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.\" MANIFEST: AUUGN Feb'98 Article
.\"
.nh 1 "The Problem"
There are numerous problems with recursive \fImake\fP,
and they are usually observed daily in practice.
Some of these problems include:
.IP \(bu 2n
It is very hard to get the
.I order
of the recursion into the sub-directories correct.
This order is very unstable
and frequently needs to be manually ``tweaked.''
Increasing the number of directories,
or increasing the depth in the directory tree,
cause this order to be increasingly unstable.
.IP \(bu 2n
It is often necessary to do more than one pass over the sub-directories
to build the whole system.  This, naturally, leads to extended build
times.
.IP \(bu 2n
Because the builds take so long, some dependency information is omitted,
otherwise development builds take unreasonable lengths of time,
and the developers are unproductive.
This usually leads to things not being updated when they need to be,
requiring frequent ``clean'' builds from scratch,
to ensure everything has actually been built.
.IP \(bu 2n
Because inter-directory dependencies are either omitted or too hard to express,
the \f(CWMakefiles\fP are often written to build
.I "too much"
to ensure that nothing is left out.
.IP \(bu 2n
The inaccuracy of the dependencies, or the simple lack of dependencies,
can result in a product which is incapable of building cleanly,
requiring the build process to be carefully watched by a human.
.LP
Not all projects experience all of these problems.  Those that do
experience the problems may do so intermittently, and dismiss the
problems as unexplained ``one off'' quirks.  This paper attempts to
bring together a range of symptoms observed over long practice, and
presents a systematic analysis and solution.
.LP
It must be emphasized that this paper does not suggest that \fImake\fP
itself is the problem.  This paper is working from the premise that
\fImake\fP does \fBnot\fP have a bug, that \fImake\fP does \fBnot\fP have
a design flaw.  The problem is not in \fImake\fP at all, but rather in
the input given to \fImake\fP \- the way \fImake\fP is being used.