Ah yes, I see what you mean:

class Test():
       x = 1
       print (x)                         # Prints 1
       print([x+i for i in range(1,3)])  # NameError (x)

Anyway, I  apologise for posting to Python-Dev on was a known issue, and turned out to be more me asking for help with development with Python, rather than development of Python.  (My original use case was a scripting language that could contain embedded Python code).  Thanks to Nick for his original answer.

Rob Cliffe

On 11/06/2018 23:31, Eric Fahlgren wrote:
On Mon, Jun 11, 2018 at 3:10 PM Rob Cliffe via Python-Dev <python-dev@python.org> wrote:
Skip, I think you have misunderstood the  point I was making.  It was
not whether the loop variable should leak out of a list comprehension. 
Rather, it was whether a local variable should, so to speak, "leak into"
a list comprehension.  And the answer is: it depends on whether the code
is executed normally, or via exec/eval.  Example:

def Test():
       x = 1
       print([x+i for i in range(1,3)])              # Prints [2,3]
       exec('print([x+i for i in range(1,3)])') # Raises NameError (x)

I (at least at first) found the difference in behaviour surprising.

​Change 'def' to 'class' and run it again.  You'll be even more surprised.​

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