2010-07-27

dependency versioning

7.10: adda/lib'mgt/dependency versioning:

[7.27: summary:
. these are rough ideas for
how to keep a library of software components
modifiable and evolvable,
without having problems with version conflicts .]

. intro to versions conflicting with portability:
"(
Forth was interesting in that
not only it was written in itself,
but all the internals were available
to any programs written in it,
and, furthermore, could be changed at will.
The thing is, Forth lacked abstraction.
Yes, you could change the compiler.
But, of course, you’d have to know
how the specific compiler worked:
eg, for threaded code, variants included:
generated {indirectly, directly, subrouting},
and generated {bytecode, machine coded}.
So it had no portability at all.
)
--. that inspired these ideas:

. in addition to there being
versions for systems;
any component that allows being changed,
must have it's own version number
for both the spec' or interface changes,
and the impl' or build changes .
. if the author (ie, the name of a fork)
is not specified with the version number;
then it's assumed to be from the main source .

. to be portable with forks,
the original site must provide
version numbers for
all components, and all forks .

. in order for a fork to use
the original project's name,
it must subscribe to the original's
versioning protocol:
a component lists its dependencies
which includes the release version
of a particular fork
modified with the release versions
for particular components .

. that means when a library or app
is introduced to a platform's lib mgt,
it gives the expected release versions:
this is described economically by saying
most components' versions are that of
some author's system release;
while a few components vary from that release,
and are described individually .
. the lib'mgt then checks these dependencies,
and tries to procure them if not present .

. the user should also be notified
when an installation has
many unique dependencies;
at least if the practical size
is significantly larger
than the app's stated size .

. each version requires its own
space in the library,
along with pointers to
whatever other units are using it;
so then, if you uninstall a unit,
all its bloat goes with it,
unless a dependency is still used
by other units .