Re: How to return an empty aggregate

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 5 Kwi, 18:04, george.p...@gmail.com wrote:

> Can you provide non-academic example?

For the empty record?
I thought I did already. :-)
This might be a challenge, because we have no judge that can say
whether something is academic or not.

Consider a logging system that is designed with OO in mind. There is a
base interface with some operation(s) for logging and a bunch of
concrete implementations for various log destinations - one for disk
file, one for network output, one for database persistency, etc. The
part of the program that does something useful takes Log'Class and
feeds its log entries via given Log'Class parameter to whatever
happens to be a concrete Log implementation - a classic strategy
pattern.

What would you do to... switch the logging off?

I would create the derived (concrete) log that is *empty* and does
nothing and pass it as Log'Class to wherever it is expected.
It cannot be simpler than that.

Is it academic? I would do it at the nearest opportunity.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com