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More readable stacktraces for Clojure

branch: master
README.md

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 user-wide basis. Just add the following to ~/.lein/profiles.clj:

{:user {:dependencies [[clj-stacktrace "0.2.7"]]
        :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 (deref new))))]}}

The :injections clause replaces the built-in stack trace printing with enhanced clj-stacktrace version; you can leave it out if you plan on invoking clj-stacktrace functions directly or are using tools which are already clj-stacktrace-aware.

License

Copyright © 2009-2013 Mark McGranaghan and contributors.

Released under an MIT license.

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