This changes the buildlink3.mk files to use an include guard for the
recursive include. The use of BUILDLINK_DEPTH, BUILDLINK_DEPENDS,
BUILDLINK_PACKAGES and BUILDLINK_ORDER is handled by a single new
variable BUILDLINK_TREE. Each buildlink3.mk file adds a pair of
enter/exit marker, which can be used to reconstruct the tree and
to determine first level includes. Avoiding := for large variables
(BUILDLINK_ORDER) speeds up parse time as += has linear complexity.
The include guard reduces system time by avoiding reading files over and
over again. For complex packages this reduces both %user and %sys time to
half of the former time.
QOF, the Query Object Framework, provides a set of C Language
utilities for performing generic structured complex queries on a
set of data held by a set of C/C++ objects. This framework is unique
in that it does NOT require SQL or any database at all to perform
the query. Thus, it allows programmers to add query support to
their applications without having to hook into an SQL Database.
Typically, if you have an app, and you want to add the ability to
show a set of reports, you will need the ability to perform queries
in order to get the data you need to show a report. Of course, you
can always write a set of ad-hoc subroutines to return the data
that you need. But this kind of a programming style is not extensible:
just wait till you get a user who wants a slightly different report.
The idea behind QOF is to provide a generic framework so that any
query can be executed, including queries designed by the end-user.
Normally, this is possible only if you use a database that supports
SQL, and then only if you deeply embed the database into your
application. QOF provides simpler, more natural way to work with
objects.
