util.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

class Singleton(type):
    _instances = {}
    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]

import traceback, sys
    
def full_stack():
    exc = sys.exc_info()[0]
    stack = traceback.extract_stack()[:-1]  # last one would be full_stack()
    if not exc is None:  # i.e. if an exception is present
        del stack[-1]       # remove call of full_stack, the printed exception
                            # will contain the caught exception caller instead
    trc = 'Traceback (most recent call last):\n'
    stackstr = trc + ''.join(traceback.format_list(stack))
    if not exc is None:
         stackstr += '  ' + traceback.format_exc().lstrip(trc)
    return stackstr


import hashlib
def md5(data):
    return hashlib.md5(data).hexdigest()


def chunks(l, n):
    """ Yield successive n-sized chunks from l.
    """
    for i in range(0, len(l), n):
        yield l[i:i+n]