What exactly is a python variable?

[Steve D'Aprano]

On Fri, 18 Nov 2016 12:19 am, BartC wrote:

> On 17/11/2016 12:20, Steve D'Aprano wrote:
>> On Thu, 17 Nov 2016 10:37 pm, BartC wrote:
> 
>>> (I don't know how to disassemble code outside a function, not from
>>> inside the same program. Outside it might be: 'python -m dis file.py')
> 
>> In the most recent versions of Python, dis.dis() will also accept a
>> string:
>>
>> py> dis.dis('y = x + 1')
>>   1           0 LOAD_NAME                0 (x)
>>               3 LOAD_CONST               0 (1)
>>               6 BINARY_ADD
>>               7 STORE_NAME               1 (y)
>>              10 LOAD_CONST               1 (None)
>>              13 RETURN_VALUE
> 
> 
> Py2 gave me (for "y=x+1"):
> 
>            0 SETUP_EXCEPT    30781 (to 30784)
>            3 STORE_SLICE+3
>            4 <49>
> 
> Py3.4 works as you say but after that result I was disinclined to take
> it further!


You may have missed the bit where I said "In the most recent versions".
Python 2.7 will be interpreting the string "y=x+1" as compiled byte-code,
and disassembling it into junk.

If in doubt, just use the compile() function first.



-- 
Steve
“Cheer up,” they said, “things could be worse.” So I cheered up, and sure
enough, things got worse.