Dear Niels and Java Maintainers, Let me thank you sincerely for your work.
I'm writing to you to share some feedback and improvements to java-propose- classpath which I hope you might find useful. But first please excuse me for starting with describing a problem: java-propose-classpath in its current form is not very useful, to say the least. The problem is that it makes assumptions that all the required dependencies can be satisfied with installed shared java libraries (jars). If the dependency is not installed the proposed class path is incomplete and there is no warning for incomplete dependency. This is very misleading. But the problem is much worse: if java-propose-classpath is given two jars, one primary and the other one providing needed classes, java-propose-classpath tries to calculate class path for both of them, completely ignoring their relationships. (unless all dependent jars are installed to /usr/share/java the calculated class path would be incorrect) Needless to say there are many cases when application may need to install private jars and java-propose-classpath could be a very useful tool to help calculate what libraries are really needed. Sadly many Java developers distribute their stuff as a bunch of jars some of which are not even needed and some of which can be substituted with debian packages providing needed dependencies. We need a better java-propose- classpath to help maintainers to package not so perfect java software. For example, java-propose-classpath could suggest what package provides the dependent java library. This could significantly ease tedious Depends calculation which for a moment can only be done manually. ===== I experienced all the above problems when I was struggling with packaging one Java application. To overcome the issues I wrote a helper bash script which successfully deals with all described problems and more. Initially I thought I would use my script to improve java-propose-classpath but this would replace over 90% of java-propose-classpath code. It appears to me that doing it the other way (merging java-propose-classpath with my script or using my slightly modified script to replace java-propose- classpath) may be an easier task. Sadly at the moment I can't afford spending enough time to do the merging work hence I'm sharing my script with you in hope that you can accommodate improvements, ideas and implementation to the package. === The attached bash script takes one or more jars as arguments and extract all the used classes to associative arrays using the method similar to one java- propose-classpath uses. If the required class is present in given jars it considered as satisfied dependency. Then script scans the jars installed to /usr/share/java and print out all the needed classes which are not provided by neither given nor shared jars. The identified shared jars providing classes required by given jars are then printed out, with corresponding packages providing them, if 'dlocate' is installed. My implementation is slightly faster and more flexible: it can use 'fastjar', but falls back to use 'jar' provided by openjdk; it can use 'jcf-dump' from gcj-jdk but falls back to 'javap' from openjdk. Because script heavily rely on bash associative arrays it is very important to use bash (>= 4.2) because older versions affected by nasty memory leak. Without the license my script have roughly the same number of lines as java- propose-classpath so in the same size it does a bit more, including some progress indication which I find very useful when scanning large jars (it sometimes takes over 20 minutes). Please let me know what do you think. Hopefully with your suggestions we can accommodate improvements into javatools package easy enough. Please CC to me as I'm not subscribed to pkg-java-maintainers list. All the best, Dmitry. P.S. Please don't worry about license compatibility because for javatools I give permission to use GPL-2+ license.
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