mmcgrana / clj-stacktrace

clj-stacktrace

clj-stacktrace is a library for creating more readable stacktraces in Clojure programs.

To install, build using ant and include the resulting clj-stacktrace.jar in your classpath.

One use for clj-stacktrace is it to print stack traces from the REPL:

=> (use 'clj-stacktrace.repl)
=> ("foo")
java.lang.ClassCastException: java.lang.String
user=> (pst)  ;instead of (.printStackTrace *e) 
java.lang.ClassCastException: java.lang.String
         Compiler.java:4163 clojure.lang.Compiler.eval
              core.clj:1497 clojure.core/eval
               main.clj:148 clojure.main/repl[fn]
               main.clj:145 clojure.main/repl
            RestFn.java:876 clojure.lang.RestFn.invoke
            repl_ln.clj:233 clojure.contrib.repl-ln/repl
            RestFn.java:402 clojure.lang.RestFn.invoke
                user.clj:71 user/eval
         Compiler.java:4152 clojure.lang.Compiler.eval
         Compiler.java:4480 clojure.lang.Compiler.load
                RT.java:327 clojure.lang.RT.loadResourceScript
                RT.java:312 clojure.lang.RT.loadResourceScript
                RT.java:308 clojure.lang.RT.maybeLoadResourceScript
                RT.java:446 clojure.lang.RT.doInit
                RT.java:286 clojure.lang.RT.<clinit>
          Namespace.java:31 clojure.lang.Namespace.<init>
         Namespace.java:116 clojure.lang.Namespace.findOrCreate
               main.java:21 clojure.main.<clinit>
           (Unknown Source) java.lang.Class.forName0
             Class.java:164 java.lang.Class.forName
      ConsoleRunner.java:69 jline.ConsoleRunner.main
Caused by: java.lang.String
                   repl-1:1 user/eval
         Compiler.java:4152 clojure.lang.Compiler.eval

In stack traces printed by pst:

• Java methods are described with the usual name.space.ClassName.methodName convention and Clojure functions with their own name.space/function-name convention.
• Anonymous clojure functions are denoted by adding an [fn] to their enclosing, named function.
• “Caused by” cascades are shown as in regular java stack traces.
• Elements are vertically aligned for better readability.
• Printing is directed to *out*.

If you want to direct the printing to somewhere other than *out*, either use pst-on to specify the output location or pst-str to capture the printing as a string.

The library also offers an API for programatically ‘parsing’ exceptions. This API is used internal for pst and can be used to e.g. improve development tools. Try for example:

=> (use '(clj-stacktrace core))
=> (try (nofn) 
     (catch Exception e 
       (prn (take 5 (:trace-elems (parse-exception e))))))

Copyright 2009 Mark McGranaghan and released under an MIT license.