[CLJ-859] Built in dynamic vars don't have :dynamic metadata

Fri, 24 Feb 2012 12:41:31 -0600

I'm sure 'built in' is probably not the right term here, but I'm not sure what these are called.

I ran into this issue earlier today while fixing a bug in clojail. Built in vars, particularly ones listed here without a source link: http://clojure.github.com/clojure/clojure.core-api.html, do not have :dynamic metadata despite being dynamic. This includes *in*, *out*, and *err* among others. Here are some examples:

user=> (meta #'*err*)
{:ns #<Namespace clojure.core>, :name *err*, :added "1.0", :doc "A java.io.Writer object representing standard error for print operations.\n\n  Defaults to System/err, wrapped in a PrintWriter"}
user=> (meta #'*in*)
{:ns #<Namespace clojure.core>, :name *in*, :added "1.0", :doc "A java.io.Reader object representing standard input for read operations.\n\n  Defaults to System/in, wrapped in a LineNumberingPushbackReader"}
user=> (meta #'*out*)
{:ns #<Namespace clojure.core>, :name *out*, :added "1.0", :doc "A java.io.Writer object representing standard output for print operations.\n\n  Defaults to System/out, wrapped in an OutputStreamWriter", :tag java.io.Writer}
user=> (meta #'*ns*)
{:ns #<Namespace clojure.core>, :name *ns*, :added "1.0", :doc "A clojure.lang.Namespace object representing the current namespace.", :tag clojure.lang.Namespace}

Clojure JIRA

[CLJ-859] Built in dynamic vars don't have :dynamic metadata