制作可重用的web apps

所谓可重用的apps，是指把开发的web apps制作成独立的packege，就像用pip安装的那些app一样。这样的web app package经过简单的配置就能整合进web工程里面直接使用。

下面用一个例子说明这个过程，假如这个app名为polls

需要用到两个工具setuptools和pip

1. 为web app新建一个父目录

例子中，给polls新建父目录django-polls

2. 把web app文件夹复制到新建的父目录下

例子中，polls整个文件夹复制到django-polls中

3. 新建README.rst文件

这个文件描述一下app的基本信息，及使用方法。

例子中，在django-polls目录下新建README.rst，如下

=====
Polls
=====

Polls is a simple Django app to conduct Web-based polls. For each
question, visitors can choose between a fixed number of answers.

Detailed documentation is in the "docs" directory.

Quick start
-----------

1. Add "polls" to your INSTALLED_APPS setting like this::

    INSTALLED_APPS = (
        ...
        'polls',
    )

2. Include the polls URLconf in your project urls.py like this::

    url(r'^polls/', include('polls.urls')),

3. Run `python manage.py migrate` to create the polls models.

4. Start the development server and visit http://127.0.0.1:8000/admin/
   to create a poll (you'll need the Admin app enabled).

5. Visit http://127.0.0.1:8000/polls/ to participate in the poll.

4. 新建LICENSE文件

说明版权及许可证信息

5. 新建setup.py文件

这个是很重要一步，setuptools这个工具使用这个文件打包app成packag。这个文件的详细写法参考

setuptools docs


例子中，setup.py如下形式：

import os
from setuptools import setup

with open(os.path.join(os.path.dirname(__file__), 'README.rst')) as readme:
    README = readme.read()

# allow setup.py to be run from any path
os.chdir(os.path.normpath(os.path.join(os.path.abspath(__file__), os.pardir)))

setup(
    name='django-polls',
    version='0.1',
    packages=['polls'],
    include_package_data=True,
    license='BSD License',  # example license
    description='A simple Django app to conduct Web-based polls.',
    long_description=README,
    url='http://www.example.com/',
    author='Your Name',
    author_email='yourname@example.com',
    classifiers=[
        'Environment :: Web Environment',
        'Framework :: Django',
        'Intended Audience :: Developers',
        'License :: OSI Approved :: BSD License', # example license
        'Operating System :: OS Independent',
        'Programming Language :: Python',
        # Replace these appropriately if you are stuck on Python 2.
        'Programming Language :: Python :: 3',
        'Programming Language :: Python :: 3.2',
        'Programming Language :: Python :: 3.3',
        'Topic :: Internet :: WWW/HTTP',
        'Topic :: Internet :: WWW/HTTP :: Dynamic Content',
    ],
)

6. 新建MANIFEST.IN文件

需要这个文件把README.rst、LICENSE或者其他文档说明包含金package中

例子中，如下形式

include LICENSE
include README.rst
recursive-include polls/static *
recursive-include polls/templates *

7. 命令行运行python setup.py sdist

这条命令创建一个新文件夹dist，里面放着已经打包好的package

版本：

• Python 2.7.9
• Django 1.8.1

参考资料：

• 
  https://docs.djangoproject.com/en/1.8/intro/reusable-apps/