Hi there, how about rewriting Ant 2.0 using Scala? Scala appears to be well suited as a scripting language. Charged with a scripting language, I could write low level macros on the fly.
// Wolfgang On Fri, Feb 17, 2012 at 2:31 AM, Bruce Atherton <br...@callenish.com> wrote: > I thought I'd expand on why I got so excited about NIO 2.0 and JSR 203 as > well as the other changes in Java 7. I can see I have done a bad job of > selling the benefits of a refactoring for potential volunteers. Reading > through the changes that were introduced in Java 7, it seems to me that Ant > was probably an inspiration for a lot of them. > > Others come from taking the performance of I/O on Java more seriously. This > has the potential to speed Ant up enormously. Projects like Tim Bray's Wide > Finder 2[1] showcased just how badly Java performed and benchmarks like that > may have been an impetus to focus resources on taking advantage of all the > features of the native filesystems. Unfortunately the results of the project > are lost due to Oracle's acquisition of Sun, but you can still see the > results from the original Wide Finder 1[2] although there isn't even an > attempt to do a Java implementation there. I can tell you from memory that > the final results on WF2 were several C implementations with innovative I/O > using parallel processing at the top, erlang and ruby and scala were up > there, but the fastest Java implementation was in the double digits in the > list as I recall. > > The basics for file handling in Java 7 are provided by Path and the Paths > Utility class, along with the FileSystemProvider classes. If Ant 2 were > created to make Resource a fundamental element and Path the Resource that > represented something on a file system (native file systems, zip/jar file > systems, and I expect eventually open source projects will add others like > HTTP, FTP, NFS and Samba), I think the LOC count on Ant could be reduced > tremendously. Writing patches would be simplified and contributing to Ant > would have a lower barrier to entry for new people coming in. Path is > immutable which suits Ant well. Path has methods to access elements in a > file path, compare, test, normalize, and relativize paths in the ways that > Ant has code to do. It has all kinds of features for determining > accessibility on the native filesystem and bulk loading file metadata > attributes whereas currently it is done one field at a time. Symbolic link > identification and handling is a core feature. And converting to and from > File objects is trivial. > > Add to that the new methods on File. There is also a Files utility helper > class. Files covers the most basic tasks in Ant implemented using all the > features of the native filesystem to make them as fast as possible: copying; > deleting; moving; reading file contents; writing; creating directories, file > and links; getting input and output streams. There is also recursion with a > method for walking a file tree that creates a FileVisitor interface > implementation, either default or custom, with 3 phases: previsit directory, > visit file, and postvisit directory. It also provides for a visit file > failed method. At each point you can continue, stop, skip subtree, or skip > other entries in the current directory. Options control whether symlinks are > followed, and cycles are detected. > > DirectoryStream includes filters like glob, regex, and custom > implementations that could be perfect for implementing Selectors. > DirectoryStream uses less resources and works much better with remote > resources. It also handles directories that are very large much more > efficiently. > > Error handling throughout is by exception rather than boolean value as it is > now, which I'm sure we all agree is preferable. > > Then there is the Watch Service which uses the native eventing service if > available, where you can get events in your build when a file is created or > deleted, or when a directory is modified. Would we translate it into > something for BuildListeners? How would we harness it, scheduling a target > and its dependencies when the a watch fired an event? > > I could keep going but this is getting rather long. I'll just point out a > few resources from other people that are clearer than I am and have more > detail: The Java 7 feature list[3] is comprehensive but has little on the > impact of features; this Doctor Dobbs post[4] has good code examples for how > NIO 2 could be used by Ant; an article listing "8 things I found most > useful"[5], all of which are relevant to a simplified Ant implementation, > details the NIO 2 changes at #8; interviews with Alan Bateman in text[6], > video[7], and podcast[8] are interesting, as is a JavaOne 2011 slide > show[9]; Leandro Pezzente sent me a link[10] (thanks, Leandro) that lists > some of the other changes to Java 7 to think about, although it only > mentions the file system changes that JSR 203 introduces in passing. > > [1] http://www.tbray.org/ongoing/When/200x/2008/05/01/Wide-Finder-2 > [2] http://www.tbray.org/ongoing/When/200x/2007/10/30/WF-Results > [3] http://openjdk.java.net/projects/jdk7/features/#f250 > [4] http://drdobbs.com/blogs/jvm/231600403 > [5] http://jaxenter.com/java-7-the-top-8-features-37156.html > [6] http://www.artima.com/lejava/articles/more_new_io.html > [7] http://www.youtube.com/watch?v=yNRS1ssLPdQ > [8] > https://blogs.oracle.com/javaspotlight/entry/java_spotlight_episode_59_alan > [9] http://openjdk.java.net/projects/nio/presentations/TS-5052.pdf > [10] > http://marxsoftware.blogspot.com/2011/03/jdk-7-new-interfaces-classes-enums-and.html > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@ant.apache.org > For additional commands, e-mail: dev-h...@ant.apache.org > -- Wolfgang Häfelinger --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@ant.apache.org For additional commands, e-mail: dev-h...@ant.apache.org
