locks

Duncan Booth duncan.booth at invalid.invalid
Wed Oct 13 16:03:37 CEST 2004


Cliff Wells wrote:

> I'm no expert at dis nor Python bytecode, but I'll give it a shot :)
> 
>>>> l = []
>>>> dis.dis(l.append(1))
> 134           0 LOAD_GLOBAL              0 (findlabels)
>               3 LOAD_FAST                0 (code)
>               6 CALL_FUNCTION            1
>               9 STORE_FAST               5 (labels)
>  
> 
> ... 
><snip dis spitting out over 500 lines of bytecode>
> ...
>  
> 172     >>  503 PRINT_NEWLINE
>             504 JUMP_ABSOLUTE           33
>         >>  507 POP_TOP
>             508 POP_BLOCK
>         >>  509 LOAD_CONST               0 (None)
>             512 RETURN_VALUE
>>>>
> 
> 
> It looks fairly non-atomic to me. 

The append method of a list returns None. dis.dis(None) disassembles the 
code from the last traceback object, nothing at all to do with your 
l.append(1) code.

Try this instead:

>>> def f():
	l.append(1)

	
>>> dis.dis(f)
  2           0 LOAD_GLOBAL              0 (l)
              3 LOAD_ATTR                1 (append)
              6 LOAD_CONST               1 (1)
              9 CALL_FUNCTION            1
             12 POP_TOP             
             13 LOAD_CONST               0 (None)
             16 RETURN_VALUE    



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