I think it's important that Clojure be good at exploring Java
libraries. Helpful and correct error messages are important for this.
I often go looking for a function at the REPL, like so:
user=> substring
java.lang.Exception: Unable to resolve symbol: substring in this
context (NO_SOURCE_FILE:0)
user=> substr
java.lang.Exception: Unable to resolve symbol: substr in this context
(NO_SOURCE_FILE:0)
user=> subs
#<core$subs__5256 clojure.core$subs__5...@37699720>
Aha! It's 'subs'. This doesn't work with Java methods though.
user=> (.substringXXXX (String. "foo"))
java.lang.IllegalArgumentException: No matching field found:
substringXXXX for class java.lang.String (NO_SOURCE_FILE:0)
user=> (.substring (String. "foo"))
java.lang.IllegalArgumentException: No matching field found: substring
for class java.lang.String (NO_SOURCE_FILE:0)
You've got to supply the right arguments else you get no hint that you
have found a method:
user=> (.substring (String. "foo") 1)
"oo"
Same thing with static methods:
user=> (String/valueOf)
java.lang.NoSuchFieldException: valueOf (NO_SOURCE_FILE:89)
Not true. And there's no hint that I'm any closer to a real method
than if I'd tried gibberish:
user=> (String/valueOfXXX)
java.lang.NoSuchFieldException: valueOfXXX (NO_SOURCE_FILE:88)
Here's the correct usage:
user=> (String/valueOf 9)
"9"
On Wed, Jun 24, 2009 at 9:38 PM, Mark Addleman<mark_addle...@bigfoot.com> wrote:
>
> Searching through this forum, I found many posts relating to improving
> Clojure's error messages. I stumbled across one where Rich makes a
> plea for concrete suggestions to specific cases. I'm very sympathetic
> to that, so I'd like to start a thread of specific coding errors that
> I've run across where I've felt the error messages could be improved.
>
> (*) Improperly specifying a map, e.g. "{:a 1 :b}" yields an array out
> of bounds exception.
>
>
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
-~----------~----~----~----~------~----~------~--~---
