Plugging in MBP Without having it Charge?

Whenever I sit around my house working on my PC laptop for hours, I usually have it plugged into the wall like a lot of people do. However, I like to have my battery unplugged while I am using the laptop as it's plugged in (as long as the battery is already charged). This helps prevent the degrading of the laptop's battery. I am planning on buying a MacBook Pro, but since the battery isn't user removable, is there a way I can still accomplish this? I know the batteries in MacBook Pros are like ten bajillion times better than PCs, but I would still like to prevent the degrading of it if I can. You know, there's no point in ruining the battery, right?

Thanks