Simplify determining whether script is executed as application

[philippjfr]

It is sometimes useful to write a Panel application in a script and also do some things that have side-effects such as setting pn.config options. If you also want this module to be importable without any side-effects you currently have to write something like this:

if __name__.startswith('bokeh_app_'):
    ...

This is ugly and weird since it looks like magic and it's a Panel app not a bokeh app. Therefore I think we should provide a helper that makes it easy to determine if we are in a panel serve execution context. Therefore I propose introducing pn.state.served:

if pn.state.served:
    ...

Ping @MarcSkovMadsen since you are the main person I've seen use this pattern. I don't love the in_app naming so am very eager to hear suggestions.

[codecov]

Codecov Report

Merging #4252 (6c919f1) into main (7419356) will decrease coverage by 0.00%.
The diff coverage is 79.16%.

@@            Coverage Diff             @@
##             main    #4252      +/-   ##
==========================================
- Coverage   82.70%   82.69%   -0.01%     
==========================================
  Files         237      237              
  Lines       34276    34283       +7     
==========================================
+ Hits        28347    28350       +3     
- Misses       5929     5933       +4     

Flag	Coverage Δ
ui-tests	37.94% <79.16%> (-0.01%)	⬇️
unitexamples-tests	73.87% <79.16%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
panel/io/state.py	70.19% <58.33%> (+0.14%)	⬆️
panel/tests/pane/test_alert.py	65.62% <100.00%> (ø)
panel/tests/pane/test_echart.py	33.33% <100.00%> (ø)
...nel/tests/template/fast/test_fast_grid_template.py	52.72% <100.00%> (+0.87%)	⬆️
...nel/tests/template/fast/test_fast_list_template.py	79.31% <100.00%> (ø)
panel/tests/template/test_manual.py	61.61% <100.00%> (ø)
panel/tests/template/test_vanilla_manual.py	15.21% <100.00%> (ø)
panel/tests/widgets/test_speech_to_text.py	62.88% <100.00%> (ø)
panel/tests/widgets/test_terminal.py	58.87% <100.00%> (ø)
panel/tests/widgets/test_text_to_speech.py	77.50% <100.00%> (ø)
... and 4 more

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[hoxbro]

I also use it a lot and would prefer this method over it. 👍

For name suggestions: app_running, running_app, serving_app

[MarcSkovMadsen]

What about .served, .is_served or .in_served_context?

[philippjfr]

Thanks @MarcSkovMadsen, decided pn.state.served was short and clear.

[maximlt]

What about .served, .is_served or .in_served_context?

I had in mind exactly these alternatives :) Happy with .served !