slsDetectorPackage/python/sphinx/error-handling.rst

Error handling

Check input in Python

As far as possible we try to check the input on the Python side before calling the slsDeteectorsSoftware. Errors should not pass silently but raise an exception

#Trimbit range for Eiger is 0-63
detector.trimbits = 98
(...)
ValueError: Trimbit setting 98 is  outside of range:0-63

Errors in slsDetectorsSoftware

The slsDetectorsSoftware uses a mask to record errors from the different detectors. If an error is found we raise a RuntimeError at the end of the call using the error message from slsDetectorsSoftware

Implement this for all functions

detector.settings = 'bananas'
(...)
RuntimeError: Detector 0:
Could not set settings.
Detector 1:
Could not set settings.
Detector 2:
Could not set settings.

Using decorators

Using decorators we can reset the error mask before the command and then check it after the command

#add decorator to check the error mask
@error_handling
def some_function():
    a = 1+1
    return a

Communication with the detector is usually the biggest overhead so this does not impact performance.

%timeit d.exposure_time
>> 1.52 ms ± 5.42 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)

%timeit d.decorated_exposure_time
>> 1.53 ms ± 3.18 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)