Helper class that works the same as a WP function `get_template_part`, but allows pass variables to that template.

class-part-factory.php

<?php

class Part_Factory
{
    protected $tpl;
    protected $name;
    protected $data = [];

    /**
     * Part_Factory constructor.
     *
     * @param string $name   Dot notation $name e.g. `partials.home.title-item` the `.php` will be added automatically.
     * @param array $data
     */
    public function __construct($name, array $data = [])
    {
        $this->data = $data;
        $this->tpl = $this->nameToPath($this->name = $name);
    }

    /**
     * Displays the content.
     */
    public function render()
    {
        echo $this->content();
    }

    /**
     * Adds vars to the tpl.
     *
     * @param mixed $var
     * @param mixed $value
     *
     * @return $this
     */
    public function with($var, $value = null)
    {
        if (is_array($var)) {
            $this->data = array_merge($this->data, $var);
        } elseif (is_string($var)) {
            $this->data[$var] = $value;
        }

        return $this;
    }

    /**
     * Makes the HTML from the passed $name and $data
     *
     * @return false|string
     */
    public function content()
    {
        try {

            if (file_exists($located = locate_template($this->tpl))) {

                extract($this->data);

                ob_start();

                include $located;

                return ob_get_clean();
            }

            throw new Exception(sprintf('The <code>%s</code> was not found', $this->tpl));
        } catch (Throwable $e) {

            error_log($e->getMessage());

            return defined('WP_DEBUG') && WP_DEBUG ? $e->getMessage() : '';
        }
    }

    /**
     * @return false|string
     */
    public function __toString()
    {
        return $this->content();
    }

    /**
     * Makes the path from the string divided by "."
     *
     * @param string $name The name with dot notation
     *
     * @return string 	Returns the path to the file.
     */
    protected function nameToPath($name)
    {
        $raw_data = (explode('.', $name));

        $file = array_pop($raw_data) . '.php';

        $path = trailingslashit(join(DIRECTORY_SEPARATOR, $raw_data));

        return $path . $file;
    }
}

helpers.php

<?php

if (!function_exists('part')) {
    /**
     * Helper to determine the theme partial template and pass the vars into it.
     * 
     * Example: 
     *  - echo part('partials.header-secondary-menu', compact('without_share'));
     *  - echo part('partials.header-secondary-menu')->with(['without_share' => true]);
     *  - echo part('partials.header-secondary-menu')->with('without_share', true);
     *
     * @param $name
     * @param array $data
     * @return Part_Factory
     * 
     * @author rumur
     */
    function part($name, array $data = [])
    {
        return new Part_Factory($name, $data);
    }
}