This is a challenging modelling issue, life progress or any other dissipative/emergent structure are "restricted" by the boundaries of your objects (e.g. if you model a flock, and it divides into two flocks, and then merges again, which flock remains? Note: I wouldn't model the Flock at all).
So it is hard to advice without knowing exactly what the use case is or how the simulation is done, but in the past I had to model a non-organic tree structure that was changing on a daily basis, where each part had it's own attributes and we should be able to query (aka "reconstruct") the "tree structure" at any point in time and query specific parts history, my solution to that was to have an "invariant" identity (E.g. "Plant #1234") and a subtree of elements, where each child wasn't the "organ" directly, but a "node" that contains the "organ" with a starting and an end date (like Joachim suggested) and know the parent "organ" (or the plant itself). In your case, the organs are not going to be transplanted (as was in my case), so the organ/node could be merged into one, which simplifies everything. I don't know if your model has a tree like structure, whether it's a lemon tree or just a dandelion :), so I don't know if, e.g., the flower contains the fruit, or as I understand biology, the plant contains the flower until some point where it stops being a flower and then you replace it by a fruit. I hope it helps you. Esteban A. Maringolo El mié., 16 ene. 2019 a las 9:19, Richard O'Keefe (<rao...@gmail.com>) escribió: > It seems to me that in the real world, a bud does not get replaced by a > flower > nor a flower by a fruit, nor is there a definite point at which a thing > stops > being a bud and starts being a flower, and so on. It's summer now, but > spring > wasn't that long ago, and I enjoyed watching the imperceptible *continuous* > changes. So anything you do is going to be imposing discontinuity on a > more- > or-less continuous process and is definitely going to be an approximation. > > You may perhaps be looking for the "State" design pattern where there is an > object with a fixed identity (*this* bud/flower/fruit) which behaves > differently at different times, and this is modelled by the "outer" object > delegating some of its behaviour to a "state" which can be replaced. > So you would have > PlantOrgan > PlantReproductiveOrgan (state) > > PlantReproductiveOrganState > Bud > Flower > DeadFlower > ImmatureFruit > MatureFruit > > You will find abundant material about the "State" design pattern on the > web. > > > On Thu, 17 Jan 2019 at 00:29, Loïc Pagès <loic.pa...@inra.fr> wrote: > >> Hi Joachim, >> >> Thank you for your reply and for your ideas. I will reply to your >> questions below. >> >> Le 16/01/2019 à 10:25, jtuc...@objektfabrik.de a écrit : >> > Loïc, >> > >> > Am I correct in assuming you are thinking about a model in which a >> > plant can have a growing and shrinking list of organs over time and >> > some of them even have (a growing list of) stages? >> >> Yes, the plant can be seen as a growing and shrinking list of organs. >> Very short list at the beginning, and becoming larger. Some organs can >> fall (leaves, roots) or even be pruned (shoots in fruit trees), so that >> shrinking can also occur. >> >> However, the list of stages for each organ is usually known at the >> beginning, for each type of organ. It depends of knowledge and level of >> detail that we include in the model. >> >> > >> > I am not an expert on the matter, but to me the stages idea sounds >> > good. It even allows for historic information (it was a bud from Date1 >> > to Date2 and since then it is a flower). So transformation would be >> > adding a new Stage and "terminate" the previous one. >> >> This can be an approach. But the conditions for passing from one stage >> to another can be more complex and involve several aspects (age, >> previous growth, pollination, etc) with a lot of code. So, if you keep >> this code into the general "reproductive organ" class, you make a "fat >> class" with a lot of tests. This was not recommended in the Pharo course >> :-) >> >> > >> > With this you can ask a plant about its current stage on the >> > reproductive front and maybe other organs as well at any point time. >> > This may be helpful if you want to build an animation of the plant's >> > development over time. You can have separate life cycles for each organ. >> This is actually an objective of such models, to be able to get the >> status of the whole plant, regarding the stages of organs. >> > >> > Does the plant transform in the real world? I mean, is a cherry tree >> > still a cherry tree, even if it's not blooming any more and carries >> > fruit instead? So why transform the object in its abstract model? >> The plant usually changes because of its development, but a cherry tree >> remains a cherry tree ! And flowers are necessary steps to get fruits >> ! The idea was not to transform the whole plant, but each individual >> organ that it carries. >> > >> > >> > Just a thought, maybe better ideas show up. >> >> OK, thank you again >> >> Loïc >> >> > >> > >> > >> > Am 16.01.19 um 10:15 schrieb Loïc Pagès: >> >> Dear Pharo users, >> >> >> >> I develop software dedicated to the simulation of plant development >> >> and 3D architecture. >> >> >> >> In the past, I used Java, but I am very interested in translating >> >> code in Pharo. I appreciated very much the language and the course. >> >> >> >> I have a question for you all : >> >> >> >> During plant development (ontogeny), new organs appear, that are >> >> gradually tranformed. For example, a bud can make a flower, and then >> >> a fruit. >> >> >> >> Organs are conveniently modelled as classes. During the course, I >> >> learned that it was better to make several classes (bud, flower, >> >> fruit) instead of a "fat class" such as "reproductive organ" with >> >> many attributes and stages (bud stage, flower stage, fruit stage). I >> >> wonder how to transform an object into another one, to represent for >> >> example the fact that the flower may become a fruit. >> >> >> >> Maybe a naive question ? >> >> >> >> Thanks for your lights ! >> >> >> >> Loïc >> >> >> >> >> >> >> >> >> > >> > >> >> >>
