On Feb 15, 2009, at 9:06 AM, Stuart Halloway wrote:
> > Does this clarify the point I was making? > > When writing macros, you cannot dynamically build one of the syntactic > sugar forms. For example, you cannot write a macro that expands cls > and member into (cls/member): > > (defmacro call-static [cls member] `(~cls/~member)) > -> java.lang.Exception: Invalid token: cls > > Instead, you should build normal, unsugared forms: > > (defmacro call-static [cls member] `(. ~cls ~member)) > -> nil First off, 'sugared forms' is too imprecise to talk about. More precise is, you can't write a macro that expands into a reader macro, because reading is finished. But that is not the case here. Again, start with, what do I want to write, and what expansion do I want? I want to write: (call-static foo bar) I want it to expand into: (foo/bar) Note the expansion does not contain any reader macros, so you can do it. It is also important not to lose track of the data structures (not strings!) you are manipulating. The expansion above is a list with one (namespace-qualified) symbol in it. You can't get a namespace- qualified symbol by putting two symbols on either side of a / , instead: (defmacro call-static [cls member] `(~(symbol (str cls) (str member)))) (macroexpand '(call-static foo bar)) (foo/bar) (call-static System nanoTime) -> 1234708658498938000 Rich --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
