Re: Interop: mutability vs. inheritance
I think that's correct (with the exception you already mention yourself: you can use a :state structure containing multiple values). OK. If you care mostly about performance, maybe using an array as :state will do. That's always mutable and access is really fast. Oh, nice idea. I forgot about that option. Thanks. -- 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/d/optout.
Interop: mutability vs. inheritance
Is the following correct? The only way to define *multiple* mutable instance variables/fields for a class visible in Java is by using deftype with :volatile-mutable or :unsynchronized-mutable. The only way to inherit from a concrete Java class is by using gen-class or proxy. gen-class allows a single mutable field using :state and :init. Thus there is no way to define a class that both inherits from a concrete class and defines more than one new instance variable. I believe these statements are correct, but gen-class is complex and deftype use has some nuances, so I want to make sure I haven't missed something. I know that I can use gen-class's state variable to hold multiple mutable structures by putting e.g. atoms inside of a map or record stored in the state variable, or by storing a deftype instance with mutable fields in the state variable. (Context: I'm getting a meaningful performance boost by replacing atoms in a map or a record in a gen-class state variable, with deftype with :volatile-mutable in a gen-class state variable. I keep wondering whether my gen-class class really needs to delegate to a deftype structure. This is for an application that needs to extend one or more Java classes. I know that :volatile-mutable and :unsynchronized-mutable are intended to be used only by experts. I'm not an expert. I've asked a question on StackOverflow http://stackoverflow.com/questions/30472496/risks-of-volatile-mutable-fields-in-single-threaded-contexts about whether the particular way that I'm using :volatile-mutable, i.e. solely in single-threaded application, is safe. Feel free to comment there or here on that issue, as well as on my main question above.) Thanks. -- 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/d/optout.
Re: Interop: mutability vs. inheritance
Mars0i marsh...@logical.net writes: I believe these statements are correct, but gen-class is complex and deftype use has some nuances, so I want to make sure I haven't missed something. You have missed one possible approach – write a small integration class in Java which delegates behavior to a parameterized something more easily expressed in idiomatic Clojure (e.g., an `IFn` function or `reify`d interface). I’ve made this joke before, but: Java is a pretty solid DSL for writing Java classes. When you need a Java class which conforms to some combination of Java-side abstract signatures (extending a base class, AOTed for discovery by name via reflection, annotations, etc), in my experience it is frequently/nearly-always easier to adapt from that interface to Clojure in Java that it is to adapt to that interface from Clojure in Clojure. Some examples: https://github.com/damballa/parkour/blob/master/src/java/parkour/hadoop/Mappers.java https://github.com/damballa/abracad/blob/master/src/java/abracad/avro/ClojureDatumReader.java HTH, -- Marshall Bockrath-Vandegrift llas...@damballa.com Principal Software Engineer, Damballa RD -- 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/d/optout.
Re: Interop: mutability vs. inheritance
Thanks--you're right, of course, Marshall. (I almost added without writing it in Java somewhere in the first part of the post. That doesn't mean writing parts in Java isn't worth considering. I'm just trying to figure out what will and won't work in Clojure itself.) -Marshall On Wednesday, May 27, 2015 at 1:17:15 PM UTC-5, Marshall Bockrath-Vandegrift wrote: Mars0i mars...@logical.net javascript: writes: I believe these statements are correct, but gen-class is complex and deftype use has some nuances, so I want to make sure I haven't missed something. You have missed one possible approach – write a small integration class in Java which delegates behavior to a parameterized something more easily expressed in idiomatic Clojure (e.g., an `IFn` function or `reify`d interface). I’ve made this joke before, but: Java is a pretty solid DSL for writing Java classes. When you need a Java class which conforms to some combination of Java-side abstract signatures (extending a base class, AOTed for discovery by name via reflection, annotations, etc), in my experience it is frequently/nearly-always easier to adapt from that interface to Clojure in Java that it is to adapt to that interface from Clojure in Clojure. Some examples: https://github.com/damballa/parkour/blob/master/src/java/parkour/hadoop/Mappers.java https://github.com/damballa/abracad/blob/master/src/java/abracad/avro/ClojureDatumReader.java HTH, -- Marshall Bockrath-Vandegrift lla...@damballa.com javascript: Principal Software Engineer, Damballa RD -- 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/d/optout.
Re: Interop: mutability vs. inheritance
Mars0i marsh...@logical.net writes: Is the following correct? The only way to define *multiple* mutable instance variables/fields for a class visible in Java is by using deftype with :volatile-mutable or :unsynchronized-mutable. The only way to inherit from a concrete Java class is by using gen-class or proxy. gen-class allows a single mutable field using :state and :init. Thus there is no way to define a class that both inherits from a concrete class and defines more than one new instance variable. I think that's correct (with the exception you already mention yourself: you can use a :state structure containing multiple values). I know that I can use gen-class's state variable to hold multiple mutable structures by putting e.g. atoms inside of a map or record stored in the state variable, or by storing a deftype instance with mutable fields in the state variable. If you care mostly about performance, maybe using an array as :state will do. That's always mutable and access is really fast. Other than that, I agree with Marshall that Java is a solid DSL for writing Java classes. Bye, Tassilo -- 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/d/optout.
