How to group compilation commands for multiple targets?

[Berche, Guillaume]

Hello,

After reading the great article "Recursive Make Considered Harmful" 
http://www.canb.auug.org.au/~millerp/rmch/recu-make-cons-harm.html I was 
thinking on how I could try to optimize my make-based build process for my 
application written in Java. 

Apart from recursive make invocation, the next slowest thing in my build 
process is that I compile each source file after the other whereas the java 
compiler (javac) can handles multiples sources files in the same command. 
Consequently, my makefile forks a javac process more often that it could.

I could not devise how to group many dependencies that need to be rebuilt into 
the same command. Can somebody enlighten me? I looked into the info files as 
well as on the web. By the way, is there a FAQ for this mailing-list? 

Here is an example. Imagine that A.java and B.java require compilation. Here is 
my makefile:


classes: A.class B.class C.class

%.class: %.java
        javac $?


How can I have make to launch the following command:

javac A.java B.java 

instead of launching

javac A.java B.java 
javac B.java 



Any idea is much welcome!

Regards,

Guillaume.