command line interface of symtable module is broken

[isidentical]

BPO	40926
Nosy	@benjaminp, @pablogsal, @isidentical
PRs	bpo-40926: Improve & fix command line usage of symtable #20757

^{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 2020-06-09.10:20:39.563>
labels = ['type-bug', 'library', '3.10']
title = 'command line interface of symtable module is broken'
updated_at = <Date 2020-06-09.10:40:22.701>
user = 'https://github.com/isidentical'

bugs.python.org fields:

activity = <Date 2020-06-09.10:40:22.701>
actor = 'BTaskaya'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2020-06-09.10:20:39.563>
creator = 'BTaskaya'
dependencies = []
files = []
hgrepos = []
issue_num = 40926
keywords = ['patch']
message_count = 1.0
messages = ['371088']
nosy_count = 3.0
nosy_names = ['benjamin.peterson', 'pablogsal', 'BTaskaya']
pr_nums = ['20757']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40926'
versions = ['Python 3.10']

Linked PRs

• gh-85098: Implement functional CLI of symtable #109112

[isidentical]

(.venv) (Python 3.10.0a0) [ 1:11ÖS ] [ isidentical@x200:~ ]
$ cat t.py
import x
a = 1
print(x)

(.venv) (Python 3.10.0a0) [ 1:11ÖS ] [ isidentical@x200:~ ]
$ python -m symtable t.py
<symbol '_symtable'> True False
<symbol 'USE'> True False
<symbol 'DEF_GLOBAL'> True False
<symbol 'DEF_NONLOCAL'> True False
<symbol 'DEF_LOCAL'> True False
...

It can clearly seen that the initial argument [t.py] is completely ignored, and this script prints out the symtable.py itself. This is because the script uses argv[0] (itself) instead of argv[1] (the first argument). I also find this output quite poor since we don't know what these boolean values are;

<symbol 'DEF_LOCAL'> True False

The fix I had in my mind is printing all properties instead of 2 boolean values

 $ ./cpython/cpython/python -m symtable t.py
<symbol 'x'> ==>{'local', 'imported', 'referenced'}
<symbol 'a'> ==>{'local', 'assigned'}
<symbol 'print'> ==>{'referenced', 'global'}

[serhiy-storchaka]

I also worked on improving the CLI of symtable. I do not remember why I did not finish the work and did not touch the code for 3.5 years. In any case I show it in #109112.

[serhiy-storchaka]

Example of the output:

$ ./python -m symtable Lib/symtable.py 
local symbol '_symtable': def_import
local symbol 'USE': use, def_import
local symbol 'DEF_GLOBAL': def_import
local symbol 'DEF_NONLOCAL': def_import
local symbol 'DEF_LOCAL': def_import
local symbol 'DEF_PARAM': def_import
local symbol 'DEF_IMPORT': def_import
local symbol 'DEF_BOUND': def_import
local symbol 'DEF_ANNOT': def_import
local symbol 'SCOPE_OFF': def_import
local symbol 'SCOPE_MASK': def_import
local symbol 'FREE': def_import
local symbol 'LOCAL': def_import
local symbol 'GLOBAL_IMPLICIT': def_import
local symbol 'GLOBAL_EXPLICIT': def_import
local symbol 'CELL': def_import
local symbol 'weakref': def_import
local symbol '__all__': def_local
local symbol 'symtable': use, def_local
 local symbol 'code': use, def_param
 local symbol 'filename': use, def_param
 local symbol 'compile_type': use, def_param
 local symbol 'top': use, def_local
 global_implicit symbol '_symtable': use
 global_implicit symbol '_newSymbolTable': use

local symbol 'SymbolTableFactory': use, def_local
 local symbol '__init__': def_local
 local symbol 'self': use, def_param
 global_implicit symbol 'weakref': use

 local symbol 'new': def_local
 local symbol 'self': def_param
 local symbol 'table': use, def_param
 local symbol 'filename': use, def_param
 global_implicit symbol '_symtable': use
 global_implicit symbol 'Function': use
 global_implicit symbol 'Class': use
 global_implicit symbol 'SymbolTable': use

 local symbol '__call__': def_local
 local symbol 'self': use, def_param
 local symbol 'table': use, def_param
 local symbol 'filename': use, def_param
 local symbol 'key': use, def_local
 local symbol 'obj': use, def_local

...

It outputs the scope separately from flags. It prints not only top-level symbols, but also symbols in nested namespaces.

It also changes the repr of Symbol.

[serhiy-storchaka]

After some thought I changed the output formatЖ

$ ./python -m symtable Lib/symtable.py
symbol table for module from file 'Lib/symtable.py':
 local symbol '_symtable': def_import
 local symbol 'USE': use, def_import
 local symbol 'DEF_GLOBAL': def_import
 local symbol 'DEF_NONLOCAL': def_import
 local symbol 'DEF_LOCAL': def_import
 local symbol 'DEF_PARAM': def_import
 local symbol 'DEF_IMPORT': def_import
 local symbol 'DEF_BOUND': def_import
 local symbol 'DEF_ANNOT': def_import
 local symbol 'SCOPE_OFF': def_import
 local symbol 'SCOPE_MASK': def_import
 local symbol 'FREE': def_import
 local symbol 'LOCAL': def_import
 local symbol 'GLOBAL_IMPLICIT': def_import
 local symbol 'GLOBAL_EXPLICIT': def_import
 local symbol 'CELL': def_import
 local symbol 'weakref': def_import
 local symbol '__all__': def_local
 local symbol 'symtable': def_local
 local symbol 'SymbolTableFactory': use, def_local
 local symbol '_newSymbolTable': def_local
...
 local symbol 'sys': use, def_import
 local symbol 'n': use, def_local

 symbol table for function 'symtable':
 local symbol 'code': use, def_param
 local symbol 'filename': use, def_param
 local symbol 'compile_type': use, def_param
 local symbol 'top': use, def_local
 global_implicit symbol '_symtable': use
 global_implicit symbol '_newSymbolTable': use

 symbol table for class 'SymbolTableFactory':
 local symbol '__init__': def_local
 local symbol 'new': def_local
 local symbol '__call__': def_local

 symbol table for function '__init__':
 local symbol 'self': use, def_param
 global_implicit symbol 'weakref': use

...

Now nested symbol tables are output after symbols and include header with some table related information. It also helps when specify several input files.