Python identation messed up in emacs

Question

I am editing python code in emacs. For some unknown reason, sometimes I open a .py file in emacs and different blocks are indented differently even though they run correctly. I have a block that looks like:

class Foo:
    def __init__(self, params, p):
    """
    Foo
    """
        self.params = params
    self.p = p
    if self.p:
        if (not ('A' in self.params)) or \
                (not 'B' in self.params):
        raise Exception, "Error"

the indentation of self.params = ... line is clearly not the same as the next line self.p = p, yet the code runs.

What is causing this and how can it be fixed?

when I run:

$ reindent -d ~/code.py

on the above file, nothing is printed.

Actually, when I pasted it into this text box it looked correctly until I pressed the {} button to make it look like code. Any clue what is happening here? it is impossible to write code with this behavior.

I don't think it's mixing tabs and spaces because whitespace-mode in emacs shows:

Answer 1

This does not reproduce for me. Make sure you're using Emacs 24.3 and that the problem occurs with emacs -nw -Q.