in reply to Re^2: Is there any way to put regex modifiers into a variable?
in thread Is there any way to put regex modifiers into a variable?

the /o modifier

Although I'm having trouble finding it at the moment, I think there was some recent discussion that /o is often not what you want. All I found so far is /o is dead, long live qr//!, although that's not recent. There's the FAQ What is /o really for?. You could perhaps look into qr//.