pn.template attribute not found when lazy loading panel about panel

[Hoxbro]

What happens if you, do this?

from lazy_loader import extension, pn

extension()

pn.template.FastListTemplate(title="Hello", main=["world"]).servable()

[Hoxbro]

Lazy loading is tricky. Maybe try to take a look at how polars does it here: https://github.com/pola-rs/polars/blob/main/py-polars/polars/dependencies.py

[MarcSkovMadsen]

The problem is that template is not imported in __init__.py :-) I'm working on a PR. But I need to figure out how to add test first.

[MarcSkovMadsen]

from lazy_loader import extension, pn

extension()

pn.template.FastListTemplate(title="Hello", main=["world"]).servable()

The problem is still there.

[MarcSkovMadsen]

This pytest will replicate issue

import importlib.util
import sys

def lazy_import(name):
    spec = importlib.util.find_spec(name)
    loader = importlib.util.LazyLoader(spec.loader)
    spec.loader = loader
    module = importlib.util.module_from_spec(spec)
    sys.modules[name] = module
    loader.exec_module(module)
    return module

def test_pn_template():
    lazy_import("panel")
    import panel as pn
    assert hasattr(pn, "template")

[MarcSkovMadsen]

Additional Context: Also issue for static analysis

The cause is that template is not imported in __init__. This also means that static analysis cannot discover it and an error is highlighted like below.

[MarcSkovMadsen]

Thanks @philippjfr

Unfortunately I start seeing more of these issues. If I lazy import holoviews then it starts failing because of below.

Do you think these are issues that can and should be solved? Or are they not issues and I should not try to use lazy loading?

I would really like to lazy load panel and holoviews as they add 3s to import time! And that is a lot of import time in a cli tool or if users are constantly running script that imports these packages.

I think these issue would have been identified if we where running mypy on the code base.