路径连接，可以输入无限制个参数，不用再担心`/`反斜线重复或者缺少。TODO：处理''.",'..'这种相对路径 这个php原生有realpath方法

join_paths.php

public function joinPaths()
{
    $args = func_get_args();
    $paths = array();
    foreach ($args as $arg) {
        $paths = array_merge($paths, (array)$arg);
    }
    $paths = array_map(create_function('$p', 'return trim($p, "/");'), $paths);
    if (substr($args[0], 0, 1) == '/') {
        $paths[0] = '/' . $paths[0];
    };
    $paths = array_filter($paths);
    return join('/', $paths);
}

joinPaths('/Users/wencheng', 'devspace', 'php'); // /Users/wencheng/devspace/php

path_helper.php

pubic