[PATCH v3 00/16] qapi: static typing conversion, pt3

[John Snow]

Hi, this series adds static types to the QAPI module.
This is part three, and it focuses on expr.py.

This series is applied and hosted here:
https://gitlab.com/jsnow/qemu/-/tree/python-qapi-cleanup-pt3

Environment:
- Python >= 3.6, <= 3.8 *
- mypy >= 0.770
- pylint >= 2.6.0
- flake8
- isort

Every commit should pass with (from ./scripts/):
 - flake8 qapi/
 - pylint --rcfile=qapi/pylintrc qapi/
 - mypy --config-file=qapi/mypy.ini qapi/
 - pushd qapi && isort -c . && popd

Please read the changelog below for some review notes that may be of interest.

V3:

001/16:[----] [--] 'qapi/expr.py: Remove 'info' argument from nested 
check_if_str'
002/16:[----] [--] 'qapi/expr.py: Check for dict instead of OrderedDict'
003/16:[0004] [FC] 'qapi/expr.py: constrain incoming expression types'
004/16:[----] [--] 'qapi/expr.py: Add assertion for union type 'check_dict''
005/16:[----] [--] 'qapi/expr.py: move string check upwards in check_type'
006/16:[----] [--] 'qapi/expr.py: Check type of 'data' member'
007/16:[0002] [FC] 'qapi/expr.py: Add casts in a few select cases'
008/16:[----] [--] 'qapi/expr.py: add type hint annotations'
009/16:[down] 'qapi/expr.py: Consolidate check_if_str calls in check_if'
010/16:[----] [--] 'qapi/expr.py: Remove single-letter variable'
011/16:[----] [--] 'qapi/expr.py: enable pylint checks'
012/16:[----] [-C] 'qapi/expr.py: Add docstrings'
013/16:[down] 'qapi/expr.py: Modify check_keys to accept any Collection'
014/16:[----] [--] 'qapi/expr.py: Use tuples instead of lists for static data'
015/16:[0004] [FC] 'qapi/expr.py: move related checks inside check_xxx 
functions'
016/16:[0011] [FC] 'qapi/expr.py: Use an expression checker dispatch table'

 - Some RB-s added, some dropped; see "Review Status" section below.
 - ("pt0" series rebased on latest origin/master.)
 - Rebased on origin/master.
 - 03: Re-ordered the Expression unpacking slightly to match the other stanzas.
       (R-Bs kept.)
 - 07: Changed capitalization of a comment. (R-Bs kept.)
 - 09: Rewritten more aggressively. (R-Bs dropped.)
 - 13: Use "Collection" instead of "Iterable" because of concerns with the
       possibly consumptive nature of Iterable; change commit name & message.
       (R-Bs dropped.)
 - 15: Use tuples everywhere, even for single items. (R-Bs kept.)
 - 16: Update ExpressionType to define a __str__ method, which allows
       the meta variable to be passed and used directly as a string.
       (R-Bs dropped.)

RFCs/notes:

- This series was written long before pt1.5 and pt2. Keep that in mind! (Sorry.)

- I used MutableMapping instead of Dict in patch 8. There's no real
  reason I couldn't have used Dict, both work - this one is more
  abstract.  Both would work for dict/OrderedDict perfectly well.

  (I think I had some reason at one point or another, but I can no
  longer remember what it is, if I am being honest. It might have to do
  with Dict being invariant, but MutableMapping being covariant, which
  might come into play much later in the six-part series. I really
  forget.)

- The dreaded _DObject comes back, this time named _JSObject. It's a bad name.
  It means "Any JSON object deserialized as a Python dict". I didn't rename it
  because I didn't want to shed the R-Bs yet. Please suggest a name.
  (Or a way to avoid needing it at all.)

  You'll probably notice that I keep futzing with the documentation near
  this definition. I opted not to fix it to avoid touching patches that
  were (so far) fully reviewed.

- Patch 12 (the docstring patch) needs to be heavily copy-edited. I
  figured I would simply address it all at once after review from
  Markus. I ask that a review of this patch be exhaustive if at all
  possible.

  I start using [Const] and [RW] markers in the summary string; I think
  I will actually remove these as they are not real markup, but I'd like
  to solicit suggestions on how to differentiate functions that modify
  expr from ones that do not.

  I also start using some fairly arbitrary syntax to try and document
  the syntactic forms being checked and normalized here, but they are
  not very consistent. Suggestions welcome.

- Patch 16 is something I am not sure I really like anymore, it has some
  mild benefit but I don't like how I repeat the expression types twice
  in one file. I consider this patch optional for now. I suspect there's
  a neater way to write it that gives us the same benefit but looks less
  ugly.

Review Status:

[01] qapi-expr-py-remove-info       # [RB] CR,EH [SOB] JS
[02] qapi-expr-py-check-for-dict    # [RB] CR,EH [SOB] JS
[03] qapi-expr-py-constrain         # [RB] CR,EH [SOB] JS
[04] qapi-expr-py-add-assertion-for # [RB] CR,EH [SOB] JS
[05] qapi-expr-py-move-string-check # [RB] CR,EH [SOB] JS
[06] qapi-expr-py-check-type-of     # [RB]    EH [SOB] JS
[07] qapi-expr-py-add-casts-in-a    # [RB] CR,EH [SOB] JS
[08] qapi-expr-py-add-type-hint     # [RB] CR,EH [SOB] JS
[09] qapi-expr-py-consolidate       #            [SOB] JS
[10] qapi-expr-py-remove-single     # [RB] CR,EH [SOB] JS
[11] qapi-expr-py-enable-pylint     # [RB] CR,EH [SOB] JS
[12] qapi-expr-py-add-docstrings    # [RB] CR    [SOB] JS
[13] qapi-expr-py-modify-check_keys #            [SOB] JS
[14] qapi-expr-py-use-tuples        # [RB] CR,EH [SOB] JS
[15] qapi-expr-py-move-related      # [RB] CR    [SOB] JS
[16] qapi-expr-py-use-an-expression #            [SOB] JS

John Snow (16):
  qapi/expr.py: Remove 'info' argument from nested check_if_str
  qapi/expr.py: Check for dict instead of OrderedDict
  qapi/expr.py: constrain incoming expression types
  qapi/expr.py: Add assertion for union type 'check_dict'
  qapi/expr.py: move string check upwards in check_type
  qapi/expr.py: Check type of 'data' member
  qapi/expr.py: Add casts in a few select cases
  qapi/expr.py: add type hint annotations
  qapi/expr.py: Consolidate check_if_str calls in check_if
  qapi/expr.py: Remove single-letter variable
  qapi/expr.py: enable pylint checks
  qapi/expr.py: Add docstrings
  qapi/expr.py: Modify check_keys to accept any Collection
  qapi/expr.py: Use tuples instead of lists for static data
  qapi/expr.py: move related checks inside check_xxx functions
  qapi/expr.py: Use an expression checker dispatch table

 scripts/qapi/expr.py  | 453 +++++++++++++++++++++++++++++++-----------
 scripts/qapi/mypy.ini |   5 -
 scripts/qapi/pylintrc |   1 -
 3 files changed, 337 insertions(+), 122 deletions(-)

-- 
2.29.2