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))
???
Or what ?
On Dec 13, 1:20 am, Cedric Greevey <cgree...@gmail.com> wrote:
> You also probably want more efficiency. Try something closer to:
>
> (defn lazy-reader [filename]
> (let [rd (fn [rdr]
> (let [buf (char-array 4096)
> n (.read rdr buf 0 4096)]
> (condp == n
> -1 (.close rdr)
> 0 (recur rdr)
> (take n buf))))
> lr (fn lr [rdr]
> (lazy-seq
> (if-let [b (rd rdr)]
> (concat b (lr rdr)))))]
> (lr (clojure.java.io/reader filename))))
>
> which should buffer the reads and terminate when the stream is
> consumed (untested). I'm not sure how to additionally make the seq
> "chunked".
>
> I avoided with-open to avoid the stream closing before the lazy seq is
> consumed. Instead, it closes only when the lazy seq is fully consumed,
> or when it's been discarded and the GC runs the stream's finalizer
> after discovering that it's become unreachable. The latter could take
> a while (and isn't guaranteed to happen short of the JVM exiting) so
> there's a risk of running out of file handles using this a lot without
> fully consuming the lazy seqs. If that could be an issue, I'd suggest
> modifying it to take a reader rather than a filename, and making the
> caller responsible for instantiating the reader, passing it in,
> (partially) consuming the sequence, and closing the reader if the
> sequence may not have been fully consumed.
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