Check fraction range; add post-constructor access to actuation_range and pulse widths.

[dhalbert]

The latest Crickit library API doesn't provide explicit constructors for servos, so actuation_range and min_pulse and max_pulse need to be settable after construction.

I just made actuation_range a visible attribute (it was previously hidden).

For pulse widths I added a function to set both, instead of property access. They are not currently saved, but just used to compute duty cycle values Setting one pulse width at a time via a property would require extra code for computation or saving the values, and usually one wants to set both anyway. If you disagree I can make it property access.

[tannewt]

Two minor things and then good to go! Thanks!

[tannewt]

I like set_pulse_width_range more.

[tannewt]

I dropped the s too.

[dhalbert]

Do you think it shouldn't have default values for the args, so you have to give both? I'm vacillating on this.

[dhalbert]

Having default values was what motivated the original choice of name.

[tannewt]

I like defaults because it allows one to use the name in the call. aka servo.set_pulse_width_range(min_pulse=700, max_pulse=2000) You could even force it with: def set_pulse_widths(self, *, min_pulse=750, max_pulse=2250):

[tannewt]

Add a triple quoted doc string here so it is included in RTD.

[dhalbert]

Since the Servo class has a docstring, it's already in RTD. See https://circuitpython.readthedocs.io/projects/motor/en/latest/api.html#adafruit_motor.servo.Servo.

Alphabetically ContinuousServo came first -- maybe that was confusing?

[tannewt]

It does for the argument but not the object attribute (like angle).

[dhalbert]

I'm confused. Here is the angle doc: https://circuitpython.readthedocs.io/projects/motor/en/latest/api.html#adafruit_motor.servo.Servo.angle

[tannewt]

Right. actuation_angle should look like angle too.

[dhalbert]

It was impressively difficult to do this. I can add a docstring after the self.actuation_range = actuation_range, but then it shows up in the RTD as "actuation_range = None". After some Googling, found a hack to add to conf.py to fix it.

The other alternative is to document actuation_range as an :ivar, but then it shows up with the parameters. The current new way looks better.

[dhalbert]

In motor.py, I can remember the throttle value as self._throttle and just return it, instead of this right now. The code below is more faithful to the underlying pwm, but it's a lot of code that we could just get rid of. What do you think?

    @property
    def throttle(self):
        """How much power is being delivered to the motor. Values range from ``-1.0`` (full
           throttle reverse) to ``1.0`` (full throttle forwards.) ``0`` will stop the motor from
           spinning and ``None`` will let the motor spin freely."""
        if self._positive.duty_cycle == 0 and self._negative.duty_cycle == 0:
            return None
        if self._positive.duty_cycle == 0xffff and self._negative.duty_cycle == 0xffff:
            return float(0)
        if self._positive.duty_cycle > 0 and self._negative.duty_cycle > 0:
            raise RuntimeError("PWMs in invalid state")
        value = max(self._positive.duty_cycle, self._negative.duty_cycle) / 0xffff
        if self._negative.duty_cycle > 0:
            return -1 * value
        return value`

That will also accidentally fix #11.

[tannewt]

@dhalbert I'm ok removing it.

[tannewt]

Thanks!