"Simulate" package namespace at development stage

Dear list,

I was wondering if it is possible to create and use a package namespace at
the development stage of a package. To clarify, I would like to make sure
that my package functions (and not some other functions that happen to have
identical names) are called by prepending function names appropriately (e.g.
my.package::foo()). Is that possible before a package is actually build and
loaded? If so, could you tell me how to do it?

Thanks a lot!
Janko