如何让你的Python程序支持多语言

本文介绍如何通过Python标准库gettext帮助你的程序支持多语言。

代码例子

import randomguessesTaken = 0PRint(_("Hello! What's your name?"))myName = input()number = random.randint(1, 20)print("Well, {}, I am thinking of a number between 1 and 20.".format(myName))while guessesTaken < 6:    print("Take a guess.")    guess = input()    try:        guess = int(guess)    except ValueError:        print("You should give me a number.")        continue    if guess < number:        print("Your guess is too low.")    if guess > number:        print("You guess is too high.")    if guess == number:        breakif guess == number:    print("Good job, {}! You guessed my number in {} guesses!".format(        myName, guessesTaken))if guess != number:    print("Nope. The number I was thinking of was {}.".format(number))

这是我们一个简单的猜数字游戏，我们执行看看过程。

$ python3 guess.py Hello! What's your name?AidanWell, Aidan, I am thinking of a number between 1 and 20.Take a guess.13You guess is too high.Take a guess.2Your guess is too low.Take a guess.12You guess is too high.Take a guess.1Your guess is too low.Take a guess.10You guess is too high.Take a guess.9Good job, Aidan! You guessed my number in 6 guesses!

程序是很漂亮了，可是老板突然要求你改成中文的，那么我们通常可能选择将字符串全部修改为相应中文，但是老板要让你自己针对不同用户不同语言就麻烦了。那有啥办法呢？Python标准库gettext可以帮助我们。

改造

我们首先用_()，然改造我们的字符串。你可以把_()想象成类似如下函数

def _(s):    spanishStrings = {'Hello world!': 'Hola Mundo!'}    frenchStrings = {'Hello world!': 'Bonjour le monde!'}    germanStrings = {'Hello world!': 'Hallo Welt!'}    if LANGUAGE == 'English':        return s    if LANGUAGE == 'Spanish':        return spanishStrings[s]    if LANGUAGE == 'French':        return frenchStrings[s]    if LANGUAGE == 'German':        return germanStrings[s]

不过，当我查看他类型时，我发现他应该是某种继承了list的扩展类型。

>>> type(_)<class 'list'>

改造后我们的代码如下

import randomguessesTaken = 0print(_("Hello! What's your name?"))myName = input()number = random.randint(1, 20)print(_("Well, {}, I am thinking of a number between 1 and 20.").format(myName))while guessesTaken < 6:    guessesTaken += 1    print(_("Take a guess."))    guess = input()    try:        guess = int(guess)    except ValueError:        print(_("You should give me a number."))        continue    if guess < number:        print(_("Your guess is too low."))    if guess > number:        print(_("You guess is too high."))    if guess == number:        breakif guess == number:    print(_("Good job, {}! You guessed my number in {} guesses!").format(        myName, guessesTaken))if guess != number:    print(_("Nope. The number I was thinking of was {}.").format(number))

提取字符串

Python 自带一个工具我们提取使用_()包裹的字符串

pygettext3 -d guess guess.py

它生成了如下文件：

$ cat guess.pot # SOME DESCRipTIVE TITLE.# Copyright (C) YEAR ORGANIZATION# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.#msgid ""msgstr """Project-Id-Version: PACKAGE VERSION/n""POT-Creation-Date: 2014-12-24 15:35+CST/n""PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE/n""Last-Translator: FULL NAME <EMAIL@ADDRESS>/n""Language-Team: LANGUAGE <LL@li.org>/n""MIME-Version: 1.0/n""Content-Type: text/plain; charset=UTF-8/n""Content-Transfer-Encoding: 8bit/n""Generated-By: pygettext.py 1.5/n"#: guess.py:5msgid "Hello! What's your name?"msgstr ""#: guess.py:9msgid "Well, {}, I am thinking of a number between 1 and 20."msgstr ""#: guess.py:12msgid "Take a guess."msgstr ""#: guess.py:17msgid "You should give me a number."msgstr ""#: guess.py:21msgid "Your guess is too low."msgstr ""#: guess.py:24msgid "You guess is too high."msgstr ""#: guess.py:30msgid "Good job, {}! You guessed my number in {} guesses!"msgstr ""#: guess.py:34msgid "Nope. The number I was thinking of was {}."msgstr ""

翻译工作

我们通过使用poedit这个非常好用的工具对其翻译成我们想要的目标文件，该工具还带有翻译词典，跨平台。地址：http://poedit.net/

翻译后的结果

翻译后生成

guess.po

# SOME DESCRIPTIVE TITLE.# Copyright (C) YEAR ORGANIZATION# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.#msgid ""msgstr """Project-Id-Version: /n""POT-Creation-Date: 2014-12-24 15:35+CST/n""PO-Revision-Date: 2014-12-24 16:23+0800/n""Last-Translator: /n""Language-Team: /n""MIME-Version: 1.0/n""Content-Type: text/plain; charset=UTF-8/n""Content-Transfer-Encoding: 8bit/n""Generated-By: pygettext.py 1.5/n""X-Generator: Poedit 1.7.1/n""Plural-Forms: nplurals=1; plural=0;/n""Language: zh/n"#: guess.py:5msgid "Hello! What's your name?"msgstr "你好！你叫什么名字？"#: guess.py:9msgid "Well, {}, I am thinking of a number between 1 and 20."msgstr "好的，{}，我心里想了个1到20之间的数。"#: guess.py:12msgid "Take a guess."msgstr "猜猜看。"#: guess.py:17msgid "You should give me a number."msgstr "你应该给我个数字。"#: guess.py:21msgid "Your guess is too low."msgstr "你猜低了。"#: guess.py:24msgid "You guess is too high."msgstr "你猜高了。"#: guess.py:30msgid "Good job, {}! You guessed my number in {} guesses!"msgstr "漂亮，{}！你用了{}次猜中了我的数字。"#: guess.py:34msgid "Nope. The number I was thinking of was {}."msgstr "不对。我想的数字是{}。"

还有一个mo扩展的文件，MO 文件是面向计算机的、由 PO 文件通过 gettext 软件包编译而成的二进制文件。

我们如下放置这两个文件

├── guess.py
├── locale
│ └── zh_CN
│ └── LC_MESSAGES
│ ├── guess.mo
│ └── guess.po

武装gettext

然后我们在代码加入

import gettextes = gettext.translation('guess', localedir='locale', languages=['zh_CN'])es.install()

终极版本

import randomimport gettextes = gettext.translation('guess', localedir='locale', languages=['zh_CN'])es.install()guessesTaken = 0print(_("Hello! What's your name?"))myName = input()number = random.randint(1, 20)print(_("Well, {}, I am thinking of a number between 1 and 20.").format(myName))while guessesTaken < 6:    guessesTaken += 1    print(_("Take a guess."))    guess = input()    try:        guess = int(guess)    except ValueError:        print(_("You should give me a number."))        continue    if guess < number:        print(_("Your guess is too low."))    if guess > number:        print(_("You guess is too high."))    if guess == number:        breakif guess == number:    print(_("Good job, {}! You guessed my number in {} guesses!").format(        myName, guessesTaken))if guess != number:    print(_("Nope. The number I was thinking of was {}.").format(number))

惊人结果

$ python3 guess.py 你好！你叫什么名字？大熊好的，大熊，我心里想了个1到20之间的数。猜猜看。10你猜高了。猜猜看。8你猜高了。猜猜看。6你猜高了。猜猜看。4漂亮，大熊！你用了4次猜中了我的数字。

结论

Python 在国际化操作方面很简单，你是否有更好的方案？