I read this in a book:
Most of the time, calls to third-party products are entangled throughout the code. But if you really abstracted the idea of a database out—to the point where it simply provides persistence as a service—then you have the flexibility to change horses in midstream.
Could you please explain to me in plain English (or by example) what does the idea written above in bold mean?
I quoted the paragraph above from a book called: The Pragmatic Programmer on page 60. The more appropriate tag for my question is reversibility but it is not available.