example of stream wrappers

register_file.php

<?php

// a fork of http://php.net/manual/ja/stream.streamwrapper.example-1.php
class VariableStream {
    var $position;
    var $varname;

    function stream_open($path, $mode, $options, &$opened_path)
    {
        //$url = parse_url($path);
        //$this->varname = $url["host"];
        $this->varname = $path;
        $this->position = 0;

        return true;
    }

    function stream_read($count)
    {
        $ret = substr($GLOBALS[$this->varname], $this->position, $count);
        $this->position += strlen($ret);
        return $ret;
    }

    function stream_write($data)
    {
        $left = substr($GLOBALS[$this->varname], 0, $this->position);
        $right = substr($GLOBALS[$this->varname], $this->position + strlen($data));
        $GLOBALS[$this->varname] = $left . $data . $right;
        $this->position += strlen($data);
        return strlen($data);
    }

    function stream_tell()
    {
        return $this->position;
    }

    function stream_eof()
    {
        return $this->position >= strlen($GLOBALS[$this->varname]);
    }

    function stream_seek($offset, $whence)
    {
        switch ($whence) {
            case SEEK_SET:
                if ($offset < strlen($GLOBALS[$this->varname]) && $offset >= 0) {
                     $this->position = $offset;
                     return true;
                } else {
                     return false;
                }
                break;

            case SEEK_CUR:
                if ($offset >= 0) {
                     $this->position += $offset;
                     return true;
                } else {
                     return false;
                }
                break;

            case SEEK_END:
                if (strlen($GLOBALS[$this->varname]) + $offset >= 0) {
                     $this->position = strlen($GLOBALS[$this->varname]) + $offset;
                     return true;
                } else {
                     return false;
                }
                break;

            default:
                return false;
        }
    }

    function stream_metadata($path, $option, $var) 
    {
        if($option == STREAM_META_TOUCH) {
            $url = parse_url($path);
            $varname = $url["host"];
            if(!isset($GLOBALS[$varname])) {
                $GLOBALS[$varname] = '';
            }
            return true;
        }
        return false;
    }

    function stream_stat()
    {
        return [];
    }
}


stream_wrapper_unregister('file');
stream_wrapper_register("file", "VariableStream");
$varname = 'tmp.txt';
$$varname = 'aaa';

echo file_get_contents("tmp.txt"); //aaa

register_http.php

 <?php
 use Vfs\FileSystem;
 use Vfs\Node\Directory;
 use Vfs\Node\File;

 require_once __DIR__.'/vendor/autoload.php';

 stream_wrapper_unregister('http');
 $fs = FileSystem::factory('http');
 $dir = new Directory(['tmp.txt' => new File('Hello')]);
 $fs->get('/')->add('example.com', $dir);

 echo file_get_contents('http://example.com/tmp.txt'); // Hello