();
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De-coupling from global state
# /public/index.php
get('acme.basket_view.controller')
->viewAction($request);
$response->send();
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De-coupling from global state
# /public/index.php
get('acme.basket_view.controller')
->viewAction($request);
$response->send();
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Going forward
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Try it yourself!
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Playground
https://github.com/mareg/legacy-summercamp-2015
- four exercises:
- add dependency injection
- add twig
- decouple from global state
- controller as service
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Questions?
Slides: speakerdeck.com/super_marek
Feedback: joind.in/talk/view/14977
Connect: @super_marek