Clojure 1.10.1
(defn haha []
(println (demunge (.getName (.getCallerClass
(java.lang.StackWalker/getInstance
java.lang.StackWalker$Option/RETAIN_CLASS_REFERENCE))))))
Syntax error compiling at (REPL:1:23).
Unable to resolve symbol: demunge in this context
在2021年4月30日星期五 UTC+8 上午4:35:45<Sean Corfield> 写道：
> That's definitely nicer:
>
> dev=> (*defn* *add* [a b]
>
> #_=> (*println* (demunge (*.getName* (*.getCallerClass* (
> *java.lang.StackWalker*/getInstance *java.lang.StackWalker$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" <se...@corfield.org>
>> *À: *"clojure" <clo...@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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>>
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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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