Question

Python (2.7) newbie here. What I want to do is have a reference to an instance of a class return a given property as the ‘default’ without having to specify that property. I want to do this because the vast majority of the time I refer to an instance, it is to access this one property.

For example, let’s say I have a couple of classes to describes a book:

class book:
    def __init__(self):
        self.title = ''
        self.author = ''
        self.page = {}

class page:
    def __init__(self):
        self.text = ''
        self.length = 0

I create an instance and fill it with the contents of a book like so:

...    
war_and_peace = book()
page_count = 0
for page in pages:  #Let's say pages is a list of strings each of a page of the book
    pagenum += 1
    war_and_peace.page[pagenum] = page

Now in the remainder of the program, 99.9% of the time I reference the text of the pages. So to make my life a little easier, I would like to be able to reference a page using:

if 'Anna' in war_and_peace[15]:
    ...

instead of

if 'Anna' in war_and_peace.page[15].text:
    ...

How might I go about this? (Sorry if this has been answered; I am probably using the wrong search terms!)

Thanks!

Answer 1

A __getitem__ override on book will give you this:

def __getitem__(self, item):
    return self.page[item].text