Ergonomic, hermetic, user-friendly software build system for Python, Go, Java, Kotlin, Protobuf, Scala, Shell. Pants lets you fearlessly scale up your codebase!

Pants

call-by-name question:
How would one retrieve a subsystem? Currently you can `await Get(Subsystem)` . There is no equivalent i call-by-name. Should there be?
E.g `await Subsystem.get_subsystem() # shed my bikes` .

I have used get `Get(Subsystem)` form inside e.g rule helpers to remove clutter from the top-level rule signature if only some code paths use said subsystem.

Example imitating real code:

```@rule
def the_rule(a: A, b: B):
    if use_system:
        return await _helper_that_does_use_system(a)
    else:
        return await _helper_that_doesnt(a, b)

async def _helper_that_does_use_system(a: A) -> ...:
    sub = await Get(Subsystem)
    ...```

It's not really an answer, but could that `_helper` be a `@rule`  that itself takes a `Subsystem` arg? I guess that only works if it's truly a separate function, though

Oh, coincidentally I just now discovered `pants.option.subsystem._construct_subsystem` <https://github.com/pantsbuild/pants/blob/a2acb196216ce5cabe45ee6a039eb5d5f530777a/src/python/pants/option/subsystem.py#L318-L320> when reviewing <https://github.com/pantsbuild/pants/pull/21258>