Re: General Question about Config Files and IoC

Paul Hammant wrote:

> Peter, Chad,
>
>>
>>> Do I need to make a separate "ObjectAConfig" class, which just holds 
>>> the config settings from the file, and then have a constructor like 
>>> this:
>>>   new ObjectA(objectAConfig, objectB)
>>>
>>> Is this the preferred approach, or am I missing something?
>>
>>
>>
>> I believe that is the preferred approach when doing constructor-based 
>> dependency injection.
>>
>> Of course, it doesn't have to be an 'ObjectAConfig' class, it could 
>> be a Properties object, a DOM document, or anything else.. but there 
>> is the general principal of passing a representation of the config 
>> via the constructor. 
>
>
>
> I'd always suggest not doing a Properties or DOM object via the ctor. 
> It is too vague.  An interface to represent the the configuration, 
> with multiple possible implementations is my preference.
>

Although I've not yet tried simplifying my life with a picocontainer, I 
have been trying out constructor-based dependency injection quite a bit 
recently.  I've sort of been following a rule of three; if I have more 
than two things to pass into my constructor I encapsulate them in a 
*Configuration class (or interface).  Although it looked a bit 
heavyweight at first, I have found that it's not that bad, and it really 
helps with readability as well.  In addition, it's nice to explicitly 
separate configuration concerns from application concerns; for instance, 
I am enjoying capturing IOExceptions and stuff during application 
startup and then not having to worry about them anymore.

--
Ryan Hoegg
ISIS Networks
http://www.isisnetworks.net/