Three ways to implement chain operations in PHP

There are many string functions in php. For example, you need to filter the spaces at the end of the string first, and then find its length. The general way of writing is:

strlen(trim($str))

If you want to implement a chain operation similar to that in js , for example, how should I write like the following?

$str->trim()->strlen()

The following are implemented in three ways:

Method 1. Use magic function __call combined with call_user_func to achieve

Idea: First define A string class StringHelper, the constructor directly assigns value, and then calls the trim() and strlen() functions in a chain. The calling relationship is handled by using call_user_func in the called magic function __call(). The implementation is as follows:

<?php
class StringHelper 
{
    private $value;
    
    function __construct($value)
    {
        $this->value = $value;
    }
    function __call($function, $args){
        $this->value = call_user_func($function, $this->value, $args[0]);
        return $this;
    }
    function strlen() {
        return strlen($this->value);
    }
}
$str = new StringHelper("  sd f  0");
echo $str->trim(&#39;0&#39;)->strlen();

Terminal execution script:

php test.php 
8

Method 2. Use magic function __call combined with call_user_func_array to implement

<?php
class StringHelper 
{
    private $value;
    
    function __construct($value)
    {
        $this->value = $value;
    }
    function __call($function, $args){
        array_unshift($args, $this->value);
        $this->value = call_user_func_array($function, $args);
        return $this;
    }
    function strlen() {
        return strlen($this->value);
    }
}
$str = new StringHelper("  sd f  0");
echo $str->trim(&#39;0&#39;)->strlen();

Instructions:

array_unshift(array,value1,value2,value3...)

array_unshift( ) function is used to insert new elements into an array. The values ​​of the new array will be inserted at the beginning of the array.

call_user_func() and call_user_func_array are both methods of dynamically calling functions. The difference lies in the way parameters are passed.

Method three, do not use the magic function __call to achieve

Just modify _call() to trim() function:

public function trim($t)
{
    $this->value = trim($this->value, $t);
    return $this;
}

The key point is to return the $this pointer to facilitate calling the latter function.

Recommended: "PHP Video Tutorial"

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