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以Python为例讨论高级编程语言程序的wire format与校验

　2010-09-22 11:26:23　来源：WEB开发网　　　

核心提示： 回顾之前分析.pyc文件格式时用的例子： demo.py： Python代码class A(): x = 1print(A.x) # 1# increment A.x by 2A.x += 2print(A.x) # 3# create an instance of Aa = A()pr

回顾之前分析.pyc文件格式时用的例子：

demo.py：

Python代码　　　

class A():
  x = 1

print(A.x) # 1

# increment A.x by 2
A.x += 2
print(A.x) # 3

# create an instance of A
a = A()
print(a.x) # 3

# increment A.x by 4
a.x += 4
print(a.x) # 7
print(A.x) # 3

demo.pyc：

Python bytecode代码　　

  1           0 LOAD_CONST               0 ('A')
              3 LOAD_CONST               5 (())
              6 LOAD_CONST               1 (<code object A at 01237BA8, file "a.py", line 1>)
              9 MAKE_FUNCTION            0
             12 CALL_FUNCTION            0
             15 BUILD_CLASS
             16 STORE_NAME               0 (A)

  4          19 LOAD_NAME                0 (A)
             22 LOAD_ATTR                1 (x)
             25 PRINT_ITEM
             26 PRINT_NEWLINE

  7          27 LOAD_NAME                0 (A)
             30 DUP_TOP
             31 LOAD_ATTR                1 (x)
             34 LOAD_CONST               2 (2)
             37 INPLACE_ADD
             38 ROT_TWO
             39 STORE_ATTR               1 (x)

  8          42 LOAD_NAME                0 (A)
             45 LOAD_ATTR                1 (x)
             48 PRINT_ITEM
             49 PRINT_NEWLINE

 11          50 LOAD_NAME                0 (A)
             53 CALL_FUNCTION            0
             56 STORE_NAME               2 (a)

 12          59 LOAD_NAME                2 (a)
             62 LOAD_ATTR                1 (x)
             65 PRINT_ITEM
             66 PRINT_NEWLINE

 15          67 LOAD_NAME                2 (a)
             70 DUP_TOP
             71 LOAD_ATTR                1 (x)
             74 LOAD_CONST               3 (4)
             77 INPLACE_ADD
             78 ROT_TWO
             79 STORE_ATTR               1 (x)

 16          82 LOAD_NAME                2 (a)
             85 LOAD_ATTR                1 (x)
             88 PRINT_ITEM
             89 PRINT_NEWLINE

 17          90 LOAD_NAME                0 (A)
             93 LOAD_ATTR                1 (x)
             96 PRINT_ITEM
             97 PRINT_NEWLINE
             98 LOAD_CONST               4 (None)
            101 RETURN_VALUE
	 
	 
	
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