Question

In my program, I need to make use of an ElementTree object in various functions in my program.

More specifically, I am doing this:

tree = etree.parse('somefile.xml')

I am passing this tree around in my program.

I was wondering whether this is a good approach, or can I do this:

1. Create a global tree (I come from a
   C++ background and I know global is
   bad)
2. Create the tree again wherever required.

Or is my approach ok?

Answer 1

In Python, (eliding complexities, making an analogy for your C++ background) all objects are passed by reference. And since “tree” is an object, you’re only passing the reference. Now, if you have a group of related methods that operate on the same tree, you might want to consider creating a class with that tree object as a member.

Also, here’s a quick reference to the complexities I glossed over above: http://www.testingreflections.com/node/view/5126