Description

isidentical

opened on Mar 16, 2020

Issue body actions

BPO	39981
Nosy	@benjaminp, @serhiy-storchaka, @pablogsal, @isidentical
PRs	bpo-39981: Default values for AST nodes #19031 bpo-39981: Introduce default values for AST node classes #21417

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-03-16.19:17:20.926>
labels = ['type-feature', 'library', '3.9']
title = 'Default values for AST Nodes'
updated_at = <Date 2020-07-09.13:33:40.873>
user = 'https://github.com/isidentical'

bugs.python.org fields:

activity = <Date 2020-07-09.13:33:40.873>
actor = 'BTaskaya'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2020-03-16.19:17:20.926>
creator = 'BTaskaya'
dependencies = []
files = []
hgrepos = []
issue_num = 39981
keywords = ['patch']
message_count = 1.0
messages = ['364355']
nosy_count = 4.0
nosy_names = ['benjamin.peterson', 'serhiy.storchaka', 'pablogsal', 'BTaskaya']
pr_nums = ['19031', '21417']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue39981'
versions = ['Python 3.9']

Activity

1. isidentical commented on Mar 16, 2020

   

   isidentical

   on Mar 16, 2020

   SponsorMemberAuthor

   More actions

   For omitting some defaults, @serhiy.storchaka already added support to initialize some ast nodes with some default values (optional fields). An example;
   >>> ast.Constant().kind is None
   True
   
   This isn't exactly a default value, but some kind of class attribute. I think we can push this one step further and initialize all kinds of default values (both optionals and sequences). An example;
   >>> func = ast.FunctionDef("easy_func", ast.arguments(), body=[ast.Pass()])
   >>> func = ast.fix_missing_locations(func)
   >>> exec(compile(ast.Module(body=[func]), "<stdin>", "exec"))
   >>> easy_func()
   
   compared to this (other way around, compiler gives errors so does most of the ast based tool, including ast.unparser)
   >>> func = ast.FunctionDef("easy_func", ast.arguments(posonlyargs=[], args=[], kwonlyargs=[], kw_defaults=[], defaults=[]), decorator_list=[], body=[ast.Pass()])
   >>> func = ast.fix_missing_locations(func)
   >>> exec(compile(ast.Module(body=[func], type_ignores=[]), "<stdin>", "exec"))
   >>> easy_func()
2. isidentical

   added

   3.9 (EOL)end of lifeend of life

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-featureA feature request or enhancementA feature request or enhancement

   on Mar 16, 2020
3. ezio-melotti

   transferred this issue fromon Apr 10, 2022
4. JelleZijlstra commented on May 19, 2024

   

   JelleZijlstra

   on May 19, 2024

   Member

   More actions

   This was implemented in #105858.
5. JelleZijlstra

   closed this as completedon May 19, 2024

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