Re: [PATCH v4 13/19] qapi/expr.py: Consolidate check_if_str calls in check_if

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> This is a small rewrite to address some minor style nits.
>
> Don't compare against the empty list to check for the empty condition, and
> move the normalization forward to unify the check on the now-normalized
> structure.
>
> With the check unified, the local nested function isn't needed anymore
> and can be brought down into the normal flow of the function. With the
> nesting level changed, shuffle the error strings around a bit to get
> them to fit in 79 columns.
>
> Note: although ifcond is typed as Sequence[str] elsewhere, we *know* that
> the parser will produce real, bona-fide lists. It's okay to check
> isinstance(ifcond, list) here.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/expr.py | 32 ++++++++++++++------------------
>  1 file changed, 14 insertions(+), 18 deletions(-)
>
> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
> index ea9d39fcf2..5921fa34ab 100644
> --- a/scripts/qapi/expr.py
> +++ b/scripts/qapi/expr.py
> @@ -144,30 +144,26 @@ def check_flags(expr: _JSONObject, info: 
> QAPISourceInfo) -> None:
>  
>  def check_if(expr: _JSONObject, info: QAPISourceInfo, source: str) -> None:
>  
> -    def check_if_str(ifcond: object) -> None:
> -        if not isinstance(ifcond, str):
> -            raise QAPISemError(
> -                info,
> -                "'if' condition of %s must be a string or a list of strings"
> -                % source)
> -        if ifcond.strip() == '':
> -            raise QAPISemError(
> -                info,
> -                "'if' condition '%s' of %s makes no sense"
> -                % (ifcond, source))
> -
>      ifcond = expr.get('if')
>      if ifcond is None:
>          return
> +
>      if isinstance(ifcond, list):
> -        if ifcond == []:
> +        if not ifcond:
>              raise QAPISemError(
> -                info, "'if' condition [] of %s is useless" % source)
> -        for elt in ifcond:
> -            check_if_str(elt)
> +                info, f"'if' condition [] of {source} is useless")

Unrelated change from interpolation to formatted string literal.

>      else:
> -        check_if_str(ifcond)
> -        expr['if'] = [ifcond]
> +        # Normalize to a list
> +        ifcond = expr['if'] = [ifcond]
> +
> +    for elt in ifcond:
> +        if not isinstance(elt, str):
> +            raise QAPISemError(info, (
> +                f"'if' condition of {source}"
> +                " must be a string or a list of strings"))
> +        if not elt.strip():
> +            raise QAPISemError(
> +                info, f"'if' condition '{elt}' of {source} makes no sense")

Likewise.

I like formatted string literals, they're often easier to read than
interpolation.  But let's try to keep patches focused on their stated
purpose.

I'd gladly consider a series that convers to formatted strings
wholesale.  But I guess we better finish the typing job, first.

>  
>  
>  def normalize_members(members: object) -> None: