@Dennis,
Thanks for your example. My structure is very similar. Perhaps I was
reading too much into Luca's below statement regarding declaring
variables.
Regards,
JonRob
Luca wrote...
>Please, note that declaring a variable in the constructor is only a
>convention: in Python you can add a variable to an object of a class
>wherever you want in your code (even if it is very dangerous and
>discouraged).
On Tue, 20 Oct 2015 20:18:35 -0400, Dennis Lee Bieber
<wlfr...@ix.netcom.com> wrote:
>On Tue, 20 Oct 2015 17:33:21 -0400, jon...@mail.python.org declaimed the
>following:
>
>>
>>
>>Hello Luca,
>>
>>I very much appreciated your comments. And I understand the
>>importance of "doing something right" (i.e. convention).
>>
>>This leads me to another question.
>>
>>Because I am interfacing with an I2C sensor I have many register
>>definations to include (30 register addresses and 26 Variables to be
>>red from some of those registers.
>>In your comment you mentioned that convention is to declare variables
>>(and constants?) in the construction (__ini__).
>>I am concerned that the sheer number of varialbe / constants would
>>make it difficult to read.
>>
>
> "Constants" are typically defined at module level, using all capitals
>as a hint to the reader (Python does not have anything that one might
>consider a true constant -- other than the language defined singletons:
>None, and maybe by now True and False).
>
> Register addresses are likely "constants". Not sure about your "26
>Variables"... Do they map directly to registers, or are they extracted as
>fields from the values returned -- that is, a register may have two or more
>"variables"? Do you read ALL registers on command and hold the values (note
>my usage -- values can be held in lists or dictionaries using a single
>"variable") for later retrieval by the user, or only read A register on
>command by the user and return that value.
>
>-=-=-=-=-
># registers for a fictitious motion sensor
>GYROXREG = 0x0010
>GYROYREG = 0x0011
>GYROZREG = 0x0001
>...
>MAGZREG = 0x0100
>
>class SensorA(I2C): #I'm assuming class I2C provides read/write functions
> _registers = [GYROXREG, GYROYREG, GYROZREG,
> ..., MAGZREG]
> def __init__(self, SCLpin, SDApin, slaveAddress):
> self._SCL = SCLpin
> self._SDA = SDApin
> self._addr = slaveAddress
> self.update() #initial load of values
> def update(self):
> #basically a loop over all addresses
> #I'm not going to try to pseudo code the full I2C protocol
> self.values = {} #yes, a dictionary
> for reg in _registers:
> aValue = self.read(self._SCL, self._SDA, self._addr,
> reg)
> #inherited from I2C class
> self.values[reg] = aValue
>....
>
>mySensor = SensorA(21, 22, 0x6)
>
>while True
> mySensor.update()
> print ("Gyro X: %s, Y: %s, Z: %s"
> % (mySensor.values[GYROXREG],
> mySensor.values[GYROYREG],
> mySensor.values[GYROZREG]))
> time.sleep(1.0)
>
>
>
>
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