[Docutils-develop] [docutils:bugs] Re: #448 `Element.index()` returns incorrect results for `Text` nodes

[Günter M. <mi...@us...>]

> This captures the bug behind `branches/index-bug`. I'm not sure the
> general case of `index` is worth fixing, as `Text` nodes are a special
> case, but it might have implications for `Node.findall`.

I am not sure whether it is an error with `nodes.Element.index()`.
[r5594] moves the proposed fix into a place in `node.traverse()` that is
now part of `node.findall()`.


`nodes.Text` inherits from `Node` and `str`. 
From `str` it inherits: `nodes.Text("tx") == nodes.Text("tx")`.
Maybe it should rather compare like `Element` instances
`nodes.Element('', nodes.Text('tx')) != nodes.Element('', nodes.Text('tx'))`
But this may break use cases. :(

Element.index() behaves like list.index(): 

    ta2 = 'ta'
    ['ta', 'tü', ta2, 'ta'].index(ta2) == 2
    
There is no documentation saying it should behave differently.

Node.findall() uses Element.index() to determine the index of a node in its
parents list of children (i.e. relative to its siblings). This fails, e.g.,
for the second "hallo" in a paragraph like "hallo *du*\ hallo *ich*".


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** [bugs:#448] `Element.index()` returns incorrect results for `Text` nodes**

**Status:** open
**Created:** Tue May 24, 2022 11:38 PM UTC by Adam  Turner
**Last Updated:** Tue May 24, 2022 11:38 PM UTC
**Owner:** nobody


This captures the bug behind `branches/index-bug`. I'm not sure the general case of `index` is worth fixing, as `Text` nodes are a special case, but it might have implications for `Node.findall`.


```python
>>> from docutils import nodes
>>> tree = nodes.Element()
>>> blah1 = nodes.Text("blah")
>>> blah2 = nodes.Text("blah")
>>> tree += [nodes.Text("node1"), blah1, blah2]
>>> print(tree.pformat())
<Element>
    node1
    blah
    blah

>>> tree[tree.index(blah2)] is blah2
False
>>> tree[tree.index(blah2)] is blah1
True
```

A


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