Condtional execution: if / then / else

Context

Let's see how we can execute some code if a condition (already evaluated) is true ( <> 0) or some other code if false (=0). A best practice would be to end up at the same cursor position for both cases.
There are multiple ways to implement such behavior, one is: set an 'else' bit to true, execute some code if condition is true, using the details mentionnes on this previous post, that would also reset condition and else bit; move to else bit and execute some code if else is still true (so, if condition was false) and reset else bit.
Initial state

• Memory: A, 0
• Cursor: first cell
• Input: any

Process

• Set second cell to 1
• While first cell is not null
• Do something
• Reset first cell
• Reset second cell
• While second cell is not null
• Do something else
• Reset second cell
• Go back to first cell (optional)

Code 

>+<[ do something [-]>-<]>[ do something else -]<

Final state

• Memory: 0, 0
• Cursor: first cell
• Input: any
• Output: unchanged

Note: another option would be to have a different cursor position during else execution between the two cases

>+<[ do something [-]>-]>[ do something else ->]<<

Here

• if condition is true, then cursor is on third cell while else is executed
• if condition is false, then cursor is on second cell while else is executed

But in all cases, cursor ends up at the same position.