Python中的setuptools工具不僅僅是簡化了distutils 的setup.py檔案的編寫，更重要的是它的包管理能力方面的增強。它可以使用一種更加透明的方法來查詢、下載並安裝依賴包；並可以在一個包的多個版本中自由進行切換，這些版本都安裝在同一個系統上；也可以宣告對某個包的特定版本的需求；還可以只使用一個簡單的命令就能更新到某個包的最新版本。說白了，這個和java中的Maven，以及在centos中使用的Yum有相似的地方；下面，先對以下幾個名詞作一個解釋：

1.distutils

distutils
(1)Part of the Python standard library since version 1.6(自1.6版本，加入python標準庫)
(2)The standard way of building and installing packages（構建、安裝包的標準方法）
(3)Primary functionality in distutils.core
(4) Developer or packager creates setup.py

#!/usr/bin/env python
from distutils.core import setup
setup (name = “foo”,
version = “1.0”,
py_modules = [“foo”])
$ python setup.py sdist (create a source distribution)
$ python setup.py bdist (create a build distribution)
$ python setup.py install (install using defaults)
* Other --install-* options (remember to update $PYTHONPATH)

setup中的引數說明：

The setup function takes a large number of arguments. These are laid out in the following table.

2.setuptools
1） A collection of enhancements to the Python distutils package that allow one to more easily build and
distribute python packages（對distutils包的增強，使用setuptools可以更加方便的構建、釋出python packages）
   2）Additional set of keyword arguments to setup()（在distutils.core.setup的基礎上,添加了一些新的引數）
3）Includes easy_install.py （包括一個easy_install.py工具，提供類似centos中的yum安裝工具）
4） Creates eggs (.egg)（關於egg,最好的解釋還是：‘Eggs are to Pythons as Jars are to Java…‘）
5）Features for developers (e.g. support for data files,MANIFEST, Pyrex, PyPI upload,…)
6）Ability to deploy project in “development mode” via setup.py develop command.

3. egg檔案

Eggs

 “Eggs are to Pythons as Jars are to Java…” ------------Phillip J. Eby
(1)Single-file importable distribution format .(這句話的意思是說，python中匯入掛鉤的更改，只要把egg加入到PYTHONPATH或者sys.path中，就可以像往常一樣匯入)
(2)Eggs are Zipfiles using the .egg extension, that support including data and C extensions as well as Python code

(egg也不一定是zipfile,setup的引數中有一個zip_safe引數,在程式打包時決定是否壓縮，如果不指定，bdist_egg會對工程中的每一個檔案作檢查，具體的解釋如下：)

（關於egg中是否會打包.py以外的資料、檔案，在setup中有3個引數控制，具體如下：）

這裡有一個例子：

The distutils have traditionally allowed installation of "data files", which are placed in a platform-specific location. However, the most common use case for data files distributed with a package is for use by the package, usually by including the data files in the package directory.

Setuptools offers three ways to specify data files to be included in your packages. First, you can simply use the include_package_data keyword, e.g.:

from setuptools import setup, find_packages
setup(
    ...
    include_package_data = True
)

This tells setuptools to install any data files it finds in your packages. The data files must be under CVS or Subversion control, or else they must be specified via the distutils' MANIFEST.in file. (They can also be tracked by another revision control system, using an appropriate plugin. See the section below on Adding Support for Other Revision Control Systems for information on how to write such plugins.)

If you want finer-grained control over what files are included (for example, if you have documentation files in your package directories and want to exclude them from installation), then you can also use the package_data keyword, e.g.:

from setuptools import setup, find_packages
setup(
    ...
    package_data = {
        # If any package contains *.txt or *.rst files, include them:
        '': ['*.txt', '*.rst'],
        # And include any *.msg files found in the 'hello' package, too:
        'hello': ['*.msg'],
    }
)

The package_data argument is a dictionary that maps from package names to lists of glob patterns. The globs may include subdirectory names, if the data files are contained in a subdirectory of the package. For example, if the package tree looks like this:

setup.py
src/
    mypkg/
        __init__.py
        mypkg.txt
        data/
            somefile.dat
            otherdata.dat

The setuptools setup file might look like this:

from setuptools import setup, find_packages
setup(
    ...
    packages = find_packages('src'),  # include all packages under src
    package_dir = {'':'src'},   # tell distutils packages are under src

    package_data = {
        # If any package contains *.txt files, include them:
        '': ['*.txt'],
        # And include any *.dat files found in the 'data' subdirectory
        # of the 'mypkg' package, also:
        'mypkg': ['data/*.dat'],
    }
)

Notice that if you list patterns in package_data under the empty string, these patterns are used to find files in every package, even ones that also have their own patterns listed. Thus, in the above example, the mypkg.txt file gets included even though it's not listed in the patterns for mypkg.

Also notice that if you use paths, you must use a forward slash (/) as the path separator, even if you are on Windows. Setuptools automatically converts slashes to appropriate platform-specific separators at build time.

(Note: although the package_data argument was previously only available in setuptools, it was also added to the Python distutils package as of Python 2.4; there is some documentation for the feature available on the python.org website.)

Sometimes, the include_package_data or package_data options alone aren't sufficient to precisely define what files you want included. For example, you may want to include package README files in your revision control system and source distributions, but exclude them from being installed. So, setuptools offers an exclude_package_data option as well, that allows you to do things like this:

from setuptools import setup, find_packages
setup(
    ...
    packages = find_packages('src'),  # include all packages under src
    package_dir = {'':'src'},   # tell distutils packages are under src

    include_package_data = True,    # include everything in source control

    # ...but exclude README.txt from all packages
    exclude_package_data = { '': ['README.txt'] },
)

The exclude_package_data option is a dictionary mapping package names to lists of wildcard patterns, just like the package_data option. And, just as with that option, a key of '' will apply the given pattern(s) to all packages. However, any files that match these patterns will be excluded from installation, even if they were listed in package_data or were included as a result of using include_package_data.

In summary, the three options allow you to:

include_package_data

Accept all data files and directories matched by MANIFEST.in or found in source control.

package_data

Specify additional patterns to match files and directories that may or may not be matched by MANIFEST.in or found in source control.

exclude_package_data

Specify patterns for data files and directories that should not be included when a package is installed, even if they would otherwise have been included due to the use of the preceding options.

NOTE: Due to the way the distutils build process works, a data file that you include in your project and then stop including may be "orphaned" in your project's build directories, requiring you to run setup.py clean --all to fully remove them. This may also be important for your users and contributors if they track intermediate revisions of your project using Subversion; be sure to let them know when you make changes that remove files from inclusion so they can run setup.py clean --all.

(3)Requires Python 2.3 or above

(4)Eggs are built using the setuptools package；eg:

python2.4 setup.py bdist_egg
(5)The published plan is to propose inclusion in the Python 2.5 standard library.(這個計劃沒有實現)
這個是我在http://www.ibm.com/developerworks/cn/linux/l-cppeak3.html上節選過來的，說的很好：

egg 是一個包含所有包資料的檔案包。在理想情況中，egg 是一個使用 zip 壓縮的檔案，其中包括了所有需要的包檔案。但是在某些情況下，setuptools 會決定（或被開關告知）包不應該是 zip 壓縮的。在這些情況下，egg 只是一個簡單的未曾壓縮的子目錄，但是裡面的內容是相同的。使用單一的版本可以方便地進行轉換，並可以節省一點磁碟空間，但是 egg 目錄從功能和組織結構上來說都是相同的。一直使用 JAR 檔案的 Java™ 技術的使用者會發現 egg 非常熟悉。

由於最新的 Python 版本中（需要 2.3.5+ 或 2.4）匯入掛鉤的更改，可以簡單地通過設定 PYTHONPATH 或 sys.path 並像往常一樣匯入相應的包來使用 egg。如果希望採用這種方法，就不需要使用 setuptools 或 ez_setup.py 了。例如，在本文使用的工作目錄中，我就為 PyYAML 包放入了一個 egg。現在我就可以使用這個包了，方法如下：

% export PYTHONPATH=~/work/dW/PyYAML-3.01-py2.4.egg
% python -c 'import yaml; print yaml.dump({"foo":"bar",1:[2,3]})'

1: [2, 3]
foo: bar

(在這個地方，我想說一下，你必須使用過setuptools才會有eazy-install.pth)

不過，PYTHONPATH 的（或者指令碼或 Python shell 會話內的 sys.path的）這種操作有些脆弱。egg 的發現最好是在新一點的 .pth 檔案中進行。在 site-packages/ 或 PYTHONPATH 中的任何 .pth 檔案都會進行解析來執行其他匯入操作，其方法類似於檢查可能包含包的那些目錄位置一樣。如果使用 setuptools 來處理包的管理功能，那麼在安裝、更新、刪除包時，就需要修改一個名為 easy-install.pth 的檔案。而且可以按照自己喜歡的方式對這個 .pth 進行命名（只要其副檔名是 .pth 即可）。例如，下面是我的 easy-install.pth 檔案的內容：

% cat /sw/lib/python2.4/site-packages/easy-install.pth
import sys; sys.__plen = len(sys.path)
setuptools-0.6b1-py2.4.egg
SQLObject-0.7.0-py2.4.egg
FormEncode-0.5.1-py2.4.egg
Gnosis_Utils-1.2.1-py2.4.egg
import sys; new=sys.path[sys.__plen:]; del sys.path[sys.__plen:];
  p=getattr(sys,'__egginsert',0); sys.path[p:p]=new;
  sys.__egginsert = p+len(new)

這種格式有點特殊：它近似於一個 Python 指令碼，但卻不完全是。需要說明的是，可以在那裡新增額外列出的 egg；更好的情況是，easy_install 會在執行時實現這種功能。也可以在 site-packages/ 下建立任意多個 .pth 檔案；每個都可以列出有哪些 egg 是可用的。

Why bother with Eggs?
    1）Enable tools like “Easy Install” Python package manager（這個很顯然）
 2）They are a “zero installation” format for pure Python packages (put them on PYTHONPATH or sys.path)（上面說的那個.pth）
 3）They can include package metadata (e.g. dependencies)
 4）They allow namespace packages (packages that contain other packages) to be split into separate distributions
 5）They allow applications or libraries to specify the needed version of a library before doing an import (e.g. require(“Twisted-Internet>=2.0”) )（這個涉及到的是setup裡install_requires引數）
 6）They provide a framework for plug-ins (similar to Eclipse’s extension point)
 7）Enables one to distribute a project that depends on other software available via PyPI a.k.a. Cheese Shop.(eazy_install或者執行python setup.py install時，會依據install_requires引數自動從http://www.python.org/pypi/上尋找規定的版本，並下載安裝好這些依賴的包)

4. eazy_install

Easy Install / easy_install.py
1)A Python module bundled with setuptools that lets one automatically build, install, and manage python
packages
2) Part of the setuptools package
3) Installs any distutils-based package
4) Can find packages on PyPI
5) Handles dependencies via arguments to setup() (e.g. install_requires = [‘foo>=1.4’,’Bar’] )

[1]http://docs.python.org/distutils/index.html

[2]http://peak.telecommunity.com/DevCenter/setuptools

[3]http://peak.telecommunity.com/DevCenter/PythonEggs

[4]http://peak.telecommunity.com/DevCenter/EasyInstall

[5]http://www.ibm.com/developerworks/cn/linux/l-cppeak3.html