Question

我不确定术语“通配符”是否可以解释我的观点，但有时在一些现成的脚本中，我们可以调用一个非定义的函数，如find_by_age(23)，其中age可以是映射到数据库的任何其他函数表记录。所以我可以致电find_by_name，find_by_email，find_by_id等等。那么我们怎么能以程序或面向对象的方式做这样的事情呢？

Answer 1

您正在寻找的术语是魔法。

基本上是这样的：

class Foo {
    public function __call($method,$args) {
        echo "You were looking for the method $method.\n";
    }
}

$foo = new Foo();
$foo->bar(); // prints "You were looking for the method bar."

对于您正在寻找的内容，您只需过滤掉错误的函数调用并重定向好的函数：

class Model {
    public function find_by_field_name($field,$value) { ... }
    public function __call($method,$args) {
        if (substr($method,0,8) === 'find_by_') {
            $fn = array($this,'find_by_field_name');
            $arguments = array_merge(array(substr($method,8)),$args);
            return call_user_func_array($fn,$arguments);
        } else {
            throw new Exception("Method not found");
        }
    }
}

Answer 2

您可以通过在类中定义__call魔术方法来使用它们，您只能在类中使用它们。全球范围

引用PHP手册：

<?php
class MethodTest {
    public function __call($name, $arguments) {
        // Note: value of $name is case sensitive.
        echo "Calling object method '$name' "
             . implode(', ', $arguments). "\n";
    }

    /**  As of PHP 5.3.0  */
    public static function __callStatic($name, $arguments) {
        // Note: value of $name is case sensitive.
        echo "Calling static method '$name' "
             . implode(', ', $arguments). "\n";
    }
}

$obj = new MethodTest;
$obj->runTest('in object context');

MethodTest::runTest('in static context');  // As of PHP 5.3.0
?>

以上示例将输出：

Calling object method 'runTest' in object context
Calling static method 'runTest' in static context

Answer 3

对于程序解决方案，您只需使用字符串连接即可完成工作。您可以通过将其称为strategy pattern的实现来稍微改变一下。

<?php

/**
 * Employ a find by name strategy
 */
function find_by_name($name)
{
    echo "You are searching for users with the name $name";
    return array();
}

/**
 * Employ a find by age strategy
 */
function find_by_age($age)
{
    echo "You are searching for users who are $age years old";
    return array();
}

/**
 * Find users by using a particular strategy
 */
function find_using_strategy($strategy='age', $parameter)
{
    $results = array();
    $search_function = 'find_by_' . $search_field;
    if (function_exists($search_function)) {
        $results = $search_function($parameter);
    }

    return $results;
}


$users = find_using_strategy('name', 'Matthew Purdon');
var_dump($users);

PHP函数中的通配符

3 个答案: