From: Adam Akhtar <adamtemporary@...>
Date: 2008-11-11T21:24:00+09:00
Subject: Re: implementing mvc - using observer pattern - beginner to OOP

Thank you so much for your help clearing that up. Im much closer to 
understanding how things fit together. Id just like to confirm 
somethings (please dont think im asking you to the write the code for 
me, im not, i just like to be a bit more certain before writing out 
lines of code ;-) )

> This bit below goes in your controller.  It's a DB, so you will want to 
> handle
> Create, Read, Update, Delete for the tasks. That's probably enough to 
> start
> with, and Read and Update mean you'll need to search for tasks, so that
> means you'll need to Tell the UI to display them.


Ok so I have three classes now.
DB which encapsulates the DB and all the tables (at the moment there is 
only one for tasks, in the future Id have anohter for categories, 
projects etc)

Task_Controller which handles the menu navigation logic and any logic 
such as what to do with a task when a user marks it as complete etc. It 
will have DB related tasks such as Create, Read, Update, Delete.

Task_UI which will have basically all the output to the screen such as 
menu text, prompts etc.

From this

>> def add_task
>     new_task = UI.new_task_form
>     DB. add_task(new_task)
>> end

Question 1
it seems your implying my class Task_Controller should define an 
instance of the DB and the UI within it, is that correct?

Question 2
Presuming Im correct about that, what is the relationship of the db to 
the view? When the DB is updated is it the DBs job to inform the view 
for it to update or does it inform the controller or .... C. do nothing 
at all　and just let the controller tell the view to update when it 
thinks its best.


>   This bit belongs in the UI
>> def new_task_form
>> puts "Enter title for task"
>   # don't put this here: new_task = Task.new
>> # new_task.title = gets.chomp
>> # return new_task
>   # You just want the UI to return a bunch of fields. the controller
>   # can validate them, and tell the UI:   UI.bzzzt("Try again!").
>> end

ok so i shouldnt create an instance of task in the UI. Rahter just 
return a bunch of fields (a hash \ array? )which contain the input from 
the user and let the controller figure out what each field represents 
and whether its valid input. The controller will create a Task instance 
and then pass it to the DB.

Question 3
When the UI presents say a form for a task to the user to fill is it 
good practice to have things like

userinput = gets.chomp

in the UI or should that be handled by the controller. Im wondering to 
what degree logic and presentation are seperated.

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