[ruby-talk:14053] Re: OO

> My question would be how are parts of a program
> supposed to talk to this
> Options object?
> 

2 cents:

>  - I could instantiate an Options object and then
> pass it to each object
>    as one of its initialization parameters

Does it make sense for each object to contain an
"Options"?  It seems like "Options" could be one of
many ways for an object to be populated with state. 
Each object shouldn't have to know about the many
possible ways.  I would keep that knowledge outside of
the objects.

>  - I could instantiate an Options object and place
> it in $OPTIONS so that
>    each object could access that object directly

This combines the object coupling of the first option
with temporal coupling ($OPTIONS has to be valid
before the objects try to use it).

>  - I could instantiate an Options object and store
> it in a Resources class
>    using a class method, and then use another class
> method to read the
>    options back, e.g. Resources.options(...)
>  - I could make Options not instantiatable at all
> and just have class methods
>    to load and access the options
> 

Your problem, IMO, isn't about instance vs. class
methods.  It's about coupling.  I don't think the
previous two possibilities address that.

What kind of data will be stored in the "Options"
object?  What do the individual classes need from it? 
It sounds like you are creating a static configuration
mechanism.  Another coupling-related fear that I would
have is that, when you pass a full "Options" into an
object, you are probably giving that object access to
any of the data in "Options".  So, you're creating
possible dependencies between every object that uses
"Options" and every possible "Option".

The solution I would propose is that you keep
"Options" outside of any objects that don't
specifically need it.  Then, from a controller object
(probably the same one that actually instantiates each
object), you can read "Options" and pass any required
data to the objects that need it.  With this approach,
"Options" doesn't know about your objects, and your
objects don't know about "Options".

This gives me my second opportunity to reference
http://www.c2.com/cgi/wiki?LawOfDemeter today. :)

Opinions?

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