流接口模式（Fluent Interface）#

1. 目的#

用来编写易于阅读的代码，就像自然语言一样（如英语）

2. 例子#

Doctrine2 的 QueryBuilder，就像下面例子中类似
PHPUnit 使用连贯接口来创建 mock 对象
Yii 框架：CDbCommand 与 CActiveRecord 也使用此模式

3. UML 图#

4. 代码#

你可以在 GitHub 上找到这些代码

Sql.php

<?php

namespace DesignPatterns\Structural\FluentInterface;

class Sql
{
    /**
     * @var array
     */
    private $fields = [];

    /**
     * @var array
     */
    private $from = [];

    /**
     * @var array
     */
    private $where = [];

    public function select(array $fields): Sql
    {
        $this->fields = $fields;

        return $this;
    }

    public function from(string $table, string $alias): Sql
    {
        $this->from[] = $table.' AS '.$alias;

        return $this;
    }

    public function where(string $condition): Sql
    {
        $this->where[] = $condition;

        return $this;
    }

    public function __toString(): string
    {
        return sprintf(
            'SELECT %s FROM %s WHERE %s',
            join(', ', $this->fields),
            join(', ', $this->from),
            join(' AND ', $this->where)
        );
    }
}

5. 测试#

Tests/FluentInterfaceTest.php

<?php

namespace DesignPatterns\Structural\FluentInterface\Tests;

use DesignPatterns\Structural\FluentInterface\Sql;
use PHPUnit\Framework\TestCase;

class FluentInterfaceTest extends TestCase
{
    public function testBuildSQL()
    {
        $query = (new Sql())
                ->select(['foo', 'bar'])
                ->from('foobar', 'f')
                ->where('f.bar = ?');

        $this->assertEquals('SELECT foo, bar FROM foobar AS f WHERE f.bar = ?', (string) $query);
    }
}

原文：

https://laravel-china.org/docs/php-design-patterns/2018/FluentInterface/1503

最后更新: 2018年8月4日 13:08:23