Passing the objects created in a class to the global workspace

Question

I'm trying to figure out how to make the objects I create inside a definition appear on the same workspace as my "name == main" area, so I can call it in other definitions. I don't think I can use a simple "return" statement in my def, because my function is designed to create n-number of objects of a particular class.

def book_to_object(subfolders):
    # converts my dictionary of book titles and volumes into individual book objects
    for key, val in subfolders.items():
        title = replace_spaces_with_underscores(key)
        # check to see if book already exists in the registry
        if title in [book.name for book in Book._registry]:
            print("Book already exists")
        else:
            exec(title + " = Book(subfolders ,key, Fpath)")

The whole program below. I'm calling this def from my if __name__ == '__main__': function

print("Done")
#converts my dictionary of book titles and volumes into individual book objects
book_to_object(subfolders)

Originally I had the code in my def in the name=main area of my code but I wanted to reduce the clutter and make it into a definition to give me more flexibility later.

The whole program below.

import os

#get date modified time of a file to determine which file is the newest
def get_date_modified(file):
    return os.path.getmtime(file)

#replace spaces with underscores in a string
def replace_spaces_with_underscores(string):
    aa = string.replace(" ", "_")
    bb= aa.replace('-', '_')
    cc= bb.replace("__", "_")
    title = cc.replace("__", "_")
    return title

# create a list of volumes that have not been exported
def get_unexported_volumes(self):
    unexported_volumes = []
    for volume in self.volumes:
        if volume not in self.last_exported:
            unexported_volumes.append(volume)
    return unexported_volumes

def book_to_object(subfolders):
    # converts my dictionary of book titles and volumes into individual book objects
    for key, val in subfolders.items():
        title = replace_spaces_with_underscores(key)
        # check to see if book already exists in the registry
        if title in [book.name for book in Book._registry]:
            print("Book already exists")
        else:
            exec(title + " = Book(subfolders ,key, Fpath)")

class Book(object):
    #__metaclass__ = IterBook
    _registry = []
    #constructor
    def __init__(self, my_dict, key, Fpath):
        self._registry.append(self)
        self.name = key
        self.volumes = my_dict[key]
        self.Filepath = Fpath + "/" +self.name
        #self.last_exported = self.volumes[0]
        self.last_exported = ""
        self.newest = self.volumes[-1]
        self.last_downloaded = self.volumes[-1]
        self.last_converted = self.volumes[-1]
        self.last_exported_date = get_date_modified(self.Filepath + "/" + self.last_exported)
        self.newest_date = get_date_modified(self.Filepath + "/" + self.newest)
        self.last_downloaded_date = get_date_modified(self.Filepath + "/" + self.last_downloaded)
        self.last_converted_date = get_date_modified(self.Filepath + "/" + self.last_converted)
        self.last_exported_volume = self.last_exported
        self.newest_volume = self.newest
        self.last_downloaded_volume = self.last_downloaded
        self.last_converted_volume = self.last_converted
        self.last_exported_volume_date = self.last_exported_date
        self.newest_volume_date = self.newest_date
        self.last_downloaded_volume_date = self.last_downloaded_date
        self.last_converted_volume_date = self.last_converted_date
        self.last_exported_volume_name = self.last_exported
        self.newest_volume_name = self.newest
        self.unexported_volumes = get_unexported_volumes(self)

if __name__ == '__main__':
    print("Starting")

    # File Paths for Debugging purposes
    Fpath = '~/'
    F_Temp_path = '~/temp'

    #parses directory for book based on folder names
    subfolders = {'Encyclopedia': ['Vol.001', 'Vol.002', 'Vol.003', 'Vol.004', 'Vol.005'], 'Enginnering_Encyclopedia': ['Avionics', 'Civil', 'Electrical', 'Materials', 'Mechanical']}

    print("Done")
    #converts my dictionary of book titles and volumes into individual book objects
    book_to_object(subfolders)

Notes: In case anyone is wondering why I'm using objects instead of keeping everything in dictionaries, I need the flexibility that objects give.

Variables such as, file_paths and subfolders are dynamic and are based on what directory the user gives and what files are in that directory, for the purpose of asking the questions they have been hard coded so someone could copy and paste my code and reproduce the problem in question.