What are the implementation methods of PHP chain operation?

How to implement chain operation in php: 1. Use magic function "__call" combined with "call_user_func" to implement; 2. Use magic function "__call" combined with "call_user_func_array" to implement; 3. Use trim() function to implement.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

There are many strings in php Function, for example, you need to filter the spaces at the end of a 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 you write it like the following

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

The following are implemented in three ways:

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

Thoughts:First define a string class StringHelper, the constructor assigns value directly, then calls the trim() and strlen() functions in a chain, and uses call_user_func in the called magic function __call() to handle the calling relationship. 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 achieve

<?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, use the trim() function to achieve

Just need to modify _call() to trim()Function is enough:

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

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

Recommended learning: "PHP Video Tutorial"

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