Clojurians Log v2

Morning

Is it expected that satisfies? returns false for vals extending the protocol with metadata?

Case in point:

(defprotocol A :extend-via-metadata true (a [this]))
(satisfies? A (with-meta {} {`a identity})) ;; => false

but as expected:

(a (with-meta {} {`a identity})) ;; => {}

Shouldn’t the protocol opt-in to extension via metadata?

@orestis you're right, my example misses that, fixed

Ah: https://clojure.atlassian.net/browse/CLJ-2426 and https://ask.clojure.org/index.php/4622/satisfies-doesnt-work-instance-based-protocol-polymorphism?show=4622#q4622

seem to cover it

so it's considered as a fix

satisfies? is also quite slow

(for now)

there's a separate ticket for that

https://clojure.atlassian.net/browse/CLJ-1814

on the downside, fixing CLJ-2426 will only hurt perf more

quick question: is the syntax #^ for meta data deprecated ? I only found this commit for v1.2 to allow ^ for metadata but unfortunately the changes.md file goes up until v1.3 😅 https://github.com/clojure/clojure/commit/a5ca8243e3ea45e6387b2b00d0e9b2624d16adbf

#^ is a deprecated synonym of ^

so this is “official” ? because I couldnt find anything stating it 😕

a long time ago ^ used to mean read-time meta and #^ was the way to do read time with-meta

^ is the "preferred" way to do it now, but #^ is never going away or change

it's deprecated in the sense that ^ is equivalent and preferred to it

There's some uses in the clojure source code still

:thumbsup::skin-tone-4:

thanks a lot for the info

https://github.com/clojure/clojure-site/blob/7493bdb10222719923519bfd6d2699a26677ee82/content/guides/weird_characters.adoc#L309 somewhat documented here

(says the same thing as @bronsa )

@bronsa are there any cases where #^ supports more than ^?

at one point I thought there was something

like in the odder cases where you hint a string :tag or something?

no they're literally the same

you're thinking of something else

https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/LispReader.java#L94 https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/LispReader.java#L109

^^ they both just invoke the MetaReader

I think some developers may have become accustomed to the idea that "deprecated" means "will likely go away in a future version" ? That does not seem to apply to Clojure, and not very often to Java.