Re: Preferred way of binding jdbc connections
Hi Shantanu, that was perfect, thanks. I note that this article only deprecates dynamic scoping in libraries, so my conclusion is that what I am considering is not an antipattern. Indeed, Stuart Sierra says the same: Applications can manage their own resources, and only the application programmer knows what the extent of those resources should be. Maybe you can pass it around as a value. Maybe you want to use dynamic binding after all. Maybe you want to stash it in a global state Var. That’s for you to decide. On Wednesday, August 28, 2013 10:55:10 PM UTC-7, Shantanu Kumar wrote: Hi Lyn, Dynamic vars for resource sharing is not a favored approach due to performance and several other reasons. This blog post explains it well: http://stuartsierra.com/2013/03/29/perils-of-dynamic-scope Shantanu On Thursday, 29 August 2013 07:21:46 UTC+5:30, Lyn Headley wrote: Hello, if I want to run some sql code in a transaction, I can do this (where clojure.java.jdbc is referred to as j): (j/db-transaction [conn dbspec] use conn here But if I have a function I want to call from this transaction, say to do a query, then I need to pass in the connection to that function: (defn query [conn] do query on conn...) (j/db-transaction [db dbspec] (query conn)) I am trying to decide whether I like passing in the connection to query, or whether I would rather use a binding like so: (def ^:dynamic *conn*) (defn query [] do query on *conn*...) (j/db-transaction [conn dbspec] (binding [*conn* conn] (query))) Looking at the jdbc docs, I notice that this style used to be directly supported but is now deprecated. Does that mean it's a bad idea to re-implement on top of the supported API, as my example would? Can someone explain the tradeoffs involved? Thanks, Lyn Headley -- -- 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.
Preferred way of binding jdbc connections
Hello, if I want to run some sql code in a transaction, I can do this (where clojure.java.jdbc is referred to as j): (j/db-transaction [conn dbspec] use conn here But if I have a function I want to call from this transaction, say to do a query, then I need to pass in the connection to that function: (defn query [conn] do query on conn...) (j/db-transaction [db dbspec] (query conn)) I am trying to decide whether I like passing in the connection to query, or whether I would rather use a binding like so: (def ^:dynamic *conn*) (defn query [] do query on *conn*...) (j/db-transaction [conn dbspec] (binding [*conn* conn] (query))) Looking at the jdbc docs, I notice that this style used to be directly supported but is now deprecated. Does that mean it's a bad idea to re-implement on top of the supported API, as my example would? Can someone explain the tradeoffs involved? Thanks, Lyn Headley -- -- 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.
Re: Preferred way of binding jdbc connections
Hi Lyn, Dynamic vars for resource sharing is not a favored approach due to performance and several other reasons. This blog post explains it well: http://stuartsierra.com/2013/03/29/perils-of-dynamic-scope Shantanu On Thursday, 29 August 2013 07:21:46 UTC+5:30, Lyn Headley wrote: Hello, if I want to run some sql code in a transaction, I can do this (where clojure.java.jdbc is referred to as j): (j/db-transaction [conn dbspec] use conn here But if I have a function I want to call from this transaction, say to do a query, then I need to pass in the connection to that function: (defn query [conn] do query on conn...) (j/db-transaction [db dbspec] (query conn)) I am trying to decide whether I like passing in the connection to query, or whether I would rather use a binding like so: (def ^:dynamic *conn*) (defn query [] do query on *conn*...) (j/db-transaction [conn dbspec] (binding [*conn* conn] (query))) Looking at the jdbc docs, I notice that this style used to be directly supported but is now deprecated. Does that mean it's a bad idea to re-implement on top of the supported API, as my example would? Can someone explain the tradeoffs involved? Thanks, Lyn Headley -- -- 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.
