Comments on: Obvious Testing or: How I Learned to Stop Using the new keyword http://lostechies.com/chrismissal/2009/03/20/obvious-testing-or-how-i-learned-to-stop-using-the-new-keyword/ Thoughts while working and playing as a Software Developer Thu, 11 Apr 2013 16:53:00 +0000 hourly 1 http://wordpress.org/?v=3.4.2 By: Pat Maddox http://lostechies.com/chrismissal/2009/03/20/obvious-testing-or-how-i-learned-to-stop-using-the-new-keyword/#comment-50 Pat Maddox Sat, 11 Apr 2009 20:44:23 +0000 /blogs/chrismissal/archive/2009/03/19/obvious-testing-or-how-i-learned-to-stop-using-the-new-keyword.aspx#comment-50 You could ask the order for the number of items it has, rather than asking it for the collection and then checking the size. Currently you're breaking encapsulation by handing out the collection of order items. One point of OO is that you *should* be able to switch between those two implementations without breaking clients. So it's not that the first implementation is wrong, but rather that the design leaves something to be desired. I wrote a blog post discussing it in more depth, as well as the Aggregate pattern from Domain Driven Design: http://www.patmaddox.com/blog/aggregate_pattern_and_encapsulation You could ask the order for the number of items it has, rather than asking it for the collection and then checking the size. Currently you’re breaking encapsulation by handing out the collection of order items. One point of OO is that you *should* be able to switch between those two implementations without breaking clients. So it’s not that the first implementation is wrong, but rather that the design leaves something to be desired.

I wrote a blog post discussing it in more depth, as well as the Aggregate pattern from Domain Driven Design: http://www.patmaddox.com/blog/aggregate_pattern_and_encapsulation

]]> By: Chris Missal http://lostechies.com/chrismissal/2009/03/20/obvious-testing-or-how-i-learned-to-stop-using-the-new-keyword/#comment-49 Chris Missal Mon, 23 Mar 2009 13:50:06 +0000 /blogs/chrismissal/archive/2009/03/19/obvious-testing-or-how-i-learned-to-stop-using-the-new-keyword.aspx#comment-49 @Morten 1) We could have implemented your first suggestion, I don't know what we would have gained from a "negative addition" function. I could see this being very useful in some domains, it just didn't fit in ours. 2) From the Law of Demeter standpoint, do you mean because OrderItems is not a wrapper class? I think it's okay in that Order isn't relying on, and reaching into another objects components. Maybe, I'm missing something else? @Morten

1) We could have implemented your first suggestion, I don’t know what we would have gained from a “negative addition” function. I could see this being very useful in some domains, it just didn’t fit in ours.

2) From the Law of Demeter standpoint, do you mean because OrderItems is not a wrapper class? I think it’s okay in that Order isn’t relying on, and reaching into another objects components. Maybe, I’m missing something else?

]]> By: Morten Lyhr http://lostechies.com/chrismissal/2009/03/20/obvious-testing-or-how-i-learned-to-stop-using-the-new-keyword/#comment-48 Morten Lyhr Sat, 21 Mar 2009 21:15:56 +0000 /blogs/chrismissal/archive/2009/03/19/obvious-testing-or-how-i-learned-to-stop-using-the-new-keyword.aspx#comment-48 Some toughts... 1). Should a Order follow double bookkeeping, so insted of remove the orderlines add a new one with a negative amount? 2). "order.OrderItems" breaks the law of demiter, I think thats why it fails not because of the "new List<>". You are exposing state, so when you alter the state, som clients might get surprised ;-) jus my 2 cents... Some toughts…

1). Should a Order follow double bookkeeping, so insted of remove the orderlines add a new one with a negative amount?

2). “order.OrderItems” breaks the law of demiter, I think thats why it fails not because of the “new List<>“. You are exposing state, so when you alter the state, som clients might get surprised ;-)

jus my 2 cents…

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