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From Andrzej Bialecki>
Subject Re: no static NutchConf
Date Wed, 04 Jan 2006 16:52:32 GMT
Stefan Groschupf wrote:

> Hi,
> to move forward in the direction of having a nutch gui, I would love  
> to start removing the static access of NutchConf.
> Based on experience first I would love to get a kind of general  
> agreement and a 'go' before wasting to much time for an unaccented  
> solution.

I agree with the general direction. Some comments below:

> I suggest:
> + removing NutchConf.get().

I'm not sure about this... Somewhere you need to instantiate the default 
config, and this looks like a good place.

> + in case a lower level object use only one, two but not more than 3  
> parameters from the nutch configuration, we add this parameter to the  
> constructor of this object.
> (e.g. MapFile.Reader needs only the parameter INDEX_SKIP)

I don't fully agree with this. In most such cases, you already have a 
NutchConf instance in the method or class context, so it makes sense to 
use it in the constructor. You could add these construtors with all 
parameters iterated, but I'd expect that the constructors using 
NutchConf would be used most frequently.

> + for higher level objects like fetcher tool- that need more than 3  
> parameters for the lower level object -  we add a instance of  
> NutchConf to the Constructor


> + for all dynamic used object that implements a specific interface  
> (interface > no control over the object constructor) we use the  
> Configurable interface to set the NutchConf in a inversion of control  
> like style.
> (e.g. Plugin Extension Implementations like Parser or Protocols)


> + PluginRegestry will not longer a singleton but will get an  
> constructor with a NutchConf instance.

Definitely yes.

> + Getting a Extension, require also a NutchConf that is injected in  
> case the Extension Object (e.g. a Parser) implements a Configurable  
> interface.

Yes. If you remember our discussion, I'd like also to follow a pattern 
where such instances are cached inside this NutchConf instance, if 
appropriate (i.e. if they are reusable and multi-threaded).

> Any comments, improvement suggestions, more use-cases?
> I would love to do this job, can I get a go from the other developers?

+1 from me.

Best regards,
Andrzej Bialecki     <><
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