Set widget class programmatically

Hello!

I need to set widget css class from widget php code. I know that i can set widget class in Attributes > Widget Class input. Is it possible to do the same, but from php code?

Also, i know that i can pass some class name in widget constructor, param $widget_options, but in this case classname will be set to main widget wrapper, but i need to set it to panel-widget-style wrapper, so in this case i can override styles using controls in Design widget settings.

Thanks!