Hi! Am 03.02.2009 um 17:26 schrieb Mark Volkmann:
> On Tue, Feb 3, 2009 at 8:24 AM, Konrad Hinsen <konrad.hin...@laposte.net > > wrote: >> >> On Feb 3, 2009, at 14:49, Mark Volkmann wrote: >> >>> I see from the feedback so far that my statements are wrong. >>> However, >>> I think it's true that there are *some* things you can do in a >>> function that you cannot do in a macro, and perhaps vice-versa. Are >>> those clearly documented anywhere? If not, what are some? >> >> I can't think of anything that would be "forbidden" in a macro but >> "allowed" in a plain function. There are many things that don't make >> sense in a macro, of course: launching agents, opening windows, ... > > Now I remember what I was thinking about. This isn't so much a > difference between macros and functions as it is a rule about > something you cannot do in a macro. Quoting from "Programming Clojure" > ... > > "You cannot write a macro that expands to any of the syntactic sugar > forms ... For example, you cannot write a macro that > expands to (Math/PI)." > > "when you are writing macros, make sure they expand to ordinary forms, > not any of the sugared short forms." It's certainly ugly and inconvenient to do it this way, but it seems to work fine: user=> (defmacro static-field [c f] (symbol (str (name c) \/ (name f)))) #'user/field user=> (macroexpand-1 '(static-field Math PI)) Math/PI user=> (static-field Math PI) 3.141592653589793 user=> (defmacro call-method [o m] `(~(symbol (str \. m)) ~o)) #'user/call user=> (macroexpand-1 '(call-method "foo" toString)) (.toString "foo") user=> (call-method "foo" toString) "foo" Kind regards, achim > -- > R. Mark Volkmann > Object Computing, Inc. > > > --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
