Hi,
Thomas Müller schrieb:
Hi,
Major new developments -- the implementation of the foreseen JCR 2.0 ACL
functionality comes to mind -- should be done on development branches and
merged back into trunk as the developer(s) see fit aka ready for release.
Regular development still takes place on trunk, of course.
If done correctly, major new development can be done in the trunk
without risk.
Sure, if it only concerns a single location or limited set of locations.
If it touches multiple places, this is not that easy.
How to do that: Use a (static final boolean) constant to
enable / disable a certain new feature or new code path. It is used in
the DataStore implementation. At first, it was disabled (only enabled
when I run tests), and now it is enabled by default:
class InternalValue {
public static final boolean USE_DATA_STORE =
Boolean.valueOf(System.getProperty("org.jackrabbit.useDataStore",
"true")).booleanValue();
}
and then, everywhere where it is required, do this:
if (USE_DATA_STORE) {
// new code
} else {
// old code
}
As an added advantage, it's easy to find out if this feature is
responsible for a problem, by disabling the system property.
I basically like the idea but have my reservations with respect to
system property use: It makes it difficult in embedded situations and
even almost makes it impossible to use in app server or servlet
container environments. For example: you want to have two repositories
in the same Java VM, one with and one without data store....
If is really just for testing, a "public" field is bad, because this
quickly becomes (de-facto) API. And a branch may still be better suited.
Probably better -- also for visibility -- would be to have a
functionality to provide this kind of setup as part of the Repository
descriptors. (And yes, I cannot imagine how to implement this in the
InternalValue class you presented. Maybe the use case is slightly wrong
in that the InternalValue should just use a "store", which in turn
either uses the new data store code or the old code and has to be setup
somehow)
Regards
Felix
