Extending NMEA-Types #146

chrissli · 2022-07-22T08:21:17Z

chrissli
Jul 22, 2022

I'm sorry if this is a dumb question, but I fairly new to python.
I have a NMEA-ish string, I guess it would be a proprietary sentence, maybe.
However, what is the appropriate way to implement this here without editing the existent code?
I tried the following, but I wouldn't work:

import pynmea2
from pynmea2 import nmea

class pynmea2_XBO(pynmea2.talker.TalkerSentence):
fields = (
('Temperature(outside)','temperature'),
('Pressure','pressure'),
('Humidity','humidity')
)

pynmea2.XBO = pynmea2_XBO

line = 'PXBO,23.3,992.2,56' # this is what the my strings are like

nmeaObj = pynmea2.parse(line)

print(nmeaObj)
#> $PXBO,23.3,992.2,56*18
print(vars(nmeaObj))
#> {'manufacturer': 'XBO', 'data': ['', '23.3', '992.2', '56']}

Where the "fields" attribute exists but is empty.
Can you please provide an example how to inject own NMEA-sentences without touching your code?
Also, sorry for poorly formated code, I just can't get this textbox working

Answered by Knio

Jul 27, 2022

You were very close.

you need to inherit from ProprietarySentence
your class name must be XBO, this is what matches on the PXBO string
you need an extra unused field at the beginning - this is because some proprietary sentences have an extra comma and some don't
no need to assign pynmea2.XBO (unless you want to), just defining the class is enough
vars() will not show the fields, since they're dynamically accessed, but repr() will

import pynmea2

class XBO(pynmea2.nmea.ProprietarySentence):
    fields = (
        ("Blank", "_blank"),
        ('Temperature(outside)','temperature'),
        ('Pressure','pressure'),
        ('Humidity','humidity')
    )

line = 'PXBO,23.3,992.2,56'
nmeaObj = …

View full answer

Knio · 2022-07-27T05:06:47Z

Knio
Jul 27, 2022
Maintainer

You were very close.

you need to inherit from ProprietarySentence
your class name must be XBO, this is what matches on the PXBO string
you need an extra unused field at the beginning - this is because some proprietary sentences have an extra comma and some don't
no need to assign pynmea2.XBO (unless you want to), just defining the class is enough
vars() will not show the fields, since they're dynamically accessed, but repr() will

import pynmea2

class XBO(pynmea2.nmea.ProprietarySentence):
    fields = (
        ("Blank", "_blank"),
        ('Temperature(outside)','temperature'),
        ('Pressure','pressure'),
        ('Humidity','humidity')
    )

line = 'PXBO,23.3,992.2,56'
nmeaObj = pynmea2.parse(line)

print(f'obj: {nmeaObj}')
print(f'type: {type(nmeaObj)}')
print(f'vars: {vars(nmeaObj)}')
print(f'repr: {repr(nmeaObj)}')
print(f'temperature: {nmeaObj.temperature}')
print(f'pressure: {nmeaObj.pressure}')
print(f'humidity: {nmeaObj.humidity}')

output:

obj: $PXBO,23.3,992.2,56*18
type: <class '__main__.XBO'>
vars: {'manufacturer': 'XBO', 'data': ['', '23.3', '992.2', '56']}
repr: <XBO(_blank='', temperature='23.3', pressure='992.2', humidity='56')>
temperature: 23.3
pressure: 992.2
humidity: 56

2 replies

chrissli Aug 2, 2022
Author

Sorry, took me a bit to test it out. That works like a charm, thank you!

The reason why I assigned

pynmea2.XBO = pynmea2_XBO

was, that I already got a class "XBO", so I had my hopes up that I can just assign the "real" class to the XBO attribute.
But that's not big of a deal, I'm just gonna adjust to that.
Again, thank you very much for your help.

chrissli Aug 2, 2022
Author

Wait no, I'm just dumb:

class XBOWhatever(pynmea2.nmea.ProprietarySentence):
    fields = (
        ("Blank", "_blank"),
        ('Temperature(outside)','temperature'),
        ('Pressure','pressure'),
        ('Humidity','humidity')
    )
pynmea2.ProprietarySentence.sentence_types['XBO'] = XBOWhatever

Will work without touching my existing class.

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Extending NMEA-Types #146

chrissli Jul 22, 2022

I'm sorry if this is a dumb question, but I fairly new to python. I have a NMEA-ish string, I guess it would be a proprietary sentence, maybe. However, what is the appropriate way to implement this here without editing the existent code? I tried the following, but I wouldn't work:

print(nmeaObj) #> $PXBO,23.3,992.2,56*18 print(vars(nmeaObj)) #> {'manufacturer': 'XBO', 'data': ['', '23.3', '992.2', '56']}

Replies: 1 comment · 2 replies

Knio Jul 27, 2022 Maintainer

chrissli Aug 2, 2022 Author

chrissli Aug 2, 2022 Author

chrissli
Jul 22, 2022

I'm sorry if this is a dumb question, but I fairly new to python.
I have a NMEA-ish string, I guess it would be a proprietary sentence, maybe.
However, what is the appropriate way to implement this here without editing the existent code?
I tried the following, but I wouldn't work:

print(nmeaObj)
#> $PXBO,23.3,992.2,56*18
print(vars(nmeaObj))
#> {'manufacturer': 'XBO', 'data': ['', '23.3', '992.2', '56']}

Replies: 1 comment 2 replies

Knio
Jul 27, 2022
Maintainer

chrissli Aug 2, 2022
Author

chrissli Aug 2, 2022
Author