When I had my first ball python, back in the 90's, I fed in its enclosure. No one told me any different, and it never occurred to me that I should do anything different. I never had a problem with any kind of aggression. He had a great feeding response, when it was time to eat. When he wasn't hungry, he was as docile as ever.

With my snakes now I have a routine that tells them when it's feeding time and when it's not. I generally don't handle them too much in the evening, which is when I do feed them. I handle them in the day time, including cleaning out their tubs and changing their waters. I also take the lid off their tub entirely when it is time for handling. Unless they are VERY hungry, they seem to realize the difference between these routines. Only one snake has ever acted like he was going to bite during the handling routine, and that was a feeding response type behavior because he skipped his last meal due to being in shed. (Only other threatened bites were from the axanthics when they were tiny and afraid of everything.)