自訂Python的import path

在import時，python會去搜尋sys.path中的每個entry。
而sys.path又是從下述所串接起來的
1.執行程式的目錄
2.PYTHONPATH環境變數
3.標準程式庫目錄(安裝時候就已經決定了)

所以若要自行新增，就需增加PYTHONPATH這環境變數。

cacaegg@cacabook:~$ export PYTHONPATH="/home/cacaegg/lib"
cacaegg@cacabook:~$ echo $PYTHONPATH
/home/cacaegg/lib
cacaegg@cacabook:~$ python
Python 2.6.4 (r264:75706, Dec  7 2009, 18:45:15)
[GCC 4.4.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print sys.path
['', '/home/cacaegg/lib', '/usr/lib/python2.6', '/usr/lib/python2.6/plat-linux2', '/usr/lib/python2.6/lib-tk', '/usr/lib/python2.6/lib-old', '/usr/lib/python2.6/lib-dynload', '/usr/lib/python2.6/dist-packages', '/usr/lib/python2.6/dist-packages/Numeric', '/usr/lib/python2.6/dist-packages/PIL', '/usr/lib/python2.6/dist-packages/gst-0.10', '/usr/lib/pymodules/python2.6', '/usr/lib/python2.6/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.6/gtk-2.0', '/usr/lib/python2.6/dist-packages/wx-2.6-gtk2-unicode', '/usr/local/lib/python2.6/dist-packages', '/usr/local/lib/python2.6/dist-packages/pygoogle']
>>> import python.lang
>>> quit()
cacaegg@cacabook:~$ ls lib/python/
__init__.py  __init__.pyc  lang.py  lang.pyc

此外需注意，由於從python.lang這樣方式去import的，所以python目錄底下需要__init__.py檔案才行。(空白的就好)