ast.literal_eval doesn't give information about node except the type of it

[isidentical]

BPO	38396
Nosy	@serhiy-storchaka, @ilevkivskyi, @isidentical
PRs	bpo-38396: dump(node) instead of repr(node) on ast.literal_eval #16620
Superseder	bpo-32888: Improve exception message in ast.literal_eval

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

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2019-10-07.19:47:55.659>
created_at = <Date 2019-10-07.15:55:56.849>
labels = ['library', '3.9']
title = "ast.literal_eval doesn't give information about node except the type of it"
updated_at = <Date 2019-10-07.19:47:55.658>
user = 'https://github.com/isidentical'

bugs.python.org fields:

activity = <Date 2019-10-07.19:47:55.658>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2019-10-07.19:47:55.659>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2019-10-07.15:55:56.849>
creator = 'BTaskaya'
dependencies = []
files = []
hgrepos = []
issue_num = 38396
keywords = ['patch']
message_count = 3.0
messages = ['354103', '354132', '354133']
nosy_count = 3.0
nosy_names = ['serhiy.storchaka', 'levkivskyi', 'BTaskaya']
pr_nums = ['16620']
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '32888'
type = None
url = 'https://bugs.python.org/issue38396'
versions = ['Python 3.9']

[isidentical]

def _convert_num(node):
        if isinstance(node, Constant):
            if type(node.value) in (int, float, complex):
                return node.value
>       raise ValueError('malformed node or string: ' + repr(node))
E       ValueError: malformed node or string: <_ast.Name object at 0x7f0e7ebab320>

When a malformed node passes into literal_eval, it raises ValueError with repr of node (which is just a memory address and type). I think using dump(node) at there is a better option, like

node = <_ast.Name object at 0x7fa8279847d0>

    def _convert_num(node):
        if isinstance(node, Constant):
            if type(node.value) in (int, float, complex):
                return node.value
>       raise ValueError('malformed node or string: ' + dump(node))
E       ValueError: malformed node or string: Name(id='a', ctx=Load())

[ilevkivskyi]

The downside however is that exception messages can become very long. So I am not sure we should change this.

[serhiy-storchaka]

I have same doubts.

See also bpo-32888.