Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
Generating readable code for IDEs is not a good reason. You should think carefully about variable capture and decide which you want. Usually, in a macro-generated defn, I do want to capture the parameters, so I would use ~'this. On Dec 30, 11:54 pm, André Thieme splendidl...@googlemail.com wrote: Am 31.12.2010 03:29, schrieb Alex Baranosky: I've been playing with making a macro to encapsulate Stuart's post, like this: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this key] (get this key (defrecord-ifn Foo [a b c]) (def foo (Foo. A B C)) (prn (map foo [:a :c])) = (A, C) I get the error: No such var: user/this. I guess this is because it is expanding 'this' to 'user/this'. What is the proper way to get a macro like this to expand properly? Others have already pointed to this# . I just would like to add that you can as well use ~'this in some cases, where your macros generate defns. The advantage is that some editors (like emacs) will show you the parameter vector and that would show a useful name and not this_auto_foobarbaz123456 . -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
Be sure to also implement the version of get which takes a not-found argument so that your objects will work with map code which uses this functionality. (defrecord map-like-object [field-1 field-2 etc] clojure.lang.IFn (invoke [this k] (get this k)) (invoke [this k not-found] (get this k not-found))) sincerely, --Robert McIntryre On Fri, Dec 31, 2010 at 11:04 AM, Alyssa Kwan alyssa.c.k...@gmail.com wrote: Generating readable code for IDEs is not a good reason. You should think carefully about variable capture and decide which you want. Usually, in a macro-generated defn, I do want to capture the parameters, so I would use ~'this. On Dec 30, 11:54 pm, André Thieme splendidl...@googlemail.com wrote: Am 31.12.2010 03:29, schrieb Alex Baranosky: I've been playing with making a macro to encapsulate Stuart's post, like this: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this key] (get this key (defrecord-ifn Foo [a b c]) (def foo (Foo. A B C)) (prn (map foo [:a :c])) = (A, C) I get the error: No such var: user/this. I guess this is because it is expanding 'this' to 'user/this'. What is the proper way to get a macro like this to expand properly? Others have already pointed to this# . I just would like to add that you can as well use ~'this in some cases, where your macros generate defns. The advantage is that some editors (like emacs) will show you the parameter vector and that would show a useful name and not this_auto_foobarbaz123456 . -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
Yes, that's intentional – implementing IFn is (as you can see) orthogonal to implementing IPersistentMap, IPersistentCollection, etc. Of course, keyword access of record slots is most idiomatic, e.g. (:my-slot some-record) If you'd like to pass around a function that accesses a record, there's always get, e.g. ((partial get some-record) :my-slot) - Chas On Dec 30, 2010, at 8:08 AM, Sunil S Nandihalli wrote: Hello everybody, An object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise .. Is this way by design? can it be made to behave like a hash-map without any performance penalty in terms of behaving like a function? Thanks, Sunil. -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
You can make it implement IFn easily enough: (defrecord Foo [a b c] clojure.lang.IFn (invoke [this key] (get this key))) It has been debated whether or not this is a good idea, design-wise, but it should not be a performance penalty. -Stuart Sierra clojure.com -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
I've been playing with making a macro to encapsulate Stuart's post, like this: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this key] (get this key (defrecord-ifn Foo [a b c]) (def foo (Foo. A B C)) (prn (map foo [:a :c])) = (A, C) I get the error: No such var: user/this. I guess this is because it is expanding 'this' to 'user/this'. What is the proper way to get a macro like this to expand properly? Alex -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
Alex Baranosky alexander.barano...@gmail.com writes: I've been playing with making a macro to encapsulate Stuart's post, like this: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this key] (get this key (defrecord-ifn Foo [a b c]) (def foo (Foo. A B C)) (prn (map foo [:a :c])) = (A, C) I get the error: No such var: user/this. I guess this is because it is expanding 'this' to 'user/this'. What is the proper way to get a macro like this to expand properly? Use autogensym. Stick a # on the end of bindings you declare inside syntax-quote: this# and key#. (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this# key#] (get this# key# -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
Worked like a charm. Thanks Alex. -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
Technically, there's no possibility of variable capture, but you should use gensyms: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this# key#] (get this# key# Thanks, Alyssa On Dec 30, 9:29 pm, Alex Baranosky alexander.barano...@gmail.com wrote: I've been playing with making a macro to encapsulate Stuart's post, like this: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this key] (get this key (defrecord-ifn Foo [a b c]) (def foo (Foo. A B C)) (prn (map foo [:a :c])) = (A, C) I get the error: No such var: user/this. I guess this is because it is expanding 'this' to 'user/this'. What is the proper way to get a macro like this to expand properly? Alex -- 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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
thanks everybody for the responses .. with macros around ... you just have to wish for it to get it .. but we need to be careful what we wish for :) Sunil. On Fri, Dec 31, 2010 at 8:18 AM, Alyssa Kwan alyssa.c.k...@gmail.comwrote: Argh! Six minutes! :P On Dec 30, 9:42 pm, Alyssa Kwan alyssa.c.k...@gmail.com wrote: Technically, there's no possibility of variable capture, but you should use gensyms: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this# key#] (get this# key# Thanks, Alyssa On Dec 30, 9:29 pm, Alex Baranosky alexander.barano...@gmail.com wrote: I've been playing with making a macro to encapsulate Stuart's post, like this: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this key] (get this key (defrecord-ifn Foo [a b c]) (def foo (Foo. A B C)) (prn (map foo [:a :c])) = (A, C) I get the error: No such var: user/this. I guess this is because it is expanding 'this' to 'user/this'. What is the proper way to get a macro like this to expand properly? Alex -- 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.comclojure%2bunsubscr...@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
Re: an object of class created using defrecord does not implement IFn .. while it behaves very similar to map otherwise ..
Am 31.12.2010 03:29, schrieb Alex Baranosky: I've been playing with making a macro to encapsulate Stuart's post, like this: (defmacro defrecord-ifn [name args] `(defrecord ~name ~...@args clojure.lang.IFn (invoke [this key] (get this key (defrecord-ifn Foo [a b c]) (def foo (Foo. A B C)) (prn (map foo [:a :c])) = (A, C) I get the error: No such var: user/this. I guess this is because it is expanding 'this' to 'user/this'. What is the proper way to get a macro like this to expand properly? Others have already pointed to “this#”. I just would like to add that you can as well use “~'this” in some cases, where your macros generate defns. The advantage is that some editors (like emacs) will show you the parameter vector and that would show a useful name and not “this_auto_foobarbaz123456”. -- 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
