allow combining `select*` and `reject*` filters with boolean logic

[flying-sheep]

Sequentially rejecting/selecting properties of list items isn’t powerful enough.

E.g. I’d like to do the following in a Sphinx autosummary template:

{% set shown_meths = [
   m for m in methods
   if m in abstract_methods or m not in inherited_methods
] %}
{% if shown_meths  %}
.. rubric:: Methods

{% for item in shown_meths %}
.. automethod:: {{ item }}
{%- endfor %}
{% endif %}

but that seems unnecessarily complex, and impossible if I care about not changing the order:

{% set regular_shown = methods | reject("in", inherited_methods) %}
{% set abstract_shown = abstract_methods | reject("in", abstract_shown) %}
{% set shuffled_shown_methods = regular_shown + abstract_shown %}

[davidism]

I'm not clear what you're asking for, could you provide a clearer example of what you want to use? Why is what you've shown (a normal comprehension with a condition) unnecessarily complex? Where is the order being changed?

These filters are already extremely complex. I'd prefer you writing a filter to do exactly what you want, rather than try to add more complexity.

[flying-sheep]

Why is what you've shown (a normal comprehension with a condition) unnecessarily complex?

The comprehension is my example of how easy it should be, but according to the docs, comprehensions aren’t allowed expressions in templates: https://jinja.palletsprojects.com/en/stable/templates/#expressions

If I can use list comprehensions in templates, I’m happy, but the docs need to be updated.

If I can’t, and you don’t want to add comprehension support, I’d like to have something like

{% set shown_meths = methods | select(lambda m: m in abstract_methods or m not in inherited_methods) %}

(lambda is of course placeholder syntax, you’d decide how that looks)

[davidism]

for expressions take an optional if expression, and have a loop variable for introspection. Something like this should work for you (untested):

{% for m in methods if m in abstract_methods or m not in inherited_methods %}
{% if loop.first %}
.. rubric:: Methods

{% endif %}
.. automethod:: {{ m }}
{% endfor %}

[flying-sheep]

beautiful, thank you!

Would be even better if this syntax was available as generators that can be piped into filters, but this should be powerful enough!