Some python util functions && classes

utils.py

#!/usr/bin/env python2
# -*- coding: utf-8 -*-
import datetime
import functools
import time


# logging
# =======

def print_rect(lines):
    if isinstance(lines, basestring):
        lines = [lines]

    lines.insert(0, datetime.now().strftime('%Y-%m-%d %H:%M:%S'))

    max_len = max([len(l) for l in lines]) + 2
    legend = '+' + '-' * max_len + '+'

    s = [legend, '\n'.join(['| %s%s |' % (l, ' ' * (max_len - len(l) - 2)) for l in lines]), legend]
    print '\n'.join(s)


def logging(func):
    def inner(*args, **kwargs):
        pretty_name = '%s(args=%s, kwargs=%s)' % (func.__name__, args, kwargs)
        print_rect('%s start ...' % pretty_name)
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print_rect('%s end %.1fs' % (pretty_name, end - start))
        return result

    return inner


# cache
# =====

def hash_object(obj):
    if isinstance(obj, (tuple, list)):
        return (type(obj), tuple([hash_object(it) for it in obj]))
    elif isinstance(obj, dict):
        return (type(obj), tuple([(k, hash_object(v))
                                  for (k, v) in obj.iteritems()]))
    else:
        return obj


# https://wiki.python.org/moin/PythonDecoratorLibrary#Cached_Properties
class Cached(object):
    def __init__(self, ttl=300):
        self.ttl = ttl
        self._cache = {}

    def __call__(self, fn, *args, **kwargs):
        @functools.wraps(fn)
        def decorated(*args, **kwargs):
            # TODO: a better hash function?
            key = hash_object((args, kwargs))
            now = time.time()
            try:
                value, last_update = self._cache[key]
                if self.ttl > 0 and now - last_update > self.ttl:
                    raise AttributeError

            except (KeyError, AttributeError):
                value = fn(*args, **kwargs)
                self._cache[key] = (value, now)

            return value

        return decorated