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https://issues.apache.org/jira/browse/HADOOP-1231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12510490
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Owen O'Malley edited comment on HADOOP-1231 at 7/5/07 2:41 PM:
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The signatures for JobConf.setMapperClass and setReducerClass should not have
parameters. I'd suggest:
{{{code}}}
public void setMapperClass(Class<? extends Mapper> mapper);
public void setReducerClass(Class<? extends Reducer> reducer);
{{{code}}}
In terms of {{LongSumReducer}} and other generic mappers and reducers, I'd be
tempted to allow the user to write either the anonymous class that you
suggested or use the current solution of:
{{{code}}}
grepJob.setReducerClass(LongSumReducer.class);
grepJob.setOutputValueClass(Text.class);
{{{code}}}
was:
The signatures for JobConf.setMapperClass and setReducerClass should not have
parameters. I'd suggest:
{{public void setMapperClass(Class<? extends Mapper> mapper); }}
In terms of {{LongSumReducer}} and other generic mappers and reducers, I'd be
tempted to allow the user to write either the anonymous class that you
suggested or use the current solution of:
{{{code}}}
grepJob.setReducerClass(LongSumReducer.class);
grepJob.setOutputValueClass(Text.class);
{{{code}}}
> Add generics to Mapper and Reducer interfaces
> ---------------------------------------------
>
> Key: HADOOP-1231
> URL: https://issues.apache.org/jira/browse/HADOOP-1231
> Project: Hadoop
> Issue Type: Improvement
> Components: mapred
> Reporter: Owen O'Malley
> Assignee: Tom White
> Attachments: HADOOP-1231.patch
>
>
> By making the input and output types of the Mapper and Reducers generic, we
> can get the information from the classes and not require the user to set them
> in the configuration.
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