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--- python:porting_python_2_to_pyton_3 [2020/01/22 15:29] – WIP apressato
+++ python:porting_python_2_to_pyton_3 [2020/01/22 18:01] (versione attuale) – WIP apressato
@@ Linea 1: / Linea 1: @@
 ====== Porting da Python 2 a Python 3  ======
-<WRAP center round important 60%>
-***WIP***: Quello seguente è un articolo in divenire
-</WRAP>
@@ Linea 552: / Linea 549: @@
 </code>
-== Python 3 ==
+== Python 2 e 3 ==
 <code python>
-# Python 2 and 3:
 for key in heights:
     ...
+</code>
+=== I Valori ===
+== Python 2 ==
+<code python>
+for value in heights.itervalues():
+    ...
+</code>
+== Python 2 e 3 ==
+<code python>
+#Opzione 0: Sconsigliata
+for value in heights.values():    # Maggiore consumo di memoria in Py2
+    ...
+</code>
+<code python>
+# Opzione 1
+from builtins import dict
+heights = dict(Fred=175, Anne=166, Joe=192)
+for key in heights.values():    # efficiente in Py2 e Py3
+</code>
+<code python>
+# Opzione 2
+from builtins import itervalues
+for key in itervalues(heights):
+    ...
+</code>
+=== Gli Elementi ===
+== Python 2 ==
+<code python>
+for (key, value) in heights.iteritems():
+    ...
+</code>
+== Python 2 e 3 ==
+<code python>
+# Opzione 1
+for (key, value) in heights.items():    # inefficiente in Py2
+    ...
+</code>
+<code python>
+# Opzione 2
+from future.utils import viewitems
+for (key, value) in viewitems(heights):   # si compporta come un set
+    ...
+</code>
+<code python>
+# Opzione 3
+from future.utils import iteritems
+for (key, value) in iteritems(heights):
+    ...
+</code>
+==== Chiavi/Valori/Elementi di un Dizionario come Lista ====
+=== Chiavi ===
+== Python 2 ==
+<code python>
+keylist = heights.keys()
+assert isinstance(keylist, list)
+</code>
+== Python 2 e 3 ==
+<code python>
+keylist = list(heights)
+assert isinstance(keylist, list)
+</code>
+=== Valori ===
+== Python 2 ==
+<code python>
+heights = {'Fred': 175, 'Anne': 166, 'Joe': 192}
+valuelist = heights.values()
+assert isinstance(valuelist, list)
+</code>
+== Python 2 e 3 ==
+<code python>
+# Opzione 1
+valuelist = list(heights.values())    # inefficiente in Py2
+</code>
+<code python>
+# Opzione 2
+from builtins import dict
+heights = dict(Fred=175, Anne=166, Joe=192)
+valuelist = list(heights.values())
+</code>
+<code python>
+# Opzione 3
+from future.utils import listvalues
+valuelist = listvalues(heights)
+</code>
+<code python>
+# Opzione 4
+from future.utils import itervalues
+valuelist = list(itervalues(heights))
+</code>
+=== Elementi ===
+== Python 2 e 3 ==
+<code python>
+# Opzione 1
+itemlist = list(heights.items())    # inefficiente in Py2
+</code>
+<code python>
+# Opzione 2
+from future.utils import listitems
+itemlist = listitems(heights)
+</code>
+<code python>
+# Opzione 3
+from future.utils import iteritems
+itemlist = list(iteritems(heights))
 </code>
@@ Linea 584: / Linea 709: @@
 </code>
 ===== Altre variazioni ai builtins =====
+==== File IO con open() ====
+<code python>
+# Python 2 only
+f = open('myfile.txt')
+data = f.read()              # as a byte string
+text = data.decode('utf-8')
+# Python 2 and 3: alternative 1
+from io import open
+f = open('myfile.txt', 'rb')
+data = f.read()              # as bytes
+text = data.decode('utf-8')  # unicode, not bytes
+# Python 2 and 3: alternative 2
+from io import open
+f = open('myfile.txt', encoding='utf-8')
+text = f.read()    # unicode, not bytes
+</code>
+==== reduce() ====
+<code python>
+# Python 2 only:
+assert reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) == 1+2+3+4+5
+# Python 2 and 3:
+from functools import reduce
+assert reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) == 1+2+3+4+5
+</code>
+==== file() ====
+<code python>
+# Python 2 only:
+f = file(pathname)
+</code>
+<code python>
+# Python 2 and 3:
+f = open(pathname)
+# But preferably, use this:
+from io import open
+f = open(pathname, 'rb')   # if f.read() should return bytes
+# or
+f = open(pathname, 'rt')   # if f.read() should return unicode text
+</code>
+==== exec ====
+<code python>
+# Python 2 only:
+exec 'x = 10'
+# Python 2 and 3:
+exec('x = 10')
+</code>
+<code python>
+# Python 2 only:
+g = globals()
+exec 'x = 10' in g
+# Python 2 and 3:
+g = globals()
+exec('x = 10', g)
+</code>
+<code python>
+# Python 2 only:
+l = locals()
+exec 'x = 10' in g, l
+# Python 2 and 3:
+exec('x = 10', g, l)
+</code>
+==== execfile() ====
+<code python>
+# Python 2 only:
+execfile('myfile.py')
+# Python 2 and 3: alternative 1
+from past.builtins import execfile
+execfile('myfile.py')
+# Python 2 and 3: alternative 2
+exec(compile(open('myfile.py').read()))
+# This can sometimes cause this:
+#     SyntaxError: function ... uses import * and bare exec ...
+# See https://github.com/PythonCharmers/python-future/issues/37
+</code>
+==== unichr() ====
+<code python>
+# Python 2 only:
+assert unichr(8364) == '€'
+# Python 3 only:
+assert chr(8364) == '€'
+# Python 2 and 3:
+from builtins import chr
+assert chr(8364) == '€'
+</code>
+==== intern() ====
+<code python>
+# Python 2 only:
+intern('mystring')
+# Python 3 only:
+from sys import intern
+intern('mystring')
+# Python 2 and 3: alternative 1
+from past.builtins import intern
+intern('mystring')
+# Python 2 and 3: alternative 2
+from six.moves import intern
+intern('mystring')
+# Python 2 and 3: alternative 3
+from future.standard_library import install_aliases
+install_aliases()
+from sys import intern
+intern('mystring')
+# Python 2 and 3: alternative 4
+try:
+    from sys import intern
+except ImportError:
+    pass
+intern('mystring')
+</code>
+==== apply() ====
+<code python>
+args = ('a', 'b')
+kwargs = {'kwarg1': True}
+# Python 2 only:
+apply(f, args, kwargs)
+# Python 2 and 3: alternative 1
+f(*args, **kwargs)
+# Python 2 and 3: alternative 2
+from past.builtins import apply
+apply(f, args, kwargs)
+</code>
+==== chr() ====
+<code python>
+# Python 2 only:
+assert chr(64) == b'@'
+assert chr(200) == b'\xc8'
+# Python 3 only: option 1
+assert chr(64).encode('latin-1') == b'@'
+assert chr(0xc8).encode('latin-1') == b'\xc8'
+# Python 2 and 3: option 1
+from builtins import chr
+assert chr(64).encode('latin-1') == b'@'
+assert chr(0xc8).encode('latin-1') == b'\xc8'
+# Python 3 only: option 2
+assert bytes([64]) == b'@'
+assert bytes([0xc8]) == b'\xc8'
+# Python 2 and 3: option 2
+from builtins import bytes
+assert bytes([64]) == b'@'
+assert bytes([0xc8]) == b'\xc8'
+</code>
+==== cmp() ====
+<code python>
+# Python 2 only:
+assert cmp('a', 'b') < 0 and cmp('b', 'a') > 0 and cmp('c', 'c') == 0
+# Python 2 and 3: alternative 1
+from past.builtins import cmp
+assert cmp('a', 'b') < 0 and cmp('b', 'a') > 0 and cmp('c', 'c') == 0
+# Python 2 and 3: alternative 2
+cmp = lambda(x, y): (x > y) - (x < y)
+assert cmp('a', 'b') < 0 and cmp('b', 'a') > 0 and cmp('c', 'c') == 0
+</code>
+==== reload() ====
+<code python>
+# Python 2 only:
+reload(mymodule)
+# Python 2 and 3
+from imp import reload
+reload(mymodule)
+</code>
 ===== Standard library =====
+==== dbm modules ====
+<code python>
+# Python 2 only
+import anydbm
+import whichdb
+import dbm
+import dumbdbm
+import gdbm
+# Python 2 and 3: alternative 1
+from future import standard_library
+standard_library.install_aliases()
-===== Modernize =====
+import dbm
+import dbm.ndbm
+import dbm.dumb
+import dbm.gnu
+# Python 2 and 3: alternative 2
+from future.moves import dbm
+from future.moves.dbm import dumb
+from future.moves.dbm import ndbm
+from future.moves.dbm import gnu
+# Python 2 and 3: alternative 3
+from six.moves import dbm_gnu
+# (others not supported)
+</code>
+==== commands / subprocess modules ====
+<code python>
+# Python 2 only
+from commands import getoutput, getstatusoutput
+# Python 2 and 3
+from future import standard_library
+standard_library.install_aliases()
+from subprocess import getoutput, getstatusoutput
+</code>
+==== subprocess.check_output() ====
+<code python>
+# Python 2.7 and above
+from subprocess import check_output
+# Python 2.6 and above: alternative 1
+from future.moves.subprocess import check_output
+# Python 2.6 and above: alternative 2
+from future import standard_library
+standard_library.install_aliases()
+from subprocess import check_output
+</code>
+==== Collections: Counter and OrderedDict ====
+<code python>
+# Python 2.7 and above
+from collections import Counter, OrderedDict
+# Python 2.6 and above: alternative 1
+from future.moves.collections import Counter, OrderedDict
+# Python 2.6 and above: alternative 2
+from future import standard_library
+standard_library.install_aliases()
+from collections import Counter, OrderedDict
+</code>
+==== StringIO module ====
+<code python>
+# Python 2 only
+from StringIO import StringIO
+from cStringIO import StringIO
+# Python 2 and 3
+from io import BytesIO
+# and refactor StringIO() calls to BytesIO() if passing byte-strings
+</code>
+==== http module ====
+<code python>
+# Python 2 only:
+import httplib
+import Cookie
+import cookielib
+import BaseHTTPServer
+import SimpleHTTPServer
+import CGIHttpServer
+# Python 2 and 3 (after ``pip install future``):
+import http.client
+import http.cookies
+import http.cookiejar
+import http.server
+</code>
+==== xmlrpc module ====
+<code python>
+# Python 2 only:
+import DocXMLRPCServer
+import SimpleXMLRPCServer
+# Python 2 and 3 (after ``pip install future``):
+import xmlrpc.server
+</code>
+<code python>
+# Python 2 only:
+import xmlrpclib
+# Python 2 and 3 (after ``pip install future``):
+import xmlrpc.client
+</code>
+==== html escaping and entities ====
+<code python>
+# Python 2 and 3:
+from cgi import escape
+# Safer (Python 2 and 3, after ``pip install future``):
+from html import escape
+# Python 2 only:
+from htmlentitydefs import codepoint2name, entitydefs, name2codepoint
+# Python 2 and 3 (after ``pip install future``):
+from html.entities import codepoint2name, entitydefs, name2codepoint
+</code>
+==== html parsing ====
+<code python>
+# Python 2 only:
+from HTMLParser import HTMLParser
+# Python 2 and 3 (after ``pip install future``)
+from html.parser import HTMLParser
+# Python 2 and 3 (alternative 2):
+from future.moves.html.parser import HTMLParser
+</code>
+==== urllib module ====
+''urllib'' è uno dei moduli più complessi da usare in compatibilità fra 2 e 3.
+<code python>
+# Python 2 only:
+from urlparse import urlparse
+from urllib import urlencode
+from urllib2 import urlopen, Request, HTTPError
+</code>
+<code python>
+# Python 3 only:
+from urllib.parse import urlparse, urlencode
+from urllib.request import urlopen, Request
+from urllib.error import HTTPError
+</code>
+<code python>
+# Python 2 and 3: easiest option
+from future.standard_library import install_aliases
+install_aliases()
+from urllib.parse import urlparse, urlencode
+from urllib.request import urlopen, Request
+from urllib.error import HTTPError
+</code>
+<code python>
+# Python 2 and 3: alternative 2
+from future.standard_library import hooks
+with hooks():
+    from urllib.parse import urlparse, urlencode
+    from urllib.request import urlopen, Request
+    from urllib.error import HTTPError
+</code>
+<code python>
+# Python 2 and 3: alternative 3
+from future.moves.urllib.parse import urlparse, urlencode
+from future.moves.urllib.request import urlopen, Request
+from future.moves.urllib.error import HTTPError
+</code>
+<code python>
+# Python 2 and 3: alternative 4
+try:
+    from urllib.parse import urlparse, urlencode
+    from urllib.request import urlopen, Request
+    from urllib.error import HTTPError
+except ImportError:
+    from urlparse import urlparse
+    from urllib import urlencode
+    from urllib2 import urlopen, Request, HTTPError
+</code>
+==== Tkinter ====
+<code python>
+# Python 2 only:
+import Tkinter
+import Dialog
+import FileDialog
+import ScrolledText
+import SimpleDialog
+import Tix
+import Tkconstants
+import Tkdnd
+import tkColorChooser
+import tkCommonDialog
+import tkFileDialog
+import tkFont
+import tkMessageBox
+import tkSimpleDialog
+import ttk
+# Python 2 and 3 (after ``pip install future``):
+import tkinter
+import tkinter.dialog
+import tkinter.filedialog
+import tkinter.scrolledtext
+import tkinter.simpledialog
+import tkinter.tix
+import tkinter.constants
+import tkinter.dnd
+import tkinter.colorchooser
+import tkinter.commondialog
+import tkinter.filedialog
+import tkinter.font
+import tkinter.messagebox
+import tkinter.simpledialog
+import tkinter.ttk
+</code>
+==== socketserver ====
+<code python>
+# Python 2 only:
+import SocketServer
+# Python 2 and 3 (after ``pip install future``):
+import socketserver
+</code>
+==== copy_reg, copyreg ====
+<code python>
+# Python 2 only:
+import copy_reg
+# Python 2 and 3 (after ``pip install future``):
+import copyreg
+</code>
+==== configparser ====
+<code python>
+# Python 2 only:
+from ConfigParser import ConfigParser
+# Python 2 and 3 (after ``pip install configparser``):
+from configparser import ConfigParser
+</code>
+==== queue ====
+<code python>
+# Python 2 only:
+from Queue import Queue, heapq, deque
+# Python 2 and 3 (after ``pip install future``):
+from queue import Queue, heapq, deque
+</code>
+==== repr, reprlib ====
+<code python>
+# Python 2 only:
+from repr import aRepr, repr
+# Python 2 and 3 (after ``pip install future``):
+from reprlib import aRepr, repr
+</code>
+==== UserDict, UserList, UserString ====
+<code python>
+# Python 2 only:
+from UserDict import UserDict
+from UserList import UserList
+from UserString import UserString
+# Python 3 only:
+from collections import UserDict, UserList, UserString
+# Python 2 and 3: alternative 1
+from future.moves.collections import UserDict, UserList, UserString
+# Python 2 and 3: alternative 2
+from six.moves import UserDict, UserList, UserString
+# Python 2 and 3: alternative 3
+from future.standard_library import install_aliases
+install_aliases()
+from collections import UserDict, UserList, UserString
+</code>
+==== itertools: filterfalse, zip_longest ====
+<code python>
+# Python 2 only:
+from itertools import ifilterfalse, izip_longest
+# Python 3 only:
+from itertools import filterfalse, zip_longest
+# Python 2 and 3: alternative 1
+from future.moves.itertools import filterfalse, zip_longest
+# Python 2 and 3: alternative 2
+from six.moves import filterfalse, zip_longest
+# Python 2 and 3: alternative 3
+from future.standard_library import install_aliases
+install_aliases()
+from itertools import filterfalse, zip_longest
+</code>
+===== Python-Modernize =====
+==== Scopo del progetto ====
+Questa libreria è un wrapper attorno a ''lib2to3'' che serve a rendere il codice Python 2 più moderno in ottica di portarlo su Python 3.
+Il comando python-modernize funziona come 2to3. Ecco come riscrivere un singolo file:
+<code bash>
+python-modernize -w example.py
+</code>
+Il sito Web del progetto è disponibile su [[https://github.com/python-modernize/python-modernize|GitHub]] e il nome del progetto PyPI è [[https://pypi.python.org/pypi/modernize|modernize]]
+==== Una nota sulla gestione delle stringhe ====
+  * Di default modernize non cambia le stringhe Unicode. \\ Questa è l'opzione più semplice se vuoi supportare Python 3.x e versioni successive insieme a Python 2.
+  * In alternativa, c'è il flag ''**--six-unicode**'' che avvolgerà le stringhe Unicode con la funzione helper **six.u()** usando il fixer contenuto in ''libmodernize.fixes.fix_unicode''.\\ Ciò è utile se si desidera supportare Python 3.1 e Python 3.2 senza grandi cambiamenti.
+  * L'ultima alternativa è il flag ''**--future-unicode**'' che importa gli ''unicode_literals'' dal modulo **<nowiki>__future__</nowiki>** usando il fixer contenuto in ''libmodernize.fixes.fix_unicode_future''.\\ Ciò richiede Python 2.6 e versioni successive e richiederà di contrassegnare le bytestring con b '' e le stringhe native in str('') o qualcosa di simile che sopravviva alla trasformazione.
+==== Preparazione ====
+Dal prompt dei comandi lanciare
+<code bash>
+pip --install modernize
+</code>
+Al termine dell'installazione avrete a disposizione l'eseguibile **python-modernize**
+==== Batch di conversione ====
+<code batch>
+set mydatetime=%date:~-4%%date:~-7,2%%date:~-10,2%_%time:~0,2%%time:~3,2%%time:~6,2%
+set logpath=.\Logs
+set logfile=%logpath%\Migrate_%Application%_2to3_%mydatetime%.log
+set RepoPath=path\to\your \web2py\applications
+set Application=Your_Folder_App_Name
+IF NOT EXIST %logpath% (
+  MKDIR %logpath%
+)
+(FOR /f "delims=" %%a IN ('DIR %RepoPath%\%Application%\*.pyc /b /s') do (del %%a))
+(FOR /f "delims=" %%a IN ('DIR %RepoPath%\%Application%\*.py /b /s') do (python-modernize -w %%a >> %LogFile%))
+(FOR /f "delims=" %%a IN ('DIR %RepoPath%\%Application%\*.bak /b /s') do (del %%a))
+</code>
@@ Linea 605: / Linea 1313: @@
   - [[https://www.geeksforgeeks.org/important-differences-between-python-2-x-and-python-3-x-with-examples/]]
   - [[https://sebastianraschka.com/Articles/2014_python_2_3_key_diff.html]]
+  - [[https://python-modernize.readthedocs.io/en/latest/]]

python/porting_python_2_to_pyton_3.1579706982.txt.gz · Ultima modifica: 2020/01/22 15:29 da apressato

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