[Python] 打包Python成exe

Reference:
[1] http://www.py2exe.org/index.cgi/Tutorial

[Python] Eric IDE For Python On Ubuntu16.04

• 安装QT5
  Ref : http://smlie-blog.blogspot.tw/2017/11/qtqt5ubuntu1604.html
• 安装相關套
• pip3
  
  #apt-get install python3-pip
  #pip3 install --upgrade pip
• PyQt5
  
  #pip3 install PyQt5
• Mercurial
  
  #apt-get install mercurial
• QScintilla
  
  #pip3 install QScintilla
• Eric
  
  #hg clone hg clone https://die-offenbachs.homelinux.org/hg/eric
  #cd eric
  #python3 install.py

Reference :
[1] https://eric-ide.python-projects.org/index.html
[2]Install Eric 6 for Python (Windows/Ubuntu)

[Python] 在Ubuntu 14.04，使用Python撰寫MySql程式

• 安裝Python 套件
#apt-get install python-mysqldb


• Sample Code
import MySQLdb

try :
    db = MySQLdb.connect("host", "username", "password", "db_name", charset='utf-8')

    sql = "SELECT field1, field2 FROM table"
    cursor = db.cursor()
    cursor.execute(sql)

    results = cursor.fetchall()
    for record in results:
       col1 = record[0]
       col2 = record[1]
       print "%s, %s" % (col1, col2)

    db.close()
except MySQLdb.Error as e:
    print "Error %d: %s" % (e.args[0], e.args[1])

Reference :
[1] 實作Python 連接MySQL 資料庫

[Python] getattr 的用途與應用

getattr(object, name[, default])

• 回傳物件裡的屬性
• Python的內建函數
• Example1
class Demo:
    def __init__(self):
            self.x = "demo_x"
            self.y = "demo_y"

    def test(self):
            print "demo_test"

demo = Demo()
print getattr(demo, "__init__")
print getattr(demo, "x")
print getattr(demo, "y")

執行結果

• Example2
  
  class WebService:
          def __init__(self):
                  self.demos = []
  
          def register(self, demo)
                  self.demos.append(demo)
  
          def exe(self, func):
                  for demo in demos.values():
                          function = getattr(demo, func)
                          return function(parms)
  
  class Demo():
  def _exe1(self, parms):
          print "_exe1: %s " % parms
  
  def _exe2(self, parms):
          print "_exe2: %s" % parms
  
  ws = WebService()
  ws.register(Demo())
  ws.exe('_exe1')

Reference:
[1] Python 3.1 快速導覽 - 內建函數 getattr()

[Python] 使用Python實作一個類似Java Synchronized之用法

Java synchronized 範例如下:

public class Sync {
        public synchronized void execute(String funcName) {
                System.out.println(funcName)
        }
}

Python 範例如下：

import time
import threading from threading
import Thread

# 實作 synchronized
def synchronized(func):
        func.__lock__ = threading.Lock()
        def synced_func(*args, **kws):
                with func.__lock__:
                return func(*args, **kws)
        return synced_func 

synchronized 使用方式：

# 需要執行synchronized的函數  

@synchronized
def execute(func_name):
        print func_name
        time.sleep(2) 

Reference:
[1] Synchronized in Python
 

[Python] Decorator 用法

Python 有一個很特殊語法，是可以在Function中可以定義Function，用法如下

def function1():
    print "execute function1"

    def inner_function1():
        print "execute inner_function1"

而基於這個方法，可在搭配Decorator，做出類似Callback Function

def callback(user_func):
    def _callback(*args, **kwargs):
        print '''執行預先處理 '''
     
        # 執行使用者函數
        return user_func(*args, **kwargs)
    return _callback

1. 一般呼叫方式

def cb(x):
    print "計算 x+x"
    return x+x

result = callback(cb)
print result(5)

輸出結果 :

執行預先處理
計算 x+x
10

2. 使用 Decorator @ --> 是Python語言的特殊字，稱之Decorator ，用法如下

@callback
def cb(x):
    print "計算 x+x"
    return x+x

print cb(5)

Reference : 
[1][python] decorator 之很難理解的快速理解法

[Python] list 轉換成 dict

Example :

x = [ "a", "1", "b", "2" ]

期望轉成

x = {"a":"1", "b":"2"}

語法：

hash = dict(x[i:i+2] for i in range(0, len(x), 2))