Simple example of using dependency injection

dependency_injection.py

# Don't do this
def get_data_bad(query_text):
    db = SQLDB()
    return db.get(query_text)
    
# What if you need to use a DocDB instance? Or a DynamoDB instance?
# Do this instead
def get_data(db, query_text):
    return db.get(query_text)
    
# Example
sqldb = SQLDB()
query = 'SELECT * FROM Foo'
data = get_data(sqldb, query)

# Or, if you need to use DocDB instead, you don't need to change your original get_data method
docdb = DocDB()
query = 'SELECT c.* FROM c'
data = get_data(docdb, query)