ah. I think i figured it out -- it's actually just a weird py.test thing. something to do with its assert-introspection-voodoo...
On 30 May 2014 16:16, Roger Gammans <ro...@gammascience.co.uk> wrote: > On Fri, 2014-05-30 at 16:07 +0100, Sven Marnach wrote: > > On 30 May 2014 15:49, Harry Percival <harry.perci...@gmail.com> wrote: > > I had the problem outside of a class body, in a normal > > function... > > > > > > The particular problem mentioned in the StackOverflow quesiton you > > linked only ever occurs inside class bodies. They are the only > > enclosing scopes that are skipped in name lookups. You can still > > access class attributes of the class by using ClassName.attribute > > inside the list comprehension, like you would have to do to access > > class attributes from inside methods. > > Hmm. It quite odd, it appears to only affect the evaluation part of the > list-comprehension too. Notice the way that a naked reference to a works > as the argument to range() , but not when used in the expr part of the > list comprehension. > > $ python3.3 > Python 3.3.3 (default, Dec 8 2013, 14:51:59) > [GCC 4.8.2] on linux > Type "help", "copyright", "credits" or "license" for more information. > >>> class X: > ... a = 3 > ... b = [ y for y in range(a) ] > ... > >>> X.b > [0, 1, 2] > >>> class X: > ... a = 3 > ... b = [ y*a for y in range(a) ] > ... > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > File "<stdin>", line 3, in X > File "<stdin>", line 3, in <listcomp> > NameError: global name 'a' is not defined > >>> class X: > ... a = 3 > ... b = [ y*X.a for y in range(a) ] > ... > >>> X.b > [0, 3, 6] > > > -- > Roger Gammans <ro...@gammascience.co.uk> > -- ------------------------------ Harry J.W. Percival ------------------------------ Twitter: @hjwp Mobile: +44 (0) 78877 02511 Skype: harry.percival
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