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From Barrie Treloar <>
Subject RE: Incremental Compilation and ant
Date Fri, 21 Jul 2000 04:39:45 GMT
On Fri, 21 Jul 2000, Conor MacNeill wrote:

> 1. Add the dependency analysis to Javac and perhaps a switch to decide
> whether to use it or not. This has been proposed by Vitaly Stulsky. I think
> we still need to whole source code for this proposal.
> 2. Add a separate dependency task which generates a dependency file. Javac
> would use that file to determine which files would need to be recompiled. I
> proposed a patch for this approach. It decouples the dependency analysis
> from the javac task
> 3. I think a third possible approach would be to have a dependency task
> which removes out of date files. Javac would then recompile all necessary
> files. This completely decouples the dependency analysis and action from the
> Javac task. It could presumably be used to specify arbitrary dependencies.

I also have to agree with Peter, this is a -1 for me.

This job is really the compilers.  If the compiler kept the parse tree
around then it could use the tree to determine what to incrementally

I had a home grown Imake system which included dependencies and it
would invoke a javac for each indivual file that needed rebuilding.
Besides being a manual process (having to hand craft the imake files)
and being slow (30-45 minute build) it was easier to do as Peter
suggests and recompile the entire source in one go (a less than 5
minute build).

Most of the time you know the dependencies and can let ant check for
out of date files.  If you have suspicions then do a clean and

You could always componentize the project so that you depend upon jar
files and thus you only need to rebuild your component which is much

Barrie Treloar

  Barrie Treloar                      Phone: +61 8 8303 3300
  Senior Analyst/Programmer           Fax:   +61 8 8303 4403 
  Electronic Commerce Division        Email:
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