Included require statement (instead of if statement) to check if msg.sender is owner before executing the rest of the addMgr function. The require statement is first so the function will fail as soon as possible and always throw an exception
Allows admin to stop functions from executing. On the front , there is an Emergency Stop button that only the admin can see. When pressed , purchasing a song will no longer work. Would be necessary when any problems are discovered.
Included modifiers and require statements so that only certain accounts can run certain functions. Only an admin can see and perform admin functions. And only a band manager can see and perform band manager functions.
Design pattern not necessary, admin can always add band managers and band managers can always add songs for sale. This could change in the future if it was decided to have a sale on songs, then prices would be reduced for a specified time and shown to visitors
Would like to investigate this design pattern for security considerations, instead ofthe current implementation of tranferring funds to the seller during a sale