Re: [PATCH v2 06/19] qapi/schema: make c_type() and json_type() abstract methods

[Markus Armbruster <armbru@redhat.com>]

John Snow <jsnow@redhat.com> writes:

> These methods should always return a str, it's only the default abstract
> implementation that doesn't. They can be marked "abstract", which
> requires subclasses to override the method with the proper return type.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/schema.py | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
> index e45d9545eda..8e25dd35562 100644
> --- a/scripts/qapi/schema.py
> +++ b/scripts/qapi/schema.py
> @@ -16,6 +16,7 @@
>  
>  # TODO catching name collisions in generated code would be nice
>  
> +from abc import ABC, abstractmethod
>  from collections import OrderedDict
>  import os
>  import re
> @@ -253,10 +254,11 @@ def visit(self, visitor):
>          visitor.visit_include(self._sub_module.name, self.info)
>  
>  
> -class QAPISchemaType(QAPISchemaDefinition):
> +class QAPISchemaType(QAPISchemaDefinition, ABC):
>      # Return the C type for common use.
>      # For the types we commonly box, this is a pointer type.
> -    def c_type(self):
> +    @abstractmethod
> +    def c_type(self) -> str:

You additionally add the type hint.  Suggest to either mention it in the
commit message, or add it only together with the other type hints in
PATCH 17.

>          pass
>  
>      # Return the C type to be used in a parameter list.
> @@ -267,7 +269,8 @@ def c_param_type(self):
>      def c_unboxed_type(self):
>          return self.c_type()
>  
> -    def json_type(self):
> +    @abstractmethod
> +    def json_type(self) -> str:

Likewise.

>          pass
>  
>      def alternate_qtype(self):