A Leiningen plugin to work around long-classpath issues on Windows.
Most Clojure tooling, including lein, run programs by constructing
a big classpath out of the dependency tree and then passing that as
a command-line argument to java.
On Windows this can be problematic when the classpath is very long, since the length of Windows command-line arguments is extremely constrained when compare to most Unix-based OSes. Depending on various factors, the maximum length can range from 8191 characters to 32K characters, but even 32K may not be enough for some applications with a large dependency tree.
The symptom of this is usually that you'll get an exception from
running lein repl that resembles this:
Exception in thread "Thread-2" java.io.IOException: Cannot run program "java" (in directory "C:\Users\tim\blah"): CreateProcess error=206, The filename or extension is too long
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
[...]
Caused by: java.io.IOException: CreateProcess error=206, The filename or extension is too long
at java.lang.ProcessImpl.create(Native Method)
[...]
The usual solution to this problem for JVM-based Windows development is
to create a "pathing jar" - that is, a jar which only contains a Manifest
that points to the various jar files that make up the entire classpath
of the program. Java can then be invoked via java -cp pathing.jar clojure.main
and the resulting JVM will have the proper classpath.
More information can be found in the tools.deps ticket TDEPS-120.
This leiningen plugin borrows an idea from tools.deps.alpha - whenever
a classpath is generated by leiningen, we compute its MD5 hash and
generate a pathing jar file based on that hash. Then we return the
location of the jar file, rather than the concatenated list of every
jar file actually on the path.
As a bonus, the generated files are compatible with the Windows tools.deps implementation.
This is intended to work as a user-level plugin. To use it, add this to
the :plugins vector of your :user profile:
{:user {:plugins [[lein-classpath-jar "0.1.0"]]}}Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.