Hi Shantanu, It depends on exactly what you want when you say "accomplish this". The Clojure "(new Foo)" and "(Foo.)" forms map to Java new. You cannot call Java new generically, from any Java language. You have to have a class already in hand.
If you want genericity at compilation time, you could write a macro that expands to a new form. But probably what you want is genericity at runtime. For this, you need to use Java reflection to instantiate the class. There is a previous thread on this that includes some sample code [1], but nothing in Clojure (yet). It is fairly easy to write a reflective factory that is good enough for a single app or library, but harder to write one that is general enough to be in Clojure proper. There is an outstanding ticket that would cover this [2] and it will probably get into the release of Clojure after 1.2. Stu [1] http://groups.google.com/group/clojure/browse_thread/thread/bd7be7bd373eadba/4bc3e7a2099ad72d [2] https://www.assembla.com/spaces/clojure/tickets/374-print-read-syntax-for-defrecords > I tried to assign a data type to a var and then instantiate it using > the var, but it doesn't seem to work: > > user=> (defrecord X []) > user.X > > user=> (X.) > #:user.X{} > > user=> X > user.X > > user=> (def hey X) > #'user/hey > > user=> (hey.) > java.lang.IllegalArgumentException: Unable to resolve classname: hey > (NO_SOURCE_FILE:59) > > user=> (new X) > #:user.X{} > > user=> (new hey) > java.lang.IllegalArgumentException: Unable to resolve classname: hey > (NO_SOURCE_FILE:61) > > user=> (apply new hey) > java.lang.Exception: Unable to resolve symbol: new in this context > (NO_SOURCE_FILE:62) > > Can anybody help me understand how to accomplish this when using the > var? This will give me a generic way to instantiate the type when I > know the parameters. > > Regards, > Shantanu > > -- > 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 -- 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
