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From Doug Cutting <cutt...@apache.org>
Subject Re: svn commit: r390260 - /lucene/hadoop/trunk/src/java/org/apache/hadoop/mapred/MapReduceBase.java
Date Tue, 04 Apr 2006 17:35:30 GMT
Andrzej Bialecki wrote:
> What is interesting is that javac didn't catch it either... strange. I 
> need to read a good book on Java basics, it seems. ;)

When you implement a method you only need to declare those exceptions 
that can actually be thrown.  But you then also narrow the set of 
exceptions which can be thrown by subclasses.

> It makes sense also to add the throws clause to configure, I think, as 
> Darek suggested in another post.

This is a larger change, since it is not already in the interface.  All 
places that call this method will need to be changed to handle whatever 
is thrown.

What exception should this throw?  IOException is tempting, since most 
calling code probably already handles that, but configure() isn't really 
an io-related operation.  One can always throw RuntimeException with no 
declaration.  Or we could define a new ConfigurationException, thrown by 
both Configurable.setConf() and JobConfigurable.configure().

Are there cases where we need to automatically distinguish between a 
configuration problem and other problems?  If so, then we should 
probably add this new exception.  But if we don't have examples of such, 
we might just stick with RuntimeException for now.

Doug

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