Extending rst.tpl fails in current master and 6.0.0a0

[matthew-brett]

Extending rst.tpl with a DictLoader has worked up until the 6.0.0a0 alpha release, but now fails, in 6.0.0a0 as in current master (b31a5af).

import nbconvert
import nbformat
from jinja2 import DictLoader

DL = DictLoader({'rst_plus_stuff.tpl': """\
{%- extends 'rst.tpl' -%}
"""})


class MyExporter(nbconvert.RSTExporter):
    template_file = 'rst_plus_stuff.tpl'

exporter = MyExporter(extra_loaders=[DL])

nb = nbformat.v4.new_notebook()
output, resources = exporter.from_notebook_node(nb)

This succeeds on current stable on pip (5.6.1), but fails for current master, with:

Traceback (most recent call last):
  File "/Users/mb312/tmp/nbconvert_check.py", line 17, in <module>
    output, resources = plots_exporter.from_notebook_node(nb)
  File "/Users/mb312/dev_trees/nbconvert/nbconvert/exporters/templateexporter.py", line 357, in from_notebook_node
    output = self.template.render(nb=nb_copy, resources=resources)
  File "/Users/mb312/.virtualenvs/test3/lib/python3.7/site-packages/jinja2/asyncsupport.py", line 76, in render
    return original_render(self, *args, **kwargs)
  File "/Users/mb312/.virtualenvs/test3/lib/python3.7/site-packages/jinja2/environment.py", line 1008, in render
    return self.environment.handle_exception(exc_info, True)
  File "/Users/mb312/.virtualenvs/test3/lib/python3.7/site-packages/jinja2/environment.py", line 780, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/mb312/.virtualenvs/test3/lib/python3.7/site-packages/jinja2/_compat.py", line 37, in reraise
    raise value.with_traceback(tb)
  File "<template>", line 1, in top-level template code
jinja2.exceptions.TemplateNotFound: rst.tpl

Nbconvert version:

• 6.0.0a0
• Current master (b31a5af)

[MSeal]

Yes, the 6.0.0 alpha has changes to the template patterns. Specifically templates now have directories with jinja (.j2) files. We released the alpha so libraries could start catching these issues early.

In this case 'rst.tpl' becomes 'rst/index.rst.j2' and the DictLoader will go back to working correctly.

[mgeier]

@matthew-brett This is the corresponding fix in nbsphinx, created by @takluyver: spatialaudio/nbsphinx#344.

[matthew-brett]

Thanks - I'll try that fix. I wonder how many of your upstream users are using --pre test envs? Is there any way of softening the backwards compatible break here? Like a DeprecationWarning, and auto-replace of rst.tpl (etc) with the new values?

[maartenbreddels]

I'm thinking about making it backwards compatible, I think that's easy to do. (from mobile phone)

…

On Thu, 2 Jan 2020, 13:26 Matthew Brett, ***@***.***> wrote: Thanks - I'll try that fix. I wonder how many of your upstream users are using --pre test envs? Is there any way of softening the backwards compatible break here? Like a DeprecationWarning, and auto-replace of rst.tpl (etc) with the new values? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1158?email_source=notifications&email_token=AANPEPKE472LVPW4VSXZKHTQ3XMQBA5CNFSM4KBWWSR2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEH6HNZA#issuecomment-570193636>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AANPEPNBB5QR5J26ZRQ2PH3Q3XMQBANCNFSM4KBWWSRQ> .

[MSeal]

We could try to emit a deprecation warning and convert the path when we detect an old-style path. That's probably a good idea for 6.0.0 and let's us wait until 6.1 to drop the older pattern completely.

[maartenbreddels]

#1173 is an alternative way to fix this. I think I should have done this from the start but didn't think it would be that simple to provide backward compatibility.

[matthew-brett]

Excellent - thanks - that is helpful.