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Author SHA1 Message Date
d41077f355 docs: update .all-contributorsrc [skip ci] 2020-08-01 08:45:39 +00:00
e4473e5c88 docs: update README.md [skip ci] 2020-08-01 08:45:38 +00:00
7af544998d Merge pull request #1465 from iluwatar/all-contributors/add-MananS77
docs: add MananS77 as a contributor
2020-08-01 11:08:05 +03:00
0a2c87d49a docs: update .all-contributorsrc [skip ci] 2020-08-01 08:07:21 +00:00
15eb49e574 docs: update README.md [skip ci] 2020-08-01 08:07:20 +00:00
661f9e1373 Merge pull request #1464 from iluwatar/all-contributors/add-charlesfinley
docs: add charlesfinley as a contributor
2020-08-01 10:42:44 +03:00
7908d38604 docs: update .all-contributorsrc [skip ci] 2020-08-01 07:41:48 +00:00
41020982de docs: update README.md [skip ci] 2020-08-01 07:41:47 +00:00
43569ecd66 Merge pull request #1463 from charlesfinley/master
Fixes Issue #1462 - Unit Test assertEquals parameters are reversed
2020-08-01 10:39:20 +03:00
fb6507ceda Corrected assertEquals order for expected, actual. 2020-07-31 22:52:23 -04:00
29f799c815 Corrected assertEquals order for expected, actual. 2020-07-31 22:50:48 -04:00
55bb1f11e0 #590 fix typo 2020-07-30 21:57:07 +03:00
8364b289b4 #590 explanation for Abstract Document 2020-07-30 21:39:11 +03:00
417f21ed3d Code cleanup (#1461)
* Code cleanup

* Fix flux tests

* Fix checkstyle errors

* Fix compile error
2020-07-30 20:28:47 +03:00
8 changed files with 208 additions and 18 deletions

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@ -1038,6 +1038,33 @@
"contributions": [
"translation"
]
},
{
"login": "charlesfinley",
"name": "Matt Dolan",
"avatar_url": "https://avatars1.githubusercontent.com/u/6307904?v=4",
"profile": "https://github.com/charlesfinley",
"contributions": [
"code"
]
},
{
"login": "MananS77",
"name": "Manan",
"avatar_url": "https://avatars3.githubusercontent.com/u/21033516?v=4",
"profile": "https://github.com/MananS77",
"contributions": [
"review"
]
},
{
"login": "nishant",
"name": "Nishant Arora",
"avatar_url": "https://avatars2.githubusercontent.com/u/15331971?v=4",
"profile": "https://github.com/nishant",
"contributions": [
"code"
]
}
],
"contributorsPerLine": 4,

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@ -9,7 +9,7 @@
[![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
[![Sonarcloud Status](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=alert_status)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
[![All Contributors](https://img.shields.io/badge/all_contributors-114-orange.svg?style=flat-square)](#contributors-)
[![All Contributors](https://img.shields.io/badge/all_contributors-117-orange.svg?style=flat-square)](#contributors-)
<!-- ALL-CONTRIBUTORS-BADGE:END -->
# Introduction
@ -239,6 +239,11 @@ This project is licensed under the terms of the MIT license.
<tr>
<td align="center"><a href="https://webpro.nl"><img src="https://avatars1.githubusercontent.com/u/456426?v=4" width="100px;" alt=""/><br /><sub><b>Lars Kappert</b></sub></a><br /><a href="#content-webpro" title="Content">🖋</a></td>
<td align="center"><a href="https://xiaod.info"><img src="https://avatars2.githubusercontent.com/u/21277644?v=4" width="100px;" alt=""/><br /><sub><b>Mike Liu</b></sub></a><br /><a href="#translation-xiaod-dev" title="Translation">🌍</a></td>
<td align="center"><a href="https://github.com/charlesfinley"><img src="https://avatars1.githubusercontent.com/u/6307904?v=4" width="100px;" alt=""/><br /><sub><b>Matt Dolan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=charlesfinley" title="Code">💻</a></td>
<td align="center"><a href="https://github.com/MananS77"><img src="https://avatars3.githubusercontent.com/u/21033516?v=4" width="100px;" alt=""/><br /><sub><b>Manan</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/pulls?q=is%3Apr+reviewed-by%3AMananS77" title="Reviewed Pull Requests">👀</a></td>
</tr>
<tr>
<td align="center"><a href="https://github.com/nishant"><img src="https://avatars2.githubusercontent.com/u/15331971?v=4" width="100px;" alt=""/><br /><sub><b>Nishant Arora</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=nishant" title="Code">💻</a></td>
</tr>
</table>

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@ -9,21 +9,182 @@ tags:
---
## Intent
Achieve flexibility of untyped languages and keep the type-safety
Use dynamic properties and achieve flexibility of untyped languages while keeping type-safety.
## Explanation
The Abstract Document pattern enables handling additional, non-static properties. This pattern
uses concept of traits to enable type safety and separate properties of different classes into
set of interfaces.
Real world example
> Consider a car that consists of multiple parts. However we don't know if the specific car really has all the parts, or just some of them. Our cars are dynamic and extremely flexible.
In plain words
> Abstract Document pattern allows attaching properties to objects without them knowing about it.
Wikipedia says
> An object-oriented structural design pattern for organizing objects in loosely typed key-value stores and exposing
the data using typed views. The purpose of the pattern is to achieve a high degree of flexibility between components
in a strongly typed language where new properties can be added to the object-tree on the fly, without losing the
support of type-safety. The pattern makes use of traits to separate different properties of a class into different
interfaces.
**Programmatic Example**
Let's first define the base classes `Document` and `AbstractDocument`. They basically make the object hold a property
map and any amount of child objects.
```java
public interface Document {
Void put(String key, Object value);
Object get(String key);
<T> Stream<T> children(String key, Function<Map<String, Object>, T> constructor);
}
public abstract class AbstractDocument implements Document {
private final Map<String, Object> properties;
protected AbstractDocument(Map<String, Object> properties) {
Objects.requireNonNull(properties, "properties map is required");
this.properties = properties;
}
@Override
public Void put(String key, Object value) {
properties.put(key, value);
return null;
}
@Override
public Object get(String key) {
return properties.get(key);
}
@Override
public <T> Stream<T> children(String key, Function<Map<String, Object>, T> constructor) {
return Stream.ofNullable(get(key))
.filter(Objects::nonNull)
.map(el -> (List<Map<String, Object>>) el)
.findAny()
.stream()
.flatMap(Collection::stream)
.map(constructor);
}
...
}
```
Next we define an enum `Property` and a set of interfaces for type, price, model and parts. This allows us to create
static looking interface to our `Car` class.
```java
public enum Property {
PARTS, TYPE, PRICE, MODEL
}
public interface HasType extends Document {
default Optional<String> getType() {
return Optional.ofNullable((String) get(Property.TYPE.toString()));
}
}
public interface HasPrice extends Document {
default Optional<Number> getPrice() {
return Optional.ofNullable((Number) get(Property.PRICE.toString()));
}
}
public interface HasModel extends Document {
default Optional<String> getModel() {
return Optional.ofNullable((String) get(Property.MODEL.toString()));
}
}
public interface HasParts extends Document {
default Stream<Part> getParts() {
return children(Property.PARTS.toString(), Part::new);
}
}
```
Now we are ready to introduce the `Car`.
```java
public class Car extends AbstractDocument implements HasModel, HasPrice, HasParts {
public Car(Map<String, Object> properties) {
super(properties);
}
}
```
And finally here's how we construct and use the `Car` in a full example.
```java
LOGGER.info("Constructing parts and car");
var wheelProperties = Map.of(
Property.TYPE.toString(), "wheel",
Property.MODEL.toString(), "15C",
Property.PRICE.toString(), 100L);
var doorProperties = Map.of(
Property.TYPE.toString(), "door",
Property.MODEL.toString(), "Lambo",
Property.PRICE.toString(), 300L);
var carProperties = Map.of(
Property.MODEL.toString(), "300SL",
Property.PRICE.toString(), 10000L,
Property.PARTS.toString(), List.of(wheelProperties, doorProperties));
var car = new Car(carProperties);
LOGGER.info("Here is our car:");
LOGGER.info("-> model: {}", car.getModel().orElseThrow());
LOGGER.info("-> price: {}", car.getPrice().orElseThrow());
LOGGER.info("-> parts: ");
car.getParts().forEach(p -> LOGGER.info("\t{}/{}/{}",
p.getType().orElse(null),
p.getModel().orElse(null),
p.getPrice().orElse(null))
);
// Constructing parts and car
// Here is our car:
// model: 300SL
// price: 10000
// parts:
// wheel/15C/100
// door/Lambo/300
```
## Class diagram
![alt text](./etc/abstract-document.png "Abstract Document Traits and Domain")
## Applicability
Use the Abstract Document Pattern when
* there is a need to add new properties on the fly
* you want a flexible way to organize domain in tree like structure
* you want more loosely coupled system
* There is a need to add new properties on the fly
* You want a flexible way to organize domain in tree like structure
* You want more loosely coupled system
## Credits
* [Wikipedia: Abstract Document Pattern](https://en.wikipedia.org/wiki/Abstract_Document_Pattern)
* [Martin Fowler: Dealing with properties](http://martinfowler.com/apsupp/properties.pdf)
* [Pattern-Oriented Software Architecture Volume 4: A Pattern Language for Distributed Computing (v. 4)](https://www.amazon.com/gp/product/0470059028/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=javadesignpat-20&creative=9325&linkCode=as2&creativeASIN=0470059028&linkId=e3aacaea7017258acf184f9f3283b492)

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@ -32,7 +32,6 @@ import java.util.stream.Stream;
*/
public interface HasParts extends Document {
default Stream<Part> getParts() {
return children(Property.PARTS.toString(), Part::new);
}

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@ -32,7 +32,6 @@ import java.util.Optional;
*/
public interface HasPrice extends Document {
default Optional<Number> getPrice() {
return Optional.ofNullable((Number) get(Property.PRICE.toString()));
}

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@ -32,7 +32,6 @@ import java.util.Optional;
*/
public interface HasType extends Document {
default Optional<String> getType() {
return Optional.ofNullable((String) get(Property.TYPE.toString()));
}

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@ -60,7 +60,7 @@ public class CashAAATest {
//Act
cash.plus(4);
//Assert
assertEquals(cash.count(), 7);
assertEquals(7, cash.count());
}
@Test
@ -71,7 +71,7 @@ public class CashAAATest {
var result = cash.minus(5);
//Assert
assertTrue(result);
assertEquals(cash.count(), 3);
assertEquals(3, cash.count());
}
@Test
@ -82,7 +82,7 @@ public class CashAAATest {
var result = cash.minus(6);
//Assert
assertFalse(result);
assertEquals(cash.count(), 1);
assertEquals(1, cash.count());
}
@Test
@ -94,6 +94,6 @@ public class CashAAATest {
var result = cash.minus(3);
//Assert
assertTrue(result);
assertEquals(cash.count(), 8);
assertEquals(8, cash.count());
}
}

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@ -44,16 +44,16 @@ public class CashAntiAAATest {
var cash = new Cash(3);
//test plus
cash.plus(4);
assertEquals(cash.count(), 7);
assertEquals(7, cash.count());
//test minus
cash = new Cash(8);
assertTrue(cash.minus(5));
assertEquals(cash.count(), 3);
assertEquals(3, cash.count());
assertFalse(cash.minus(6));
assertEquals(cash.count(), 3);
assertEquals(3, cash.count());
//test update
cash.plus(5);
assertTrue(cash.minus(5));
assertEquals(cash.count(), 3);
assertEquals(3, cash.count());
}
}