Won't work. The "def" gets executed at compile time, before the JAR
file exists.

On Oct 22, 3:55 pm, ataggart <alex.tagg...@gmail.com> wrote:
> (defn get-version []
>   (-> (str "jar:" (-> my.ns.name (.getProtectionDomain)
>                                  (.getCodeSource)
>                                  (.getLocation))
>                   "!/META-INF/MANIFEST.MF")
>     (URL.)
>     (.openStream)
>     (Manifest.)
>     (.. getMainAttributes)
>     (.getValue "Build-number")))
>
> (def *version* (get-version))
>
> On Oct 22, 11:56 am, Ralph <grkunt...@gmail.com> wrote:
>
>
>
> > I have a Clojure program that I build as a JAR file using Maven.
> > Embedded in the JAR Manifest is a build-version number, including the
> > build timestamp.
>
> > I can easily read this at runtime from the JAR Manifest using the
> > following code:
>
> > (defn set-version
> >   "Set the version variable to the build number."
> >   []
> >   (def version
> >     (-> (str "jar:" (-> my.ns.name (.getProtectionDomain)
> >                                    (.getCodeSource)
> >                                    (.getLocation))
> >                     "!/META-INF/MANIFEST.MF")
> >       (URL.)
> >       (.openStream)
> >       (Manifest.)
> >       (.. getMainAttributes)
> >       (.getValue "Build-number"))))
> > but I've been told that it is bad karma to use def inside defn.
>
> > What is the Clojure-idiomatic way to set a constant at runtime? I
> > obviously do not have the build-version information to embed in my
> > code as a def, but I would like it set once (and for all) from the
> > main function when the program starts. It should then be available as
> > a def to the rest of the running code.

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