Re: import statement - package visibility problem

[Kristóf Stróbl]

Hi!
Laszlo Zsolt Nagy wrote:
I have the following structure:
/Lib/Server/Db/
   __init_.py
   DatabaseConnection.py
   Adapters/
      __init__.py
      FireBirdConnection.py
Important file contents are:
/Lib/Server/Db/__init__.py:
   import DatabaseConnection
   import Adapters
/Lib/Server/Db/DatabaseConnection.py:
   class DatabaseConnection(object):
         pass
/Lib/Server/Db/Adapters/__init__.py
   import FireBirdConnection
/Lib/Server/Db/Adapters/FireBirdConnection.py:
   from DatabaseConnection import DatabaseConnection
   class FireBirdConnection(DatabaseConnection):
          pass
...
My problem is that Lib/Server/Db/Adapters/FireBirdConnection.py does not 
see Lib/Server/Db/DatabaseConnection.py.
Two solutions come into my mind:
1. Do not inherit from DatabaseConnection, but pass a DatabaseConnection object 
as a parameter to the FireBirdConnection's __init__function. After this you can 
delegate the necessary functionality to the DatabaseConnection (by using 
__getattr__). This introduces less coupling between DatabaseConnection and 
FireBirdConnection, event module testing is easier.
2. Maybe the layering of your application is wrong. If DatabaseConnection 
provides common functionality to the different Adapters, it should be on the 
same layer or one beneath the Adapters.
Hard to say which can be applied to your application without knowing more about 
it, though.
Kristóf
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