2015-02-14 20:23 GMT+01:00 Steve Miner <[email protected]>:
> Clojure doesn't give you direct access to the name of the function you're
> defining. However, you could use a macro to get that. Here’s one way.
> This macro binds the strange symbol %0 to the symbol naming the current
> function.
>
> ;; %0 is bound to the function's symbolic name within the function.
> Useful for pre-conditions,
> ;; logging and error reporting.
> (defmacro defn0 [fname & fdcls]
> `(let [~'%0 (symbol (name (ns-name *ns*)) (name '~fname))]
> (defn ~fname ~@fdcls)))
>
> ;; For example...
> (defn0 my-func [x]
> (println "calling" %0 x)
> (+ x 3))
>
> user=> (my-func 11)
> calling user/my-func 11
> 14
>
> The downside to using something like this is that other people might have
> a harder time reading your code. I thought it was clever when I wrote it,
> but I don't actually use it much.
>
Very handy. Another place where I can use it to write a general function
to check parameters. When I have several functions that use almost the same
parameters I could write a generic function to check them (DRY) and give
the function name to handle the differences.
I rewrote it a little to make it more clear:
(defmacro defn-with-functionname [fname & fdcls]
`(let [~'%FUNCNAME (symbol (name (ns-name *ns*)) (name '~fname))]
(defn ~fname ~@fdcls)))
(defn-with-functionname my-func [x]
(println "calling" %FUNCNAME x)
(+ x 3))
>
>
> > On Feb 14, 2015, at 11:11 AM, Cecil Westerhof <[email protected]>
> wrote:
> >
> > In Bash I use the following construct:
> > printf "${FUNCNAME} needs an expression\n"
> >
> > In this way I do not have to change the print statement when the name of
> the function changes. Is something like this also possible in clojure?
>
--
Cecil Westerhof
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