Add TprTrigger default timing mode

[slactjohnson]

Description

Make LCLS2 the default timing mode for the TprTrigger class.

Motivation and Context

closes #1241

How Has This Been Tested?

Tested interactively.

Where Has This Been Documented?

This PR.

Screenshots (if appropriate):

Pre-merge checklist

• [x] Code works interactively
• [x] Code contains descriptive docstrings, including context and API
• [x] New/changed functions and methods are covered in the test suite where possible
• [x] Test suite passes locally
• [x] Test suite passes on GitHub Actions
• [x] Ran docs/pre-release-notes.sh and created a pre-release documentation page
• [x] Pre-release docs include context, functional descriptions, and contributors as appropriate

[slactjohnson]

Hmm, looks like Happi may have similar trouble with this enum:

[tangkong]

Yeah happi wouldn't know to interpret "TimingMode.LCLS1" as an enum it needs to import, so I guess we definitely need some type of string parsing here. Maybe something like:

def __init__(self, prefix, *, channel, name, timing_mode: TimingMode | str =TimingMode.LCLS2, **kwargs):
    if isinstance(timing_mode, str):
        try:
            timing_mode = getattr(TimingMode, timing_mode)
        except AttributeError as ex:
            raise ValueError(
                'Provided timing mode not recognized, please choose from: '
                f'{[mode.name for mode in TimingMode]}'
            )
    ...     

[ZLLentz]

Enums have built-in tools for consuming strings and returning enum values:

In [1]: from pcdsdevices.tpr import TimingMode

In [2]: TimingMode["LCLS1"]
Out[2]: <TimingMode.LCLS1: 1>

In [3]: TimingMode["LCLS2"]
Out[3]: <TimingMode.LCLS2: 2>

In [4]: TimingMode(1)
Out[4]: <TimingMode.LCLS1: 1>

In [5]: TimingMode(2)
Out[5]: <TimingMode.LCLS2: 2>

This makes it very easy to convert str and int inputs into the enum members.

These each raise a ValueError if the input isn't valid.

[ZLLentz]

One more mini-tip: the call/int version also accepts the enums, reducing the number of cases to check:

In [6]: TimingMode(TimingMode.LCLS1)
Out[6]: <TimingMode.LCLS1: 1>

In [7]: TimingMode(TimingMode.LCLS2)
Out[7]: <TimingMode.LCLS2: 2>

[slactjohnson]

My recent commit takes advantage of the tricks @ZLLentz mentioned, and now makes specifying timing_mode much more flexible while still erroring out on an invalid setting.

I kept running into errors with the type hints in Robert's example and I wasn't type hint savvy enough to figure it out.

[tangkong]

Ah that's my bad, I kinda just pseudocoded and didn't actually run the code myself. You probably have to use the explicit typing.Union

from typing import Union

...

def __init__(self, prefix, *, channel, name, timing_mode: Union[TimingMode, str]  = TimingMode.LCLS2, **kwargs):

Of course you could also leave it out as you have.

[slactjohnson]

I think I'm happy enough with this as is.