[jira] [Issue Comment Edited] (MAHOUT-633) Add SequenceFileIterable; put Iterable stuff in one place

["Dmitriy Lyubimov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAHOUT-633?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13010497#comment-13010497 ] 

Dmitriy Lyubimov edited comment on MAHOUT-633 at 3/23/11 10:39 PM:
-------------------------------------------------------------------

if you want to be true to the Hadoop contract, you need to refactor the following to use hadoop's ReflectionUtils and pass in the configuration. There are tons of writables around that are also Configurable. Including one of my Mahout's branches that equips VectorWritable with additional capabilties and controls them by making it Configurable.

{code}
private void instantiateKeyValue() throws IOException {
+    try {
+      key = keyClass.newInstance();
+      if (noValue) {
+        value = null;
+      } else {
+        value = valueClass.newInstance();
+      }
+    } catch (InstantiationException ie) {
+      throw new IOException(ie);
+    } catch (IllegalAccessException iae) {
+      throw new IOException(iae);
+    }
+  }
{code}

      was (Author: dlyubimov):
    if you want to be true to the Hadoop contract, you need to refactor the following use hadoop's ReflectionUtils and pass in the configuration. There are tons of writables around that are also Configurable. Including one of my Mahout's branches that equips VectorWritable with additional capabilties and controls them by making it Configurable.

{code}
private void instantiateKeyValue() throws IOException {
+    try {
+      key = keyClass.newInstance();
+      if (noValue) {
+        value = null;
+      } else {
+        value = valueClass.newInstance();
+      }
+    } catch (InstantiationException ie) {
+      throw new IOException(ie);
+    } catch (IllegalAccessException iae) {
+      throw new IOException(iae);
+    }
+  }
{code}
  
> Add SequenceFileIterable; put Iterable stuff in one place
> ---------------------------------------------------------
>
>                 Key: MAHOUT-633
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-633
>             Project: Mahout
>          Issue Type: Improvement
>          Components: Classification, Clustering, Collaborative Filtering
>    Affects Versions: 0.4
>            Reporter: Sean Owen
>            Assignee: Sean Owen
>            Priority: Minor
>              Labels: iterable, iterator, sequence-file
>             Fix For: 0.5
>
>         Attachments: MAHOUT-633.patch
>
>
> In another project I have a useful little class, SequenceFileIterable, which simplifies iterating over a sequence file. It's like FileLineIterable. I'd like to add it, then use it throughout the code. See patch, which for now merely has the proposed new classes. 
> Well it also moves some other iterator-related classes that seemed to be outside their rightful home in common.iterator.

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