Backwards Compatibility

Artyom Desyatnikov

Points

Backwards Compatibility

Concept
Why it is hard
What if we don't

Concept

Versioning
Consistence between versions
Stable API

is not enough

Why it is hard

Undocumented behaviour
Sim City & Windows 95

stable consistent API is sometimes not enough a strict sense of it should not only be the API which is to conform to the previous version behaviour but also the every single piece of information on the underlying software accessible to a user. to say nothing about responding to interactions undocumented or even prohibited in the API contract. consider an example of a notorious city simulator game under the name of SimCity. on market since MS-DOS times turned out not to work with Win95. used memory after freeing it. MS spent resources to introduce a specially designed mode of memory management. turning to my next point i'll try to clarify why such policy is the way to go in the OS development.

Backwards Compatibility

Points