... I would suggest not worrying about hierarchies yet. You have a good start on the behaviors these things should provide... ... I don't get the sense from...
Right, Role and Player (http://c2.com/cgi/wiki?RoleAndPlayer) can be powerful, even if Coad is too reductionist. But unless I've misunderstood Steven's...
Ubiquitous language need to connect the domain to the code, not just reflect the domain. It may be very useful to call out or invent the language for the parts...
Perhaps I missunderstood I thought he was trying to use it in multiple contexts where being not an either or but one or more. If the type is exclusively one...
... Nobody anywhere (with a mind, that is) is claiming that TDD is a sufficient condition for success. -- J. B. Rainsberger, Diaspar Software Services ...
... It may be that Customer Testing practice does more to enhance DDD than TDD does. In particular, I'm thinking about one key consequence of Customer Testing:...
I was thinking about the initial question "Choosing between entity and value objects". In my mind all real world objects are have an implied unique identity....
My last post probably seems backwards to most people... I was thinking about why value types are generally immutable and entities generally not, why values are...
The first part of your post, about values depending for context on the object that contains them, while entities can be tracked independently of other objects,...
I've got a question for Eric -- What are your thoughts on Coad's ideas on use of color in UML diagrams? t.allan This message is for the designated recipient...
I might suggest a single Order class with a Workflow attached and some kind of dataholder attached. That would be one experiment I might try. But the truth is...
... Eric liked this, but I don't. It is probably true that if you are not interested in tracking an object outside the context of another object then it can...
Oops! I meant to type "value object", not entity. I hope context made it clear to others, as well. It should have read: Even if all red crayons are distinct...
... font ... tracking ... certainly ... application ... The number 2 is a "entity" but the integer that represents the number 2 is concidered a "value type"....
Hmm... perhaps this is exactly what I was looking for... value types represent *relationships* between 2 entities. I cannot think of a instance were you...
I realize that the value/entity distinction is a subtle one, and I admire your energy in searching for a way to grasp it. But I think it is simpler than you...
On Tuesday, February 3, 2004, at 05:57 PM, Eric Evans wrote: [...] ... In the above example, 1000 would be a value, but the part of the Money field that...
Eric wrote: "I don't really know what you mean by 'value-type' in software. This entity-value distinction is a modeling distinction." I'm not sure if that...
I'll hit a few points out of the message, but I think we are reaching diminishing returns. I would urge you to look at other parts of the pattern language and...
Yes, the USD currency is an enumeration, and could reasonably be considered an entity. The number 1000 is a value, as you say. But here's the interesting...
... *soley* ... with ... understand ... If those domain experts understand it, how does it improve the communication and thinking? Will they look differently...
Eric, I am on a project at the moment where these points are being discussed. It seems to me there are two senses of domain, which are not being clearly ...
Eric, I am on a project at the moment where these points are being discussed. It seems to me there are two senses of domain, which are not being clearly ...
Which model is more like the "real world". That is a philosophical question. Maybe it is unknowable. What we want for software (and in most other situations...
... discussed. ... clearly ... Object, ... an ... marker. ... think of it. ... way they ... sense 2. ... Yes exactly, in the ontological model there is no...
... Same domain; different domain model. ... No, the use of a qualifier helps in identifying the entity, in this case. It does not change whether the President...
... this case. It ... I still say President in the qualified domain model is a Value Object because it can be *derived* from Country and Year. It is the same...
... A president isn't derived from country and year, it is *looked up* from country and year. The name of the president is a value. The president is an entity....
I've often had the question, "What is the difference between domain-driven design and model-driven design?". So I wrote a short article to lay out the ...
