1. 自定义交互式界面(cmd)

有时候我们希望我们的服务有一个可交互的客户端,就像数据库操作.

Python提供了交互界面的自定义功能,通过cmd模块我们可以将一些指令放入交互界面中,便于直接调用

我们制作一个python自带的绘图工具turtle的交互界面作为例子:

%%writefile src/turtleshell.py #!/usr/bin/env python # --*-- coding:utf-8 --*-- from __future__ import print_function import cmd, sys from turtle import *  class TurtleShell(cmd.Cmd):     intro = 'Welcome to the turtle shell.   Type help or ? to list commands.\n'     prompt = '(turtle) '     file = None      # ----- basic turtle commands -----     def do_forward(self, arg):         'Move the turtle forward by the specified distance:  FORWARD 10'         forward(*parse(arg))     def do_right(self, arg):         'Turn turtle right by given number of degrees:  RIGHT 20'         right(*parse(arg))     def do_left(self, arg):         'Turn turtle left by given number of degrees:  LEFT 90'         left(*parse(arg))     def do_goto(self, arg):         'Move turtle to an absolute position with changing orientation.  GOTO 100 200'         goto(*parse(arg))     def do_home(self, arg):         'Return turtle to the home position:  HOME'         home()     def do_circle(self, arg):         'Draw circle with given radius an options extent and steps:  CIRCLE 50'         circle(*parse(arg))     def do_position(self, arg):         'Print the current turle position:  POSITION'         print('Current position is %d %d\n' % position())     def do_heading(self, arg):         'Print the current turle heading in degrees:  HEADING'         print('Current heading is %d\n' % (heading(),))     def do_color(self, arg):         'Set the color:  COLOR BLUE'         color(arg.lower())     def do_undo(self, arg):         'Undo (repeatedly) the last turtle action(s):  UNDO'     def do_reset(self, arg):         'Clear the screen and return turtle to center:  RESET'         reset()     def do_bye(self, arg):         'Stop recording, close the turtle window, and exit:  BYE'         print('Thank you for using Turtle')         self.close()         bye()         return True      # ----- record and playback -----     def do_record(self, arg):         'Save future commands to filename:  RECORD rose.cmd'         self.file = open(arg, 'w')     def do_playback(self, arg):         'Playback commands from a file:  PLAYBACK rose.cmd'         self.close()         with open(arg) as f:             self.cmdqueue.extend(f.read().splitlines())     def precmd(self, line):         line = line.lower()         if self.file and 'playback' not in line:             print(line, file=self.file)         return line     def close(self):         if self.file:             self.file.close()             self.file = None  def parse(arg):     'Convert a series of zero or more numbers to an argument tuple'     return tuple(map(int, arg.split()))  if __name__ == '__main__':     TurtleShell().cmdloop() 

Writing src/turtleshell.py 

在命令行运行下试试

(turtle) CIRCLE 50 (turtle) bye 

接着是一个支持sqlite,mysql,pg的命令行客户端

%%writefile src/sqlshell.py #!/usr/bin/env python3 import argparse import cmd, sys import pandas as pd import readline from playhouse.db_url import connect   class SqlShell(cmd.Cmd):     def __init__(self,completekey='tab', stdin=None, stdout=None,sql_uri=None):         super().__init__(completekey=completekey, stdin=stdin, stdout=stdout)         self.uri = sql_uri or "sqlite:///:memory:"         self.db = connect(self.uri)         self.db.connect()         self.intro = 'Welcome to the sql shell.   Type help or ? to list commands.\n'         self.prompt = "("+self.uri.split("://")[0]+" <<<)"         self.file = None         self.sql_string = ""       def _run_sql(self):         try:             q = self.db.execute_sql(self.sql_string,require_commit=False)         except Exception as e:             print(type(e))             print(str(e))         else:             if q.description:                 titles = [i[0] for i in q.description]                 rows = q.fetchall()                 t = [{t:v for (t,v) in zip(titles,i)} for i in rows]                 table = pd.DataFrame(t)                 print("+++++++++++Result+++++++++++")                 print(table.to_string())                 #print(titles)                 #print(rows)                 print("++++++++++++++++++++++++++++")             else:                 print('done!')      # ----- basic turtle commands -----     def default(self, string):         self.sql_string += string.strip()         if self.sql_string.endswith(";"):             print(self.sql_string)             self._run_sql()             self.sql_string = ""      def do_uri(self, arg):         print(self.uri)      def do_bye(self, arg):         'Stop recording, close the sqlshell window, and exit:  BYE'         print('Thank you for using This tool')         self.close()         self.db.close()         return True      def do_exit(self, arg):         return self.do_bye(arg)      def do_quit(self, arg):         return self.do_bye(arg)      # ----- record and playback -----     def do_record(self, arg):         'Save future commands to filename:  RECORD rose.cmd'         self.file = open(arg, 'w')     def do_playback(self, arg):         'Playback commands from a file:  PLAYBACK rose.cmd'         self.close()         with open(arg) as f:             self.cmdqueue.extend(f.read().splitlines())     def precmd(self, line):         line = line.lower()         if self.file and 'playback' not in line:             print(line, file=self.file)         return line     def close(self):         if self.file:             self.file.close()             self.file = None  def shell(args):     SqlShell(sql_uri = args.dburi).cmdloop()  def main(argv):     parser = argparse.ArgumentParser()     parser.add_argument("-d","--dburi", help=u"指定dburi",type=str)     parser.set_defaults(func=shell)     args = parser.parse_args(argv)     args.func(args)   if __name__ == '__main__':     main(argv=sys.argv[1:]) 

Writing src/sqlshell.py