v9.6.0 no longer supports using `_copier_conf` in questions

[TimMonko]

Describe the problem

This morning, a user of napari-plugin-template reported an issue where _copier_conf is undefined when trying to copy our template.

Our template uses _copier_conf.dst_path | basename for a default value. This works on 9.5.0 but not 9.6.0. I'm not seeing this as an intentional change in the release notes.

I can put debugging in the _message_before_copy and see that _copier_conf is defined, but it does not seem to be defined in the questions:

_message_before_copy: |
    ...
    DEBUG INFO:
    _defined: {{ 'defined' if _copier_conf is defined  }}
    _copier_conf: {{ _copier_conf.keys() | list if _copier_conf is defined else 'undefined' }}
    _basename: {{ _copier_conf.dst_path | basename }}

plugin_name:
    default: "{{ _copier_conf.dst_path | basename if _copier_conf is defined else 'napari-plugin' }}"
    help: The name of your plugin, used to name the package and repository
    type: str
    validator: >-
        {% if not (plugin_name | regex_search('^[a-z][a-z0-9\-]+$')) %}
        plugin_name must be lowercase, no spaces, and may contain hyphens.
        {% endif %}

Template

https://github.com/napari/napari-plugin-template

To Reproduce

copier copy --trust https://github.com/napari/napari-plugin-template plugin-test

Logs

copier copy --trust https://github.com/napari/napari-plugin-template plugin-test
No git tags found in template; using HEAD as ref

Welcome to the napari plugin template!
This template will help you create a new napari plugin with all the necessary structure of a Python package.

For more detailed information about each prompt, see:
https://github.com/napari/napari-plugin-template/blob/main/PROMPTS.md

'_copier_conf' is undefined

Expected behavior

_copier_conf is defined in the question portion of the template

Screenshots/screencasts/logs

No response

Operating system

Windows

Operating system distribution and version

Windows 11

Copier version

9.6.0

Python version

3.12

Installation method

pip+pypi

Additional context

No response

[sisp]

Ouch ... Yes, prior to v9.5.0, we only exposed answers when rendering questions. #1880 added keys like _copier_conf to that rendering context but only as a side effect of the implementation without explicit intent. As #1880 introduced a regression (#1977), we revised (and partially reverted) the changes of #1880 in #1993 which restored the pre-v9.5.0 (or rather pre-#1880) rendering context for questions. This really is an unfortunate situation. Are you able to work without _copier_conf in the questions context?

[TimMonko]

Thank you! So, just to clarify, this _copier_conf only happened to be available in the one version (9.5.0) for questions specifically? It didn't seem to be too out of line when I made the change, considering _copier_conf is available in other parts of copier.yml

So this revert in 9.6.0 is intentional? We can definitely accommodate, I was just using it as a nice way to add some helpful info for the user in the template (our template is intended to be understood by beginners to coding)

[sisp]

Thank you! So, just to clarify, this _copier_conf only happened to be available in the one version (9.5.0) for questions specifically?

Yes, that's right.

It didn't seem to be too out of line when I made the change, considering _copier_conf is available in other parts of copier.yml

You're right, and essentially this feature has been requested before in #1050.

So this revert in 9.6.0 is intentional?

In a way, yes, but rather from the angle of fixing the regression introduced in #1880 and restoring the original behavior, as extending the rendering context for questions wasn't the intent of that PR.

We can definitely accommodate, I was just using it as a nice way to add some helpful info for the user in the template (our template is intended to be understood by beginners to coding)

This is an unfortunate situation that I'd like to resolve as smoothly as possible. As essentially this feature has been requested and approved in #1050, I've decided to work on a solution that restores compatibility with v9.5.0 and your use case. This is the PR: #2023

Sorry for the inconvenience! 🙇

[TimMonko]

@sisp thank you for working so swiftly to re-implement this! This is a greatly beneficial feature for us -- even if I accidentally implemented at the 'wrong' time. Much appreciated!

[francesco086]

@sisp After almost one month still no new release 9.6.1? 😢

I would like to mention that this is a documented user feature (https://copier.readthedocs.io/en/stable/creating/#_copier_conf) and it is broken.

Also, it works on version 9.5, but not on version 9.4.

Would it be useful to add a test to verify that this feature works?