1 working directory 변경

2 변수의 데이터형 알아내기

3 동적 실행

import os
print os.getcwd() #현재 working directory 알아내기
os.chdir('d:\pydata')

>>> a = 'dynamic'
>>> x = type(a)
>>> x
<type 'str'>
>>> x.__name__
'str'
>>> 

>>> isinstance('aaa', str)
True
>>> isinstance(123, int)
True

• expression -> a + 1
  
• statments -> a = a + 1
  
  

>>> a = 1
>>> a = eval('a+1')
>>> a
2

>>> exec 'a = a + 1'
>>> a
3

>>> a = 1
>>> compiled_code = compile('a + 1', '<string>', 'eval')
>>> a = 1
>>> for i in range(5): 
...     a = eval(compiled_code)
...     
>>> a
6

• expression 이면 'eval'
  
• 단일 statment 이면 'single'
  
• 복합 statment 이면 'exec'