That's definitely nicer:
dev=> (*defn* *add* [a b]
#_=> (*println* (demunge (*.getName* (*.getCallerClass* (
*java.lang.StackWalker*/getInstance *java.lang.StackWalker$Option*
/RETAIN_CLASS_REFERENCE)))))
#_=> (*+* a b))
#'dev/add
dev=> (add 1 2)
dev/add
3
dev=>
Thanks, Rémi!
On Thu, Apr 29, 2021 at 12:08 PM Remi Forax <fo...@univ-mlv.fr> wrote:
>
>
> ------------------------------
>
> *De: *"Sean Corfield" <s...@corfield.org>
> *À: *"clojure" <clojure@googlegroups.com>
> *Envoyé: *Jeudi 29 Avril 2021 01:26:34
> *Objet: *Re: How get function name in body?
>
> Consider that:
>
> (defn add [a b] (+ a b))
>
> is expanded to (something like):
>
> (def add (fn [a b] (+ a b)))
>
> So the actual code that runs is an anonymous function, which is bound to
> the (global) var #'add -- the function itself has no name.
>
> dev=> (*macroexpand* '(*defn**add* [a b] (*+* a b)))
>
> (def add (clojure.core/fn ([a b] (+ a b))))
>
> dev=> (*defn**add* [a b] (*+* a b))
>
> #'dev/add
>
> dev=> add
>
> #object[dev$add 0x72f91c91 "dev$add@72f91c91"]
>
> So the value of add is an object, with type dev$add, a class that
> implements a bunch of things including clojure.lang.IFn and
> java.lang.Runnable and java.util.concurrent.Callable etc.
>
> The "name" of function is hard to get to, inside a function because of
> that.
>
> One way to figure that out at runtime is to dig into the stack, which you
> can get at by creating an exception and inspecting it: be aware that this
> is an expensive operation!
>
> dev=> (*defn**add* [a b]
>
> #_=> (*let* [frame (*first* (*:trace* (*Throwable->map* (*ex-info**""*
> {}))))]
>
> #_=> (*println* (demunge (*name* (*first* frame))))
>
> #_=> (*+* a b)))
>
> #'dev/add
>
> dev=> (add 1 2)
>
> dev/add
>
> 3
>
> dev=>
>
> demunge is what turns Clojure's generated classnames back into readable
> source names.
>
>
> Instead of using the stacktrace of java.lang.Throwable, you can use
> StackWalker.getCallerClass() if you are using a jdk 9+
>
>
> The more important question is: why do you want the function's name inside
> the body?
> --
> Sean A Corfield -- (904) 302-SEAN
> An Architect's View -- https://corfield.org/
> World Singles Networks, LLC. -- https://worldsinglesnetworks.com/
>
> "Perfection is the enemy of the good."
> -- Gustave Flaubert, French realist novelist (1821-1880)
>
>
> Rémi
>
> [1]
> https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/StackWalker.html#getCallerClass()
>
> --
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> .
>
--
Sean A Corfield -- (904) 302-SEAN
An Architect's View -- https://corfield.org/
World Singles Networks, LLC. -- https://worldsinglesnetworks.com/
"Perfection is the enemy of the good."
-- Gustave Flaubert, French realist novelist (1821-1880)
--
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first post.
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