java annotations are evil

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Аннотации — это зло

Yegor Bugayenko

Annotations Are Evil

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“Егор в своем стиле: все гондурасы, а я д’Артаньян.”

Д’Артаньян и три мушкетёра (1978)

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“Попал как будто на выступление лидера какой-то секты.”

The Evil Cult (1993)

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“Автор — маньяк.”

The Silence of the Lambs (1991)

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1000+

takes.org

14000+

jcabi.comrultor.comjare.io

since1988

2007

250+

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since 2014

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Compiler: @Override, @Deprecated, @SuppressWarning DI: @Inject, @Singleton, etc. Serialization: @XmlElement, etc. Validation: @NotNull, etc. Behavior: @GET, @Transaction AOP: @RetryOnFailure, @Cacheable Unit testing: @Test, @Before, @Rule, etc. Lombok: @ToString, @EqualsAndHashCode, etc.

Something else?…

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class Page { @GET String index() { return “Hello, world!”; } }

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class Page { String index(Request request) { if (request.method().equals(“GET”)) { return “Hello, world!”; } return “Method not allowed”; } }

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class Page { @GET String index() { return “Hello, world!”; } }

class Dispatcher { String dispatch(Page page, Request request) { if (request.method().equals(“GET”) && page.getClass().getMethod(“index”) .isAnnotationPresent(GET.class)) { return page.index(); } return “Method not allowed”; } }

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Page Dispatcher

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Page

Dispatcher

1 upside down

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Page

Dispatcher

2 unclear dependencies

???

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—Ты BeanPostProcessor видишь? —Нет. —А он есть!

ДМБ (2000)

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Page

3 no encapsulation

Data

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HelloPage

GETPage

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class HelloPage implements Page { @Override String index(Request request) { return “200 Hello, world!”; } }

class GETPage implements Page { private final Page page; @Override String index(Request request) { if (request.method().equals(“GET”)) { return page.index(); } return “Method not allowed”; } }

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procedural

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object-oriented

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Compiler: @Override, @Deprecated, @SuppressWarning DI: @Inject, @Singleton, etc. Serialization: @XmlElement, etc. Validation: @NotNull, etc. Behavior: @GET, @Transaction AOP: @RetryOnFailure, @Cacheable Unit testing: @Test, @Before, @Rule, etc. Lombok: @ToString, @EqualsAndHashCode, etc.

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Can I see the code?Можно ли посмотреть код?

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The Shining (1980)

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