Data access from multiple code modules

[Bruno Desthuilliers]

simon.hibbs at gmail.com wrote:
> Lets say that I have an application consisting of 3 files. A main.py
> file, gui.py and a data.py which handles persistent data storage.
> Suppose data.py defines a class 'MyDB' which reads in data from a
> database, and main.py creates an instance of this object. How does code
> in gui.py access this object? 

Obviously, you need to pass whatever relevant to this code...

> Here's simplified pseudocode:
> 
> MAIN.PY
> import gui, data
> DataObject = data.MyDB(blah)
> 
> How do I write code in gui.py that can access DataObject? 

Passing DataObject to code in guy.py seems like a very straightforward
solution...

> Is this
> entirely the wrong way to approach this sort of problem?

> Actualy the problem is more complex because the GUI consists of a main
> GUI form, and panels defined as seperate objects in seperate files.
> Various panels will contain controlls for manipulating data in the
> DataObject, or wherever data storage end up.

Hmmm... Hard to tell without seeing the code (and I've not done GUI
programmer for a long time), but putting application logic in the GUI is
usually a bad idea IME.  Better to put the application logic in a
separate controler (that has a reference to the model -> here your
DataObject), and have the GUI part call on the controler.

> 
> Best regards,
> 
> Simon Hibbs
> (who strugles to get his head round this OOP stuff sometimes).

Well, actually one can do MVC without OO. It's more a matter of
separating concerns. Now I agree that it's not always obvious to know
for sure which part should be responsible for what...

-- 
bruno desthuilliers
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