src/Leevel/Kernel/App.php
public function appPath($app = false, string $path = ''): string
    {
        return ($this->appPath ?? $this->path.\DIRECTORY_SEPARATOR.'application').
            ($app ? \DIRECTORY_SEPARATOR.$this->normalizeApp($app) : $app).
            $this->normalizePath($path);
    }
public function appPath($app = false, string $path = ''): string
    {
        return ($this->appPath ?? $this->path.\DIRECTORY_SEPARATOR.'application').
            ($app ? \DIRECTORY_SEPARATOR.$this->normalizeApp($app) : $app).
            $this->normalizePath($path);
    }
应用路径.

@param bool|string $app
@param string      $path

@return string