Re: [PATCH v4 11/19] qapi/expr.py: Modify check_keys to accept any Collection

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> This is a minor adjustment that allows the 'required' and 'optional'
> keys fields to take a default value of an empty, immutable sequence (the
> empty tuple).
>
> This reveals a quirk of this function, which is that "a + b" is
> list-specific behavior. We can accept a wider variety of types if we
> avoid that behavior. Using Collection allows us to accept things like
> lists, tuples, sets, and so on.
>
> (Iterable would also have worked, but Iterable also includes things like
> generator expressions which are consumed upon iteration, which would
> require a rewrite to make sure that each input was only traversed once.)
>
> Signed-off-by: John Snow <jsnow@redhat.com>

The commit message confused me briefly, until I realized v3 of this
patch came later in the series, where it modified check_keys() type
hints and added default values.

What about this:

  This is a minor adjustment that lets parameters @required and
  @optional take tuple arguments, in particular ().  Later patches will
  make use of that.

> ---
>  scripts/qapi/expr.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
> index 505e67bd21..7e22723b50 100644
> --- a/scripts/qapi/expr.py
> +++ b/scripts/qapi/expr.py
> @@ -100,7 +100,7 @@ def pprint(elems):
>              "%s misses key%s %s"
>              % (source, 's' if len(missing) > 1 else '',
>                 pprint(missing)))
> -    allowed = set(required + optional)
> +    allowed = set(required) | set(optional)
>      unknown = set(value) - allowed
>      if unknown:
>          raise QAPISemError(