[Cuis-dev] Code design, circular reference

[Gerald Klix]

On 6/21/23 11:43 AM, H. Fernandes via Cuis-dev wrote:
> Yes a dynabook may be linked to several schools.
> A course only takes place in a given school.
IC
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> Yes some diagrams and more details on the project
> https://docs.google.com/document/d/1_67XzOLi78DWaf-deZsEMmhINhdSX3Tf6iy_SK88AYY/edit?usp=sharing
WOW, IC you are quit serious about this!

Any plans to include Luciano Notarfrancesco's Arrows CAS?

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> ----- Mail original -----
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> May one ask some questions about the requirements?
> 
> A Dynabook may be linked to more than one school (or university)?
> Is it possible that one course can belong to more than one school?
> 
> Is there a datamodel/ER-Diagram/UML-Object/Class-Diagram?
Now, that I have seen your class-diagram, I suggest to just
add deadlines to tasks. If try to model this time-slot business
in a simple manner, it will always be incomplete and
it will collide with the pupils', teachers' and
schools' time-management, thus annoying every one ...

Just my to Fr. 0.02!


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> On 6/21/23 10:05 AM, H. Fernandes via Cuis-dev wrote:
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>> Hi folks,
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>> I have a design question with circular reference I want to avoid, and I am investigating options. Here is the situation:
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>> - a Dynabook object (likely a singleton) with a schools attribute
>> - each School instance has a timeSlots attribute , a collection of TimeSlot describes the time division of a school day
>> - deep in the objects tree, Dynabook>school>course> courseHours describe the time schedulle of a Course
>>
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>> The courseHours GUI editor needs to refer to the timeSlots collection in the parent School instance. I wonder how to do that properly.
> What will this editor be editing?
> The Dynabook's course hours, the school's course hours, ...?
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>> There are possibly several School instances (a person may teach in several schools with different time slot).
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>> I though of several options:
>> - to have a school attribute in the Course instance, I don't like the idea
> IHMO. this makes sense: I can remember cases of German gymnasiums were a
> course was held at one school, but was on the curriculum of more than
> one gymnasium. Pupils from two gymnasiums attended the course.
> Same story for German university lectures. Therefore there should
> be a schools (plural) attribute.
> 
>>
>> - to have a schoolContext attribute in the Dynabook object. The attribute refers to the School instance in use. I am afraid it could be out of synch easily.
> There should be more than school. It is possible to study at
> more than one university at the same time.
> I studied Computer Science at TUM (Technische Universität München) and
> Theoretical Linguistics at LMU (Ludwig-Maximilians-Universität München).
>>
>> - to pass in reference the School instance to intermediate GUI methods, a bit tedious
>> - to search for the School parent instance of a given attribute in the tree by interogating the Dynabook instance. Should work well, may be overkill.
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>> Options? Opinions?
> If in doubt design and implement a simulation of the reality.
> Of course this will become complicated with lots of circular references.
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> (I can provide anecdotal reference about how complicate this can become)
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>> Thanks
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>> Hilaire
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> You are welcome!
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> Best Reagrds,
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> Gerald
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