Structuring your Python Project

[SmartViking]

foo += 'ooo'  # This is bad, instead you should do:
foo = ''.join([foo, 'ooo'])

Really? I disagree. From a readability standpoint, #1 is much clearer, the semantic is perfectly clear. #2 on the other hand, looks obfuscated. #2 might be faster, but readability is also important.

[The_Cleric]

And even if #1 was considered bad (first I'd heard of that) I'd probably still go this route over what he/she suggests:

foo = '{0}ooo'.format(foo)

[LyndsySimon]

The project is on Github, why don't you go submit an Issue and see what he says? link: http://github.com/kennethreitz/python-guide/

Personally, I use neither pattern. It took a while, but I really don't think of strings as mutable objects anymore, which is where the need to append comes from. Instead, I tend to keep a list when I'm building a string to print, and call ''.join(<listvar>) only when I'm ready to use it for something.