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From: Marc 'BlackJack' Rintsch <marc@rintsch.de>
Newsgroups: de.comp.lang.python
Subject: Re: Konstanten in Struct-Form in Python
Date: Wed, 28 Apr 2021 10:04:42 +0000 (UTC)
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On Mon, 22 Feb 2021 07:00:47 +0100, Michael S. wrote:

> Ich habs jetzt so gemacht. Da muss ich in der Anwendung nur die
> CAN-Signals_Klasse instanzieren, dafür halt in der Lib jeweils jedes
> eigene Signal. Aber die Lib wird eh automatisch generiert.
> 
> class C_frequency:
> 	def __init__(self):
> 		self.ID = "10FC80FC"
> 		self.BitOffset = 48 self.BitLength = 8 self.Gain = 1 
self.ValueOffset
> 		= 0 self.Unit = "Hz"
> 		self.Rate = 0.5
> 
> class C_OutputVoltage:
> 	def __init__(self):
> 		self.ID = "25FF1250"
> 		self.BitOffset = 32 self.BitLength = 16 self.Gain = 0.1
> 		self.ValueOffset = 0 self.Unit = "V"
> 		self.Rate = 0.25
> 
> class C_Cable_temp:
> 	def __init__(self):
> 		self.ID = "12FA5AFC"
> 		self.BitOffset = 0 self.BitLength = 8 self.Gain = 1 
self.ValueOffset =
> 		-40 self.Unit = "°C"
> 		self.Rate = 10
> 		
> class CAN_Signals:
> 	def __init__(self):
> 		self.frequency = C_frequency() self.OutputVoltage = 
C_OutputVoltage()
> 		self.Cable_temp = C_Cable_temp()

Verschiedene Klassen mit genau den gleichen Attributen sieht ”falsch” aus.  Da
würde man eher *eine* Klasse schreiben, die die Attribute hat, und davon dann
mehrere Exemplare erstellen.

Mit `collections.namedtuple()` und Namen die sich an PEP8 halten, könnte das
dann so aussehen:

from collections import namedtuple

Signal = namedtuple(
    "Signal", "id bit_offset bit_length gain value_offset unit rate"
)

FREQUENCY = Signal("10FC80FC", 48, 8, 1, 0, "Hz", 0.5)
OUTPUT_VOLTAGE = Signal("25FF1250", 32, 16, 0.1, 0, "V", 0.25)
CABLE_TEMPERATURE = Signal("12FA5AFC", 0, 8, 1, -40, "°C", 10)

Ciao,
	Marc 'BlackJack' Rintsch
-- 
“I don't care WHO you
 are but your not walking
 on the water while I'm fishing”