Author Dusty Phillips Reviewers

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Organizing module contents
Inside any one module, we can specify variables, classes, or functions. They can be 
a handy way to store the global state without namespace conflicts. For example, we 
have been importing the 
Database
class into various modules and then instantiating 
it, but it might make more sense to have only one 
database
object globally available 
from the 
database
module. The 
database
module might look like this:
class Database:
# the database implementation
pass
database = Database()
Then we can use any of the import methods we've discussed to access the 
database
object, for example:
from ecommerce.database import database
A problem with the preceding class is that the 
database
object is created 
immediately when the module is first imported, which is usually when the program 
starts up. This isn't always ideal since connecting to a database can take a while, 
slowing down startup, or the database connection information may not yet be 
available. We could delay creating the database until it is actually needed by calling 
an 
initialize_database
function to create the module-level variable:
class Database:
# the database implementation
pass
database = None
def initialize_database():
global database
database = Database()
The 
global
keyword tells Python that the database variable inside 
initialize_
database
is the module level one we just defined. If we had not specified the 
variable as global, Python would have created a new local variable that would be 
discarded when the method exits, leaving the module-level value unchanged.
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Objects in Python