remove need for re module

[jepler]

The goal of the regular expression is to test that the letters in the byteorder string are only from the set R, G, B, W, and P. This strip() formulation achieves the same goal.

[ladyada]

yes please!

[ladyada]

good find!

[caternuson]

This will help with #8

[ladyada]

@caternuson is it fixed now?

[caternuson]

@ladyada yep. seems like it. mpy-cross'd it and tried it out.
thanks @jepler

FAIL CASE

Adafruit CircuitPython 4.1.2 on 2019-12-18; Adafruit Gemma M0 with samd21e18
>>> import board
>>> import neopixel
>>> pixels = neopixel.NeoPixel(board.D1, 8, pixel_order="OMG_CUTE_KITTEH")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "neopixel.py", line 117, in __init__
  File "adafruit_pypixelbuf.py", line 55, in __init__
  File "adafruit_pypixelbuf.py", line 123, in parse_byteorder
ValueError: Invalid Byteorder string
>>> 

SUCCESS CASE

Adafruit CircuitPython 4.1.2 on 2019-12-18; Adafruit Gemma M0 with samd21e18
>>> import board
>>> import neopixel
>>> pixels = neopixel.NeoPixel(board.D1, 8, pixel_order="GRBW")
>>> pixels.fill(0xADAF00)
>>> pixels.brightness = 0.2
>>> pixels[2] = 0xff0000
>>> pixels[4] = 0x00ff00
>>> pixels[6] = 0x0000ff
>>> 

[dhalbert]

This is clever! I hadn't seen strip used in this way.

[dhalbert]

@caternuson did I merge this prematurely? I'm confused by the convo above.

[caternuson]

@dhalbert nah, i don't think so. approved and tested. should be fine.

[tannewt]

This doesn't validate internal characters because strip only trims the ends of a string. https://docs.python.org/3.8/library/stdtypes.html#str.strip

So, it will fail for "RXB".

You could use a set comparison instead.

[caternuson]

Seems to work? Idea is to have nothing left after the strip. Otherwise, there's an unexpected character.

>>> "RGB".strip("RGBWP") != ""
False
>>> "GRB".strip("RGBWP") != ""
False
>>> "GRBW".strip("RGBWP") != ""
False
>>> "RGBW".strip("RGBWP") != ""
False
>>> "RXB".strip("RGBWP") != ""
True

[caternuson]

But it's not robust the other way - if you spam it with acceptable characters:

>>> "RRGBGRGBRWWRGBRPPGBR".strip("RGBWP") != ""
False

[ladyada]

cater, neither was the re version tho :)

[dhalbert]

Doc: The outermost leading and trailing chars argument values are stripped from the string. Characters are removed from the leading end until reaching a string character that is not contained in the set of characters in chars. A similar action takes place on the trailing end.

So basically it's doing a set membership.

[tannewt]

Ah, ok. I'm wrong. :-) Carry on.