Exceptions in micro python

[kjm]

try:
    1/0
except Exception as e:
    sys.print_exception(e)

produces

division by zero
Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
ZeroDivisionError: division by zero

But I'd like to be able to store the error and the line number that produced it in a file instead of printing it. Storing the error is easy enough

with open('ErrorFile', 'wb') as f: f.write(str(e))

but I can't figure out a way to access & store the line number. Anyone out there in the pycom firmament mastered this trick?

[ronald gevern]

@kjm said in Exceptions in micro python:

ZeroDivisionError: division by zero

The super class of ZeroDivisionError is ArithmeticError. This exception raised when the second argument of a division or modulo operation is zero. In Mathematics, when a number is divided by a zero, the result is an infinite number. It is impossible to write an Infinite number physically. Python interpreter throws “ZeroDivisionError: division by zero” error if the result is infinite number. While implementing any program logic and there is division operation make sure always handle ArithmeticError or ZeroDivisionError so that program will not terminate.

try:
    z = x / y
except ZeroDivisionError:
    z = 0

Or check before you do the division:

if y == 0:
    z = 0
else:
    z = x / y

The latter can be reduced to:

z = 0 if y == 0 else (x / y)

[kjm]

Thnx again Robert, for anyone else with a similar requirement I ended up with....

except Exception as e:
  import sys; from uio import StringIO
  s=StringIO(); sys.print_exception(e, s)  
  s=s.getvalue(); s=s.split('\n')                                                                   
  line=s[1].split(','); line=line[1]; error=s[2]; err=error+line; print(err)
  with open ('error.log', 'a') as f: f.write(err) 

[robert-hh]

@kjm follow these steps. I just executed at the prompt:

>>> from uio import StringIO
>>> import sys
>>> s = StringIO()
>>> try:
...     1/0
... except Exception as e:
...     sys.print_exception(e, s)
...
>>> x=s.getvalue()
>>> x
'Traceback (most recent call last):\n  File "<stdin>", line 2, in <module>\nZeroDivisionError: divis
ion by zero\n'
>>>

[kjm]

Hey Robert I need to filter out the double inverted commas before I store in the error.log file I tried

err=sys.print_exception(e)
err=err.replace('"',"")

but I got AttributeError: 'NoneType' object has no attribute 'replace'

[kjm]

Ah, perfect! Tanks muchly.

[robert-hh]

@kjm You could do as follows:

try:
    1/0
except Exception as e:
    import sys
    with open("error.log", "a") as f:
        sys.print_exception(e, f)

This works for me,
Pycom MicroPython 1.20.0.rc6 [8d824a0-dirty] on 2019-01-28; FiPy with ESP32

[kjm]

Anybody out there manage to store traceback line numbers to a file on the gpy?

[robert-hh]

@kjm I'll have to check that tonight. I have no device here at the moment.

[kjm]

not on the gpy you can't!

[robert-hh]

@eric73 just tried thst on windows MP. If you open a file beforehand, you can use that file handle as second argument to sys.print_exception.

[Eric73]

@kjm in documentation function prototype is

sys.print_exception(exc, file=sys.stdout)

Have you try to open a file and use it with sys.print_exception to see what happened inside the file?
(Sorry i have no module to test)