Re: [Qemu-devel] [PATCH v4 08/19] qapi: Better error messages for bad expressions

[Kevin Wolf <kwolf@redhat.com>]

Am 24.09.2014 um 09:34 hat Markus Armbruster geschrieben:
> Eric Blake <eblake@redhat.com> writes:
> 
> > On 09/23/2014 08:56 AM, Markus Armbruster wrote:
> >> Eric Blake <eblake@redhat.com> writes:
> >>> Add check_keys to cover these situations, and update testcases to
> >>> match.  A couple other tests (enum-missing-data, indented-expr) had
> >>> to change since the validation added here occurs so early.
> >>>
> >>> While valid .json files won't trigger any of these cases, we might
> >>> as well be nicer to developers that make a typo while trying to add
> >>> new QAPI code.
> >>>
> >>> Signed-off-by: Eric Blake <eblake@redhat.com>
> >> 
> >
> >>> +def check_keys(expr_elem, meta, required, optional=[]):
> >>> +    expr = expr_elem['expr']
> >>> +    info = expr_elem['info']
> >>> +    name = expr[meta]
> >> 
> >> Caller ensures expr[meta] exists.  Okay.
> >> 
> >>> +    if not isinstance(name, basestring):
> >> 
> >> I'm a Python noob: why basestring and not str?
> >
> > Me too.  No clue.  Copy and paste from existing code.
> > http://git.qemu.org/?p=qemu.git;a=blob;f=scripts/qapi.py;h=77d46aa;hb=769188d3b#l361
> 
> Yes.  It's our only use of basestring.  Other places use isinstance(FOO,
> str).
> 
> The basestring use comes from Kevin's commit b35284e.  Kevin, why
> basestring and not str?

Do I look as if I knew what I'm doing when I write Python code? :-)

Apparently basestring is the superclass for ASCII and Unicode strings. I
seem to dimly remember that I did indeed get a Unicode string somewhere
(even though probably no non-ASCII characters in it) and it caused
trouble. Might well have been here.

Kevin