[New-bugs-announce] [issue16806] col_offset is -1 for multiline string expressions resembling docstrings

[Carsten Klein]

New submission from Carsten Klein:

Given an input module such as

class klass(object):
    """multi line comment
    continued on this line
    """

    """single line comment"""

    """
    Another multi
    line
    comment"""


and implementing a custom ast.NodeVisitor such as


import as

class CustomVisitor(ast.NodeVisitor):

    def visit_ClassDef(self, node):

        for childNode in node.body:

            self.visit(childNode)

    def visit_Expr(self, node):

        print(node.col_offset)
        print(node.value.col_offset)


and feeding it the compiled ast from the module above


f = open('./module.py')
source = f.read()
node = ast.parse(source, mode = 'exec')
visitor = CustomVisitor()
visitor.visit(node)


should yield -1/-1 for the docstring that is the first
child node expression of the classdef body.

it will, however, yield the correct col_offset of 4/4 for
the single line docstring following the first one.

the multi line docstring following that will again
yield a -1/-1 col_offset.



It believe that this behaviour is not correct and instead
the col_offset should be 4 for both the expression node
and its str value.

----------
components: Interpreter Core
messages: 178444
nosy: carsten.klein at axn-software.de
priority: normal
severity: normal
status: open
title: col_offset is -1 for multiline string expressions resembling docstrings
type: enhancement
versions: Python 3.4

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue16806>
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