[Python-bugs-list] [ python-Bugs-471928 ] global made w/nested list comprehensions (original) (raw)

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Thu, 18 Oct 2001 09:15:24 -0700

Bugs item #471928, was opened at 2001-10-16 18:35 You can respond by visiting: http://sourceforge.net/tracker/?func=detail&atid=105470&aid=471928&group_id=5470

Category: Python Interpreter Core Group: Python 2.2

Status: Closed Resolution: Fixed Priority: 5 Submitted By: Neal Norwitz (nnorwitz) Assigned to: Jeremy Hylton (jhylton) Summary: global made w/nested list comprehensions

Initial Comment: This bug affects Python 2.1.1 & 2.2a4+.

In nested list comprehension code like this:

    [bad for s in 'a b' for bad in s.split()]

the variable bad becomes a global, but it should be local variable.

The attached file shows the disassembled byte code, along with a test case.

The original source of the error was found from cgi.py:209 in the standard library:

pairs = [s2 for s1 in qs.split('&') for s2 in

s1.split(';')]

Neal

Comment By: Jeremy Hylton (jhylton) Date: 2001-10-18 09:15

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The symbol table pass wasn't visiting nested list comprehenesions. Fixed in rev. 2.227 of compile.c.

Comment By: Tim Peters (tim_one) Date: 2001-10-17 18:22

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Reassigned to Jeremy, as I expect he's got a better chance of understanding why the symbol-table code is calling one of these local and the other global (listcomp codegen treats them the same).

Comment By: Guido van Rossum (gvanrossum) Date: 2001-10-16 23:06

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Good catch! I don't know the list comprehension code generation, and I don't know who does. Maybe Thomas Wouters?

You can respond by visiting: http://sourceforge.net/tracker/?func=detail&atid=105470&aid=471928&group_id=5470