I've never tried, but I've always read the opposite. I've seen many claims of coding better when high.
Then again, I've seen many claims of playing pool better when drunk, and that's definitely not true.
No, it really doesn't work.
Yes, it really doesn't help focusing. But on the other hand I heard many stories where people fought addiction with weed. Smoking some in the evening as a reward instead of drinking might be helpful.