Versioning scheme

This is versioning scheme used in all Michalis' software on these pages. This versioning scheme is of course inspired by versioning schemes of many other programs and libraries, so you don't have to search far to find software with similar or just plainly the same versioning scheme.

Also some thoughts about "what good versioning scheme should look like" are given at the bottom of this page.

Major number:

1. Final programs: incremented on some major achievement (like VRML 97 conformance in castle-model-viewer).
2. Libraries or programs that are meant to be used by other programs (in "batch" mode, like std UNIX programs): incremented on incompatible changes. This should be connected with "some major achievement", since there really must exist a good reason to do some "incompatible change".

Minor number:

Incremented when some improvements that are really noticeable to all users are done. Incrementing this means "all users should really upgrade, because it's really significantly better than last version".

This doesn't concern my programs on these pages for now, but it is generally good idea and known convention : If program maintains some sort of stable and unstable branches, then it's a good idea to distinguish them by odd and even minor numbers.

Release number:

Incremented each time I upload new compiled version to these pages. Sometimes new release fixes only some minor problems (that are significant only for a very small amount of users), or implement some minor functionality that isn't so significant to increment minor number.

This doesn't concern my programs on these pages for now, but it is generally good idea and known convention : If program has public CVS (or SVN, or similar "live" code repository), then it's a good idea to increment release number right before and right after each "official" public release. This means that even release numbers indicate some real, "fixed" version of the program, and odd release numbers indicate CVS-version, that has no guarantee about stability, and changes on every commit.

What IMHO good versioning scheme should look like ?

• There must be some release number that can be incremented on every, even most minor, change to uploaded binaries. This way version number specifies the exact version of a program.
• For libraries/batch programs there must be a number to indicate incompatible changes.
• There should be a number to indicate "significant changes" to user. Two numbers, major and minor, seem to be good convention.
• If program maintains stable/unstable branches (whether it's a good idea to do so depends on the program — it's size, number of developers involved etc.) then there must be some easy way to distinguish releases of stable and unstable branches.
• If program maintains public code repository, like CVS (so that users can see state of code in the middle of development), then there should be some easy way to distinguish versions compiled from the code in the middle of development and actual, "fixed" versions.

Things to avoid in good versioning scheme (IMHO, as usual):

• Don't use numbers like "9" or "99" in minor/release number to indicate "we're really close to releasing next version". This is a nice indication for users, but usually one cannot keep the schedule. Bad examples (as of 2004-01-16): xine: version v0.99.3, xcdroast: version 0.98alpha15. Such version numbers tell only that "author thinks that it's close to next major release", but they really don't tell users how close it is (since noone believes that next xine or xcdroast will have 1.0 version. I bet these will be 0.99.4 and 0.98alpha16). So they are actually useless for users. And they make confusion, because noone is able to tell any more how many minor releases program had (without looking at some HISTORY file, that is). E.g. I don't suppose that xine had exactly 99 releases (from 0.1 to 0.99) and then 3 more.
• For the same reason, don't make assumption like "minor number is always 2 decimal digits". This is the same problem as discussed above, as it implies that after 0.99 you will have to switch to 1.0. What's so special about the number 99 ? Nothing. You can be sure that you will need a lot less or a lot more releases than 99 before you will be able to proudly present 1.0 release of your software.