Re: [PATCH v5 16/36] qapi/common.py: Convert comments into docstrings, and elaborate

[Markus Armbruster <armbru@redhat.com>]

John Snow <jsnow@redhat.com> writes:

> As docstrings, they'll show up in documentation and IDE help.
>
> The docstring style being targeted is the Sphinx documentation
> style. Sphinx uses an extension of ReST with "domains". We use the
> (implicit) Python domain, which supports a number of custom "info
> fields". Those info fields are documented here:
> https://www.sphinx-doc.org/en/master/usage/restructuredtext/domains.html#info-field-lists
>
> Primarily, we use `:param X: descr`, `:return[s]: descr`, and `:raise[s]
> Z: when`. Everything else is the Sphinx dialect of ReST.
>
> (No, nothing checks or enforces this style that I am aware of. Sphinx
> either chokes or succeeds, but does not enforce a standard of what is
> otherwise inside the docstring. Pycharm does highlight when your param
> fields are not aligned with the actual fields present. It does not
> highlight missing return or exception statements. There is no existing
> style guide I am aware of that covers a standard for a minimally
> acceptable docstring. I am debating writing one.)
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> Reviewed-by: Cleber Rosa <crosa@redhat.com>
> ---
>  scripts/qapi/common.py | 53 +++++++++++++++++++++++++++++++-----------
>  1 file changed, 39 insertions(+), 14 deletions(-)
>
> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
> index 74a2c001ed9..0ef38ea5fe0 100644
> --- a/scripts/qapi/common.py
> +++ b/scripts/qapi/common.py
> @@ -15,15 +15,24 @@
>  from typing import Optional, Sequence
>  
>  
> +#: Sentinel value that causes all space to its right to be removed.

What's the purpose of : after # ?

I'm not sure this is a "sentinel value".  Wikipedia:

    In computer programming, a sentinel value (also referred to as a
    flag value, trip value, rogue value, signal value, or dummy data)[1]
    is a special value in the context of an algorithm which uses its
    presence as a condition of termination, typically in a loop or
    recursive algorithm.

    https://en.wikipedia.org/wiki/Sentinel_value

Perhaps

   # Magic string value that gets removed along with all space to the
   # right.

>  EATSPACE = '\033EATSPACE.'
>  POINTER_SUFFIX = ' *' + EATSPACE
>  _C_NAME_TRANS = str.maketrans('.-', '__')
>  
>  
> -# ENUMName -> ENUM_NAME, EnumName1 -> ENUM_NAME1
> -# ENUM_NAME -> ENUM_NAME, ENUM_NAME1 -> ENUM_NAME1, ENUM_Name2 -> ENUM_NAME2
> -# ENUM24_Name -> ENUM24_NAME
>  def camel_to_upper(value: str) -> str:
> +    """
> +    Converts CamelCase to CAMEL_CASE.
> +
> +    Examples:
> +      ENUMName -> ENUM_NAME
> +      EnumName1 -> ENUM_NAME1
> +      ENUM_NAME -> ENUM_NAME
> +      ENUM_NAME1 -> ENUM_NAME1
> +      ENUM_Name2 -> ENUM_NAME2
> +      ENUM24_Name -> ENUM24_NAME
> +    """

I wonder whether these indented lines get wrapped into one
unintelligible parapgraph.

Have you eyeballed the output of Sphinx?

>      c_fun_str = c_name(value, False)
>      if value.isupper():
>          return c_fun_str
> @@ -45,21 +54,33 @@ def camel_to_upper(value: str) -> str:
>  def c_enum_const(type_name: str,
>                   const_name: str,
>                   prefix: Optional[str] = None) -> str:
> +    """
> +    Generate a C enumeration constant name.
> +
> +    :param type_name: The name of the enumeration.
> +    :param const_name: The name of this constant.
> +    :param prefix: Optional, prefix that overrides the type_name.
> +    """
>      if prefix is not None:
>          type_name = prefix
>      return camel_to_upper(type_name) + '_' + c_name(const_name, False).upper()
>  
>  
> -# Map @name to a valid C identifier.
> -# If @protect, avoid returning certain ticklish identifiers (like
> -# C keywords) by prepending 'q_'.
> -#
> -# Used for converting 'name' from a 'name':'type' qapi definition
> -# into a generated struct member, as well as converting type names
> -# into substrings of a generated C function name.
> -# '__a.b_c' -> '__a_b_c', 'x-foo' -> 'x_foo'
> -# protect=True: 'int' -> 'q_int'; protect=False: 'int' -> 'int'
>  def c_name(name: str, protect: bool = True) -> str:
> +    """
> +    Map ``name`` to a valid C identifier.
> +
> +    Used for converting 'name' from a 'name':'type' qapi definition
> +    into a generated struct member, as well as converting type names
> +    into substrings of a generated C function name.
> +
> +    '__a.b_c' -> '__a_b_c', 'x-foo' -> 'x_foo'
> +    protect=True: 'int' -> 'q_int'; protect=False: 'int' -> 'int'
> +
> +    :param name: The name to map.
> +    :param protect: If true, avoid returning certain ticklish identifiers
> +                    (like C keywords) by prepending ``q_``.
> +    """
>      # ANSI X3J11/88-090, 3.1.1
>      c89_words = set(['auto', 'break', 'case', 'char', 'const', 'continue',
>                       'default', 'do', 'double', 'else', 'enum', 'extern',
> @@ -129,12 +150,16 @@ def decrease(self, amount: int = 4) -> None:
>          self._level -= amount
>  
>  
> +#: Global, current indent level for code generation.
>  indent = Indentation()
>  
>  
> -# Generate @code with @kwds interpolated.
> -# Obey indent, and strip EATSPACE.
>  def cgen(code: str, **kwds: object) -> str:
> +    """
> +    Generate ``code`` with ``kwds`` interpolated.
> +
> +    Obey `indent`, and strip `EATSPACE`.
> +    """
>      raw = code % kwds
>      if indent:
>          raw = re.sub(r'^(?!(#|$))', str(indent), raw, flags=re.MULTILINE)