Provide Default Values for .add_metric(unit=) and .add_metric(value=)

Is your feature request related to a problem? Please describe.
Approximately 2/3rd of my metrics are just posting singletons to a given metric, where unit=MetricUnit.Count and value=1. This results in repeating myself frequently.

Describe the solution you'd like
Provide default values for unit and value, such that I can .add_metric() by providing just a name= value.

Describe alternatives you've considered
A wrapper function that provides the same functionality might also be useful, but this seems like overkill compared to providing default values.

Additional context
This is the first time I've opened a Feature Request on a public repo... did I provide enough detail? :-)

[boring-cyborg]

Thanks for opening your first issue here! We'll come back to you as soon as we can.

[heitorlessa]

Hey @nsandar That's a great idea for unit, not for value as this can trip people both when reading the code later and on testing. As for the details, they are super crispy, so thank you for a high quality request ;)

This could be similar to how we've done default dimensions.

I'm currently out of bandwidth to implement it until other higher priorities enhancements are done - I can however provide guidance to contribute it if you could help.

We'd need a couple of things to implement this:

• A new public method set_default_metric_unit(self, value: str): ...
• A new public method clear_default_metric_unit
• Update clear_metrics method to include set_default_metric_unit with previously used value. This is used by customers in unit testing so their defaults are always re-added and metrics cleared for each test

[florian42]

Hey, @heitorlessa, I would like to contribute a pr for this.
But I have trouble with persisting the default metric unit between instances.
My idea is to make the changes in metrics.py, mainly by adding the following instance variable _default_metric_unit: Optional[Union[MetricUnit, str]] = None and then overriding the add_metric method from the parent class, for example:

# metrics.py

def add_metric(self, name: str, value: float, unit: Optional[Union[MetricUnit, str]] = None) -> None:
    if unit is None and self.default_metric_unit is None:
        raise MetricUnitError("specify a unit")
    super().add_metric(name=name, value=value, unit=unit)

Note that this also means that unit and value have switched positions - maybe that is even a breaking change (in case I rely on positional arguments)?

[heitorlessa]

Hey @florian42 thanks a lot for the help. We're going through a big feature now (Event Handler route splitting) and I can have a look at this with you later this week.

On the positioning, yep, a mistake I've made early was not enforcing kwarg only *, name: str.... Need to think more carefully about this.