1 / 18

Documentation / References

Documentation / References. Python Full Documentation http://docs.python.org/index.html Python Quick Reference http://rgruet.free.fr/ IPython <object>? help <object> tab completion. Basics. Tabbing is crucial and mandatory DO NOT mix tabs with spaces, choose one method and stick to it

kasi
Download Presentation

Documentation / References

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Documentation / References • Python Full Documentation • http://docs.python.org/index.html • Python Quick Reference • http://rgruet.free.fr/ • IPython • <object>? • help <object> • tab completion

  2. Basics • Tabbing is crucial and mandatory • DO NOT mix tabs with spaces, choose one method and stick to it • Comments: • # single line comment • """ long comment """ • Philosophic mindset • Shorter and simpler is better, without getting cryptic • Intuitive to existing programmers • No deliberate way to do the same code in two different ways • Keywords • None • True • False • pass

  3. Duck Typing • “when I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.” - James Whitcomb Riley • Casting: • int(variable) • int('FF', 16) == 255 • float(variable) • also definable by adding a period • str(variable) • Type Comparison • type(variable) == type([]) • type(variable) == type(“”) • type(variable) == type(0)

  4. Data Types • Modules • Objects • Integer • Float • Strings • List • Dictionary • Tuple • Decorators • Generators

  5. Modules • Two methods of importing • import math • Now, functions or attributes defined in math can be accessed like so: math.pi, math.sin(), etc. • from math import * • Now, all of math is imported into the global namespace and can be accessed like so: pi, sin(), etc. • from math import pi • Now, only pi is in the global namespace

  6. Numbers • Types: • Integers • Floats • Infinite length • Math • ( + - * / % ^ & | ) • ** instead of ^ (but ^ exists as XOR, be careful) • += exists, but ++ does not (use +=1) • More math • import math • math.e, math.pi, math.cos(), math.acos(), math.cosh(), math.log(), math.ceil(), math.sqrt()

  7. Control Flow Statements • if, elif, else… and, or, not • while • continue • break • for • More like foreach in other languages • try, except list = [2, 3, 1, 7] i = 0 while i < len(list): print "output:", str(i) i += 1 output: 2 output: 3 output: 1 output: 7 list = [2, 3, 1, 7] for x in list: print "output:”, str(x) output: 2 output: 3 output: 1 output: 7 try: dict_array[0]['item’] # code for success except IndexError: # code if [0] fails except KeyError: # code if ['item'] fails if len(dict_array) == 0: # code if [0] fails elifdict_array.has_key('item‘): # code if ['item'] fails else: # code for success

  8. switch Control Structure • There isn’t one. • Alternatives to switch: • if, elif, else • dictionary forms {'one': lambda x: x+1, 'two': lambda x: x+2, 'three': lambda x: x+3 }[var](var) if var == 'one': # do 'one' specific code elifvar == 'two': # do 'two' specific code elifvar == 'three': # do 'three' specific code else: # do default code def one_code(): # do 'one' specific code def two_code(): # do 'two' specific code def three_code(): # do 'three' specific code def default_code(): # do default code {'one': one_code, 'two': two_code, 'three': three_code}[var]()

  9. Strings • Defined in usual ways • Important Methods: • strip() • join() • split() • String formatting (like printf) mystr = " first second third" myarr = mystr.strip().split(" ") for i in xrange(0, len(myarr)): print "output:", myarr[i] print "mystr::%s::" % " ".join(myarr) output: first output: second output: third mystr::first second third::

  10. Lists • Important methods • append() • extend() • insert() • pop() list = [3, 4, 5] print "pop: %d" % list.pop(1) list.insert(0, 2) list.append(6) list.extend([7, 8]) print "list: %s" % str(list) pop: 4 list: [2, 3, 5, 6, 7, 8]

  11. Slicing • A more complex way of handling list items and strings list = [2, 3, 1, 7, 5] print list print list[1:2] print list[2:] print list[-2:] print list[:-2] [2, 3, 1, 7, 5] [3] [1, 7, 5] [7, 5] [2, 3, 1]

  12. Tuple • Collection of a fixed amount of values • Tuple unpacking def output_three_multiples(self, number): return (number*2, number*3, number*4) (first,second,_) = output_three_multiples(7)

  13. File Manipulation • First thing that made me like Python file = open("filename", "r") contents = file.read() file.close() print contents file = open("filename", "r") contents = file.readlines() file.close() line_num = 1 for line in contents: print "%d: %s" % (line_num, line) line_num += 1

  14. Classes • Everything involving classes in Python is weird • All classes extend "object" • Like Java • Historically this was not the case, so be careful • Constructor is: def __init__(self): • Private methods prefixed with two underscores • Static methods use @staticmethod decorator • Super methods are weird, too

  15. Class Code import attrdict import errors from execute import * class server(attrdict): def __init__(self, dict): super(server, self).__init__(dict) # no executer until a function makes one self.executer = None def __do_execute(self, cmd): ret = self.require_remote() if ret: return (None,None,None) if self.executer: return self.executer.execute(cmd) else: return execute_srv(self.remote_server, cmd) def require_remote(self): if not self.require_dict(self.remote_server, [ "ip", "port" ]): return errors.throw(errors.BACKEND_INVALID_INPUT)

  16. Class Code 2 import errors, glob, server from execute import * class master(server): def __init__(self, dict): super(master, self).__init__(dict) @staticmethod def __do_execute(cmd): return execute(cmd) def remove_key(self): ret = self.require_remote() if ret: return ret # strip keys from remote server (exit_code,_,_) = self.__do_execute( "ssh -i %s " % glob.config.get("paths", "master_private_key") + "-p " + str(self.remote_server['port']) + " root@" + self.remote_server['ip'] + " " + "\"sed -r \\\"/^.*_panenthe$/d\\\" -i %s\"" % glob.config.get("paths", "user_ssh_authorized_keys") ) # fail if exit_code != 0: return errors.throw(errors.SERVER_REMOTE_REMOVE) # return return errors.throw(errors.ERR_SUCCESS)

  17. Libraries

More Related