Re: [PATCH v2 04/16] qapi/expr.py: Add assertion for union type 'check_dict'

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> mypy isn't fond of allowing you to check for bool membership in a
> collection of str elements. Guard this lookup for precisely when we were
> given a name.

Spoilsport.

Peeking at the patch... aha, it's about check_type()'s parameter
@allow_dict.

@allow_dict tells us whether an anonymous type is allowed, and also
whether its member names may violate the naming rules.

* a str: allow anonymous type, waive member naming rules if @allow_dict
  is in .name_case_whitelist.

  Used for checking struct's 'data' and union's 'base'.

* True: allow anonymous type, enforce member naming rules

  Used for checking 'data' of commands and events.  Waiving the naming
  rules is simply not implemented there.

* False (default): do not allow anonymous type

Perhaps the "is in .name_case_whitelist" check should be lifted into the
two callers that pass a str.  We could then turn the parameter into an
enum.  Meh.  Perhaps a separate @permit_upper parameter, only valid with
allow_dict=True.  Meh again.

Splitting check_type() into multiple functions feels more promising.
Not now.

> Signed-off-by: John Snow <jsnow@redhat.com>
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> Reviewed-by: Cleber Rosa <crosa@redhat.com>
> ---
>  scripts/qapi/expr.py | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
> index f7c7f91326ef..2c4c341d5243 100644
> --- a/scripts/qapi/expr.py
> +++ b/scripts/qapi/expr.py
> @@ -173,7 +173,9 @@ def check_type(value, info, source,
>          raise QAPISemError(info,
>                             "%s should be an object or type name" % source)
>  
> -    permit_upper = allow_dict in info.pragma.name_case_whitelist
> +    permit_upper = False
> +    if isinstance(allow_dict, str):
> +        permit_upper = allow_dict in info.pragma.name_case_whitelist

Slightly more compact:

       permit_upper = (isinstance(allow_dict, str)
                       and allow_dict in info.pragma.name_case_whitelist)

Matter of taste.

>  
>      # value is a dictionary, check that each member is okay
>      for (key, arg) in value.items():