As Carlo said, we need to keep track of when things are running. Within the context of any given unquote, for instance ~@(for [meth meths] ...), we're actually executing code. So if you don't quote the expression `(~method-name ~args ~@body), you (1) will try to execute the function "method-name" right there, giving the *result* to the reify macro instead of giving the *expression* to reify.
The REPL is very helpful when digging into why quoting works the way it does (and `macroexpand-1` / `macroexpand` in particular for using syntax-quoting in macros). One other idea to look at, besides the great ones Gary mentioned, is a blog I did awhile back quoting: http://blog.8thlight.com/colin-jones/2012/05/22/quoting-without-confusion.html - Colin On Tuesday, June 18, 2013 2:47:58 AM UTC-5, Hussein B. wrote: > > I don't get why we have to use a second 'back tick'. I thought one > backtick at the beginning and then we use ~ and ~@ when needed. > > On Tuesday, June 18, 2013 2:09:44 AM UTC+2, Carlo wrote: >> >> I can't speak to the issues that Gary raised, but I can help you with >> your macro. >> >> (defmacro servlet [servlet-name & meths] >> `(reify Servlet >> ~@(for [meth meths] >> (let [[method-name args & body] meth >> method-name (hyphenated->camel-case method-name)] >> `(~method-name ~args ~@body))))) >> >> The key here is to keep track of when things are run. The `for` must be >> run at compile time in order to generate the code we want, so we have to >> escape it with ~@. The code that the `for` creates (in the form of a list) >> must then be (quasi-)quoted again by the backtick. >> >> Macros certainly take some getting used to. >> >> >> On Tue, Jun 18, 2013 at 8:12 AM, Hussein B. <hubag...@gmail.com> wrote: >> >>> Here is my fourth attempt: >>> >>> (defmacro servlet [servlet-name & meths] >>> `(reify Servlet >>> (for [meth ~meths] >>> (let [[method-name args & body] ~meth >>> camel-case-method-name (hyphenated->camel-case >>> ~method-name)] >>> (camel-case-method-name ~args ~@body))))) >>> >>> Still it is not working :( >>> >>> How to fix it? >>> >>> On Tuesday, June 18, 2013 12:04:50 AM UTC+2, Gary Trakhman wrote: >>> >>>> Unquoting 'camel-case-method-name' is going to try and replace the >>>> symbol with it's value during compile-time in the context of the macro >>>> itself. >>>> >>>> also, reify isn't going to work if you need a named class to actually >>>> wire up your servlet, for example with a web.xml. Also, consider that >>>> you'll need some AOT compilation for the container to actually see the >>>> servlet class. >>>> >>>> >>>> On Mon, Jun 17, 2013 at 4:38 PM, Hussein B. <hubag...@gmail.com> wrote: >>>> >>>>> Hi, >>>>> >>>>> My target is to have something like this: >>>>> >>>>> (servlet "ArticlesServlet" >>>>> (do-get [this request response] >>>>> (println "Get Request")) >>>>> (do-post [this request response] >>>>> (println "Post Request"))) >>>>> >>>>> >>>>> I started with this: >>>>> >>>>> (defmacro servlet [servlet-name meths] >>>>> `(reify Servlet >>>>> (for [meth ~@meths] >>>>> (let [[method-name params & body] meth >>>>> camel-case-method-name (hyphenated->camel-case >>>>> method-name)] >>>>> (~camel-case-method-name ~@body))))) >>>>> >>>>> But of course, it is not working :) >>>>> >>>>> I get: >>>>> >>>>> CompilerException java.lang.RuntimeException: Unable to resolve >>>>> symbol: camel-case-method-name in this context >>>>> >>>>> Why? >>>>> >>>>> And of course, feel super free to correct my Macro :) >>>>> >>>>> Thanks for help and time. >>>>> >>>>> -- >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To post to this group, send email to clo...@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+u...@**googlegroups.com >>>>> >>>>> For more options, visit this group at >>>>> http://groups.google.com/**group/clojure?hl=en<http://groups.google.com/group/clojure?hl=en> >>>>> --- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to clojure+u...@**googlegroups.com. >>>>> >>>>> For more options, visit >>>>> https://groups.google.com/**groups/opt_out<https://groups.google.com/groups/opt_out> >>>>> . >>>>> >>>>> >>>>> >>>> >>>> -- >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Clojure" group. >>> To post to this group, send email to clo...@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+u...@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 unsubscribe from this group and stop receiving emails from it, send >>> an email to clojure+u...@googlegroups.com. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >>> >>> >> >> -- -- 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 unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
