{"id":2709,"date":"2016-05-25T22:55:21","date_gmt":"2016-05-25T14:55:21","guid":{"rendered":"http:\/\/ixyzero.com\/blog\/?p=2709"},"modified":"2016-05-25T22:55:21","modified_gmt":"2016-05-25T14:55:21","slug":"%e4%b8%80%e4%ba%9b%e5%ae%9e%e7%94%a8%e7%9a%84python%e8%a3%85%e9%a5%b0%e5%99%a8","status":"publish","type":"post","link":"https:\/\/ixyzero.com\/blog\/archives\/2709.html","title":{"rendered":"\u4e00\u4e9b\u5b9e\u7528\u7684Python\u88c5\u9970\u5668"},"content":{"rendered":"

=Start=<\/p>\n

\u4e4b\u524d\u5728\u5b66\u4e60Python\u88c5\u9970\u5668\u7684\u65f6\u5019\u770b\u4e86\u5f88\u591a\u6587\u7ae0\uff0c\u4f46\u6ca1\u6709\u53ca\u65f6\u6574\u7406\u3001\u603b\u7ed3\uff0c\u6700\u8fd1\u5728\u5199\u7a0b\u5e8f\u7684\u65f6\u5019\u53d1\u73b0\u5f88\u591a\u88c5\u9970\u5668\u5177\u6709\u8f83\u5f3a\u7684\u5b9e\u7528\u4ef7\u503c\uff0c\u6240\u4ee5\u62bd\u51fa\u65f6\u95f4\u6574\u7406\u5982\u4e0b\uff1a<\/p>\n

\u51fd\u6570\u6267\u884c\u8017\u65f6\u7edf\u8ba1<\/h6>\n
import time\ndef timing(f):\n    def wrap(*args):\n        print '<function name: {0}>'.format(f.func_name)\n        time1 = time.time()\n        ret = f(*args)\n        time2 = time.time()\n        print '[timecosts: {0} ms]'.format((time2-time1)*1000.0)\n        return ret\n    return wrap<\/pre>\n
\u4f7f\u7528\u65b9\u6cd5\uff1a<\/p>\n
@timing\ndef hello(name):\n    print \"hello, %s\" % name\n\nhello('tom')<\/pre>\n
\u7ed9\u51fd\u6570\u8c03\u7528\u505a\u7f13\u5b58<\/h6>\n
from functools import wraps\ndef memo(fn):\n    cache = {}\n    miss = object()\n    @wraps(fn)\n    def wrapper(*args):\n        result = cache.get(args, miss)\n        if result is miss:\n            result = fn(*args)\n            cache[args] = result\n        return result\n    return wrapper<\/pre>\n
\u4f7f\u7528\u65b9\u6cd5\uff1a<\/p>\n
@memo\ndef fib(n):\n    if n < 2:\n        return n\n    return fib(n - 1) + fib(n - 2)\n\nfib(100) #\u8fd9\u91cc\u5176\u5b9e\u53ef\u4ee5\u4f7f\u7528\u4e0a\u9762\u7684\u51fd\u6570\u8017\u65f6\u7edf\u8ba1\u7684decorator\u8fdb\u884c\u8017\u65f6\u6bd4\u5bf9\nfib(101) #\u7528\u4ee5\u5224\u65admemo\u88c5\u9970\u5668\u662f\u5426\u8d77\u5230\u4f5c\u7528<\/pre>\n
\u5931\u8d25\u91cd\u8bd5\u51fd\u6570<\/h6>\n
import time\nimport math\n\n# Retry decorator with exponential backoff\ndef retry(tries, delay=3, backoff=2):\n    '''Retries a function or method until it returns True.\n    delay sets the initial delay in seconds, and backoff sets the factor by which\n    the delay should lengthen after each failure. backoff must be greater than 1,\n    or else it isn't really a backoff. tries must be at least 0, and delay\n    greater than 0.'''\n    if backoff <= 1:\n        raise ValueError(\"backoff must be greater than 1\")\n    tries = math.floor(tries)\n    if tries < 0:\n        raise ValueError(\"tries must be 0 or greater\")\n    if delay <= 0:\n        raise ValueError(\"delay must be greater than 0\")\n    def deco_retry(f):\n        def f_retry(*args, **kwargs):\n            mtries, mdelay = tries, delay # make mutable\n            rv = f(*args, **kwargs) # first attempt\n            while mtries > 0:\n                if rv is True: # Done on success\n                    return True\n                mtries -= 1      # consume an attempt\n                time.sleep(mdelay) # wait...\n                mdelay *= backoff  # make future wait longer\n                rv = f(*args, **kwargs) # Try again\n            return False # Ran out of tries :-(\n        return f_retry # true decorator -> decorated function\n    return deco_retry  # @retry(arg[, ...]) -> true decorator<\/pre>\n
\u4f7f\u7528\u65b9\u6cd5\uff1a<\/p>\n
@retry(5)\ndef some_func():\n    pass\n\nsome_func()<\/pre>\n
\u8d85\u65f6\u9000\u51fa\u51fd\u6570<\/h6>\n
\u8fd9\u4e2a\u51fd\u6570\u7684\u4f5c\u7528\u5728\u4e8e\u53ef\u4ee5\u7ed9\u4efb\u610f\u53ef\u80fd\u4f1ahang\u4f4f\u7684\u51fd\u6570\u6dfb\u52a0\u8d85\u65f6\u529f\u80fd\uff0c\u8fd9\u4e2a\u529f\u80fd\u5728\u7f16\u5199\u5916\u90e8API\u8c03\u7528 \u3001\u7f51\u7edc\u722c\u866b\u3001\u6570\u636e\u5e93\u67e5\u8be2\u7684\u65f6\u5019\u7279\u522b\u6709\u7528<\/p>\n
import signal, functools\nclass TimeoutError(Exception): pass #\u5b9a\u4e49\u4e00\u4e2aException\uff0c\u5728\u8d85\u65f6\u60c5\u51b5\u4e0b\u629b\u51fa\n\ndef timeout(seconds, error_message = 'Function call timed out'):\n    def decorated(func):\n        def _handle_timeout(signum, frame):\n            raise TimeoutError(error_message)\n        def wrapper(*args, **kwargs):\n            signal.signal(signal.SIGALRM, _handle_timeout)\n            signal.alarm(seconds)\n            try:\n                result = func(*args, **kwargs)\n            finally:\n                signal.alarm(0)\n            return result\n        return functools.wraps(func)(wrapper)\n    return decorated<\/pre>\n
\u4f7f\u7528\u65b9\u6cd5\uff1a<\/p>\n
@timeout(5) #\u9650\u5b9a\u4e0b\u9762\u7684slowfunc\u51fd\u6570\u5982\u679c\u57285s\u5185\u4e0d\u8fd4\u56de\u5c31\u5f3a\u5236\u629bTimeoutError Exception\u7ed3\u675f\ndef slowfunc(sleep_time):\n    import time\n    time.sleep(sleep_time) #\u8fd9\u4e2a\u51fd\u6570\u5c31\u662f\u4f11\u7720sleep_time\u79d2\n\nslowfunc(3)     #sleep 3\u79d2\uff0c\u6b63\u5e38\u8fd4\u56de\uff0c\u6ca1\u6709\u5f02\u5e38\nslowfunc(10)   #\u88ab\u7ec8\u6b62<\/pre>\n
\u6253\u5370\u8c03\u8bd5\u4fe1\u606f\u51fd\u6570<\/h6>\n
import sys, os, linecache\ndef trace(f):\n    def globaltrace(frame, why, arg):\n        if why == \"call\": return localtrace\n        return None\n    def localtrace(frame, why, arg):\n        if why == \"line\":\n            filename = frame.f_code.co_filename\n            lineno = frame.f_lineno\n            bname = os.path.basename(filename)\n            print \"{}({}): {}\".format(bname, lineno, linecache.getline(filename, lineno)),\n        return localtrace\n    def _f(*args, **kwds):\n        sys.settrace(globaltrace)\n        result = f(*args, **kwds)\n        sys.settrace(None)\n        return result\n    return _f<\/pre>\n
\u4f7f\u7528\u65b9\u6cd5\uff1a<\/p>\n
@trace\ndef simple_print():\n    print 1\n    print 22\n    print 333\n\nsimple_print() #\u8c03\u7528<\/pre>\n
\u53c2\u8003\u94fe\u63a5\uff1a<\/h5>\n