LonoCloud / clj-stacktrace

More readable stacktraces for Clojure

clj-stacktrace

A library for creating more readable stacktraces in Clojure programs.

For example, to print a nice stack trace in a REPL:

=> (use 'clj-stacktrace.repl)
=> ("foo")
java.lang.ClassCastException: java.lang.String cannot be cast to clojure.lang.IFn (NO_SOURCE_FILE:0)
       Compiler.java:5440 clojure.lang.Compiler.eval
       Compiler.java:5391 clojure.lang.Compiler.eval
            core.clj:2382 clojure.core/eval
             main.clj:183 clojure.main/repl[fn]
             main.clj:204 clojure.main/repl[fn]
             main.clj:204 clojure.main/repl
          RestFn.java:422 clojure.lang.RestFn.invoke
             main.clj:262 clojure.main/repl-opt
             main.clj:355 clojure.main/main
          RestFn.java:398 clojure.lang.RestFn.invoke
             Var.java:361 clojure.lang.Var.invoke
             AFn.java:159 clojure.lang.AFn.applyToHelper
             Var.java:482 clojure.lang.Var.applyTo
             main.java:37 clojure.main.main
Caused by: java.lang.String cannot be cast to clojure.lang.IFn
         NO_SOURCE_FILE:2 user/eval100
       Compiler.java:5424 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
    (parse-exception e)))

Leiningen

If you use Leiningen, you can install clj-stacktrace on a per-user basis.

For Leiningen 2.x, add the following to ~/.lein/profiles:

{:user {:dependencies {clj-stacktrace "0.2.4"}
        :injections [(let [orig (ns-resolve (doto 'clojure.stacktrace require)
                                            'print-cause-trace)
                           new (ns-resolve (doto 'clj-stacktrace.repl require)
                                           'pst)]
                       (alter-var-root orig (constantly @new)))]

For Leiningen 1.x:

$ lein plugin install clj-stacktrace 0.2.4

Add this to your ~/.lein/init.clj file:

(try (require 'leiningen.hooks.clj-stacktrace-test)
     (def settings {:repl-options [:init (require 'clj-stacktrace.repl)
                                   :caught 'clj-stacktrace.repl/pst+]})
  (catch java.io.FileNotFoundException _))

The hook will enable clj-stacktrace to be used across all the projects you work on in clojure.test and other things that use the clojure.stacktrace library. The :repl-options settings will cause clj-stacktrace to be used in the repl and swank tasks.

License

Copyright © 2009-2011 Mark McGranaghan and released under an MIT license.