摘要：例如等價于到結束，但不包括。例如返回沒有每次跳躍的間距，默認為。

單個異常處理：

try:
    print(num)

except NameError:
    print("沒有定義變量")

except FileNotFoundError:
    print("找不到文件路徑")

print(1)

多個異常處理：

try:
    print(num)
    # 11/0
    # open("xxx.txt")
except (NameError, FileNotFoundError, ZeroDivisionError): # 多個異常統一處理
    print("異常")

print(1)

所有異常處理：

try:
    print(num)
except Exception: # 所有異常處理
    print("所有異常處理")

print(1)

查看原來異常輸出:

try:
    print(num)
except Exception as err:
    print(err)
print(1)    

沒有異常執行

try:
    a = 1

execpt Exception as err:
    print(err)

else:
    print("沒有異常執行")

finally:
    print("不管是否出現異常, 都執行")

print(1)     

import time
try:
    f = open("test.txt")
    try:
        while True
            content = f.readline()
            if len(content) == 0:
                break
            time.sleep(2)
            print(content)
    except Exception:
        # pass
        print("文件產生異常")
    finally:
        f.close()
        print("關閉文件")
except Exception:
    print("沒有這個文件")

try與except需要同時存在
當函數嵌套的時候，如果函數出現異常，會返回異常，然后捕獲到異常

raise: 拋出一個自定義異常

raise語句如果不帶參數，就會把當前錯誤原樣拋出。

def main ():
    try:
        s = input("請輸入-->")
        if len(s) < 3:
            raise ShortInputException(len(s), 3)
        else:
            print(s)
    except ShortInputException as result:
        print("ShortInputException: 輸入的長度是 %d, 長度至少需要是 %d" % (result.length, result.atleast))
    else:
        print("沒有異常發生.")

class ShortInputException(Exception):
    """自定義異常類"""
    def __init__(self, length, atleast):
        # super().__init()
        self.length = length
        self.atleast = atleast

main()

如何獲取當前模塊的文件名: __file__

引入模塊

import sys導入模塊中的全部功能
from argv import sys, from argv import sys,executable導入模塊中的多帶帶功能
from sys import *
from sys as s 別名

__name__: 用于表示當前模塊的名字，同時還能反映一個包的結構

導入輸出的是當前模塊名

模塊被直接運行時模塊名為：__main__

if __name__ == "__main__": # 如果模塊是被直接運行的，則代碼塊被運行，如果模塊是被導入的，則代碼塊不被運行。
    # code

常用內建模塊

hashlib

import hashlib
m = hashlib.md5()   # 創建hash對象，md5:(message-Digest Algorithm 5)消息摘要算法,得出一個128位的密文
print m             # 
m.update("alogy")  # 更新哈希對象以字符串參數
print m.hexdigest() # 返回十六進制數字字符串

例子：用于注冊、登錄

import hashlib
import datetime
KEY_VALUE = "alogy"
now = datetime.datetime.now()
m = hashlib.md5()
str = "%s%s" % (KEY_VALUE,now.strftime("%Y%m%d"))
m.update(str.encode("utf-8"))
value = m.hexdigest()
print(value) # c69c59b58209a94f40e6a7a425f9a977

functools

["WRAPPER_ASSIGNMENTS", "WRAPPER_UPDATES", "__builtins__", "__doc__", "__file__", "__name__", "__package__", "cmp_to_key", "partial", "reduce", "total_ordering", "update_wrapper", "wraps"]

partial()

把一個函數的某些參數設置默認值，返回一個新函數，調用這個新函數會更簡單。

import functools

def showarg(*args, **kw):
    print(args)
    print(kw)

p1 = functools.partial(showarg, 1, 2, 3)
p1()
p1(4,5,6)
p1(a="python", b="alogy")

p2 = functools.partial(showarg, a=3, b="linux")
p2()
p2(1, 2)
p2(a="python", b="alogy")

wraps()

使用裝飾器時，被裝飾后等函數其實已經是另外一個函數（函數名等函數屬性會發生變化）

添加后由于函數名和函數的doc發生了改變，對測試結果有一些影響，例如:

def note(func):
    "note function"
    def wrapper():
        "wrapper function"
        print("note something")
        return func()
    return wrapper

@note
def test():
    "test function"
    print("I am test")

test()
print(test.__doc__)

運行結果

note something
I am test
wrapper function

所以，Python的functools包中提供了一個叫wraps的裝飾器來消除這樣的副作用。例如：

import functools
def note(func):
    "note function"
    @functools.wraps(func) # 保存外邊函數名
    def wrapper():
        "wrapper function"
        print("note something")
        return func()
    return wrapper

@note
def test():
    "test function"
    print("I am test")

test()
print(test.__doc__)

運行結果

note something
I am test
test function

常用擴展庫

例如：讀寫excel文件

安裝esay_install工具
sudo apt-get install python-setuptools

安裝模塊
sudo easy_install xlrd
sudo easy_install xlwt

所有內置模塊

import sys
sys.modules.keys()

["builtins", "sys", "_frozen_importlib", "_imp", "_warnings", "_thread", "_weakref", "_frozen_importlib_external", "_io", "marshal", "nt", "winreg", "zipimport", "encodings", "codecs", "_codecs", "encodings.aliases", "encodings.utf_8", "_signal", "__main__", "encodings.latin_1", "io", "abc", "_weakrefset", "site", "os", "errno", "stat", "_stat", "ntpath", "genericpath", "os.path", "_collections_abc", "_sitebuiltins", "sysconfig", "idlelib", "idlelib.run", "linecache", "functools", "_functools", "collections", "operator", "_operator", "keyword", "heapq", "_heapq", "itertools", "reprlib", "_collections", "types", "collections.abc", "weakref", "tokenize", "re", "enum", "sre_compile", "_sre", "sre_parse", "sre_constants", "_loc
ale", "copyreg", "token", "queue", "threading", "time", "traceback", "warnings", "tkinter", "_tkinter", "tkinter.constants", "idlelib.autocomplete", "string", "_string", "idlelib.autocomplete_w", "platform", "subprocess", "signal", "msvcrt", "_winapi", "idlelib.multicall", "idlelib.config", "configparser", "_bootlocale", "encodings.gbk", "_codecs_cn", "_multibytecodec", "idlelib.hyperparser", "idlelib.pyparse", "idlelib.calltips", "inspect", "ast", "_ast", "dis", "opcode", "_opcode", "importlib", "importlib._bootstrap", "importlib._bootstrap_external", "importlib.machinery", "textwrap", "idlelib.calltip_w", "idlelib.debugger_r", "idlelib.debugger", "bdb", "fnmatch", "posixpath", "idlelib.macosx", "idlelib.scrolledlist", "idlelib.windows", "idlelib.debugobj_r", "idlelib.rpc", "pickle", "struct", "_struct", "_compat_pickle", "_pickle", "select", "socket", "_socket", "selectors", "math", "socketserver", "idlelib.iomenu", "shlex", "tempfile", "shutil", "zlib", "bz2", "_compression", "_bz2", "lzma", "_lzma", "random", "hashlib", "_hashlib", "_blake2", "_sha3", "bisect", "_bisect", "_random", "locale", "idlelib.stackviewer", "idlelib.debugobj", "idlelib.tree", "idlelib.zoomheight", "pydoc", "importlib.util", "importlib.abc", "contextlib", "pkgutil", "urllib", "urllib.parse"]

內置全局變量：vars()

{"__name__": "__main__", "__doc__": None, "__package__": None, "__loader__": , "__spec__": None, "__annotations__": {}, "__builtins__": }

第三方模塊：
anaconda: 數十個常用的第三方模塊

內建屬性

python類的內建屬性和方法

["__class__", "__delattr__", "__dict__", "__doc__", "__format__", "__getattribute__", "__hash__", "__init__", "__module__", "__new__", "__reduce__", "__reduce_ex__", "__repr__", "__setattr__", "__sizeof__", "__str__", "__subclasshook__", "__weakref__"]

__getattribute__例子：

class Person(object):
    def __init__(self, subject1):
        self.subject1 = subject1

    # 屬性訪問時攔截器，打log
    def __getattribute__(self, obj):
        if obj == "subject1":
            print("log subject1")
        return "redirect python"

    def show(self):
        print("this is Person")

p = Person("python")
print(p.subject1)

內建函數

dir(__builtins__)

["ArithmeticError", "AssertionError", "AttributeError", "BaseException", "BufferError", "BytesWarning", "DeprecationWarning", "EOFError", "Ellipsis", "EnvironmentError", "Exception", "False", "FloatingPointError", "FutureWarning", "GeneratorExit", "IOError", "ImportError", "ImportWarning", "IndentationError", "IndexError", "KeyError", "KeyboardInterrupt", "LookupError", "MemoryError", "NameError", "None", "NotImplemented", "NotImplementedError", "OSError", "OverflowError", "PendingDeprecationWarning", "ReferenceError", "RuntimeError", "RuntimeWarning", "StandardError", "StopIteration", "SyntaxError", "SyntaxWarning", "SystemError", "SystemExit", "TabError", "True", "TypeError", "UnboundLocalError", "UnicodeDecodeError", "UnicodeEncodeError", "UnicodeError", "UnicodeTranslateError", "UnicodeWarning", "UserWarning", "ValueError", "Warning", "ZeroDivisionError", "__debug__", "__doc__", "__import__", "__name__", "__package__", "abs", "all", "any", "apply", "basestring", "bin", "bool", "buffer", "bytearray", "bytes", "callable", "chr", "classmethod", "cmp", "coerce", "compile", "complex", "copyright", "credits", "delattr", "dict", "dir", "divmod", "enumerate", "eval", "execfile", "exit", "file", "filter", "float", "format", "frozenset", "getattr", "globals", "hasattr", "hash", "help", "hex", "id", "input", "int", "intern", "isinstance", "issubclass", "iter", "len", "license", "list", "locals", "long", "map", "max", "memoryview", "min", "next", "object", "oct", "open", "ord", "pow", "print", "property", "quit", "range", "raw_input", "reduce", "reload", "repr", "reversed", "round", "set", "setattr", "slice", "sorted", "staticmethod", "str", "sum", "super", "tuple", "type", "unichr", "unicode", "vars", "xrange", "zip"]

range()

range(stop) # 整數列表
range(start, stop[, step]) # 整數列表

strat: 計數從start開始，默認是從0開始。例如：range(5)等價于range(0, 5)

stop: 到stop結束，但不包括stop。例如：range(0, 5), 返回[0, 1, 2, 3, 4]沒有5

step: 每次跳躍的間距，默認為1。例如：range(0, 5)等價于range(0, 5, 1)

map()

map函數會根據提供的函數作為指定序列做映射

map(function, sequence[, sequence, ...]) -> list

function: 一個函數

sequence: 一個或多個序列，取決于function需要幾個參數

返回值是一個list

# 函數需要一個參數
map(lambda x: x*x, [1, 2, 3]) # [1, 4, 9]

# 函數需要兩個參數
map(lambda x, y: x+y, [1, 2, 3], [4, 5, 6]) # [5, 7, 9]


def f1( x, y ):  
    return (x, y)
l1 = [0, 1, 2, 3, 4, 5, 6]  
l2 = ["Sun", "M", "T", "W", "T", "F", "S"]
l3 = map(f1, l1, l2) 
print(list(l3))
# [(0, "Sun"), (1, "M"), (2, "T"), (3, "W"), (4, "T"), (5, "F"), (6, "S")]

filter()

filter()會對指定序列執行過濾操作

filter(function or None, sequence) -> list, tuple, or string

function: 接受一個參數，返回布爾值True或False

sequence: 序列可以是str,tuple, list

返回值list, tuple, string

filter(lambda x: x%2, [1, 2, 3, 4])
[1, 3]

filter(None, "a")
"a"

reduce()

reduce會對參數序列中對元素進行累積

reduce(function, sequence[, initial]) -> value

function:該函數有兩個參數
sequence:序列可以是str，tuple，list
initial:固定初始值

function: 該函數有二個參數

sequence: 序列可以是str, tuple, list

initial: 固定初始值

返回value

reduce(lambda x, y: x+y, [1,2,3,4]) # 10

reduce(lambda x, y: x+y, [1,2,3,4], 5) # 15

reduce(lambda x, y: x+y, ["aa", "bb", "cc"], "dd") # "ddaabbcc"

sorted()

sorted(iterable, cmp=None, key=None, reverse=False) --> new sorted list

iterable: 迭代器

key: 函數

reverse: 正序，倒序

返回一個新的列表

sorted([1, 4, 2, 6, 3, 5]) # [1, 2, 3, 4, 5, 6]

sorted([1, 4, 2, 6, 3, 5], reverse = 1) # 倒序 # [6, 5, 4, 3, 2, 1]

sorted(["dd", "aa", "cc", "bb"]) # ["aa", "bb", "cc", "dd"]

lst = [3, -19, -1, 28, 7, 0, -2, -5, 7, 8, 0 -3, 9, 0, 11]
sorted(lst, key=lambda x: (x >= 0, -x if x >= 0 else x)) # [-19, -5, -3, -2, -1, 28, 11, 9, 8, 7, 7, 3, 0, 0] ????
sorted(lst, key=lambda x: (x >= 0, -abs(x))) # [-19, -5, -3, -2, -1, 28, 11, 9, 8, 7, 7, 3, 0, 0] ????

模塊中的__all__的作用

__all__只影響from import *這種導入方式

__all__ = ["test"]

def test():
    print("test")

包、__init__.py的作用

某個文件夾下具有__init.py的，稱之為包

__init__.py作用：

package的標識

定義package中的__all__，用來模糊導入

模塊的發布和安裝

新建一個setup.py寫入：

from distutils.core import setup

setup(name="alogy", version="1.0", description="a", author="alogy", py_modules=["suba.aa"]) # suba.aa 包名.模塊名

發布：

> python setup.py build

> python setup.py sdist

安裝：

> python setup.py install

import搜索路徑

import sys
sys.path # sys.path的先后順序

重新導入模塊

模塊被導入后，import module不能重新導入模塊，需要重新導入

from imp import *
reload("module") # module模塊名

pdb是基于命令行的調試工具

運行時啟動

python -m pdb xxx.py

l: list 查看運行的代碼
n: next 往下行執行
c: continue 繼續執行代碼直到結束
b 7，b 行數: break 添加斷點(通過c執行)
b: 查看所有斷點
clear 斷點序號: 清除指定斷點
s: step 進入當前作用域中
p 變量名: 查看指定變量名的值
a: 查看所有當前作用域的變量名和變量值
q: quit 退出調試
r: return 快速執行到函數最后一行

交互式調試

import pdb
pdb.run("testfun(args)") # 此時會打開pdb調試，注意：先使用s跳轉到testfun函數中，然后可以使用

程序里埋點

當程序執行到pbd.set_trace()位置時停下來調試

import pdb

pdb.set_trace()

常用內置模塊：
sys: 系統模塊, 程序與python解釋器的交互, 用于操控python的運行時環境
os: 操作系統模塊, 程序與操作系統的交互, 系統操作IO等行為
time，datetime: 時間模塊
re: 正則
json: json處理
urllib: 網絡處理
random: 隨機

不常用內置模塊：
itertools: 一些特殊的函數可以操作可迭代對象或者排列組合
copy: 拷貝的函數（賦值一般是傳遞對象的引用，修改一個對象，會導致其它對象也受到改變）
string: String模塊包含大量實用常量和類

Naked

Naked: 一個Python命令行應用程序框架. 可用于執行JS代碼

from Naked.toolshed.shell import execute_js, muterun_js
import sys

response = muterun_js("file.js")
if response.exitcode == 0:
  print(response.stdout)
else:
  sys.stderr.write(str(response.stderr))

shutil

用于復制和歸檔文件和目錄樹的實用函數。

# 清dist目錄
clearDist = (len(sys.argv) == 4 and (sys.argv[3] == "--clear"))
if clearDist:
    shutil.rmtree("./dist/")

subprocess

訪問I/O流的子進程

# 編譯vue
buildStat = subprocess.call("node build/build.js " + webPath + " " + verPath, shell=True)
if buildStat != 0:
    print("vue 編譯錯誤")
    sys.exit(1)

six

Python 2和3兼容庫

import six


def bytes_to_str(s, encoding="utf-8"):
    """Returns a str if a bytes object is given."""
    if six.PY3 and isinstance(s, bytes):
        return s.decode(encoding)
    return s

給程序傳遞參數

import sys

print(sys.argv) # 接收運行時接受的參數

終止程序運行

import sys
sys.exit(1)