Ok, now by now i think to have understand... To do right, I should build a macro similar to let where I pass the filename and after execute the body close the stream, right ?
On Dec 13, 9:42 pm, Cedric Greevey <cgree...@gmail.com> wrote: > On Tue, Dec 13, 2011 at 10:14 PM, Simone Mosciatti <mweb....@gmail.com> wrote: > > No, I'm sure to not use all the sequence, so I will follow your second > > advice, but... > > > Cause of my non-perfect english I've not really understand the last > > part. > > Who is the caller ? > > You suggest something like this: > > > (let [fl (clojure.java.io/reader "path/filename") > > rd (lazy-reader fl)] > > (do-my-operation-with-lazy-reader) > > (.close fl)) > > > ??? > > Pretty much, yes. The lazy-reader function will of course not call > clojure.java.io/reader on its argument, instead just passing it > directly to its internal function lr. And if > (do-my-operation-with-lazy-reader) returns a lazy sequence that's > backed by the lazy-reader sequence, then either it needs to be doall'd > before (.close fl) or the responsibility for creating and closing the > reader needs to be pushed up to *its* user. Generally, if dealing with > data that might not fit in main memory you'd need to push the reader's > lifetime management up to the level where you're not just wrapping the > seq but reducing over it, searching it for an item (with something > like (first (filter ...)) or (first (remove ...)) or (last ...) or > (some ...)), or picking a limited sample (e.g. (take > some-finite-number (filter foo (some-wrapped-lazy-reader-seq rdr)))). -- 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
