On Thu, Nov 19, 2009 at 4:42 PM, Alf P. Steinbach <al...@start.no> wrote: > * Steven D'Aprano: >> >> On Thu, 19 Nov 2009 21:37:17 +0100, Alf P. Steinbach wrote: >> >>> The CPython 3.1.1 language reference §4.1 says >>> >>> "Each command typed interactively is a block." >>> >>> It also says >>> >>> "If a name is bound in a block, it is a local variable of that block, >>> unless >>> declared as nonlocal" >>> >>> Even with a non-literal try-for-best-meaning reading I can't get this to >>> mesh with the actual behavior of the interpreter, e.g. >>> >>> >>> for x in "poi": >>> ... fandango = 666 >>> ... >>> >>> fandango >>> 666 >>> >>> _ >>> >>> My current understanding is (A) that the interpreter is correct in this >>> respect (for one would harldly want the effects of statements to be >>> fundamentally different in interpreted mode, except the presentation of >>> expression results), and (B), but here I'm less sure, that the >>> documentation is incorrect. >> >> >> Why do you say that? I don't see what it is in the command you typed that >> leads you to think the documentation is incorrect. >> >> The first command you type is: >> >> for x in "poi": >> fandango = 666 >> >> >> which binds two names, x and fandango. Since you are not typing them in a >> function or class definition, locals() is globals() and the two local names >> you create happen to also be globals. > > Thanks, that may be it. > > In most other languages I'm familiar with, if a name is local then it isn't > global (and vice versa), and I had that as an underlying assumption since it > doesn't appear to be mentioned in the documentation. > > However, I find a language reference statement that alludes to this: "(The > variables of the module code block are local and global.)" > > Hm... > > >> The next two commands you type: >> >> fandango >> _ >> >> don't bind anything, so aren't relevant. > > Well it showed that 'fandango' had been defined as a global. :-) > > >> If it helps: >> >> >>>>> for x in "poi": >> >> ... fandango = 666 >> ... >>>>> >>>>> locals() is globals() >> >> True >>>>> >>>>> fandango >> >> 666 >>>>> >>>>> locals()['fandango'] >> >> 666 >>>>> >>>>> import __main__ >>>>> __main__.fandango >> >> 666 > > Yeah, helps. > > I feel that there's still something lacking in my understanding though, like > how/where the "really actually just pure local not also global" is defined > for function definition, but it's now just a vague feeling of something > missing, not a feeling of direct contradiction as I had when I believed > local != global. >
It's because the only blocks in python that have their own scope are classes and functions. For loops don't have their own scope- they use the enclosing one, which in this case is globals. > > Cheers, & thanks, > > - Alf > -- > http://mail.python.org/mailman/listinfo/python-list > -- http://mail.python.org/mailman/listinfo/python-list
