Fix bug background workunits were printed in UI

[cattibrie]

Problem

Background workunits were present in UI output. The reason is that background root workunit start to have a parent - main thread root.

Solution

Print workunit label in UI only if it is not under the background root workunit.

[Eric-Arellano]

I recommend using a keyword only arg here, so that callers must use a kwarg.

Suggested change

	def is_background(self, background_root_workunit):
	def is_background(self, *, background_root_workunit):

[stuhood]

This is a required parameter of a particular type, rather than a boolean or optional parameter. So I'm not sure I agree in this case.

But @cattibrie : it would be good to add a docstring for this method.

[cosmicexplorer]

@Eric-Arellano Is it likely to ever accept more than one argument? I think that if not (it seems not), then a positional param seems ok (with a docstring, as above).

[Eric-Arellano]

Eh after typing up the below example, I agree that yes it's fine to not use kwarg only here:

lint_workunit.is_background(compile_workunit)
lint_workunit.is_background(background_root_workunit=compile_workunit)

--

However, in general, want to respond to this:

This is a required parameter of a particular type, rather than a boolean or optional parameter.

True, but there is often (not always) value in enforcing kwarg only for required parameters too. For example, from strutil.py:

def strip_prefix(string: str, prefix: str) -> str: ...

strip_prefix("hello world", "hello")
strip_prefix("hello world", prefix="hello")

You can of course figure it out with the first version, but the second has no ambiguity and I would argue is worth the extra few characters.

[stuhood]

@Eric-Arellano : If the arguments had different types, explicitly naming them would be slightly less valuable though: that's what I was referring to here.

[stuhood]

Thanks!

[stuhood]

This is a required parameter of a particular type, rather than a boolean or optional parameter. So I'm not sure I agree in this case.

But @cattibrie : it would be good to add a docstring for this method.

[wisechengyi]

Thanks @cattibrie !

nit: let's rename ret (to curr_workunit?), since it no longer carries the meaning of the possible return value, unlike the methods above.